U.S. patent application number 14/739920 was filed with the patent office on 2015-11-05 for methods and devices for delivering glp-1 and uses thereof.
This patent application is currently assigned to VALERITAS, INC.. The applicant listed for this patent is Valeritas, Inc.. Invention is credited to Robert R. Gonnelli.
Application Number | 20150314065 14/739920 |
Document ID | / |
Family ID | 35207451 |
Filed Date | 2015-11-05 |
United States Patent
Application |
20150314065 |
Kind Code |
A1 |
Gonnelli; Robert R. |
November 5, 2015 |
Methods and Devices for Delivering GLP-1 and Uses Thereof
Abstract
The invention provides various devices for delivering
Glucagon-Like Peptide-1 (7-36), in various infusion patterns and
rates, to optimally stimulate carbohydrate metabolism, to inhibit
gastropancreatic secretion and gastric motility, and to treat
various disease conditions (including diabete) as described in the
instant specification. The devices and methods of the invention
provide various ways to deliver doses (escalating, constant, on
demand, etc.) of GLP-1 in response to different patient need.
Inventors: |
Gonnelli; Robert R.;
(Mahwah, NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Valeritas, Inc. |
Bridgewater |
NJ |
US |
|
|
Assignee: |
VALERITAS, INC.
Bridgewater
NJ
|
Family ID: |
35207451 |
Appl. No.: |
14/739920 |
Filed: |
June 15, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11175990 |
Jul 5, 2005 |
9089636 |
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14739920 |
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60585330 |
Jul 2, 2004 |
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Current U.S.
Class: |
604/500 ;
604/151 |
Current CPC
Class: |
A61M 2005/14506
20130101; A61M 5/155 20130101; A61M 2005/14513 20130101; A61K 38/00
20130101; A61K 38/26 20130101; A61K 38/22 20130101; A61M 5/14248
20130101; A61M 5/1452 20130101; A61M 5/148 20130101; A61M 5/14593
20130101 |
International
Class: |
A61M 5/145 20060101
A61M005/145; A61K 38/22 20060101 A61K038/22 |
Claims
1. A system for delivering an effective amount of a GLP-1 compound
to a patient in need of GLP-1 receptor stimulation, the system
comprising: (1) a pump-driven fluid delivery device; (2) a liquid
form of said GLP-1 compound stored in said pump-driven fluid
delivery device.
2. The system of claim 1, wherein said pump-driven fluid delivery
device comprises: (1) a pump chamber, and a fluid storage chamber
having an orifice and being functionally connected to said pump
chamber by a moveable barrier; (2) a hydraulic fluid reservoir for
storing a high viscosity fluid, said reservoir being connected to
said pump chamber via a restrictor capable of controlling the rate
of flow of the high viscosity fluid, and, (3) an actuator
functionally connected to said hydraulic fluid reservoir to cause
said hydraulic fluid to flow into said pump chamber through said
restrictor, thereby expanding the volume of said pump chamber,
displacing said moveable barrier and causing a quantity of said
liquid component stored in said fluid storage chamber to be
delivered at a sustained rate.
3. A method of stimulating a GLP-1 receptor in a subject in need of
such stimulation, said method comprising the step of administering
to a patient an effective amount of a GLP-1 compound using a
pump-driven fluid delivery device with a liquid form of said GLP-1
compound stored therein.
4. The method of claim 3, wherein said GLP-1 compound is GLP-1.
5. The method of claim 3, wherein said GLP-1 compound is a GLP-1
analog with substantially the same or better potency than that of
GLP-1.
6. The method of claim 3, wherein said GLP-1 compound is a
derivative of GLP-1 or GLP-1 analog, with substantially the same or
better potency than that of GLP-1.
7. The method of claim 3, wherein said GLP-1 compound is delivered
continuously.
8. The method of claim 7, wherein the rate of delivery is
equivalent to about 0.25 to 6 pmol/kg body weight/min., preferably
from about 0.5 to about 1.2 pmol/kg/min., or from about 0.6 to
about 2.4 pmol/kg/min. of GLP-1.
9. The method of claim 3, wherein said GLP-1 compound is delivered
intermittently.
10. The method of claim 9, wherein the rate of delivery, as
averaged over the entire delivery period, is equivalent to about
0.25 to 6 pmol/kg body weight/min., preferably from about 0.5 to
about 1.2 pmol/kg/min., or from about 0.6 to about 2.4 pmol/kg/min.
of GLP-1.
11. The method of claim 7, wherein the entire delivery period for
said GLP-1 compound is about 6 hrs, about 12 hrs, about 1 day,
about 3 days, about 5 days, about 2 weeks, about 1 month, about 3
months, about 6 months, about 1 year or more.
12. The method of claim 9, wherein the entire delivery period for
said GLP-1 compound is about 6 hrs, about 12 hrs, about 1 day,
about 3 days, about 5 days, about 2 weeks, about 1 month, about 3
months, about 6 months, about 1 year or more.
Description
REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of the filing date of
U.S. Provisional Application 60/585,330, filed on Jul. 2, 2004, the
entire content of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] Glucagon-like peptide-1 (GLP-1) is a relatively recently
discovered gastrointestinal hormone (Holst, Gastroenterology 107:
1848-1855, 1994) that has attracted considerable interest because
of its potent actions on carbohydrate metabolism and its potential
use as a therapeutic agent in the treatment of type-2 diabetes
(Gutniak et al., N. Engl. J. Med. 326: 1316-1322, 1992; Nathan et
al., Diabetes Care 15: 270-276, 1992). It arises from
tissue-specific processing of the glucagon precursor, proglucagon,
within the L-cell of the distal intestinal mucosa (Bell et al.,
Nature (London) 304: 368-371, 1983; Mojsov et al., J. Biol. Chem.
261: 11800-11889, 1986; Orskov et al., Endocrinology 119:
1467-1475, 1986), from which it is secreted in response to meal
ingestion (Elliott et al., J. Endocrinol. 38: 159-166, 1993;
Herrmann et al., Digestion 56: 117-126, 1995; Orskov et al., Scand.
J. Gastroenterol. 31: 665-670, 1996).
[0003] The processing pattern of proglucagon leading to the
formation of GLP-1 is known in detail (Bell, supra; Mojsov, supra;
Orskov et al., Endocrinology 119: 1467-1475, 1986; Orskov et al.,
Diabetes. 43: 535-539, 1994; Orskov et al., Diabetologia. 30:
874-881, 1987). Initial studies of GLP-1 biological activity in the
mid 1980s utilized the full length N-terminal extended forms of
GLP-1 (1-37 and 1-36amide). These larger GLP-1 molecules were
generally devoid of biological activity. In 1987, 3 independent
research groups demonstrated that removal of the first 6 amino
acids resulted in a shorter version of the GLP-1 molecule with
substantially enhanced biological activity. The majority of
circulating biologically active GLP-1 is found in the
GLP-1(7-36)amide form), with lesser amounts of the bioactive
GLP-1(7-37) form also detectable. See Orskov et al. (Diabetes
43(4): 535-9, 1994) for the human data. Both peptides appear
equipotent in all biological paradigms studied to date. GLP-1 is
secreted from gut endocrine cells in response to nutrient ingestion
and plays multiple roles in metabolic homeostasis following
nutrient absorption.
[0004] Furthermore, the two naturally occurring truncated peptides,
GLP-1(7-37)OH and GLP-1(7-36)NH.sub.2, are rapidly cleared in vivo
and have extremely short in vivo half-lives. In several studies
(Deacon et al., J. Clin. Endocrinol. Metab. 80: 952-957, 1995;
Deacon et al., Diabetes. 44: 1126-1131, 1995; Mentlein et al., Eur.
J. Biochem. 214: 829-835, 1993), it was found that GLP-1, in
addition to its renal and hepatic elimination (Deacon et al., Am.
J. Physiol. Endocrinol. Metab. 34: E458-E464, 1996), is degraded in
plasma by the enzyme dipeptidyl peptidase IV (DPP-IV). The enzyme
removes a dipeptide from the N terminus of GLP-1 (Deacon, supra;
Mentlein, supra), producing the truncated fragment GLP-1
(9-36)amide. This cleavage of GLP-1 seems to be relevant for its
actions on the endocrine pancreas. Thus, in a recent study of the
interaction of GLP-1 (9-36) amide with the cloned GLP-1 receptor,
GLP-1 (9-36) amide antagonized the action of GLP-1 7-36 amide
(Knudsen and Pridal, Eur. J. Pharmacol. 318: 429-435, 1996). In
another study, after showing previously that GLP-1 strongly
inhibited cephalic-induced antral motility in pigs, Wettergren et
al. (Peptides 19(5): 877-882, 1998) reported that an intact N
terminus is essential for the gastrointestinal actions of GLP-1,
and that its primary metabolite, GLP-1 (9-36)amide, may even act as
an endogenous antagonist.
[0005] Further, GLP-1 compound formulations currently in
development cannot be given orally and like insulin, must be
injected. Thus, despite the clear medical advantages associated
with therapy involving GLP-1, the short half-life which results in
a drug that must be injected one or more times a day has impeded
commercial development efforts. Generally, moving patients to an
injectable therapy is quite difficult. For example, many diabetics
are unwilling to undertake any type of intensive injection therapy
due to the discomfort associated with the many injections required
to maintain adequate glucose control. Furthermore, diabetics on
insulin are generally required to monitor their blood glucose,
which involves additional needle sticks. This type of therapy can
be both psychologically and physically painful. This is especially
true when patients have been treated solely with oral medications
throughout the progression of the disease.
[0006] Therefore, there is a need in the art for more effective
ways to deliver GLP-1 to patients in need thereof, preferably
through less-invasive delivery means, so as to overcome or at least
reduce several problems associated with GLP-1 therapy, such as the
potentially inhibitory function of the natural metabolites of
GLP-1, and the painful and invasive delivery means.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The present disclosure may be better understood and its
numerous features and advantages made apparent to those skilled in
the art by referencing the accompanying drawings.
[0008] FIG. 1 is a high-level functional schematic drawing of a
hydraulic pump system, according to one embodiment of the
invention.
[0009] FIG. 2 is a high-level functional schematic drawing of a
fluid delivery system comprising the hydraulic pump system,
according to one embodiment of the invention.
[0010] FIGS. 3A and 3B are schematic drawings illustrating one of
the advantages of the fluid delivery system comprising the
hydraulic pump system.
[0011] FIGS. 4A to 4C are high-level functional schematic drawings
of several fluid delivery systems with various barriers.
[0012] FIG. 5 is a high-level functional schematic drawing of an
alternative fluid delivery system, according to one embodiment of
the invention. The alternative fluid delivery system in this
embodiment features arrayed microneedles on an transdermal
patch.
[0013] FIGS. 6A to 6C are high-level functional schematic drawings
of several actuator mechanisms that can be used with the fluid
delivery system employing the hydraulic pump, according to one
embodiment of the invention.
[0014] FIG. 7 is a high-level functional schematic drawing of the
adjustable control for aperture opening size.
[0015] FIGS. 8A and 8B are high-level functional schematic drawings
of several fluid delivery system with multiple actuators, according
to one embodiment of the invention.
[0016] FIG. 9 depicts one embodiment of a microneedle coupled to
the subject fluid delivery system, which employs a sensor for
detecting the presence of one or more analytes and control delivery
rate.
[0017] The use of the same reference symbols in different drawings
indicates similar or identical items.
SUMMARY OF THE INVENTION
[0018] Disclosed herein are systems, methods, apparatus, and
reagents for delivering GLP-1 and its analogs or derivative
compounds to a human or non-human mammalian patient using a pump,
partly to overcome the difficulty of treating such patients with
GLP-1 associated with the short half-life of GLP-1, especially the
short half-life of GLP-1 in vivo.
[0019] The subject drug delivery systems (comprising a drug/device
combination) provide a means to deliver GLP-1 compounds at various
dosage schemes, quantity, and speed, preferably over a sustained
period of time, so as to ensure the most effective amount of GLP-1
compounds in vivo to achieve optimum efficacy.
[0020] Thus one aspect of the invention provides a system for
delivering an effective amount of a GLP-1 compound to a patient in
need of GLP-1 receptor stimulation, the system comprising: (1) a
pump-driven fluid delivery device; (2) a liquid form of said GLP-1
compound stored in said pump-driven fluid delivery device.
[0021] In one embodiment, the pump-driven fluid delivery device
comprises: (1) a pump chamber, and a fluid storage chamber having
an orifice and being functionally connected to said pump chamber by
a moveable barrier; (2) a hydraulic fluid reservoir for storing a
high viscosity fluid, said reservoir being connected to said pump
chamber via a restrictor capable of controlling the rate of flow of
the high viscosity fluid, and, (3) an actuator functionally
connected to said hydraulic fluid reservoir to cause said hydraulic
fluid to flow into said pump chamber through said restrictor,
thereby expanding the volume of said pump chamber, displacing said
moveable barrier and causing a quantity of said liquid component
stored in said fluid storage chamber to be delivered at a sustained
rate.
[0022] In other embodiments, other pump devices, such as those
described herein, with their various embodiments, can also be used
to in the subject drug-device combination to deliver GLP-1
compounds.
[0023] Another aspect of the invention provides a method of
stimulating a GLP-1 receptor in a subject in need of such
stimulation, said method comprising the step of administering to a
patient an effective amount of a GLP-1 compound using a pump-driven
fluid delivery device with a liquid form of said GLP-1 compound
stored therein.
[0024] In one embodiment, the GLP-1 compound is GLP-1.
[0025] In one embodiment, the GLP-1 compound is a GLP-1 analog with
substantially the same or better potency than that of GLP-1.
[0026] In one embodiment, the GLP-1 compound is a derivative of
GLP-1 or GLP-1 analog, with substantially the same or better
potency than that of GLP-1.
[0027] In one embodiment, the GLP-1 compound is delivered
continuously.
[0028] In one embodiment, the rate of delivery is equivalent to
about 0.25 to 6 pmol/kg body weight/min., preferably from about 0.5
to about 1.2 pmol/kg/min., or from about 0.6 to about 2.4
pmol/kg/min. of GLP-1.
[0029] In one embodiment, the GLP-1 compound is delivered
intermitantly.
[0030] In one embodiment, the rate of delivery, as averaged over
the entire delivery period, is equivalent to about 0.25 to 6
pmol/kg body weight/min., preferably from about 0.5 to about 1.2
pmol/kg/min., or from about 0.6 to about 2.4 pmol/kg/min. of
GLP-1.
[0031] In one embodiment, the entire delivery period for said GLP-1
compound is about 6 hrs, about 12 hrs, about 1 day, about 3 days,
about 5 days, about 2 weeks, about 1 month, about 3 months, about 6
months, about 1 year or more.
[0032] It is contemplated that each embodiment can be combined with
other embodiments whenever appropriate.
