U.S. patent application number 13/382276 was filed with the patent office on 2012-04-26 for pegylated l-asparaginase.
Invention is credited to Thierry Abribat.
Application Number | 20120100121 13/382276 |
Document ID | / |
Family ID | 42232655 |
Filed Date | 2012-04-26 |
United States Patent
Application |
20120100121 |
Kind Code |
A1 |
Abribat; Thierry |
April 26, 2012 |
Pegylated L-Asparaginase
Abstract
Disclosed is a conjugate of a protein having substantial
L-asparagine aminohydrolase activity and polyethylene glycol. In
particular, the polyethylene glycol has a molecular weight less
than or equal to about 5000 Da and the protein is an L-asparaginase
from Erwinia. The conjugate of the invention has shown superior
properties such as maintenance of a high level of in vitro activity
and an unexpected increase in half-life in vivo. Also disclosed are
methods of producing the conjugate and use of the conjugate in
therapy. In particular, a method is disclosed for use of the
conjugate in the treatment of cancer, particularly Acute
Lymphoblastic Leukemia (ALL). More specifically, a method is
disclosed for use of the conjugate as a second line therapy for
patients who have developed hypersensitivity or have had a disease
relapse after treatment with other L-asparaginase preparations.
Inventors: |
Abribat; Thierry; (Sainte
Foy Les Lyon, FR) |
Family ID: |
42232655 |
Appl. No.: |
13/382276 |
Filed: |
July 6, 2010 |
PCT Filed: |
July 6, 2010 |
PCT NO: |
PCT/EP10/59599 |
371 Date: |
January 4, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61223320 |
Jul 6, 2009 |
|
|
|
Current U.S.
Class: |
424/94.3 ;
435/188 |
Current CPC
Class: |
Y02A 50/30 20180101;
A61K 47/60 20170801; A61P 35/02 20180101; C12N 9/96 20130101; C12N
9/82 20130101; C12Y 305/01001 20130101; A61P 35/00 20180101; A61K
38/50 20130101 |
Class at
Publication: |
424/94.3 ;
435/188 |
International
Class: |
A61K 38/50 20060101
A61K038/50; A61P 35/02 20060101 A61P035/02; C12N 9/96 20060101
C12N009/96; A61P 35/00 20060101 A61P035/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 30, 2010 |
EP |
PCT/EP2010/054156 |
Claims
1. A conjugate comprising an L-asparaginase from Erwinia having at
least 80% identity to the amino acid of SEQ ID NO: 1 and
polyethylene glycol (PEG), wherein the PEG has a molecular weight
less than or equal to about 5000 Da.
2. The conjugate of claim 1, wherein said L-asparaginase has at
least from 90% to 99% identity to the amino acid of SEQ ID NO:
1.
3. (canceled)
4. The conjugate of claim 1, wherein said L-asparaginase comprises
the amino acid sequence of SEQ ID NO: 1.
5. The conjugate of claim 1, wherein said PEG has a molecular
weight of less than or equal to about 5000 Da.
6-30. (canceled)
31. The conjugate of claim 1 wherein the PEG is covalently linked
to one or more amino of said L-asparaginase.
32. The conjugate of claim 31, wherein the PEG is covalently linked
to said one or more amino groups by an amide bond.
33. The conjugate of claim 31, wherein the PEG is covalently linked
to at least from about 40% to about 100% of the accessible amino
groups.
34. (canceled)
35. The conjugate of claim 1 having the formula:
Asp-[NH--CO--(CH2)x-CO--NH-PEG]n wherein Asp is the L-asparaginase,
NH is one or more of the NH groups of the lysine residues and/or
the N-terminus in the Asp, PEG is a polyethylene glycol moiety, n
is a number that represents at least 40% to about 100% of the
accessible amino groups in the Asp, and x is an integer ranging
from 1 to 8.
36-38. (canceled)
39. The conjugate of claim 1, wherein said PEG is
monomethoxy-polyethylene glycol.
40. A method of making the conjugate of claim 1, said method
comprising combining an amount of said PEG with an amount of said
L-asparaginase in a buffered solution for a time period sufficient
to covalently link said PEG to said L-asparaginase.
41. The method of claim 40, wherein said buffered solution has a pH
value of between about 7.0 and about 9.0.
42. (canceled)
43. The method of claim 40, wherein the amount of said
L-asparaginase is a protein concentration of between about 0.5
mg/mL and about 25 mg/mL.
44-45. (canceled)
46. The method of claim 40, wherein the amount of said PEG is a
molar excess of polymer over amino groups in said L-asparaginase of
less than about 20:1.
47-48. (canceled)
49. The method of claim 40, wherein said PEG is
monomethoxy-polyethylene glycol.