DETAILED DESCRIPTION OF THE INVENTION
[0033] Various systems, devices and methods are provided for more
effective administration of GLP-1 to a patient in need thereof,
which allow administration of GLP-1 therapeutics in continuous, or
otherwise predetermined pattern, so as to achieve the maximum
effect of stimulating insulin production by pancreatic beta cells
without using toxic or near toxic levels of GLP-1. In particular,
drug-device combinations (systems) are provided herein which enable
more effective, less invasive administration of GLP-1.
[0034] For example, traditional bolus injection of GLP-1 may
account for the high in vivo degredation rate of GLP-1, and
requires administering a higher-than-necessary bolus dose of GLP-1
into the patient's system. This dose is limited by the maximal
tolerable amount of GLP-1 in the patient's system. From there, the
effective level of GLP-1 decreases in vivo, and may quickly drop
below the effective range of GLP-1 concentration. This problem may
be worse where the maximum tolerable dose may still fall below the
most effective concentration of GLP-1. In that case, as soon as the
GLP-1 therapeutic is administered, it starts to drift further away
from the most effective range in vivo. Thus ideally, the
concentration of GLP-1 should be kept near the maximal tolerable
dose as long as possible/necessary.
[0035] The methods of the invention can be used to deliver GLP-1 at
a continuous fashion, over a relatively long period of time.
[0036] In one embodiment, the patient has a condition characterized
by abnormal carbohydrate metabolism, such as diabetes, especially
type II diabetes.
[0037] In another embodiment, the patient has a condition
characterized by excessive gastropancreatic secretion and gastric
motility.
[0038] Transportation of molecules through the microneedles can be
controlled or monitored using, for example, various combinations of
valves, pumps, sensors, actuators, and microprocessors. These
components can be produced using standard manufacturing or
microfabrication techniques. Actuators that may be useful with the
microneedle devices disclosed herein include micropumps,
microvalves, and positioners. In a preferred embodiment, a
microprocessor is programmed to control a pump or valve, thereby
controlling the rate of delivery.
Hydraulic Pump for Long-Duration Sustained-Release of GLP-1
[0039] U.S. Ser. No. 60/465,070 (filed on Apr. 23, 2003, titled
"HYDRAULICALLY ACTUATED PUMP FOR LONG DURATION MEDICAMENT
ADMINISTRATION") and U.S. Ser. No. 10/831,354 (filed on Apr. 23,
2004, titled "HYDRAULICALLY ACTUATED PUMP FOR LONG DURATION
MEDICAMENT ADMINISTRATION") describe a hydraulic actuated pump for
long-duration sustained release of therapeutic agents (such as
GLP-1) to a patient (the entire contents incorporated herein by
reference). The hydraulic device is suitable for delivering a
sustained flow of liquid, especially in small amounts and over a
long period of time. Partly due to the hydraulic pressure system,
the operation of the device is relatively insensitive to
environmental changes, such as ambient temperature, altitude, or
external pressure.
[0040] The hydraulic pump-driven drug delivery system provides pump
devices for delivering a medicament, e.g., GLP-1 and analogs
thereof to a patient, typically through the skin. To this end, the
system includes an actuator that operates on a reservoir of viscous
fluid. The actuator causes the viscous fluid to apply pressure to
medicament to the medicament being delivered. The viscous fluid is
controlled by a restrictor that, in one practice, controls the rate
of flow of the fluid so that an uneven application of pressure to
the reservoir is mediated, and a controlled rate of fluid movement
is achieved. This controlled rate of fluid movement is employed to
cause a medicament to be delivered at a selected rate.
[0041] In one embodiment the systems and methods described herein
include a hydraulic pump system that may include a chamber (the
"pump chamber") that can be filled with high viscosity fluid,
which, when forced by pressure, enters the pump chamber through a
restrictor, for example an opening/aperture, which is dimensionally
adapted to control the rate of fluid flow therethrough. In one
embodiment, the aperture is about the size of a 1-100 .mu.m
diameter circle (but not necessarily circular in shape). However,
those of skill in the art will understand that any suitable
restrictor may be employed, and that the size and the shape of the
restrictor can vary to achieve the desired flow rate of the fluid
being mediated under the expected conditions, including temperature
and ambient pressure.
[0042] The increase in volume of the working fluid inside the pump
chamber triggers the movement of a barrier mechanism, which can be
coupled to other devices, such as a second, fluid storage
chamber.
[0043] One advantage of the instant hydraulic pump system resides
with the restrictor through which the high viscosity working fluid
flows. For example, when the restrictor is an aperture, when
subjected to varying pressure, the working fluid enters the chamber
through the aperture at a slow, yet relatively constant rate, thus
mostly eliminating the potentially large variations in the force
generating the pressure, while ensuring a substantially less
variable expansion in volume of the working fluid in the chamber.
This in turn leads to a relatively smooth and constant movement of
the coupled barrier mechanism.
[0044] An additional advantage of the hydraulic pump system is that
its relatively low requirement for a constant pressure source, or
its high ability to tolerate relatively large variations in force
generated by the pressure source. This is especially useful in
manufacturing simple and inexpensive devices, such as single-use,
disposable devices for medical use.
[0045] Partly because of the over-pressure employed in the
hydraulic pump system, a further advantage is that the hydraulic
pump is relatively insensitive to environmental changes, such as
ambient temperature, altitude, or external pressure.
[0046] One illustrative embodiment of the hydraulic fluid system
described herein is shown in the high-level functional drawing of
FIG. 1. The pump chamber 110 may be shaped like, but is not limited
to, a cylinder. The hatched lines represent a moveable barrier 130,
which may (but need not to) be at the distal end of aperture 152.
Hydraulic fluid 112 enters aperture 152 on pump chamber wall 150
into pump chamber 110, optionally via a connective passage 116.
[0047] The hydraulic pump system can be employed in a fluid
delivery system that can be manufactured inexpensively, and could
take advantage of the slow, yet relatively constant delivery rate
associated with the hydraulic pump system. Partly due to the slow
rate of delivery, the fluid delivery system can be used to
continuously deliver a fluid over a long period of time, e.g. 6
hrs, 12 hrs, 1 day, 3 days, 5 days, 10 days, one month, etc. The
fluid delivery system comprises the hydraulic pump, coupled to a
separate chamber for storing fluid to be delivered (the "fluid
storage chamber" or "fluid chamber" in short). There could be
various mechanisms coupling the movement of the barrier mechanism
in the hydraulic pump to the fluid chamber, such that a small
amount of fluid (ideally equal to, or at least proportional to the
amount of the working fluid entering the hydraulic pump chamber) is
expelled from the fluid chamber, through one or more orifice, in
response to the movement of the barrier.
[0048] One embodiment of the fluid delivery system is illustrated
in a high-level schematic drawing in FIG. 2 (see detailed
description below). This type of fluid delivery system/device can
be used for a broad range of applications, including but are not
limited to biomedical research (e.g. microinjection into cells,
nuclear or organelle transplantation, isolation of single cells or
hybridomas, etc.), and clinical applications (administration of
medicaments, etc.).
[0049] Hydraulic cylinder 100, as described in FIG. 2, consists of
two chambers, 110 and 120. Chamber 110 (corresponding to the pump
chamber) is filled by hydraulic working fluid 112 from a hydraulic
reservoir 114. Filling is accomplished by means of a connective
passage 116, such as (but not limited to) a tube or lumen either
flexibly or rigidly connecting hydraulic reservoir 114 and
hydraulic cylinder 100. As hydraulic fluid 112 is forced out of
reservoir 114 by actuator 135 (consisting, in an exemplary
embodiment, of peristaltic compression plates 135A and 135B and
hinge 135C), chamber 110 fills with hydraulic fluid expanding its
volume and thus forcing piston element 130 (barrier mechanism) into
chamber 120 (corresponding to the fluid chamber). The dotted lines
in the actuator and the piston in FIG. 2 represent the
later-in-time position of a plate-hinge actuating mechanism, and
the later-in-time position of the barrier/piston.
[0050] FIG. 3 is a schematic diagram illustrating one advantage of
the fluid delivery system, e.g., its ability to tolerate relatively
large variations in force generating the over-pressure, to create a
relatively constant fluid delivery rate over time or distance
traveled by the barrier piston. It is apparent that without the
hydraulic pump system, any direct use of force to expel fluid in
the fluid chamber will be hard to control, and will be subjected to
a large variation in delivery rate of the fluid (FIG. 3A). In
contrast, with the hydraulic pump, the delivery rate is much more
constant (FIG. 3B).
[0051] FIGS. 4-8 describe various exemplary embodiments of the
hydraulic pump-driven drug delivery system. The details of these
pump embodiments are described in U.S. Ser. No. 60/465,070 (filed
on Apr. 23, 2003, titled "HYDRAULICALLY ACTUATED PUMP FOR LONG
DURATION MEDICAMENT ADMINISTRATION") and U.S. Ser. No. 10/831,354
(filed on Apr. 23, 2004, titled "HYDRAULICALLY ACTUATED PUMP FOR
LONG DURATION MEDICAMENT ADMINISTRATION") (the entire contents
incorporated herein by reference).
[0052] In its simplest embodiment, the hydraulic pump may form a
portion of a single-use dispenser (e.g. syringe) for delivering
GLP-1 through any of the standard, infusions sets available on the
market today or likely to be available in the future. The pump,
formed in some embodiments of low-cost plastic parts, may comprise
a hydraulic cylinder containing two chambers. In those embodiments,
the hydraulic cylinder may be configured similarly to most
conventional hydraulic cylinders, and the wall, especially the
inner wall of at least the chamber for storing a liquid medicament
to be delivered, may be composed of bio-inert and inexpensive
materials. The hydraulic cylinder typically consists of two
chambers, one of which stores the medicament to be delivered (e.g.
GLP-1 therapeutics), the other is filled with a high viscosity,
ultrapure hydraulic working fluid entered from a linked hydraulic
reservoir through a connective passage. The hydraulic fluid is
forced out of the reservoir by an actuator (consisting, in an
exemplary embodiment, of peristaltic compression plates and a
hinge), and enters the working fluid chamber through an extremely
fine aperture with a diameter of about 2-3 .mu.m. Because of the
limited sized of the aperture, fluid enters the working fluid
chamber at a slow, yet relatively consistent rate (such as about
100 nl-.mu.l per minute, about 1-10 .mu.l per minute, or about
10-100 .mu.l per minute), which is relatively insensitive to other
operation conditions, such as ambient temperature, pressure, etc.
The working fluid enters the working fluid chamber, and displaces a
barrier separating the working fluid chamber with the adjacent
medicament chamber, causing a corresponding amount of GLP-1
medicament to exit through an orifice on the medicament chamber and
into the connected infusion set mentioned above. The flow rate of
the GLP-1 therapeutics can be controlled by the aperture size and
the force generated by the actuator. Therefore, using this type of
hydraulic pump, GLP-1 can be administered to a patient continuously
to compensate for the constant degredation of the functional form
of the GLP-1 therapeutics.
[0053] The dose of GLP-1, GLP-1 analog, or GLP-1 derivatives, or
active fragments effective in a particular subject to cause desired
effect (e.g. weight-loss) will depend on a number of factors, among
which are included the subject's sex, weight and age, the
underlying causes of disease or condition being treated, the route
of administration and bioavailability, the persistence of the
administered compound in the body, the formulation, and the
potency. Where administration is intermittent, the dose per
administration should also take into account the interval between
doses, and the bioavailability of the administered compound. For
weight-loss treatment, where administration is continuous, a
suitable dosage rate is between 0.25 and 6 pmol/kg body weight/min,
preferably from about 0.5 to about 1.2 pmol/kg/min, or from about
0.6 to about 2.4 pmol/kg/min. Typically, the maximum infusion rate
can be controlled to no more than 2 pmol kg.sup.-1 min..sup.-1 of
GLP-1, since higher doses may be associated with the risk of side
effects (Vilsboll et al., Diabetes Care 23: 807-812, 2000; Larsen
et al., Diabetes Care 24: 1416-1421, 2001). It is within the skill
of the ordinary physician to titrate the dose and rate of
administration of compositions containing GLP-1, GLP-1 analogs, or
GLP-1 derivatives, or active fragments thereof to achieve the
desired clinical result.
Osmotic Pumps
[0054] In certain embodiments of the invention, GLP-1 therapeutics
can be administered to a mammalian patient (including human or
non-human animals) through the use of osmotic pumps. Elementary
osmotic pumps are known in the art (see, e.g., Theeuwes, Drug Dev.
& Indust. Pharm. 9: 1331-1357, 1983; Boudier, Trends in
Pharmacol. Sci. pp. 162.164, April 1982, both of which are hereby
incorporated by reference). These pumps were developed in response
to the need to maintain the concentrations of drugs into a
patient's plasma, particularly those that require chronic
administration, within a safe and effective range. Conventionally,
patients receive their medication by bolus administration (e.g., by
injecting or otherwise administering a set amount of a drug).
Immediately after such administration, the plasma level of the drug
can exceed the maximum level for safety. But before the next
scheduled administration, the level can fall below the minimum
level required for effectiveness. As a result, patients are
repeatedly exposed to both toxic and ineffective concentrations of
drugs. The ratio of these two levels (the maximum level for safety
and the minimum level for effectiveness) is known as the
therapeutic index. While these fluctuations can be minimized by
dosing at frequent time intervals, the required regimen can be
extremely inconvenient for the patient (particularly where the drug
has a short half-life). This is precisely the situation with
GLP-1.
[0055] Examples of delivery systems in which osmotic pressure is
the driving force behind drug release include PROGESTASERT7, a
contraceptive system that releases progesterone to the uterine
lumen at a rate of 65 microgram per day for one year, and OCUSERT7,
an ocular system that releases pilocarpine to the eye at rates of
20 or 40 micrograms/hour for one week. Similarly, an elementary
osmotic pump, such as described by Theeuwes (supra) can be used to
dispense therapeutic agents into the gastrointestinal (GI) tract at
a rate independent of external factors such as GI tract pH and
motility. These systems illustrate two of the most prominent
advantages of osmotic minipumps: constant and prolonged delivery of
a drug at a predetermined rate and the ability to target delivery
to a particular tissue or organ.
[0056] Structurally, osmotic pumps can include a solid core,
semi-permeable membrane and an orifice for drug delivery. Osmosis
is the force driving expulsion of a drug from the device: water
imbibed, e.g., from the environment, crosses the membrane at a
controlled rate and causes the drug solution to exit through the
delivery orifice. Delivery rate is controlled by osmotic properties
of the core and membrane area, its thickness, and permeability to
water.
[0057] WO0048669A1 (incorporated herein by reference) describes a
type of osmotic pump relying on the change in the charge of the
electroactive polymer within the pores of the device. This type of
device can serve as a self-regulating osmotic pump, that might also
be used to deliver GLP-1 into a patient. In this type of pump,
charge neutralization can occur by migration of water and ions into
and out of an electroactive polymer (i.e., by doping and undoping),
thereby creating an osmotic pumping action.
[0058] When GLP-1 solution as a therapeutic agent is contained
within that type of device and has access to the pores of the
device (the GLP-1 therapeutic agent will be positioned so that it
can move through the pores and into a patient's body), modulation
of the diameter of the pore can, alone, be sufficient to allow
sufficient movement of the therapeutic agent(s) into the outer
electrolyte solution.
[0059] In another embodiment, the modulated current generated by
charging the electroactive polymer in response to the level of
analyte can be used to control an electro-mechanical pump that,
when activated, forces the agent(s) through the open pore and into
the outer electrolyte solution. Thus, in effect, the analyte level
modulates both the pore opening and the pumping force. This double
feed-back redundancy is an added safety feature of that type of
system. If, for some reason, the pump failed to shut off at the
appropriate time, the declining analyte concentration would cause
the pore to close. When pressure within the reservoir containing
the therapeutic agent(s) increases to a pre-set level, electrical
contact to the pump is shut off until the pressure falls back to
within its normal range of operation. If the pore fails to close as
the analyte level falls (in response to infusion of the therapeutic
agent(s)) the current generated by charging the electroactive
polymer will also fall and the pump will gradually shut down.
[0060] If electron transfer between the GLP-1 therapeutic solution
and the electroactive polymer is slower than between the member and
the electroactive polymer, and if the applied potential across the
polymer network is pulsed, then pulsing of the pore opening can
also be achieved. During the "off" period, all or part of the
polymer can be reduced or oxidized by the therapeutic agent so that
the polymer returns to its virgin state. This opens the pore. The
amount of charge transferred between pulses determines the size of
the pore opening. When the potential is again turned on, the
polymer is again fully charged and it closes. In effect, this
on/off cycling can cause a pumping action. Thus, the pore size and
the pumping action are modulated by the amount of analyte in the
outer electrolyte solution. If a therapeutic agent was dissolved
and stored on the inner side of the pore, pulsing of the pore could
force the agent from inside the pore to the outer electrolyte
solution. If the level of analyte was modulated by the amount of
drug in the outer solution, the combination of the processes above
would constitute a self-regulating drug delivery device. As in the
case described above, pumping of the drug could be done through use
of a conventional electro-mechanical pump.
[0061] In another embodiment, self-regulated pumping can be
achieved by storing therapeutic agent(s) within a collapsible
reservoir. As the pore open, the natural tendency would be for the
drug to move from a solution of high concentration to a solution of
low concentration until equilibrium is achieved. Modulation of the
pore opening may also be used to regulate the amount of water
imbibed by a collapsible reservoir surrounding the drug reservoir.
Water imbibed when the pore is open causes the volume within the
osmotic reservoir to increase, thereby forcing the therapeutic
agent(s) out of the device.
[0062] The device itself can be used in a number of environments.
It can be used in vivo or ex vivo (e.g., in a cell culture
environment). In the event the device is used in vivo it may be
wholly or partially internalized in a patient's body. For example,
the device can include an adhesive component and a probe that
extends beneath the body surface. When a portion of the device is
worn externally, it can be attached to the patient by a belt,
strap, or adhesive (e.g., it can be attached to the patient's skin
by an adhesive patch). In some instances, an adhesive and a second
security device (e.g., a belt or strap) can be used.
[0063] The amount of therapeutic agent carried within the device
can vary. The amount can include less than 1, less than 2, less
than 5 or less than 10 days supply of a therapeutic agent or
agents.
Administration of Compositions
[0064] Administration may be via any route known to be effective by
the physician of ordinary skill. Peripheral, parenteral
administration is preferred. Parenteral administration is commonly
understood in the medical literature as the injection of a dosage
form into the body by a sterile syringe or the infusion pump
described herein. Peripheral parenteral routes include intravenous,
intramuscular, subcutaneous, and intraperitoneal routes of
administration. Intravenous, intramuscular, and subcutaneous routes
of administration of the compounds used in the present invention
are more preferred. Intravenous and subcutaneous routes of
administration of the compounds used in the present invention are
yet more highly preferred. For parenteral administration, an active
compound used in the present invention preferably is combined with
distilled water at an appropriate pH. For human subjects, an active
compound used in the present invention is combined with
pyrogen-free distilled water at an appropriate pH, which meets FDA
standard for human subject administration.
GLP-1 Analogs and Derivatives
[0065] Human GLP-1 amino acid sequence is described in numerous
literatures, and is listed below:
TABLE-US-00001 1 mksiyfvagl fvmlvqgswq rslqdteeks rsfsasqadp
lsdpdqmned krhsqgtfts 61 dyskyldsrr aqdfvqwlmn tkrnrnniak
rhdeferhae gtftsdvssy legqaakefi 121 awlvkgrgrr dfpeevaive
elgrrhadgs fsdemntild nlaardfinw liqtkitdrk
[0066] See NCBI RefSeq NP.sub.--002045. Other alternative sequences
from other mammals can be readily obtained from BLAST search of the
nr database at NCBI or other public databases. All these sequences
are incorporated herein by reference.
[0067] WO 03/018516 A2 describes various GLP-1 analogs with
modifications at one or more of the following positions on GLP-1:
7, 8, 12, 16, 18, 19, 20, 22, 25, 27, 30, 33, and 37 (The entire
teachings of these references are incorporated herein by
reference). These novel GLP-1 analogs are extremely potent compared
with ValB-GLP-1(7-37)OH. The increased potency of these analogs
facilitates the use of delivery technology associated with limited
bioavailability.
[0068] As used herein, "GLP-1 analogs" include GLP-1 compounds
which are not natural GLP-1, but have sufficient homology to
GLP-1(7-37)OH, GLP-1(7-36)NH.sub.2 or a fragment of GLP-1(7-37)OH
or GLP-1(7-36)NH.sub.2, such that the analog has at least one
biological function of GLP-1 (e.g., the ability to bind to a GLP-1
receptor, or insulinotropic activity, etc.). Preferably, a GLP-1
analog has the amino acid sequence of GLP-1(7-37)OH or a fragment
thereof, modified so that from one, two, three, four, five, or six
amino acids differ from the amino acid in the corresponding
position of GLP-1(7-37)OH or a fragment of GLP-1(7-37)OH. In the
nomenclature used herein to designate GLP-1 compounds, the
substituting amino acid and its position is indicated prior to the
parent structure.
[0069] A "GLP-1 derivative" is defined as a molecule having the
amino acid sequence of GLP-1 or of a GLP-1 analog, but additionally
having at least one chemical modification of one or more of its
amino acid side groups, .alpha.-carbon atoms, terminal amino group,
or terminal carboxylic acid group. A chemical modification includes
adding chemical moieties, creating new bonds, and removing chemical
moieties. Modifications at amino acid side groups include acylation
of lysine .epsilon.-amino groups, N-alkylation of arginine,
histidine, or lysine, alkylation of glutamic or aspartic carboxylic
acid groups, and deamidation of glutamine or asparagine.
Modifications of the terminal amino include the des-amino, N-lower
alkyl, N-di-lower alkyl, and N-acyl modifications. Modifications of
the terminal carboxy group include the amide, lower alkyl amide,
dialkyl amide, and lower alkyl ester modifications. A lower alkyl
is a C1-C4 alkyl. Furthermore, one or more side groups, or terminal
groups, may be protected by protective groups known to the
ordinarily-skilled protein chemist. The .alpha.-carbon of an amino
acid may be mono- or di-methylated.
[0070] Preferred GLP-1 analogs suitable for use in the instant
invention include those described by formulae I and II of WO
03/018516 A2. Preferably, the GLP-1 analog compounds do not differ
from GLP-1(7-37)OH or GLP-1(7-36)NH.sub.2 by more than 6 amino
acids, by more than 5 amino acids, by more than 4 amino acids, or
by more than 3 amino acids. It is also preferable that the GLP-1
compounds of formulae I and II have valine or glycine at position 8
and glutamic acid at position 22. It is also preferable that the
GLP-1 compounds of formulae I and II have valine or glycine at
position 8 and glutamic acid at position 30. It is also preferable
that the GLP-1 compounds of formulae I and II have valine or
glycine at position 8 and histidine at position 37.
[0071] The GLP-1 compounds described in WO 03/018516 A2 have
increased potency compared to Val8-GLP-1(7-37) OH. Native
GLP-1(7-37)OH is rapidly degraded by dipeptidylaminopeptidase IV
(DPP-IV) after injection and the half-life of GLP-1(7-37)OH is
approximately five minutes. Analogs such as Val8-GLP-1(7-37)OH
wherein the alanine at position 8 has been substituted with a
different amino acid have been developed because these analogs are
resistant to DPP-IV degradation and thus, have an increased
half-life. However, these analogs may not be potent enough to make
administration by alternative delivery technology feasible on a
commercial scale. Thus, Val8-GLP-1(7-37)OH is used as a comparator
to illustrate the increased potency of the novel GLP-1 compounds
encompassed in WO 03/018516 A2.
[0072] Preferably, the GLP-1 compounds described therein comprise
GLP-1 analogs wherein the backbone for such analogs or fragments
contains an amino acid other than alanine at position 8 (position 8
analogs). The backbone may also include L-histidine, D-histidine,
or modified forms of histidine such as desamino-histidine,
2-amino-histidine, P-hydroxy-histidine, homohistidine,
a-fluoromethylhistidine, or u-methyl-histidine at position 7. It is
preferable that these position 8 analogs contain one or more
additional changes at positions 12, 16, 18, 19, 20, 22, 25, 27, 30,
33, and 37 compared to the corresponding amino acid of native
GLP-1(7-37)OH. It is more preferable that these position 8 analogs
contain one or more additional changes at positions 16, 18, 22, 25
and 33 compared to the corresponding amino acid of native
GLP-1(7-37)OH.
[0073] Furthermore, many of these more potent analogs have a
reduced propensity to aggregate and thus, have increased stability.
GLP-1 compounds can exist in at least two different forms. The
first form is physiologically active and dissolves readily in
aqueous solution at physiological pH (7.4). A second inactive form
is readily produced when aqueous GLP-1 solutions are agitated,
exposed to hydrophobic surfaces or have large air/water interfaces.
The tendency to convert to the insoluble form considerably
complicates the production of commercial quantities of active GLP-1
compounds. Thus, GLP-1 compounds that have a reduced propensity to
aggregate in solution and are more potent than Val8-GLP-1(7-37)OH
are preferred.
[0074] Numerous GLP-1 analogs and derivatives are also disclosed,
to name but a few, in EP1408050A1, EP1100530A1, EP1368055A2,
EP1306092A2, EP1187628A2, WO9111457A1, U.S. Pat. No. 5,545,618,
DE69129226C0, EP0946191A1, EP0964692A1, EP0964873A1, U.S. Pat. No.
6,006,753, JP2001011095A2, U.S. Pat. No. 6,191,102, WO0135988A1,
US20010011071A1, and U.S. Pat. No. 6,458,924. It is contemplated
that other known GLP-1 analogs/derivatives already described in
patent and other scientific literatures are all suitable to be
administered using the pump technology of the invention.
[0075] In addition, novel heterologous GLP-1 fusion proteins
comprises a GLP-1 compound fused to human albumin or to the Fc
portion of an immunoglobulin are described in EP1355942A2
(Incorporated herein by reference.)
[0076] As used herein, the term "GLP-1 compound," including GLP-1,
its fusion proteins, derivatives and analogs, also includes
pharmaceutically acceptable salts of the compounds described
herein. A GLP-1 compound can possess a sufficiently acidic, a
sufficiently basic, or both functional groups, and accordingly
react with any of a number of inorganic bases, and inorganic and
organic acids, to form a salt.
[0077] The pharmaceutical composition can be a solution or, if
administered parenterally, a suspension of the GLP-1 compound or a
suspension of the GLP-1 compound complexed with a divalent metal
cation such as zinc. Suitable pharmaceutical carriers may contain
inert ingredients which do not interact with the GLP-1 peptide or
peptide derivative. Standard pharmaceutical formulation techniques
may be employed such as those described in Remington's
Pharmaceutical Sciences, Mack Publishing Company, Easton, Pa.
Suitable pharmaceutical carriers for parenteral administration
include, for example, sterile water, physiological saline,
bacteriostatic saline (saline containing about 0.9% mg/ml benzyl
alcohol), phosphate-buffered saline, Hank's solution,
Ringer's-lactate and the like. Some examples of suitable excipients
include lactose, dextrose, sucrose, trehalose, sorbitol, and
mannitol.
[0078] A pharmaceutically-acceptable salt form of GLP-1, of a GLP-1
analog, or of a GLP-1 derivative may be used in the present
invention. Acids commonly employed to form acid addition salts are
inorganic acids such as hydrochloric acid, hydrobromic acid,
hydroiodic acid, sulfuric acid, phosphoric acid, and the like, and
organic acids such as p-toluenesulfonic acid, methanesulfonic acid,
oxalic acid, p-bromophenyl-sulfonic acid, carbonic acid, succinic
acid, citric acid, benzoic acid, acetic acid, and the like.
Examples of such salts include the sulfate, pyrosulfate, bisulfate,
sulfite, bisulfite, phosphate, monohydrogenphosphate,
dihydrogenphosphate, metaphosphate, pyrophosphate, chloride,
bromide, iodide, acetate, propionate, decanoate, caprylate,
acrylate, formate, isobutyrate, caproate, heptanoate, propiolate,
oxalate, malonate, succinate, suberate, sebacate, fumarate,
maleate, butyne-1,4-dioate, hexyne-1,6-dioate, benzoate,
chlorobenzoate, methylbenzoate, dinitrobenzoate, hydroxybenzoate,
methoxybenzoate, phthalate, sulfonate, xylenesulfonate,
phenylacetate, phenylpropionate, phenylbutyrate, citrate, lactate,
gamma-hydroxybutyrate, glycolate, tartrate, methanesulfonate,
propanesulfonate, naphthalene-1-sulfonate, naphthalene-2-sulfonate,
mandelate, and the like. Preferred acid addition salts are those
formed with mineral acids such as hydrochloric acid and hydrobromic
acid, and, especially, hydrochloric acid.
[0079] Base addition salts include those derived from inorganic
bases, such as ammonium or alkali or alkaline earth metal
hydroxides, carbonates, bicarbonates, and the like. Such bases
useful in preparing the salts of this invention thus include sodium
hydroxide, potassium hydroxide, ammonium hydroxide, potassium
carbonate, and the like. The salt forms are particularly
preferred.
[0080] A GLP-1, GLP-1 analog, or GLP-1 derivative used in the
present invention may be formulated with one or more excipients
before use in the present invention. For example, the active
compound used in the present invention may be complexed with a
divalent metal cation by well-known methods. Such metal cations
include, for example, Zn.sup.++, Mn.sup.++, Fe.sup.++, Co.sup.++,
Cd.sup.++, Ni.sup.++, and the like.