50. A method of treating a disease treatable by L-asparagine
depletion in a patient, said method comprising administering to
said patient an effective amount of the conjugate of claim 1.
51. The method of claim 50, wherein said disease treatable by
L-asparagine depletion is a cancer.
52. The method of claim 51, wherein said cancer is selected from
the group consisting of Acute Lymphoblastic Leukemia (ALL),
non-Hodgkin's lymphoma, NK lymphoma, and pancreatic cancer.
53. The method of claim 52, wherein said cancer is ALL.
54. The method of claim 53, wherein said conjugate is administered
at an amount of about 5 U/kg to about 25 U/kg.
55. (canceled)
56. The method of claim 53, wherein said conjugate is administered
in a dose that depletes L-asparagine to undetectable levels for a
period of about 3 days to about 10 days.
57-59. (canceled)
60. The method of claim 50, wherein said conjugate is administered
intravenously or intramuscularly.
61. (canceled)
62. The method of claim 50, wherein said conjugate is administered
once or twice per week.
63. (canceled)
64. The method of claim 50, wherein said conjugate is administered
less than once per week.
65. The method of claim 50, wherein said conjugate is administered
as monotherapy.
66. The method of claim 65, wherein said conjugate is not
administered with an asparagine synthetase inhibitor.
67. The method of claim 50, wherein said patient has had a previous
hypersensitivity to an L-asparaginase selected from the group
consisting of an E. coli L-asparaginase, Erwinia L-asparaginase and
PEGylated form thereof.
68. (canceled)
69. The method of claim 67, wherein said hypersensitivity is
selected from the group consisting of allergic reaction,
anaphylactic shock, and silent hypersensitivity.
70. The method of claim 50, wherein said patient has had a disease
relapse.
71. The method of claim 70, wherein said disease relapse occurs
after treatment with an E. coli L-asparaginase or PEGylated form
thereof.
72. A pharmaceutical composition comprising the conjugate of claim
1.
73-94. (canceled)
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention concerns a conjugate of a protein
having substantial L-asparagine aminohydrolase activity and
polyethylene glycol, particularly wherein the polyethylene glycol
has a molecular weight less than or equal to about 5000 Da,
particularly a conjugate wherein the protein is a L-asparaginase
from Erwinia, and its use in therapy.
[0003] 2. Background
[0004] Proteins with L-asparagine aminohydrolase activity, commonly
known as L-asparaginases, have successfully been used for the
treatment of Acute Lymphoblastic Leukemia (ALL) in children for
many years. ALL is the most common childhood malignancy (Avramis
and Panosyan, Clin. Pharmacokinet. (2005) 44:367-393).
[0005] L-asparaginase has also been used to treat Hodgkin's
disease, acute myelocytic leukemia, acute myelomonocytic leukemia,
chronic lymphocytic leukemia, lymphosarcoma, reticulosarcoma, and
melanosarcoma (Kotzia and Labrou, J. Biotechnol. 127 (2007)
657-669). The anti-tumor activity of L-asparaginase is believed to
be due to the inability or reduced ability of certain malignant
cells to synthesize L-asparagine (Kotzia and Labrou, J. Biotechnol.
127 (2007) 657-669). These malignant cells rely on an extracellular
supply of L-asparagine. However, the L-asparaginase enzyme
catalyzes the hydrolysis of L-asparagine to aspartic acid and
ammonia, thereby depleting circulating pools of L-asparagine and
killing tumor cells which cannot perform protein synthesis without
L-asparagine (Kotzia and Labrou, J. Biotechnol. 127 (2007)
657-669).
[0006] L-asparaginase from E. coli was the first enzyme drug used
in ALL therapy and has been marketed as Elspar.RTM. in the USA or
as Kidrolase.RTM. and L-asparaginase Medac.RTM. in Europe.
L-asparaginases have also been isolated from other microorganisms,
e.g., an L-asparaginase protein from Erwinia chrysanthemi, named
crisantaspase, that has been marketed as Erwinase.RTM. (Wriston
Jr., J. C. (1985) "L-asparaginase" Meth. Enzymol. 113, 608-618;
Goward, C. R. et al. (1992) "Rapid large scale preparation of
recombinant Erwinia chrysanthemi L-asparaginase", Bioseparation 2,
335-341). L-asparaginases from other species of Erwinia have also
been identified, including, for example, Erwinia chrysanthemi 3937
(Genbank Accession #AAS67028), Erwinia chrysanthemi NCPPB 1125
(Genbank Accession #CAA31239), Erwinia carotovora (Genbank
Accession #AAP92666), and Erwinia carotovora subsp. Astroseptica
(Genbank Accession #AAS67027). These Erwinia chrysanthemi
L-asparaginases have about 91-98% amino acid sequence identity with
each other, while the Erwinia carotovora L-asparaginases have
approximately 75-77% amino acid sequence identity with the Erwinia
chrysanthemi L-asparaginases (Kotzia and Labrou, J. Biotechnol. 127
(2007) 657-669).
[0007] L-asparaginases of bacterial origin have a high immunogenic
and antigenic potential and frequently provoke adverse reactions
ranging from mild allergic reaction to anaphylactic shock in
sensitized patients (Wang, B. et al. (2003) "Evaluation of
immunologic cross reaction of anti-asparaginase antibodies in acute
lymphoblastic leukemia (ALL and lymphoma patients), Leukemia 17,
1583-1588). E. coli L-asparaginase is particularly immunogenic,
with reports of the presence of anti-asparaginase antibodies to E.
coli L-asparaginase following i.v. or i.m. administration reaching
as high as 78% in adults and 70% in children (Wang, B. et al.
(2003) Leukemia 17, 1583-1588).
[0008] L-asparaginases from Escherichia coli and Erwinia
chrysanthemi differ in their pharmacokinetic properties and have
distinct immunogenic profiles, respectively (Klug Albertsen, B. et
al. (2001) "Comparison of intramuscular therapy with Erwinia
asparaginase and asparaginase Medac: pharmacokinetics.
pharmacodynamics, formation of antibodies and influence on the
coagulation system" Brit. J. Haematol. 115, 983-990). Furthermore,
it has been shown that antibodies that developed after a treatment
with L-asparaginase from E. coli do not cross react with
L-Asparaginase from Erwinia (Wang, B. et al., Leukemia 17 (2003)
1583-1588). Thus, L-asparaginase from Erwinia (crisantaspase) has
been used as a second line treatment of ALL in patients that react
to E. coli L-asparaginase (Duval, M. et al. (2002) "Comparison of
Escherichia coli-asparaginase with Erwinia-asparaginase in the
treatment of childhood lymphoid malignancies: results of a
randomized European Organisation for Research and Treatment of
Cancer, Children's Leukemia Group phase 3 trial" Blood 15,
2734-2739; Avramis and Panosyan, Clin. Pharmacokinet. (2005)
44:367-393).
[0009] In another attempt to reduce immunogenicity associated with
administration of microbial L-asparaginases, an E. coli
L-asparaginase has been developed that is modified with
methoxy-polyethyleneglycol (mPEG). This method is commonly known as
"PEGylation" and has been shown to alter the immunological
properties of proteins (Abuchowski, A. et al. (1977) "Alteration of
Immunological Properties of Bovine Serum Albumin by Covalent
Attachment of Polyethylene Glycol," J. Biol. Chem. 252 (11),
3578-3581). This so-called mPEG-L-asparaginase, or pegaspargase,
marketed as Oncaspar.RTM. (Enzon Inc., USA), was first approved in
the U.S. for second line treatment of ALL in 1994, and has been
approved for first-line therapy of ALL in children and adults since
2006. Oncaspar.RTM. has a prolonged in vivo half-life and a reduced
immunogenicity/antigenicity.
[0010] Oncaspar.RTM. is E. coli L-asparaginase that has been
modified at multiple lysine residues using 5 kDa mPEG-succinimidyl
succinate (SS-PEG) (U.S. Pat. No. 4,179,337). SS-PEG is a PEG
reagent of the first generation that contains an insatiable ester
linkage that is sensitive to hydrolysis by enzymes or at slightly
alkaline pH values (U.S. Pat. No. 4,670,417; Makromol. Chem. 1986,
187, 1131-1144). These properties decrease both in vitro and in
vivo stability and can impair drug safety.
[0011] Furthermore, it has been demonstrated that antibodies
developed against L-asparaginase from E. coli will cross react with
Oncaspar.RTM. (Wang, B. et al. (2003) "Evaluation of immunologic
cross-reaction of anti-asparaginase antibodies in acute
lymphoblastic leukemia (ALL and lymphoma patients)," Leukemia 17,
1583-1588). Even though these antibodies were not neutralizing,
this finding clearly demonstrated the high potential for
cross-hypersensitivity or cross-inactivation in vivo. Indeed, in
one report 30-41% of children who received pegaspargase had an
allergic reaction (Wang, B. et al. (2003) Leukemia 17,
1583-1588).
[0012] In addition to outward allergic reactions, the problem of
"silent hypersensitivity" was recently reported, whereby patients
develop anti-asparaginase antibodies without showing any clinical
evidence of a hypersensitivity reaction (Wang, B. et al. (2003)
Leukemia 17, 1583-1588). This reaction can result in the formation
of neutralizing antibodies to E. coli L-asparaginase and
pegaspargase; however, these patients are not switched to Erwinia
L-asparaginase because there are not outward signs of
hypersensitivity, and therefore they receive a shorter duration of
effective treatment (Holcenberg, J., J. Pediatr. Hematol. Oncol. 26
(2004) 273-274).