[0081] The GLP-1 compounds may be formulated for administration
such that blood plasma levels are maintained in the efficacious
range for extended time periods. Various means can be employed to
achieve a protracted time action including, for example, the
incorporation of GLP-1 compounds into suspended amorphous or
crystalline particles wherein the GLP-1 compound is complexed with
zinc and slowly solubilizes upon administration. GLP-1 particles
that provide a protracted action are described in EP 926 159 by
Hoffmann et al. and EP 619 322 by Danley et al. In addition, depot
formulations wherein a bioadsorbable polymer is used to provide
sustained release over time are also suitable for use in the
present invention.
[0082] Preparation of GLP-1 Analogs and Derivatives
[0083] Alterations to a precursor GLP-1 or GLP-1 amino acid
sequence to produce a desired GLP-1 analog or GLP-1 derivative, or
active fragment thereof, are made by well-known methods:
solid-phase peptide synthesis techniques, chemical modification,
enzymatic modification, or a combination of chemical and enzymatic
modifications. The techniques of classical solution phase methods
and semi-synthetic methods may also be useful for preparing the
GLP-1 molecules used in the present invention. Methods for
preparing the GLP-1 molecules of the present invention are well
known to an ordinarily skilled peptide chemist. Peptide
synthesizers are commercially available from, for example, Applied
Biosystems in Foster City Calif. Reagents for solid phase synthesis
are commercially available, for example, from Midwest Biotech is
(Fishers, Ind.). Solid phase peptide synthesizers can be used
according to manufacturers instructions for blocking interfering
groups, protecting the amino acid to be reacted, coupling,
decoupling, and capping of unreacted amino acids. Identity of
peptides can be verified by mass spectrometry. Peptides can be
solubilized in aqueous buffers at neutral pH.
[0084] Addition of an acyl group to the epsilon amino group of
Lys34 may be accomplished using any one of a variety of methods
known in the art (Bioconjugate Chem. 1990; Hashimoto et al., 1989).
For example, an N-hydroxy-succinimide ester of octanoic acid can be
added to the lysyl-epsilon amine using 50% acetonitrile in borate
buffer. The peptide can be acylated either before or after the
imidazolic group is added. Moreover, if the peptide is prepared
recombinantly, acylation prior to enzymatic cleavage is possible.
Also, the lysine in the GLP-1 derivative can be acylated as taught
in WO 96/29342.
[0085] The existence and preparation of a multitude of protected,
unprotected, and partially-protected, natural and unnatural,
functional analogs and derivatives of GLP-1 (7-36)amide and
GLP-1(7-37) molecules have been described (U.S. Pat. Nos.
5,120,712; 5,545,618 and 5,118,666; Orskov et al., 1989; WO
91/11457).
[0086] Optionally, the amino and carboxy terminal amino acid
residues of GLP-1 derivatives may be protected, or, optionally,
only one of the termini is protected. Reactions for the formation
and removal of such protecting groups are described in works known
to those of skill in the art including, for example, Protective
Groups in Organic Chemistry 1973; Green, 1981; Schroder and Liibke,
1965. Representative amino-protecting groups include, for example,
formyl, acetyl, isopropyl, butoxycarbonyl,
fluorenylmethoxycarbonyl, carbobenzyloxy, and the like.
Representative carboxy-protecting groups include, for example,
benzyl ester, methyl ester, ethyl ester, t-butyl ester, p-nitro
phenyl ester, and the like.
[0087] Carboxy-terminal, lower-alkyl-ester, GLP-1 derivatives used
in the present invention are prepared by reacting the desired
(C1-C4) alkanol with the desired polypeptide in the presence of a
catalytic acid such as hydrochloric acid. Appropriate conditions
for such alkyl ester formation include a reaction temperature of
about 50.degree. C. and reaction time of about 1 hour to about 3
hours. Similarly, alkyl ester derivatives of the Asp and/or Glu
residues can be formed.
[0088] Preparation of a carboxamide derivative of a compound used
in the present invention is formed, for example, as described in
Stewart et al., 1984.
Exemplary Embodiments of Delivering GLP-Land Analogs Thereof
[0089] The GLP-1 therapeutics, including GLP-1 and analogs thereof,
may be delivered as medicaments to human or other non-human
mammalian patients in various dosing schemes, depending on specific
needs of the patients.
[0090] In certain embodiments, the medicament may be delivered in a
constant rate, over a period spanning several hours, several days,
several weeks, or even several months or years, so as to keep the
concentration/amount of the medicament in vivo at a relatively
constant level. For example, the fluid delivery system utilizing a
hydraulic pump, as described in U.S. Ser. No. 60/465,070 and the
related U.S. utility application U.S. Ser. No. 10/831,354, filed on
Apr. 23, 2004, claiming priority to U.S. Ser. No. 60/465,070 (all
incorporated herein be reference), may be employed for this
purpose. The fluid delivery system takes advantage of a hydraulic
pump, driven by a high-viscosity, ultrapure working fluid entering
from a reservoir to a pump chamber through an extremely small
aperture (about 1-100 .mu.m in diameter) on the wall of the pump
chamber, thus achieving slow, yet constant and smooth delivery of
medicament stored in an adjacent storage chamber. As described
therein, that type of device may be used to deliver potent
medicaments such as GLP-1 and analogs thereof at a constant slow
rate, over a long period of time (from several hours to days,
weeks, or months).
[0091] In an alternative embodiment as described in U.S. Ser. No.
60/465,070 and the related utility application, a second reservoir
that can be separately controlled can be attached to the pump
chamber, either though the same or a different aperture (see FIG.
8). That separate reservoir may be used as a separate control
mechanism to, for example, deliver an "on-demand boost" dose at
predetermined intervals. Thus, when combined with the first
reservoir, which delivers a constant dose of medicament, the second
reservoir can be used to deliver a bolus of extra amount of
medicament at times of need, such as after a meal, in additional to
the low, constant level of medicament. In this embodiment, the
boost does may be administered by the patient himself, or a
qualified care provider, by simply activate the actuator attached
to the second reservoir. For example, if the second actuator is a
simple spring-plate mechanism held inactive by a barrier mechanism,
as described in U.S. Ser. No. 60/465,070, it can be activated by
temporarily removing a barrier mechanism by the patient or the care
taker. After the boost administration, the barrier mechanism will
be allowed to inactivate the second reservoir before the next boost
administration.
[0092] In certain embodiments, medicaments may be delivered as
doses that can be controlled through sensors and dose control
indicator coupled to microneedles or microneedle arrays used to
deliver the medicament. Several exemplary embodiments are described
in detail in WO 03/024507 (incorporated herein be reference). Such
devices contain a dose control system that selects or regulates a
delivered dose based, at least in part, on a change in an
electrical, magnetic or optical parameter. Briefly, the microneedle
devices disclosed therein in some embodiments include a substrate;
one or more microneedles; and, optionally, a reservoir for delivery
of drugs or collection of analyte, as well as pump(s), sensor(s),
and/or microprocessor(s) to control the interaction of the
foregoing.
[0093] The pump-driven microneedle device may include a reservoir
in communication with the pump and microneedles, so that fluid
stored in the reservoir, when driven by the attached pump, may exit
through the microneedles (or arrays/patches thereof). The reservoir
can be attached to the substrate by any suitable means. In a
preferred embodiment, the reservoir is attached to the back of the
substrate (opposite the microneedles) around the periphery, using
an adhesive agent (e.g., glue). A gasket may also be used to
facilitate formation of a fluid-tight seal. In one embodiment, the
reservoir contains drug (e.g. GLP-1 and analogs thereof), for
delivery through the microneedles. The reservoir may be a hollow
vessel, a porous matrix, or a solid form including drug which is
transported therefrom. The reservoir can be formed from a variety
of materials that are compatible with the drug or biological fluid
contained therein. Preferred materials include natural and
synthetic polymers, metals, ceramics, semiconductors, organics, and
composites.
[0094] The microneedle device can include one or a plurality of
chambers for storing materials to be delivered. In the embodiment
having multiple chambers, each can be in fluid connection with all
or a portion of the microneedles of the device array. In one
embodiment, at least two chambers are used to separately contain
drug (e.g., a lyophilized drug, such as a vaccine) and an
administration vehicle (e.g., saline) in order to prevent or
minimize degradation during storage. Immediately before use, the
contents of the chambers may be mixed. Mixing can be triggered by
any means, including, for example, mechanical disruption (i.c.
puncturing or breaking), changing the porosity, or electrochemical
degradation of the walls or membranes separating the chambers. In
another embodiment, a single device is used to deliver different
drugs, which are stored separately in different chambers. In this
embodiment, the rate of delivery of each drug can be independently
controlled.
[0095] In a preferred embodiment, the reservoir is in direct
contact with the microneedles and have holes through which drug
could exit the reservoir and now into the interior of hollow or
porous microneedles. In another preferred embodiment, the reservoir
has holes which permit the drug to transport out of the reservoir
and onto the skin surface. From there, drug is transported into the
skin, either through hollow or porous microneedles, along the sides
of solid microneedles, or through pathways created by microneedles
in the skin.
[0096] The pump-driven microneedle device described therein is
capable of transporting material across the barrier (e.g. skin) at
a useful rate, e.g., a rate sufficient to be therapeutically
useful. The device may include a housing with microelectronics and
other micromachined structures to control the rate of delivery
either according to a preprogrammed schedule or through active
interface with the patient, a healthcare professional, or a
biosensor. The rate can be controlled by manipulating a variety of
factors, including the characteristics of the drug formulation to
be delivered (e.g., its viscosity, electric charge, and chemical
composition); the dimensions of each microneedle (e.g., its outer
diameter and the area of porous or hollow openings); the number of
microneedles in the device; the application of a driving force
(e.g., a concentration gradient, a voltage gradient, a pressure
gradient); and the use of a valve.
[0097] The rate also can be controlled by interposing between the
drug in the reservoir and the opening(s) at the base end of the
microneedle polymeric or other materials selected for their
diffusion characteristics. For example, the material composition
and layer thickness can be manipulated using methods known in the
art to vary the rate of diffusion of the drug of interest through
the material, thereby controlling the rate at which the drug flows
from the reservoir through the microneedle and into the tissue.
[0098] Transportation of molecules through the micioneedles can be
controlled or monitored using, for example, various combinations of
valves, pumps, sensors, loactuators, and microprocessors. These
components can be produced using standard manufacturing or
microfabrication techniques. Actuators that may be useful with the
microneedle devices disclosed herein include micropumps,
microvalves, and positioners. In a preferred embodiment, a
microprocessor is programmed to control a pump or valve, thereby
controlling the rate of delivery.
[0099] Flow of molecules through the microneedles can usually occur
based on diffusion, capillary action, or can be induced using
mechanical pumps (conventional or the subject hydraulic pump, one
of a preferred embodiments) or non-mechanical driving forces, such
as electroosmosis or electrophoresis, or convection. For example,
in electroosmosis, electrodes are positioned on the biological
barrier surface, one or more microneedles, and/or the substrate
adjacent the needles, to create a convective flow which carries
oppositely charged ionic species and/or neutral molecules toward or
into the biological barrier. In a preferred embodiment, the
microneedle device is used in combination with another mechanism
that enhances the permeability of the biological barrier, for
example by increasing cell uptake or membrane disruption, using
electric fields, ultrasound, chemical enhancers, viruses, pH, heat
and/or light.
[0100] Passage of the microneedles, or drug to be transported via
the microneedles, can be manipulated by shaping the microneedle
surface, or by selection of the material forming the microneedle
surface (which could be a coating rather than the microneedle per
se). For example, one or more grooves on the outside surface of the
microneedles can be used to direct the passage of drug,
particularly in a liquid state.
[0101] Alternatively, the physical surface properties of the
microneedle could be manipulated to either promote or inhibit
transport of material along the microneedle surface, such as by
controlling hydrophilicity or hydrophobicity.
[0102] The flow of molecules can be regulated using a wide range of
valves or gates. These valves can be the type that are selectively
and repeatedly opened and closed, or they can be single-use types.
For example, in a disposable, single-use drug delivery device, a
fracturable barrier or one-way gate may be installed in the device
between the reservoir and the opening of the microneedles. When
ready to use, the barrier can be broken or gate opened to permit
flow through the microneedles. Other valves or gates used in the
microneedle devices can be activated thermally, electrochemically,
mechanically, or magnetically to selectively initiate, modulate, or
stop the flow of molecules through the needles. In a preferred
embodiment, flow is controlled by using a rate-limiting membrane as
a "valve." The microneedle devices can further include a flowmeter
or other dose control system to monitor flow and optionally control
flow through the microneedles and to coordinate use of the pumps
and valves.
[0103] Useful sensors may include sensors of pressure, temperature,
chemicals, and/or electromagnetic fields. Biosensors can be
employed, and in one arrangement, are located on the microneedle
surface, inside a hollow or porous microneedle, or inside a device
in communication with the body tissue via the microneedle (solid,
hollow, or porous). These microneedle biosensors may include any
suitable transducers, including but not limited to potentionietric,
amperometric, optical, magnetic and physiochemical. An amperometric
sensor monitors currents generated when electrons are exchanged
between a biological system and an electrode. Blood glucose sensors
frequently are of this type, and is particularly useful for
controlling the administration of GLP-1 and its functional analogs.
As described herein, the sensors may be formed to sense changes
resulting from an election transfer agent interacting with analyte
or analytes of interest, e.g. blood glucose level.
[0104] The microneedle may function as a conduit for fluids,
solutes, electric charge, light, or other materials. In one
embodiment, hollow microneedles can be filled with a substance,
such as a gel, that has a sensing functionality associated with it.
In an application for sensing based on binding to a substrate or
reaction mediated by an enzyme, the substrate or enzyme can be
immobilized in the needle interior, which would be especially
useful in a porous needle to create an integral needle/sensor.
[0105] Wave guides can be incorporated into the microneedle device
to direct light to a specific location, or for dection, for
example, using means such as a pH dye for color evaluation.
Similarly, heat, electricity, light or other energy forms may be
precisely transmitted to directly stimulate, damage, or heal a
specific tissue or intermediary (e.g., tattoo remove for dark
skinned persons), or diagnostic purposes, such as measurement of
blood glucose based on IR spectra or by chromatographic means,
measuring a color change in the presence of immobilized glucose
oxidase in combination with an appropriate substrate.
[0106] In a preferred embodiment, the microneedle device includes
an adhesive to temporarily secure the device to the surface of the
biological barrier. The adhesive can be essentially anywhere on the
device to facilitate contact with the biological barrier. For
example, the adhesive can be on the surface of the collar (same
side as microneedles), on the surface of the substrate between the
microneedles (near the base of the microneedles), or a combination
thereof.
[0107] Pages 13-18 of the published PCT WO 03/024507 describes in
detail the different embodiments of the microneedles and arrays
thereof that may be coupled to the subject fluid delivery system.
The contents are incorporated herein by reference.
[0108] Methods of manufacturing, as well as various design features
and methods of using, the microneedles and microneedle arrays
described herein are diklosed, for example, in Published PCT patent
application WO 99/64580, entitled "Microneedle Devices and Methods
of Manufacture and Use Thereof," Published PCT patent application
WO 00/74763, entitled "Devices and Methods for Enhanced Microneedle
Penetration or Biological Barriers," Published PCT patent
application WO 01/49346, and published PCT WO 00/48669, each of
which is incorporated herein by reference. Generally, the
microneedles and arrays thereof can be prepared using a variety of
ways, including electrochemical etching techniques, plasma etching
techniques, electroplating techniques, and microfabrication
techniques.