[0013] Erwinia chrysanthemi L-asparaginase treatment is often used
in the event of hypersensitivity to E. coli-derived
L-asparaginases. However, it has been observed that as many as
30-50% of patients receiving Erwinia L-asparaginase are
antibody-positive (Avramis and Panosyan, Clin. Pharmacokinet.
(2005) 44:367-393). Moreover, because Erwinia chrysanthemi
L-asparaginase has a significantly shorter elimination half-life
than the E. coli L-asparaginases, it must be administered more
frequently (Avramis and Panosyan, Clin. Pharmacokinet. (2005)
44:367-393). In a study by Avramis et al., Erwinia asparaginase was
associated with inferior pharmacokinetic profiles (Avramis et al.,
J. Pediatr. Hematol. Oncol. 29 (2007) 239-247). E. coli
L-asparaginase and pegaspargase therefore have been the preferred
first-line therapies for ALL over Erwinia L-asparaginase.
[0014] Numerous biopharmaceuticals have successfully been PEGylated
and marketed for many years. In order to couple PEG to a protein,
the PEG has to be activated at its OH terminus. The activation
group is chosen based on the available reactive group on the
protein that will be PEGylated. In the case of proteins, the most
important amino acids are lysine, cysteine, glutamic acid, aspartic
acid, C-terminal carboxylic acid and the N-terminal amino group. In
view of the wide range of reactive groups in a protein nearly the
entire peptide chemistry has been applied to activate the PEG
moiety. Examples for this activated PEG-reagents are activated
carbonates, e.g., p-nitrophenyl carbonate, succinimidyl carbonate;
active esters, e.g., succinimidyl ester; and for site specific
coupling aldehydes and maleimides have been developed (Harris, M.,
Adv. Drug Del. Rev. 54 (2002), 459-476). The availability of
various chemical methods for PEG modification shows that each new
development of a PEGylated protein will be a case by case study. In
addition to the chemistry the molecular weight of the PEG that is
attached to the protein has a strong impact on the pharmaceutical
properties of the PEGylated protein. In most cases it is expected
that, the higher the molecular weight of the PEG, the better the
improvement of the pharmaceutical properties (Sherman, M. R., Adv.
Drug Del. Rev. 60 (2008), 59-68; Holtsberg, F. W., Journal of
Controlled Release 80 (2002), 259-271). For example, Holtsberg et
al. found that, when PEG was conjugated to arginine deaminase,
another amino acid degrading enzyme isolated from a microbial
source, pharmacokinetic and pharmacodynamic function of the enzyme
increased as the size of the PEG attachment increased from a
molecular weight of 5000 Da to 20,000 Da (Holtsberg, F. W., Journal
of Controlled Release 80 (2002), 259-271).
[0015] However, in many cases, PEGylated biopharmaceuticals show
significantly reduced activity compared to the unmodified
biopharmaceutical (Fishburn, C. S. (2008) Review "The Pharmacology
of PEGylation: Balancing PD with PK to Generate Novel Therapeutics"
J. Pharm. Sci., 1-17). In the case of L-asparaginase from Erwinia
carotovora, it has been observed that PEGylation reduced its in
vitro activity to approximately 57% (Kuchumova, A. V. et al. (2007)
"Modification of Recombinant asparaginase from Erwinia carotovora
with Polyethylene Glycol 5000" Biochemistry (Moscow) Supplement
Series B: Biomedical Chemistry, 1, 230-232). The L-asparaginase
from Erwinia carotovora has only about 75% homology to the Erwinia
chrysanthemi L-asparaginase (crisantaspase). For Oncaspar.RTM. it
is also known that its in vitro activity is approximately 50%
compared to the unmodified E. coli L-asparaginase.
[0016] The currently available L-asparaginase preparations do not
provide alternative or complementary therapies--particularly
therapies to treat ALL--that are characterized by high catalytic
activity and significantly improved pharmacological and
pharmacokinetic properties, as well as reduced immunogenicity.
BRIEF SUMMARY OF THE INVENTION
[0017] The present invention is directed to a conjugate of a
protein having substantial L-asparagine aminohydrolase activity and
polyethylene glycol, wherein the polyethylene glycol has a
molecular weight less than or equal to about 5000 Da, particularly
a conjugate where the protein is a L-asparaginase from Erwinia. In
one embodiment, the conjugate comprises an L-asparaginase from
Erwinia having at least 80% identity to the amino acid of SEQ ID
NO:1 and polyethylene glycol (PEG), wherein the PEG has a molecular
weight less than or equal to about 5000 Da. In one embodiment, the
L-asparaginase has at least about 80%, 85%, 90%, 91%, 92%, 93%,
94%, 95%, 96%, 97%, 98%, 99%, or 100% identity to the amino acid of
SEQ ID NO:1. In some embodiments, the PEG has a molecular weight of
about 5000 Da, 4000, Da, 3000 Da, 2500 Da, or 2000 Da. In one
embodiment, the conjugate has an in vitro activity of at least 60%,
65%, 70%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%,
86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%,
99%, or 100% as compared to the L-asparaginase when not conjugated
to PEG. In another embodiment, the conjugate has an L-asparagine
depletion activity at least about 10, 20, 30, 40, 50, 60, 70, 80,
90, or 100 times more potent than the L-asparaginase when not
conjugated to PEG. In another embodiment, the conjugate depletes
plasma L-asparagine levels to an undetectable level for at least
about 12, 24, 48, 96, 108, or 120 hours.
[0018] In one embodiment, the conjugate has a longer in vivo
circulating half life compared to the L-asparaginase when not
conjugated to PEG. In a specific embodiment, the conjugate has a
longer t.sub.1/2 than pegaspargase (i.e., PEG-conjugated
L-asparaginase from E. coli) administered at an equivalent protein
dose (e.g., measured in .mu.g/kg). In a more specific embodiment,
the conjugate has a t.sub.1/2 of at least about 58 to about 65
hours at a dose of about 50 .mu.g/kg on a protein content basis,
and a t.sub.1/2 of at least about 34 to about 40 hours at a dose of
about 10 .mu.g/kg on a protein content basis, following iv
administration in mice. In another specific embodiment, the
conjugate has a t.sub.1/2 of at least about 100 to about 200 hours
at a dose ranging from about 10,000 to about 15,000 IU/m.sup.2
(about 20-30 mg protein/m.sup.2). In one embodiment, the conjugate
has a greater area under the curve (AUC) compared to the
L-asparaginase when not conjugated to PEG. In a specific
embodiment, the conjugate has a mean AUC that is at least about 3
times greater than pegaspargase at an equivalent protein dose.
[0019] In one embodiment, the PEG is covalently linked to one or
more amino groups (wherein "amino groups" includes lysine residues
and/or the N-terminus) of the L-asparaginase. In a more specific
embodiment, the PEG is covalently linked to the one or more amino
groups by an amide bond. In another specific embodiment, the PEG is
covalently linked to at least from about 40% to about 100% of the
accessible amino groups (e.g., lysine residues and/or the
N-terminus of the protein) or at least from about 40% to about 90%
of total amino groups (e.g., lysine residues and/or the N-terminus
of the protein). In one embodiment, the conjugate has the
formula:
Asp-[NH--CO--(CH2)x-CO--NH-PEG]n
wherein Asp is the L-asparaginase, NH is one or more of the NH
groups of the lysine residues and/or the N-terminus of the Asp, PEG
is a polyethylene glycol moiety, n is a number that represents at
least about 40% to about 100% of the accessible amino groups (e.g.,
lysine residues and/or the N-terminus) in the Asp, and x is an
integer ranging from about 1 to about 8, more specifically, from
about 2 to about 5. In a specific embodiment, the PEG is
monomethoxy-polyethylene glycol (mPEG).
[0020] In another aspect, the invention is directed to a method of
making a conjugate comprising combining an amount of PEG with an
amount of the L-asparaginase in a buffered solution for a time
period sufficient to covalently link the PEG to the
L-asparaginase.
[0021] In another aspect, the invention is directed to a
pharmaceutical composition comprising the conjugate of the
invention.
[0022] In another aspect, the invention is directed to a method of
treating a disease treatable by L-asparagine depletion in a patient
comprising administering an effective amount of the conjugate of
the invention. In one embodiment, the disease is a cancer. In a
specific embodiment, the cancer is ALL. In another specific
embodiment, the conjugate is administered at an amount of about 5
U/kg body weight to about 50 U/kg body weight. In another specific
embodiment, the conjugate is administered at a dose ranging from
about 10,000 to about 15,000 IU/m.sup.2 (about 20-30 mg
protein/m.sup.2). In some embodiments, the administration may be
intravenous or intramuscular and may be less than once per week
(e.g., once per month or once every other week), once per week,
twice per week, or three times per week. In other specific
embodiments, the conjugate is administered as monotherapy and, more
specifically, without an asparagine synthetase inhibitor. In other
embodiments, the conjugate is administered as part of a combination
therapy (but in some embodiments, the combination therapy does not
comprise an asparagine synthetase inhibitor). In a specific
embodiment, the patient receiving treatment has had a previous
hypersensitivity to an E. coli asparaginase or PEGylated form
thereof or to an Erwinia asparaginase. In another specific
embodiment, the patient receiving treatment has had a disease
relapse, in particular a relapse that occurs after treatment with
an E. coli asparaginase or PEGylated form thereof.
BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES
[0023] FIG. 1: SDS-polyacrylamide gel electrophoresis of purified
recombinant Erwinia chrysanthemi L-asparaginase. Purified
recombinant Erwinia chrysanthemi L-asparaginase (r-crisantaspase)
was analyzed on SDS-PAGE. Protein bands were stained with silver
nitrate. Lane 1: Molecular Weight Marker (116, 66.2, 45, 35, 25,
18.4, and 14.4 kDa), lane 2: purified recombinant Erwinia
chrysanthemi L-asparaginase (r-crisantaspase).
[0024] FIG. 2: SDS-PAGE analysis of mPEG-r-crisantaspase
conjugates.
[0025] FIG. 3: Plasma L-asparagine levels following a single
intravenous dose of Erwinase.RTM. (5 U/kg, 25 U/kg, 125 U/kg and
250 U/kg body weight).
[0026] FIG. 4: Plasma L-asparagine levels following a single
intravenous injection of mPEG-r-crisantaspase conjugates compared
to Erwinase.RTM. in mice. The numbers "40%" and "100%" indicate an
approximate degree of PEGylation of, respectively, about 40-55%
(partially PEGylated) and about 100% (maximally PEGylated) of the
accessible amino groups.
[0027] FIG. 5: Area under the curves (AUC) (residual enzymatic
activity) calculated from L-asparaginase profiles following a
single intravenous injection of mPEG-r-crisantaspase conjugates in
mice.
[0028] FIG. 6: Plasma L-asparagine levels following a single
intravenous dose in mice of 2 kDa-100% mPEG-r-crisantaspase (5
U/kg, 25 U/kg and 50 U/kg body weight) (FIG. 6A), 5 kDa-100%
mPEG-r-crisantaspase (5 U/kg, 25 U/kg and 50 U/kg body weight)
(FIG. 6B), or 2 kDa-100% mPEG-r-crisantaspase (5 U/kg), 5 kDa-100%
mPEG-r-crisantaspase (5 U/kg), and pegaspargase (Oncaspar.RTM.) (1
U/kg) (FIG. 6C). Administration of an equivalent quantity of
protein (10 .mu.g/kg) of either 2 kDa-100% mPEG-r-crisantaspase (5
U/kg), 5 kDa-100% mPEG-r-crisantaspase (5 U/kg), or pegaspargase
(Oncaspar.RTM., 1 U/kg), resulted in a similar L-asparagine
depletion over 72 hours.
[0029] FIG. 7: Dose-effect Relationship of 2 kDa-100% PEGylated
r-crisantaspase compared to 5 kDa-100% PEGylated r-crisantaspase.
FIG. 7A shows the residual enzymatic activity in plasma following a
single intravenous dose of 2 kDa-100% PEGylated r-crisantaspase at
5 U/kg (10 .mu.g/kg on a protein content basis), 25 U/kg, and 50
U/kg. FIG. 7B shows the residual enzymatic activity in plasma
following a single intravenous dose of 5 kDa-100% PEGylated
r-crisantaspase at 5 U/kg (10 .mu.g/kg on a protein content basis),
25 U/kg, and 50 U/kg.
[0030] FIG. 8: Dose-effect relationship of 2 kDa-100% PEGylated
r-crisantaspase compared to 5 kDa-100% PEGylated r-crisantaspase.
AUCs of the residual enzymatic activity measured in mice after a
single intravenous dose of 2 kDa-100% or 5 kDa-100%
mPEG-conjugates. Overall, when compared at the same dose level,
AUCs measured for the 5 kDa-100% mPEG-r-crisantaspase were higher
than those observed for the 2-kDa-100% mPEG-r-crisantaspase. A
difference of 31, 37, and 14% was observed at 5, 25, and 50 U/kg
doses, respectively.
[0031] FIG. 9: Pharmacokinetics of mPEG-r-crisantaspase conjugates
vs. pegaspargase (Oncaspar.RTM.) in mice. FIG. 9A represents the
residual enzymatic activity measured in mice after a single
intravenous dose of 2 kDa-100% mPEG-r-crisantaspase, 5 kDa-100%
mPEG-r-crisantaspase, or pegaspargase (Oncaspar.RTM.). FIG. 9B
represents AUCs of the residual enzymatic activity measured in mice
after a single intravenous dose of 2 kDa-100% mPEG-r-crisantaspase,
5 kDa-100% mPEG-r-crisantaspase, or pegaspargase
(Oncaspar.RTM.).
[0032] FIG. 10: Serum levels of anti-crisantaspase specific
antibodies after treatment with mPEG-r-crisantaspase conjugates or
Erwinase.RTM.. Antibodies are directed toward crisantaspase. Data
are expressed as means.+-.SD (N=8).