[0109] FIG. 9 depicts the microneedle 200 with a sensor
electrically coupled between the metal layer 102 and the metal
layer 106. The sensor can be suitable sensor capable of measuring
or detecting a change in an electrical parameter, such as voltage,
current, capacitance, resistance and/or inductance. The sensor may
comprise a resistor, differential amplifier, capacitance meter or
any other suitable device. In the embodiment of FIG. 5, the sensor
measures changes in an electrical parameter, but is other
embodiments, the sensor may be capable of measuring a magnetic
parameter, such as a hall effect device, or an optical,
characteristic. The sensor may generate a signed capable of
operating a dose control system or flow meter that controls or
allows the flow of a drug to the patient.
[0110] Optionally, the sensor may control an alarm or indicator
that may be visual, or auditory.
[0111] In embodiments, microneedles, microneedle arrays, and/or
microneedle systems can be involved in delivering drugs. For
example, a system can include a sample section and a delivery
section. The sections can be in communication so that the delivery
section delivers one or more desired medicaments in response to a
signal from the sample section.
[0112] The device may be used for single or multiple uses for rapid
transport across a biological barrier or may be left in place for
longer times (e.g., hours or days) for long-term transport of
molecules. Depending on the dimensions of the device, the
application site, and the route in which the device is introduced
into (or onto) the biological barrier, the device may be used to
introduce or remove molecules at specific locations.
[0113] In one embodiment, the microneedle device may be used in a
transdermal application to deliver GLP-1 or analogs. The device is
applied to the skin such that the microneedles penetrate through
the stratum corneum and enter the viable epidermis so that the tip
of the microneedle at least penetrates into the viable epidermis.
In a preferred embodiment, drug molecules in a reservoir within the
upper portion flow through or around the microneedles and into the
viable epidermis, where the drug molecules then diffuse into the
dermis for local treatment or for transport through the body.
[0114] To control the transport of material out of or into the
device through the microneedles, a variety of forces or mechanisms
can be employed. These include pressure gradients, concentration
gradients, electricity, ultrasound, receptor binding, heat,
chemicals, and chemical reactions. Mechanical or other gates in
conjunction with the forces and mechanisms described above can be
used to selectively control transport of the material.
[0115] In particular embodiments, the device should be
"user-friendly." For example, in some transdermal applications,
affixing the device to the skin should be relatively simple, and
not require special skills. This embodiment of a microneedle may
include an array of microneedles attached to a housing containing
drug in an internal reservoir, wherein the housing has a
bioadhesive coating around the microneedles. The patient can remove
a peel-away backing to expose an adhesive coating, and then press
the device onto a clean part of the skin, leaving it to administer
drug over the course of, for example, several days.
[0116] In this way, many drugs can be delivered at a variety of
therapeutic rates. The rate can be controlled by varying a number
of design factors, including the outer diameter of the microneedle,
the number and size of pores or channels in each microneedle, the
number of microneedles in an array, the magnitude and frequency of
application of the force driving the drug through the microneedle
and/or the holes created by the microneedles. For example, devices
designed to deliver drug at different rates might have more
microneedles for more rapid delivery and fewer microneedles for
less rapid delivery. As another example, a device designed to
deliver drug at a variable rate could vary the driving force (e.g.,
pressure gradient controlled by a pump) for transport according to
a schedule which was preprogrammed or controlled by, for example,
the user or his doctor. The devices can be affixed to the skin or
other tissue to deliver drugs continuously or intermittently, for
durations ranging from a few seconds to several hours or days.
[0117] One of skill in the art can measure the rate of drug
delivery for particular microneedle devices using in vitro and in
vivo methods known in the art. For example, to measure the rate of
transdermal drug delivery, human cadaver skin mounted on standard
diffusion chambers can be used to predict actual rates. See
Hadgraft & Guy, eds., Transdermal Drug Delivery: Developmental
Issues and Research Initiatives (Marcel Dekker, New York 1989);
Bronaugh & Maibach, Percutaneous Absorption,
Mechanisms--Methodology--Drug Delivery (Marcel Dekker, New York
1989). After filling the compartment on the dermis side of the
diffusion chamber with saline, a microneedle array is inserted into
the stratum corneum; a drug solution is placed in the reservoir of
the microneedle device; and samples of the saline solution are
taken over time and assayed to determine the rates of drug
transport.
Exemplary Therapeutic Uses of GLP-1
[0118] GLP-1 compounds encompassed by the present invention exert
their biological effects by acting at a receptor referred to as the
"GLP-1 receptor" (see U.S. Pat. No. 5,670,360). Subjects with
diseases and/or conditions that respond favorably to GLP-1 receptor
stimulation or to the administration of GLP-1 compounds can
therefore be treated with the GLP-1 compounds of the present
invention. These subjects are said to "be in need-of treatment with
GLP-1 compounds" or "in need of GLP-1 receptor stimulation."
[0119] Included are subjects with non-insulin dependent diabetes,
insulin dependent diabetes, stroke (see WO 00/16797 by Efendic),
myocardial infarction (see WO 98/08531 by Efendic), obesity (see WO
98/19698 by Efendic), catabolic changes after surgery (see U.S.
Pat. No. 6,006,753 to Efendic), functional dyspepsia and irritable
bowel syndrome (see WO 99/64060 by Efendic). Also included are
subjects requiring prophylactic treatment with a GLP-1 compound,
e.g., subjects at risk for developing non-insulin dependent
diabetes (see WO 00/07617). Additional subjects include those with
impaired glucose tolerance or impaired fasting glucose, subjects
whose body weight is about 25% above normal body weight for the
subject's height and body build, subjects with a partial
pancreatectomy, subjects having one or more parents with
non-insulin dependent diabetes, subjects who have had gestational
diabetes and subjects who have had acute or chronic pancreatitis
are at risk for developing non-insulin dependent diabetes.
[0120] The GLP-1 compounds can be used to normalize blood glucose
levels, prevent pancreatic P-cell deterioration, induce P-cell
proliferation, stimulate insulin gene transcription, up-regulate
IDX-I/PDX-1 or other growth factors, improve P-cell function,
activate dormant cells, differentiate cells into P-cells, stimulate
P-cell replication, inhibit P-cell apoptosis, regulate body weight,
and induce weight loss.
[0121] An "effective amount" of a GLP-1 compound is the quantity
which results in a desired therapeutic and/or prophylactic effect
without causing unacceptable side effects when administered to a
subject in need of GLP-1 receptor stimulation. A "desired
therapeutic effect" includes one or more of the following: 1) an
amelioration of the symptom(s) associated with the disease or
condition; 2) a delay in the onset of symptoms associated with the
disease or condition; 3) increased longevity compared with the
absence of the treatment; and 4) greater quality of life compared
with the absence of the treatment. For example, an "effective
amount" of a GLP-1 compound for the treatment of diabetes is the
quantity that would result in greater control of blood glucose
concentration than in the absence of treatment, thereby resulting
in a delay in the onset of diabetic complications such as
retinopathy, neuropathy or kidney disease. An "effective amount" of
a GLP-1 compound for the prevention of diabetes is the quantity
that would delay, compared with the absence of treatment, the onset
of elevated blood glucose levels that require treatment with
anti-hypoglycaemic drugs such as sulfonyl ureas,
thiazolidinediones, insulin and/or bisguanidines.
[0122] An "effective amount" of the GLP-1 compound administered to
a subject will also depend on the type and severity of the disease
and on the characteristics of the subject, such as general health,
age, sex, body weight and tolerance to drugs. Typically, the GLP-1
compounds of the present invention will be administered such that
plasma levels are within the range of about 5 picomoles/liter and
about 200 picomoles/liter. Optimum plasma levels for
Val8GLP-1(7-37)OH were determined to be between 30 picomoles/liter
and about 200 picomoles/liter. Because some of the GLP-1 analogs
are more potent than Val8-GLP-1 (7-37) OH, the optimum plasma
levels will be lower. Generally, a GLP-1 compound that has an in
vitro or in vivo potency that is 3-fold better than
Val8-GLP-1(737)OH will be administered such that plasma levels are
3-fold lower than the optimum levels determined for
Val8-GLP1(7-37)OH.
[0123] A typical dose range for the GLP-1 compounds will range from
about 0.01 mg per day to about 1000 mg per day for an adult.
Preferably, the dosage ranges from about 0.1 mg per day to about
100 mg per day, more preferably from about 1.0 mg/day to about 10
mg/day.
[0124] A "subject" or a "patient" is a mammal, preferably a human,
but can also be an animal, e.g., companion animals (e.g., dogs,
cats, and the like), farm animals (e.g., cows, sheep, pigs, horses,
and the-like) and laboratory animals (e.g., rats, mice, guinea
pigs, and the like).
[0125] The following section describes in detail various biological
effects of GLP-1 and analogs thereof. In many cases, these effect
of GLP-1 can be effectuated by infusion of GLP-1, either
continuously, or intermittently, using the various pump devices
described above to achieve pre-determined infusion rates and
patterns.
[0126] The biological activities of GLP-1 include stimulation of
glucose-dependent insulin secretion and insulin biosynthesis,
inhibition of glucagon secretion and gastric emptying, and
inhibition of food intake. GLP-1 appears to have a number of
additional effects in the GI tract and central nervous system
(CNS), as reviewed in Diabetes 1998 47(2):159-69; Drucker,
Endocrinology 142(2): 521-7, 2001; Drucker, Curr Pharm Des. 7(14):
1399-412, 2001; Drucker, Gastroenterology 122(2): 531-44, 2002.
These include strong inhibition of gastropancreatic secretion and
gastric motility (O'Halloran et al., J. Endocrinol. 126: 169-173,
1990; Schjoldager et al., Dig. Dis. Sci. 34: 703-708, 1989;
Wettergren et al., Scand. J. Gastroenterol. 32: 552-555, 1997;
Wettergren et al., Scand. J. Gastroenterol. 29: 501-505, 1994;
Wettergren et al., Dig. Dis. Sci. 4: 665-673, 1993), and mediating
the ileal-brake effect (i.e., the endocrine inhibition of upper
gastrointestinal motility and secretion elicited by the presence of
nutrients in the distal small intestine; Layer et al., Dig. Dis.
Sci. 40: 1074-1082, 1995).
GLP-1 and the .beta. Cell
[0127] One of the first actions identified for GLP-1 was the
glucose-dependent stimulation of insulin secretion from islets in
rodents, humans, or from islet cell lines. See Mojsov et al., J.
Clin. Invest. 79(2): 616-9, 1987; Kreymann et al., Lancet 2(8571):
1300-4, 1987; Holst et al., FEBS Lett. 211(2): 169-74, 1987; and
Drucker et al., PNAS USA. 84(10): 3434-8, 1987. Following the
detection of GLP-1 receptors on islet beta cells, a large body of
evidence has accumulated illustrating that GLP-1 exerts multiple
actions on various signaling pathways and gene products in the
.beta. cell. For a summary of .beta. cell genes and proteins
activated by GLP-1, see table below.
TABLE-US-00002 Summary of .beta. Cell genes and proteins activated
by GLP-1 Experimental Model Gene or Protein INS-1 cells Akt and IRS
proteins INS-1 cells Glucokinase RIN1046-38 cells GLUT-1 RNA
RIN1046-38 cells Hexokinase I RNA INS-1 cells Immediate early genes
Multiple cell models Insulin RNA INS-1 cells Kir 6.2 RNA Multiple
islet cell lines Pdx-1 RNA and protein RIN1046-38 cells SNAP-25
phosphorylation INS-1 cells Calcineurin and NFAT
GLP-1, Islet Proliferation and Differentiation and Apoptosis
[0128] The finding that GLP-1 lowers blood glucose in patients with
diabetes, taken together with suggestions that GLP-1 may restore
.beta. cell sensitivity to exogenous secretagogues, suggests that
augmenting GLP-1 signaling is a useful strategy for treatment of
diabetic patients. There are a number of different GLP-1 targets or
loci that may be exploited to enhance GLP-1 action in diabetic
subjects.
[0129] Mounting evidence also strongly suggests that GLP-1
signaling regulates islet proliferation and islet neogenesis. The
observations that GLP-1R agonists including exendin-4 may play a
role in islet neogenesis or differentiation have engendered
considerable interest and excitement given the potential of these
actions to enhance b cell function in subjects with Type 2
diabetes. Furthermore, the possibility that GLP-1 receptor
activation may enhance .beta. cell mass in patients with Type 1
diabetes is also under active investigation, in a NIH sponsored
clinical trial (Effect of AC2993 with or without Immunosuppression
on Beta Cell Function in Patients with Type I Diabetes, Sponsored
by National Institute of Diabetes and Digestive and Kidney Diseases
(NIDDK)).
[0130] Complementary findings from several labs, using a variety of
experimental rodent and cell models, indicate that GLP-1 agonists
may modulate .beta. cell mass in part via reduction of .beta. cell
apoptosis. These actions may be directly relevant to protection of
human islet .beta. cells as incubation of human islets with native
GLP-1 for 5 days preserved islet morphology, reduced the expression
of pro-apoptotic genes, decreased cell death, and improved
glucose-stimulated insulin secretion. See Farilla et al.,
Endocrinology 144(12): 5149-58, 2003; Drucker, Endocrinology
144(12): 5145-5148, 2003.
[0131] The anti-apoptotic properties of GLP-1 agonists have been
demonstrated in Zucker diabetic rats and db/db mice. A 2 day
infusion of GLP-1 increased islet size and .beta. cell mass, and
reduced the numbers of apoptotic cells in the exocrine portion of
the pancreas. The percentage of apoptotic .beta. cells in this
study was surprisingly high at greater than 20%, and was
significantly reduced by GLP-1 treatment. See Farilla et al.,
Endocrinology 143(11): 4397-4408, 2002.
[0132] Treatment of normoglycemic db/db mice with daily exendin-4
for 14 days prevented the progression to more frank diabetes,
increased .beta. cell mass, and numbers of BrdU+ islet cells, and
reduced numbers of Tunel+ apoptotic .beta. cells. Exendin-4-treated
rats also exhibited increased levels of pancreatic Akt1, the
prosurvival kinase, increased p44 MAP kinase, and reduced
expression of activated caspase-3. See Wang and Brubaker,
Diabetologia 45(9): 1263-73, 2002.
[0133] Similarly, treatment of mice with exendin-4 reduced .beta.
cell apoptosis induced by streptozotocin (STZ), whereas GLP-1R-/-
mice exhibited increased susceptibility to STZ-induced .beta. cell
apoptosis. Furthermore, exendin-4 directly reduced the extent of
apoptotic cell death in purified rat b cells exposed to a
combination of cytotoxic cytokines, and GLP-1 or exendin-4
increased cell survival and reduced caspase activation in BHK
fibroblasts expressing a transfected GLP-1 receptor. Hence these
findings implicate a direct role for .beta. cell GLP-1 receptor
signaling in regulation of the resistance to cellular apoptosis.