[0033] FIG. 11: Serum levels of anti-conjugate specific antibodies
after treatment with mPEG-r-crisantaspase maximally (100%)
PEGylated conjugates. FIG. 11A: results presented as mean.+-.SD
(n=8); FIG. 11B: results presented as the percentage of animals
with absorbance values >0.5 in the anti-conjugate ELISA.
DETAILED DESCRIPTION OF THE INVENTION
[0034] In one aspect, the problem to be solved by the invention is
to provide an L-asparaginase preparation with: [0035] High in vitro
bioactivity; [0036] A stable PEG-protein linkage; [0037] Prolonged
in vivo half-life; [0038] Significantly reduced immunogenicity, as
evidenced, for example, by the reduction or elimination of an
antibody response against the L-asparaginase preparation following
repeated administrations; and [0039] Usefulness as a second-line
therapy for patients who have developed sensitivity to first-line
therapies using, e.g., E. coli-derived L-asparaginases.
[0040] This problem has not been solved by known L-asparaginase
conjugates, which either have significant cross-reactivity with
modified L-asparaginase preparations (Wang, B. et al. (2003)
Leukemia 17, 1583-1588, incorporated herein by reference in its
entirety), or which have considerably reduced in vitro activity
(Kuchumova, A. V. et al. (2007) Biochemistry (Moscow) Supplement
Series B: Biomedical Chemistry, 1, 230-232, incorporated herein by
reference in its entirety). This problem is solved according to the
present invention by providing a conjugate of Erwinia
L-asparaginase with a hydrophilic polymer, more specifically, a
polyethylene glycol with a molecular weight of 5000 Da or less, a
method for preparing such a conjugate and the use of the
conjugate.
[0041] Described herein is a PEGylated L-asparaginase from Erwinia
with improved pharmacological properties as compared with the
unmodified L-asparaginase protein, as well as compared to the
pegaspargase preparation from E. coli. The PEGylated L-asparaginase
conjugate described herein, e.g., Erwinia chrysanthemi
L-asparaginase PEGylated with 5000 Da molecular weight PEG, serves
as a therapeutic agent particularly for use in patients who show
hypersensitivity (e.g., an allergic reaction or silent
hypersensitivity) to treatment with L-asparaginase or PEGylated
L-asparaginase from E. coli. or unmodified L-asparaginase from
Erwinia. The PEGylated L-asparaginase conjugate described herein is
also useful as a therapeutic agent for use in patients who have had
a disease relapse, e.g., a relapse of ALL, and have been previously
treated with another form of asparaginase, e.g., with
L-asparaginase or PEGylated L-asparaginase from E. coli.
[0042] As described in detail herein, the conjugate of the
invention shows unexpectedly superior properties compared to known
L-asparaginase preparations such as pegaspargase. For example,
unmodified L-asparaginase from Erwinia chrysanthemi (crisantaspase)
has a significantly lower half-life than unmodified L-asparaginase
from E. coli (Avramis and Panosyan, Clin. Pharmacokinet. (2005)
44:367-393, incorporated herein by reference in its entirety). The
PEGylated conjugate of the invention has a half life that is
greater than PEGylated L-asparaginase from E. coli at an equivalent
protein dose.
DEFINITIONS
[0043] Unless otherwise expressly defined, the terms used herein
will be understood according to their ordinary meaning in the
art.
[0044] As used herein, the term "including" means "including,
without limitation," and terms used in the singular shall include
the plural, and vice versa, unless the context dictates
otherwise.
[0045] As used herein, the term "disease treatable by depletion of
asparagine" refers to a condition or disorder wherein the cells
involved in or responsible for the condition or disorder either
lack or have a reduced ability to synthesize L-asparagine.
Depletion or deprivation of L-asparagine can be partial or
substantially complete (e.g., to levels that are undetectable using
methods and apparatus that are known in the art).
[0046] As used herein, the term "therapeutically effective amount"
refers to the amount of a protein (e.g., asparaginase or conjugate
thereof), required to produce a desired therapeutic effect.
L-Asparaginase Protein
[0047] The protein according to the invention is an enzyme with
L-asparagine aminohydrolase activity, namely an L-asparaginase.
[0048] Many L-asparaginase proteins have been identified in the
art, isolated by known methods from microorganisms. (See, e.g.,
Savitri and Azmi, Indian J. Biotechnol 2 (2003) 184-194,
incorporated herein by reference in its entirety). The most widely
used and commercially available L-asparaginases are derived from E.
coli or from Erwinia chrysanthemi, both of which share 50% or less
structural homology. Within the Erwinia species, typically 75-77%
sequence identity was reported between Erwinia chrysanthemi and
Erwinia carotovora-derived enzymes, and approximately 90% sequence
identity was found between different subspecies of Erwinia
chrysanthemi (Kotzia G A, Labrou E, Journal of Biotechnology (2007)
127:657-669, incorporated herein by reference in its entirety).