See Li et al., J. Biol. Chem. 278(1): 471-8, 2003.
[0134] Treatment of Min6 mouse islet cells with GLP-1 reduced the
extent of hydrogen peroxide-induced apoptosis in vitro. The
anti-apoptotic effects of GLP-1 were partially blocked by either
the cAMP "antagonist" Rp-cAMP, or the PI 3-kinase inhibitor
LY294002. GLP-1 prevented cell death only when applied prior to
exposure of cells to peroxide. See Hui et al., Endocrinology
144(4): 1444-55, 2003.
[0135] Similarly, induction of fatty acid induced apoptosis in
Rinm5F cells with palmitate was markedly reduced by agents that
increased levels of cyclic AMP, including Cyclic AMP
dose-dependently prevents palmitate-induced apoptosis by both PKA-
and cAMP- GEF-dependent pathways in beta-cells. Kwon et al., J.
Biol. Chem. 279(10): 8938-45, 2004 (Epub 2003 Dec. 19).
[0136] Related studies using rat INS-1 cells demonstrated that
protein kinase B (Akt) is rapidly activated by Glucagon-like
peptide-1 regulates proliferation and apoptosis via activation of
protein kinase B in pancreatic INS-1 beta cells. Wang et al.,
Diabetologia 47(3): 478-87, 2004 (Epub 2004 Feb. 5).
[0137] The anti-apoptotic actions of GLP-1 agonists have been
demonstrated in cultured fetal rat hippocampal neurons which
exhibit GLP-1-dependent increases in cAMP formation. Both GLP-1 and
exendin-4 significantly reduced the extent of glutamate-induced
cell death in short term cultures of hippocampal neurons.
Furthermore, both GLP-1 and exendin-4 reduced depletion of choline
acetyltransferase immunoreactivity, a marker for cholinergic
neurons in the basal forebrain, following administration of
ibotenic acid. See Perry et al., J. Pharmacol. Exp. Ther. 302(3):
881-8, 2002; Gilman et al., J. Neurochem. 87(5): 1137-44, 2003.
[0138] The calpain-10 molecule has also been linked to .beta. cell
apoptosis, and may be modified by GLP-1 receptor activation. GLP-1
decreased calpain activity, reversed ryanodine-induced calpain
activation and apoptosis in .beta. cells and MIN6 cells, as shown
in RyR2 and calpain-10 delineate a novel apoptosis pathway in
pancreatic islets. Johnson et al., J. Biol. Chem. 2004 Mar. 25
[Epub ahead of print].
[0139] Evidence that GLP-1 stimulates islet cell proliferation in
vitro is illustrated in Glucose and glucoincretin peptides
synergize to induce c-fos, c-jun, junB, zif-268, and nur-77 gene
expression in pancreatic beta(INS-1) cells. Susini et al., FASEB J.
12(12): 1173-82, 1998; Buteau et al., Diabetologia 42(7): 856-64,
1999.
[0140] The signal transduction system activated by the GLP-1R
signaling system depends on the islet cell model under study, with
cAMP, PKC and PI-3-kinase activated by the GLP-1R in several
studies. Buteau et al., Diabetes 50(10): 2237-2243, 2001.
[0141] Provocative experiments using the INS-1 cell line
demonstrate the potential involvement of the EGFR and EGFR ligands
such as betacellulin in the direct and indirect GLP-1R-dependent
activation of cell proliferation as shown in Glucagon-Like Peptide
1 Induces Pancreatic beta-Cell Proliferation Via Transactivation of
the Epidermal Growth Factor Receptor. Buteau et al., Diabetes
52(1): 124-32, 2003.
[0142] The cyclic AMP-dependent transcription factor CREB has been
linked to GLP-1-mediated cell growth and survival, as outlined in
cAMP promotes pancreatic beta-cell survival via CREB-mediated
induction of IRS2. Jhala et al., Genes Dev. 17(13): 1575-80,
2003.
[0143] Incubation of pancreatic exocrine cells with GLP-1 or
exendin-4 promotes differentiation of the AR42J cell line to an
endocrine phenotype. Differentiated cells exhibited increased
expression of .beta. cell genes and the capacity for
glucose-dependent insulin secretion. Zhou et al., Diabetes 48(12):
2358-66, 1999.
[0144] Similarly, treatment of fetal (75-90 day gestational age)
pig islet clusters with GLP-1 promoted glucose-dependent insulin
secretion and after several days of treatment with GLP-1R agonists,
the cells exhibited increased Pdx-1 expression and enhanced
differentiation along the .beta. cell pathway. Furthermore,
transplantation of the GLP-1-treated islet clusters into SCID mice
revealed a significantly increased number of functionally mature
.beta. cells after 8 weeks in vivo. See Hardikar et al.,
Endocrinologyl 43(9):3505-14, 2002.
[0145] GLP-1(1-37) also plays a role in intestinal differentiation.
The vast majority of GLP-1 produced in gut endocrine cells is
either GLP-1(7-36)amide or GLP-1(7-37). Very little is known about
the generation and biological activity of GLP-1(1-37). Suzuki et
al. demonstrate that GLP-1(1-37) is capable of inducing intestinal
cells to undergo 13 cell-like differentiation, in association with
development of glucose-dependent insulin secretion. These effects
were observed using organ culture in vitro, blocked by the GLP-1R
antagonist exendin(9-39) and were also detected following injection
of pregnant or adult mice with GLP-1(1-37) in vivo. See Suzuki et
al., Proc. Natl. Acad. Sci. U.S.A. 100(9): 5034-9, 2003 (Epub 2003
Apr. 17).
[0146] GLP-1 is further implicated in human .beta. cell
differentiation. A series of elegant experiments now demonstrates
that a combination of GLP-1 receptor agonists (such as exendin-4),
pdx-1 expression, and cell-cell contact, promotes the development
of a more differentiated .beta. cell in vitro. See de la Tour et
al., Mol. Endocrinol. 15(3): 476-483, 2001. Similarly, incubation
of the human ductal cell line Capan-1, which expresses the GLP-1R,
with exendin-4 results in a significant increase in the number of
cells exhibiting immunopositivity for insulin or glucagon, and
induction of islet genes such as PDX-1, BETA2/NeuroD, and HNF-3b.
Increased binding of HNF-3b to Pdx-1 promoter elements may
represent one component of the differentiation mechanism activated
by the GLP-1R in these cells. See Zhou et al., J. Cell. Physiol.
192(3): 304-14, 2002.
[0147] GLP-1R (receptor for GLP-1) has also been localized to
nestin positive islet-derived progenitor cells (NIPs) identified in
islets and duct cells. About 60% of NIPs exhibit GLP-1R
immunopositivity, and the GLP-1R is capable of transducing a
functional [Ca.sup.2+]i response that is blocked by the GLP-1R
antagonist exendin(9-39); this response was detected at normal but
not elevated glucose concentrations. Incubation of human NIP cells
with GLP-1 or exendin-4 induced insulin expression in subsets of
cells, and also produced changes in cellular morphology. GLP-1R
agonists also induced insulin secretion in .about.30% of NIP
clones. Intriguingly, NIP cultures that approached confluence
expressed the proglucagon gene and secreted GLP-1 into the culture
medium, raising the possibility of an autocrine
GLP-1-differentiation loop in these cells. See Abraham et al.,
Endocrinology 143(8): 3152-61, 2002.
[0148] Exendin-4 has also been shown to enhance Pdx-1 expression,
but not insulin expression, in human islet-like cell clusters
treated for 4 days in vitro, and exendin-4 treatment of rats (10
days of injections initiated 48 hrs after the transplantation
procedure) with transplanted clusters induced functional maturation
of transplanted cells, and promoted the differentiation and growth
of clusters transplanted under the kidney capsule, as assessed 8
weeks following the transplant. See Movassat et al., J. Clin.
Endocrinol. Metab. 87(10): 4775-4781, 2002.
[0149] Several lines of evidence support a role for GLP-1 in the
control of islet proliferation and regeneration in rodent studies
in vivo. Administration of subcutaneous GLP-1 for 2 days to lean
mice increased the islet labeling index, as shown by Edvell and
Lindstrom in Endocrinology 140(2): 778-83, 1999. Initiation of
increased pancreatic islet growth in young normoglycemic mice (Umea
+/?). In complementary studies using normal rats and the rat
pancreatectomy model, Xu et al demonstrated that exendin-4
increases islet neogenesis and .beta. cell proliferation.
Furthermore, exendin-4 attenuates glucose intolerance following
partial pancreatectomy in the rat. Diabetes 48(12): 2270-6, 1999.
Exendin-4 stimulates both beta-cell replication and neogenesis,
resulting in increased beta-cell mass and improved glucose
tolerance in diabetic rats. Similarly, infusion of GLP-1 for 5 days
in both young and old rats increased .beta. cell mass and promoted
enhanced pdx-1 expression and islet neogenesis Glucagon-like
peptide-1 induces cell proliferation and pancreatic-duodenum
homeobox-1 expression and increases endocrine cell mass in the
pancreas of old, glucose-intolerant rats. Perfetti et al.,
Endocrinology 141(12): 4600-5, 2000.
[0150] If administered to young 6 week old prediabetic db/db mice,
daily exendin-4 treatment for 2 weeks prevented the progression to
more severe diabetes, in association with expansion of islet mass
and improved glucose tolerance and insulin secretion. See Wang and
Brubaker Diabetologia 45(9): 1263-73, 2002. Similarly, NN2211 and
exendin-4 increased .beta. cell proliferation in db/db mice, but
not in ob/ob mice, as shown in Rolin et al., Am. J. Physiol.
Endocrinol. Metab. 283(4): E745-52, 2002 and islet proliferative
effects were also detected following a 2 week treatment period with
exendin-4 in young db/db mice. See Wang and Brubaker, Diabetologia.
45(9): 1263-73, 2002.
[0151] Administration of the GLP-1R agonist Liraglutide (NN2211) to
normal and ZDF rats as well as to 60% pancreatectomized rats
demonstrated that the ability of Liraglutide to expand b cell mass
was correlated with the metabolic milieu, and the duration of
treatment, with normoglycemic normal animals failing to show an
increase in b cell mass, whereas hyperglycemic animals responded to
Liraglutide with an increase in b cell mass. Similarly, b cell mass
was increased in non-diabetic Sprague-Dawley rats treated with
Liraglutide for 1 week, but after 6 weeks of treatment, b cell mass
was comparable in treated vs control rats, as described in The
endocrine pancreas in non-diabetic rats after short-term and
long-term treatment with the long-acting GLP-1 derivative NN2211.
Bock et al., APMIS. 111(12): 1117-1124, 2003. Hence, the trophic
effects of GLP-1R agonists in the islet, like their insulinotropic
properties, are probably coupled to the presence of hyperglycemia.
See Sturis et al., Br J Pharmacol. 140(1): 123-132, 2003.
[0152] Complementary studies of GLP-1 or exendin-4 administration
for 5 days in the neonatal GK rat demonstrate persistent
improvement in glucose homeostasis, enhanced pancreatic insulin
content and total beta-cell mass due to stimulation of beta-cell
neogenesis and regeneration. Follow-up from day 7 to adult age (2
months) demonstrated GLP-1 or Ex-4 treated rats maintained enhanced
beta-cell mass and improved glycemic control at adult (2 months)
age. See Tourrel et al., Diabetes. 51(5): 1443-1452, 2002.
[0153] The finding of only modest and subtle abnormalities in islet
development in GLP-1R-/- mice suggest that islets develop normally
in the absence of GLP-1R signaling. Furthermore, the development of
islet hyperplasia and hyperinsulinemia in the setting of insulin
resistance, hyperglycemia and leptin deficiency is not compromised
in the ob/ob:GLP-1R-/- mutant mouse. Hence it appears that although
activation of GLP-1R signaling stimulates islet neogenesis and
proliferation, the GLP-1R signaling pathway is not required for
islet adaptation in the mouse in vivo. See Scrocchi et al.,
Diabetes 49(9): 1552-60, 2000.
[0154] A complementary approach to address the importance of
endogenous GLP-1 receptor expression for b cell regeneration
involves analysis of the islet regenerative responsive to partial
pancreatectomy. Wildtype mice subjected to partial pancreatectomy
were infused with the antagonist exendin(9-39); partial
pancreatectomy was also carried out in GLP-1R-/- mice. In
Ex(9-39)-treated sham-operated mice, persistent fasting
hyperglycemia was observed, but b cell mass was not diminished. In
pancreatectomized mice, persistent glucose intolerance was noted,
but this was not further exacerbated by Ex(9-39) and recovery of b
cell mass in Ppx mice was not impaired. In contrast, GLP-1R(-/-)
mice exhibited greater hyperglycemia after pancreatectomy compared
with wild-type mice, and this correlated with a significant defect
in regeneration of b cell mass. Hence, the importance of endogenous
GLP-1R signaling following partial pancreatectomy depends on the
experimental context. See Role of Endogenous Glucagon-Like
Peptide-1 in Islet Regeneration After Partial Pancreatectomy. De
Leon et al., Diabetes 52(2): 365-371, 2003.
[0155] These new findings add yet another important mechanism to
the broad spectrum of GLP-1 actions which converge on lowering
blood glucose in vivo. Furthermore, the possibility that activation
of GLP-1 signaling might be therapeutically useful for regeneration
of 13 cell mass has important implications for the treatment of
Type 1 and Type 2 Diabetes.
[0156] Several studies address the possibility that islet A cell
may produce GLP-1 in the context of islet development or
regeneration, by demonstrating induction of PC1 expression in A
cells, the prohormone convertase responsible for liberating GLP-1
from proglucagon. Pancreatic and A cell expression of PC1 is
induced in rats given streptozotocin, leading to small but
significant increases in the levels of bioactive GLP-1 in the rat
pancreas Regulation of pancreatic PC1 and PC2 associated with
increased glucagon-like peptide 1 in diabetic rats. Nie et al., J.
Clin. Invest. 105(7): 955-65, 2000. A second study documents the
developmental expression of proglucagon and PC1 in the embryonic
mouse pancreas from E10.5 to E 15.5 Expression pattern of IAPP and
prohormone convertase 1/3 reveals a distinctive set of endocrine
cells in the embryonic pancreas. Wilson et al., Mech. Dev.
115(1-2): 171-176, 2002, raising the possibility that bioactive
GLP-1 might be liberated from these cells with potential
implications for .beta. cell growth and development. These studies
do not prove that bioactive GLP-1 exerts a role during development
or regeneration, but they certainly expand our concepts to include
a potential for some islet A cells to produce GLP-1 in the correct
developmental or experimental setting.
GLP-1 in CNS
[0157] There is also considerable study in the role(s) of GLP-1 in
CNS in the control of satiety and food intake. A large body of
evidence demonstrates that ICV GLP-1 can reduce food intake in both
acute and chronic studies. Conversely, ICV administration of the
GLP-1 antagonist exendin (9-39) can acutely increase food intake
and promote weight gain in chronic rodent studies. These
satiety-related effects have also been observed in human studies
with peripheral administration of GLP-1 to both normal and diabetic
subjects.
[0158] CNS GLP-1 is synthesized largely in the brainstem and
transported along axonal networks to diverse CNS regions, including
the hypothalamus. The GLP-1 receptor has been localized to numerous
CNS nuclei using a combination of receptor autoradiography or in
situ hybridization studies. The studies by Turton, Bloom and
colleagues demonstrated that ICV GLP-1 clearly inhibits food intake
(Nature 379(6560): 69-72, 1996).
[0159] Peripheral administration of GLP-1 is taken up into the CNS,
as illustrated by Kastin et a. in J. Mol. Neurosci. 18(1-2): 7-14,
2002. Administration of the radio-labeled protease-resistant
analogue [Ser8]GLP-1, revealed uptake of this peptide into the CNS
that was not saturable, nor competed by wildtype GLP-1 or the GLP-1
receptor antagonist exendin(9-39), suggesting that the GLP-1
receptor is not involved in the rapid entry into brain. [Ser8]GLP-1
was detected within the brain parenchyma, but a large proportion
was loosely associated with the vasculature at the BBB. These
studies demonstrate that a radio-labeled GLP-1 analogue can enter
the brain. Similar studies using CD1 mice have demonstrated that
exendin-4 readily crosses the blood brain barrier, even more
efficiently than native GLP-1, as illustrated by Kastin and
Akerstrom in Int. J. Obes. Relat. Metab. Disord. 27(3): 313-318,
2003.
[0160] GLP-1 is also implicated in aversive stimulation and stress
in CNS. Although the data linking GLP-1 to inhibition of food
intake are quite solid, it is also important to consider a role for
GLP-1 in the CNS response to aversive stimuli. A link between GLP-1
and the stress response was first suggested, albeit indirectly, by
studies from Larsen and colleagues who demonstrated that ICV GLP-1
activated hypothalamic CRH+ neuroendocrine neurons leading to
increased corticosterone secretion in rats Central administration
of glucagon-like peptide-1 activates hypothalamic neuroendocrine
neurons in the rat. Larsen et al., Endocrinology 138(10): 4445-55,
1997.
[0161] More recent experiments have confirmed the intricate
anatomical association between GLP-1R+ nerve terminals in neuronal
projections that abut CRH+ neurons in the hypothalamic PVN, as
described in Sarkar et al., Brain Res. 985(2): 163-8, 2003.
[0162] A series of experiments also demonstrated that many of the
aversive effects of Lithium chloride administration in rats are
blocked by ICV preadministration of exendin (9-39), the GLP-1
receptor antagonist, as illustrated in Seeley et al., J. Neurosci.
20(4): 1616-21, 2000.
[0163] To localize the CNS regions responsive to GLP-1 that mediate
the anorexic versus visceral illness (CTA) effects of GLP-1, Kinzig
and colleagues injected various doses of GLP-1 into the lateral or
4th ventricle of rats. Both sites could transduce a GLP-1 signal
linked to food intake, whereas only GLP-1 instilled into the
lateral ventricle evoked a CTA response. The central nucleus of the
amygdala was identified as a key GLP-1R+ site important for the
response to visceral illness. These findings illustrate the
compartmentalization of the CNS GLP-1R response to differential CNS
inputs as outlined in Kinzig et al., J. Neurosci. 22(23): 10470-6,
2002. Similar experiments demonstrated that the endocrine component
of the stress response is activated following GLP-1 injection into
the hypothalamic PVN, whereas the anxiety response is induced by
GLP-1 administration in the central nucleus of the amygdala. See
Kinzig et al., J. Neurosci. 23(15): 6163-70, 2003.
[0164] Other studies corroborate the GLP-1-mediated activation of
stress-related signaling pathways in the CNS. The data in
Interoceptive stress activates glucagon-like peptide-1 neurons that
project to the hypothalamus. Rinaman (Am. J. Physiol. 277(2 Pt 2):
R582-590, 1999) demonstrates that LiCl, LPS and CCK activate GLP-1
neurons, whereas the same neurons are not activated following
ingestion of a large meal. A similar story emerges in "A functional
role for central glucagon-like peptide-1 receptors in lithium
chloride-induced anorexia," by Rinaman, Am. J. Physiol. 277(5 Pt
2): R1537-40, 1999. Central infusion of the GLP-1 antagonist
exendin (9-39) increases the febrile response to LPS, suggesting
that GLP-1R signaling may normally function to attenuate the
response in vivo. See Rinaman and Comer, Auton. Neurosci. 85(1-3):
98-101, 2000.
[0165] Complementary studies in mice demonstrate that several
behavioral tests that reflect anxiety, as well as the
corticosterone response to stress, are abnormal in the absence of
intact GLP-1R signaling. See MacLusky et al., Endocrinology
141(2):752-62, 2000.
[0166] GLP-1 is also found to have central and peripheral
cardiovascular effects.
[0167] Blazquez et al. have demonstrated that both i.v and
peripheral GLP-1 administration increase heart rate and blood
pressure in rats. See Barragan et al., Am. J. Physiol. 266(3 Pt 1):
E459-66, 1994; Barragan et al., Regul. Pept. 67(1): 63-8, 1996;
Barragan et al., Am. J. Physiol. 277(5 Pt 1): E784-91, 1999.
Similar observations have been made by Edwards et al., Exp.
Physiol. 82(4): 709-16, 1997. The hypertensive and chronotropic
actions of GLP-1 in the rat are evident even in the setting of
hypovolemia, and associated with further augmentation of
circulating vasopressin and oxytocin, as shown by Bojanowska and
Stempniak in J. Endocrinol. 172(2): 303-310, 2002.
[0168] More recent studies have demonstrated that even moderate
doses of GLP-1 agonists at levels not sufficient to lower blood
glucose result in activation of central sympathetic neurons and
adrenal medullary chromaffin cells that produce catecholamines.
Centrally and peripherally administered GLP-1R agonists including
native GLP-1 and the lizard peptide exendin-4 dose-dependently
increased blood pressure and heart rate in rats. GLP-1R activation
induced c-fos expression in the adrenal medulla and neurons in
autonomic control sites in the rat brain, including medullary
catecholamine neurons providing input to sympathetic preganglionic
neurons. Furthermore, GLP-1R agonists rapidly activated tyrosine
hydroxylase transcription in AP neurons which express the GLP-1R,
as shown in Yamamoto et al., J. Neurosci. 23(7): 2939-2946, 2003.
These findings suggest that the central GLP-1 system represents a
regulator of sympathetic outflow leading to downstream activation
of cardiovascular responses in the rodent, and are consistent with
previous reports demonstrating that GLP-1R systems function as a
component of neural networks transducing the CNS response to
aversive stimuli. See Yamamoto et al., J. Clin. Invest. 110: 43-52,
2002.
[0169] ICV GLP-1 has also been shown to increase fecal output in
rats, and these actions were blocked by treatment with either
exendin (9-39) or the CRF receptor antagonist, astressin. Hence,
these findings provide yet another link between GLP-1 actions in
the CNS, stress, and the CRH pathway. See Ali Gulpinar et al.,
AJP--Gastrointest. Liver. Physiol. 278: G924-G929, 2000.
[0170] There might also be a connection between leptin and GLP-1 in
the CNS. It was suggested that GLP-1 may be downstream of leptin
action in the brain. Indeed, some studies show that leptin
activates a subset of GLP-1 neurons in the brainstem. Elias et al.,
J. Comp. Neurol. 423(2): 261-81, 2000. Nevertheless, GLP-1 receptor
signaling is not required for leptin action in the CNS. Scrocchi et
al., Diabetes 49: 1552-1560, 2000.
[0171] GLP-1 may also has neuroprotection, learning and memory
function in the CNS. A study in rats infused with an exendin (5-39)
GLP-1R antagonist demonstrated decreased neurotoxicity following
infusion with beta amyloid protein. See Oka et al., Brain Res.
878(1-2): 194-198, 2000. In contrast, studies using the rat PC12
pheochromocytoma cell line, which expresses the GLP-1 receptor,
suggest that GLP-1 agonists promote neurite outgrowth and
NGF-induced differentiation, and may enhance cell survival
following withdrawal of NGF, depending on the timing of exendin-4
administration. The differentiation actions of GLP-1 were abrogated
by the kinase inhibitors LY294002 or PD98059, but the PKA inhibitor
H-89 had only modest effects on these actions. Hence, these
findings suggest that GLP-1R signaling, perhaps independent of PKA
activation, may be neurotrophic in the correct cellular context.
See Perry et al., J. Pharmacol. Exp. Ther. 300(3): 958-66, 2002.
Another study demonstrated that GLP-1, and exendin-4, can
completely protect cultured rat hippocampal neurons against
glutamate-induced apoptosis, and both GLP-1 and exendin-4 reduced
ibotenic acid-induced depletion of choline acetyltransferase
immunoreactivity in rat basal forebrain cholinergic neurons.
Similarly, GLP-1 can reduce the levels of amyloid-beta peptide
(Abeta) in the brain in vivo and reduced levels of amyloid
precursor protein (APP) in cultured neuronal cells. Furthermore,
GLP-1 and exendin-4 protect cultured hippocampal neurons against
death induced by Abeta and iron See Perry et al., J. Neurosci. Res.
72(5): 603-12, 2003.
[0172] Hence, these results suggests that GLP-1 action in the brain
may be neuroprotective, perhaps via activation of anti-apoptotic
signaling pathways in specific neurons. See Perry et al., J.
Pharmacol. Exp. Ther. 302(3): 881-8, 2002.
[0173] During et al. have shown, using a variety of gene therapy,
and peptide-based technologies, that activation of CNS GLP-1R
signaling enhances associative and spatial learning through GLP-1R.
These investigators used a novel N-terminal exendin-4 derivative,
[Ser(2)]exendin(1-9), which when administered peripherally, gains
access to the CNS, and activates the CNS GLP-1R system.
GLP-1R-deficient mice exhibit a learning deficit phenotype which is
restored after hippocampal GLP-1R gene transfer. Furthermore, gain
of function studies in rats overexpressing the GLP-1R in the
hippocampus show improved learning and memory. GLP-1R-deficient
mice also have enhanced seizure severity and neuronal injury after
kainate administration, with correction after GLP-1R gene transfer
in hippocampal somatic cells. Systemic administration of the GLP-1R
agonist peptide [Ser(2)]exendin(1-9) in wild-type animals prevents
kainate-induced apoptosis of hippocampal neurons. See During et
al., Nat. Med. 9(9): 1173-9, 2003 (Epub 2003 Aug. 17).
GLP-1 and Food Intake
[0174] Following the publication of data demonstrating that ICV
GLP-1 dose-dependently inhibits food intake (Wilding et al., Nature
379(6560): 69-72, 1996), subsequent studies demonstrated that
blockade of CNS GLP-1 action using ICV infusion of exendin (9-39)
increased food intake and promoted weight gain in rats. Meeran et
al., Endocrinology 140(1): 244-50, 1999. Similarly, injection of
exendin (9-39) into the lateral hypothalamus increased food intake
in satiated rats. Schick et al., Am. J. Physiol. Regul. Integr.
Comp. Physiol. 284(6): R1427-35, 2003.
[0175] Over the last several years, the evidence linking GLP-1
action in the CNS to regulation of food intake and body weight has
been confirmed by multiple independent laboratories. Although the
PVN of the hypothalamus was the initial focus of studies linking
GLP-1 actions to satiety, several studies have now demonstrated,
using direct injection approaches, that multiple brain regions are
capable of transducing a CNS satiety effect in response to GLP-1,
including the LH, DMH, and VMH, as shown in Kinzig et al., J.
Neurosci. 22(23): 10470-6, 2002; Schick et al., Am. J. Physiol.
Regul. Integr. Comp. Physiol. 284(6): R1427-35, 2003.
[0176] Furthermore, it is clear that peripheral administration of
long-acting GLP-1 agonists to diabetic rodents can also reduce food
intake and achieve weight loss, in studies of several weeks
duration. The Novo Nordisk GLP-1 analogue NN2211 induced weight
loss in both lean control rats and in MSG-lesioned rats, hence the
anorectic actions were presumably mediated by signaling systems
outside the region of the hypothalamus affected by neonatal
monosodium glutamate administration. To review the experimental
data, including analyses of body composition after NN2211, see
Larsen et al., Diabetes 50 (11): 2530-2539, 2001.
[0177] Over a dozen human studies in both normal subjects and in
patients with obesity or type 2 diabetes have examined the
relationship between GLP-1 infusion and food intake. The majority
of studies have shown a small but significant inhibition of
short-term food intake with concurrent GLP-1 infusion. A
Meta-Analysis of these studies has concluded that there is a
dose-dependent reduction in food intake associated with a reduction
of gastric emptying in human subjects. See Verdich et al., J. Clin.
Endocrinol. Metab. 86(9): 4382-9, 2001.
[0178] An important but as yet not-so-well-understood phenomenon
surrounds the effects of intermittent vs. continuous GLP-1
administration on food intake and body weight. GLP-1 given by
subcutaneous injection 30 minutes before meals in a 5 day
randomized cross-over study of obese human subjects was more
effective in producing weight loss relative to a continuous 5 day
subcutaneous GLP-1 infusion. However, a key difference between the
different arms of the study was the peak plasma level of GLP-1
achieved, which was significantly higher (269.4 vs. 88.7 pM) in the
patients given subcutaneous injections. Hence, it is not possible
to make firm conclusions as to whether peripheral vs. continuous
GLP-1 delivery exerts differential effects on weight loss. See
Naslund et al., Br. J. Nutr. 91(3): 439-46, 2004.
GLP-1 and Gastric Emptying
[0179] Although GLP-1 was originally identified as a .beta. cell
secretagogue, a considerable body of experimental evidence in
rodents, pigs and human studies demonstrates that GLP-1 is a potent
regulator of gastrointestinal motility and gastric secretion. This
action of GLP-1 accounts for the observation that glycemic
excursion is often blunted and insulin secretion is frequently
attenuated, following oral nutrient ingestion in the setting of
co-administered exogenous GLP-1. These properties of GLP-1, taken
together with the tight correlation between the levels of
circulating GLP-1 and the rate of gastric emptying (Wishart et al.,
Peptides 19(6): 1049-53, 1998), have prompted some to opine that
the gastric emptying actions of GLP-1 may be as or more important
than the "incretin" actions of GLP-1, as outlined in Nauck et al.,
Am. J. Physiol. 73(5 Pt 1): E981-8, 1997; Nauck Diabetologia 42(3):
373-9, 1999.
[0180] Indeed, the potent dose-dependent inhibition of gastric
emptying observed following GLP-1 infusion in human subjects with
Type 2 diabetes will produce significant lowering of meal-related
glycemic excursion, even without any increase in levels of
circulating insulin, as outlined in Meier et al., J. Clin.
Endocrinol. Metab. 88(6): 2719-25, 2003.
[0181] A direct role for GLP-1 in gastric physiology was shown by
demonstrating stimulation of cAMP formation in rat gastric gland
preparations and the human HGT-1 human cancer cell line. See Hansen
et al., FEBS Lett. 236(1): 119-22, 1988, which was followed by the
demonstration that GLP-1 also inhibited pentagastrin-stimulated
gastric acid secretion in human studies at physiologically relevant
concentrations. See Schjoldager et al., Dig. Dis. Sci. 34(5):
703-8, 1989; O'Halloran et al., J. Endocrinol. 126(1): 169-73,
1990. C. f. Nauck et al., Digestion 52(3-4): 214-21, 1992. However,
the effect of GLP-1 on inhibition of gastric acid secretion is lost
in human subjects previously subjected to a vagotomy for control of
ulcer disease. See Wettergren et al., Gut. 40(5): 597-601, 1997.
Similarly, the vagal afferents play an important role in mediating
both the central and peripheral effects of GLP-1 on gastric
emptying in rats, as shown in Imeryuz et al., Am. J. Physiol. 273(4
Pt 1): G920-7, 1997. Rat studies have also shown potent inhibition
of small bowel motility. Tolessa et al., Dig. Dis. Sci. 43(10):
2284-90, 1998. Vagal innervation is also important for the
inhibitory effects of GLP-1 on gut motility in pigs. Wettergren et
al., Am. J. Physiol. 275(5 Pt 1): G984-92, 1998. Pharmacological
levels of GLP-1 appear to inhibit both gastric emptying and gastric
acid secretion in normal human subjects (Wettergren et al., Dig.
Dis. Sci. 38(4): 665-73, 1993) and in obese subjects (Naslund et
al., Am. J. Clin. Nutr. 68(3): 525-30, 1998). In addition,
administration of exendin (9-39) to gastric fistula rats reverses
the glucose meal-induced inhibition of gastric emptying if the
antagonist is given peripherally, but not following icy injection.
See Schepp et al., Am. J. Physiol. 273(4 Pt 1): G920-7, 1997.
[0182] In studies using rat parietal cell preparations, both
exendin-4 and GLP-1 display similar properties with respect to H+
and cAMP production and the actions of these peptides are blocked
by the GLP-1 receptor antagonist exendin(9-39). Schepp et al., Eur.
J. Pharmacol. 269(2): 183-91, 1994.
[0183] The inhibitory effect of GLP-1 on gastric emptying likely
accounts for at least part of the glucose-lowering effects observed
in Type 1 diabetic patients (Dupre et al., Diabetes 44(6): 626-30,
1995). GLP-1 also inhibits gastric emptying in subjects with type 2
diabetes following a liquid test meal (Willms et al., J. Clin.
Endocrinol. Metab. 81(1): 327-32, 1996; Diabetologia 39(12):
1546-53, 1996), and following ingestion of only water (Naslund et
al., Scand. J. Gastroenterol. 36(2): 156-62, 2001), or following
ingestion of a solid meal (Naslund et al., Am. J. Physiol. 277(3 Pt
2): R910-6, 1999; Delgado-Aros et al., Am. J. Physiol.
Gastrointest. Liver. Physiol. 282(3): G424-31, 2002). The
inhibitory effects of GLP-1 on GI motility are also detected in
human studies in the inter-digestive state (Schirra et al., Gut
46(5): 622-31, 2000; Shirra et al., Gut 50(3): 341-8, 2002).
[0184] The glucose-lowering effect of the drug acarbose may be
attributed in part to the inhibition of gastric emptying perhaps
due to the increase in levels of circulating GLP-1 that are
detected following acarbose administration (Ranganath et al.,
Diabet. Med. 15(2): 120-4, 1998; Enc et al., Am. J. Physiol.
Gastrointest. Liver. Physiol. 281(3): G752-63, 2001).
Co-administration of acarbose and sucrose leads to a delay and
sustained release of GLP-1 in human subjects (Seifarth et al.,
Diabet. Med. 15(6): 485-91, 1998).
GLP-1 and the Cardiovescular System
[0185] In February 2004, a pilot study reported the effect of acute
GLP-1 administration in 10 human subjects with LV dysfunction and
acute MI following angioplasty. Native GLP-1 was administered as a
72-hour infusion at a rate of 1.5 pmol/kg per minute.
Echocardiograms were obtained after reperfusion and after the
completion of the GLP-1 infusion. GLP-1 significantly improved LVEF
(from 29+2% to 39+2%, P<0.01), global wall motion score indexes
(1.94+0.11 to 1.63+0.09, P<0.01), and regional wall motion score
indexes (2.53+0.08 to 2.02+0.11, P<0.01) compared with control
subjects. The benefits of GLP-1 were independent of AMI location or
history of diabetes. GLP-1 administration was accompanied by a
significant decrease in plasma glucose and free fatty acids and was
associated with reduced mortality and duration of hospital stay.
See Nikolaidis et al., Circulation 109(8): 962-5, 2004 (Epub 2004
Feb. 23).
[0186] GLP-1 administered intravenously or by ICV injection
increases heart rate and blood pressure in rats. See Barragan et
al., Am. J. Physiol. 266(3 Pt 1): E459-66, 1994; J. Biol. Chem.
275(44): 34471-7, 2000. These effects can be blocked by intravenous
or ICV administration of the antagonist exendin(9-39) and bilateral
vagotomy blocked the cardiovascular effects of ICV, but not
peripherally administered GLP-1 (Barragan et al., Am. J. Physiol.
277(5 Pt 1): E784-91, 1999). Analysis of direct GLP-1 actions on
cardiac muscle cells was studied using cultures of rat cardiac
myocytes. Although GLP-1 increased intracellular cAMP in cardiac
myocytes, in contrast to the positive inotropic actions of
isoproterenol, GLP-1 induced a decrease in contraction amplitude
with no change in intracellular calcium transit. Furthermore, both
isoproterenol and GLP-1 produced an intracellular acidosis. Hence,
these findings demonstrate that coupling of cardiomyocyte GLP-1R
signaling to cAMP generation produces distinct downstream signaling
events when compared to adrenergic agonists. See Vila et al., Circ.
Res. 89(5): 445-452, 2001.
[0187] Even moderate doses of GLP-1 agonists infused at levels not
sufficient to lower blood glucose result in activation of central
sympathetic neurons and adrenal medullary chromaffin cells that
produce catecholamines. Centrally and peripherally administered
GLP-1R agonists including native GLP-1 and the lizard peptide
exendin-4 dose-dependently increased blood pressure and heart rate
in rats. GLP-1R activation induced c-fos expression in the adrenal
medulla and neurons in autonomic control sites in the rat brain,
including medullary catecholamine neurons providing input to
sympathetic preganglionic neurons. Furthermore, GLP-1R agonists
rapidly activated tyrosine hydroxylase transcription in AP neurons
which express the GLP-1R, as shown in Yamamoto et al., J. Neurosci.
23(7): 2939-2946, 2003.
[0188] These findings suggest that the central GLP-1 system
represents a regulator of sympathetic outflow leading to downstream
activation of cardiovascular responses in the rodent, and are
consistent with previous reports demonstrating that GLP-1R systems
function as a component of neural networks transducing the CNS
response to aversive stimuli. See Yamamoto et al., J. Clin. Invest.
110: 43-52, 2002.
[0189] The importance of cholinergic and nicotinic acid receptors
for transduction of the central cardiovascular response to GLP-1
was determined in normal rats. The nicotinic receptor antagonist
mecamylamine and the muscarinic receptor antagonist atropine
prevented the stimulatory effect of GLP-1 on blood pressure whereas
only mecamylamine blocked the GLP-1-dependent increase in heart
rate. Intraarterial application of a V(1) receptor antagonist
blocked the GLP-1 effects on blood pressure. See Isbil-Buyukcoskun
and Gulec, Regul Pept. 118(1-2): 33-8, 2004.
[0190] In contrast to data suggesting that acute administration of
GLP-1 may increase heart rate and blood pressure in rodents,
chronic 14 day treatment of salt-sensitive rats on a high salt diet
with recombinant GLP-1 reduced the development of hypertension,
proteinuria and improved endothelial function with decreased renal
and cardiac damage. The authors postulated that the protective
effects of GLP-1 were attributable to increased urine flow and
sodium excretion notable for the first 3 days following elevation
in sodium intake. See Yu et al., J. Hypertens. 21(6): 1125-1135,
2003.
GLP-1 Treatment in Human Subjects
[0191] To date, almost all of the actions reported for GLP-1 in
animal studies have been validated in several dozen human studies
of both normal and diabetic subjects. The glucose-lowering actions
of GLP-1 in studies of diabetic patients are secondary to
inhibition of gastric emptying and glucagon secretion, and
stimulation of insulin secretion. GLP-1 also lowers appetite in
short term studies of patients with type 2 diabetes, however the
long terms effects of GLP-1 or exendin-4 on body weight in diabetic
subjects have not yet been reported.
[0192] Enhanced interest in the potential use of GLP-1 for the
treatment of diabetes followed the NEJM publication demonstrating
that GLP-1 lowered blood glucose in both patients with Type 2 and
Type 1 diabetes (Gutniak et al., N. Engl. J. Med. 326(20): 1316-22,
1992).
[0193] Although the majority of interest in GLP-1 as a therapeutic
agent is focused on Type 2 diabetes, several studies have shown
modest glucose-lowering effects of GLP-1 administration in Type 1
diabetes, likely due to effects on gastric emptying and inhibition
of glucagon secretion. See Vella et al., Diabetes 50(3): 565-72,
2001; Creutzfeldt et al., Diabetes. Care 19(6): 580-6, 1996; Dupre
et al., Diabetes 44(6): 626-30, 1995.
[0194] Although there has been some controversy about whether GLP-1
stimulates insulin-independent glucose uptake, some studies have
suggested GLP-1 promotes insulin or glucagon-independent glucose
clearance and/or suppression of glucose production. Studies of
endogenous glucose production (Ra) and glucose disposal (Rd) in 8
human volunteers were carried out with fixed insulin and glucagon
concentrations (octreotide infusion) while glucose was maintained
at the fasting level and insulin and glucagon were replaced to
maintain blood glucose near fasting levels. A 60 minute infusion of
GLP-1 (30 pmol/kg/h) decreased plasma glucose in all 8 subjects
which was accounted for by a significant, 17% decrease in Ra, with
no significant change in Rd. Hence, GLP-1 may lower fasting blood
glucose in normal individuals through effects on the liver,
possibly through portal neural mechanisms. See Prigeon et al., Am.
J. Physiol. Endocrinol. Metab. 285(4): E701-7, 2003 (Epub 2003 May
28).
[0195] GLP-1 functions as an incretin in human subjects, as
infusion of the GLP-1 antagonist exendin (9-39) blocked the
insulinotropic and glucagonostatic effects of exogenous GLP-1, and
also increased plasma glucagon during euglycemia and hyperglycemia.
Exendin (9-39 also increased insulin during hyperglycemia. These
findings agree with similar studies in rodent "loss of function"
models, and demonstrate the physiological importance of GLP-1
action for glucose regulation in normal human subjects. See Schilla
et al., J. Clin. Invest. 101(7): 1421-30, 1998. Similarly, blockade
of endogenous GLP-1 with Glucagon-like peptide 1 has a
physiological role in the control of postprandial glucose in humans
(Edwards et al., Diabetes 48(1): 86-93, 1999).
Other Biological Effects of GLP-1
[0196] As described above, although the principal focus of GLP-1
research has been on pleiotropic actions that ultimately converge
on regulation of nutrient intake and disposal through effects on
CNS satiety centers, gastrointestinal motility, islet function and
pi cell growth, the GLP-1 receptor is widely expressed in several
tissues not considered classic metabolic regulators of energy
homeostasis, such as the heart, kidney, and lungs.
[0197] GLP-1 and Hypothalamic-Pituitary Function:
[0198] Although much recent attention has focused on the role of
hypothalamic GLP-1 in the control of food intake, GLP-1 may also
regulate the hypothalamic pituitary axis (HPA) via effects on LH,
TSH, CRH, oxytocin and vasopressin secretion. See Beak et al.,
Endocrinology 137(10): 4130-8, 1996; Beak et al., J. Clin. Invest.
101(6): 1334-41, 1998; Larsen et al., Endocrinology 138(10):
4445-55, 1997. But these GLP-1 actions do not appear to be
essential for HPA function, as GLP-1R-/- mice cycle normally, are
fertile, and exhibit normal basal levels of plasma osmolarity,
corticosterone, thyroid hormones, estradiol, and testosterone
(MacLusky et al., Endocrinology 141(2): 752-62, 2000.
[0199] GLP-1 and the Lung:
[0200] GLP-1 receptor mRNA transcripts have been localized to the
lung in rodents and humans, and several studies have confirmed the
presence of GLP-1 binding sites using rat lung membrane
preparations. Several reports have suggested that GLP-1 may exert
actions both on airways (tracheal rings) and on pulmonary
vasculature. Addition of GLP-1 to lung preparations increased
macromolecule secretion and relaxed preconstricted pulmonary
arteries. See Richter et al., Am. J. Physiol. 265(4Pt1): L374-81,
1993. Subsequent studies demonstrated that GLP-1 increases
pulmonary surfactant production from isolated rat pneumocytes (Vara
et al., Endocrinology 139(5): 2363-8, 1998) and similar studies
have also been carried out using human lung cells (Vara et al., Am.
J. Respir. Crit. Care. Med. 163(4): 840-846, 2001.
[0201] GLP-1 Action in Fat and Muscle Cells:
[0202] GLP-1 has been shown to exert modest effects on fat and
muscle cells in vitro. Nevertheless, there continue to be reports
describing actions of GLP-1 on muscle, including studies with human
muscle cells and strips, suggesting actions of glucagon-like
peptide agonists and antagonists. In muscle strips, GLP-1
stimulated glycogen synthesis, glycogen synthase a activity, and
glucose oxidation and utilization, and inhibited glycogen
phosphorylase a activity. In cultured myotubes, GLP-1 at very low
doses of 0.1-1 pM stimulated glucose incorporation into glycogen.
Curiously, exendin-4 and its truncated form 9-39 amide (Ex-9) both
exert the same types of effects on glycogen synthesis and synthase
a activity without stimulating an increase in cAMP accumulation.
See Luque et al., J. Endocrinol. 173(3): 465-73, 2002.
EQUIVALENTS
[0203] Those skilled in the art will know or be able to ascertain
using no more than routine experimentation, many equivalents to the
embodiments and practices described herein. Accordingly, it will be
understood that the invention is not to be limited to the
embodiments disclosed herein.
[0204] The contents of all references, patents and published patent
applications cited throughout this application, as well as the
Figures are hereby incorporated by reference.
* * * * *