Some representative Erwinia L-asparaginases include, for example,
those provided in Table 1:
TABLE-US-00001 TABLE 1 % IDENTITY TO ERWINIA GENBANK CHRYSANTHEMI
SPECIES ACCESSION NO. NCPPB 1066 Erwinia chrysanthemi AAS67028 91%
3937 Erwinia chrysanthemi CAA31239 98% NCPPB 1125 Erwinia
carotovora subsp. AAS67027 75% Astroseptica Erwinia carotovora
AAP92666 77%
[0049] The sequences of the Erwinia L-asparaginases and the GenBank
entries of Table 1 are herein incorporated by reference. Preferred
L-asparaginases used in therapy are L-asparaginase isolated from E.
coli and from Erwinia, specifically, Erwinia chrysanthemi.
[0050] The L-asparaginases may be native enzymes isolated from the
microorganisms. They can also be produced by recombinant enzyme
technologies in producing microorganisms such as E. coli. As
examples, the protein used in the conjugate of the invention can be
a protein form E. coli produced in a recombinant E. coli producing
strain, of a protein from an Erwinia species, particularly Erwinia
chrysanthemi, produced in a recombinant E. coli producing
strain.
[0051] Enzymes can be identified by their specific activities. This
definition thus includes all polypeptides that have the defined
specific activity also present in other organisms, more
particularly in other microorganisms. Often enzymes with similar
activities can be identified by their grouping to certain families
defined as PFAM or COG. PFAM (protein family database of alignments
and hidden Markov models; http://pfam.sanger.ac.uk/) represents a
large collection of protein sequence alignments. Each PFAM makes it
possible to visualize multiple alignments, see protein domains,
evaluate distribution among organisms, gain access to other
databases, and visualize known protein structures. COGs (Clusters
of Orthologous Groups of proteins;
http://www.ncbi.nlm.nih.gov/COG/) are obtained by comparing protein
sequences from 43 fully sequenced genomes representing 30 major
phylogenetic lines. Each COG is defined from at least three lines,
which permits the identification of former conserved domains.
[0052] The means of identifying homologous sequences and their
percentage homology and/or identity are well known to those skilled
in the art, and include in particular the BLAST programs, which can
be used from the website http://blast.ncbi.nlm.nih.gov/Blast.cgi
with the default parameters indicated on that website. The
sequences obtained can then be exploited (e.g., aligned) using, for
example, the programs CLUSTALW
(http://www.ebi.ac.uk/Tools/clustalw2/index.html) or MULTALIN
(http://bioinfo.genotoul.fr/multalin/muitalin.html) with the
default parameters indicated on those websites. Using the
references given on GenBank for known genes, those skilled in the
art are able to determine the equivalent genes in other organisms,
bacterial strains, yeasts, fungi, mammals, plants, etc. This
routine work is advantageously done using consensus sequences that
can be determined by carrying out sequence alignments with genes
derived from other microorganisms, and designing degenerate probes
to clone the corresponding gene in another organism. These routine
methods of molecular biology are well known to those skilled in the
art, and are described, for example, in Sambrook et al. (1989
MOLECULAR CLONING: A LABORATORY MANUAL. 2nd ed. Cold Spring Harbor
Lab., Cold Spring Harbor, N.Y.).
[0053] Indeed, a person skilled in the art will understand how to
select and design homologous proteins retaining substantially their
L-asparaginase activity. Typically, a Nessler assay is used for the
determination of L-asparaginase activity according to a method
described by Mashburn and Wriston (Mashburn, L., and Wriston, J.
(1963) "Tumor Inhibitory Effect of L-Asparaginase," Biochem Biophys
Res Commun 12, 50, incorporated herein by reference in its
entirety).
[0054] In a particular embodiment of the conjugate of the
invention, the L-asparaginase protein has at least about 80%
homology or identity with the protein comprising the sequence of
SEQ ID NO:1, more specifically at least about 85%, 86%, 87%, 88%,
89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%
homology or identity with the protein comprising the sequence of
SEQ ID NO:1. SEQ ID NO:1 is as follows:
TABLE-US-00002 (SEQ ID NO: 1)
ADKLPNIVILATGGTIAGSAATGTQTTGYKAGALGVDTLINAVPEVKKLA
NVKGEQFSNMASENMTGDVVLKLSQRVNELLARDDVDGVVITHGTDTVEE
SAYFLHLTVKSDKPVVFVAAMRPATAISADGPMNLLEAVRVAGDKQSRGR
GVMVVLNDRIGSARYITKTNASTLDTFKANEEGYLGVIIGNRIYYQNRID
KLHTTRSVFDVRGLTSLPKVDILYGYQDDPEYLYDAAIQHGVKGIVYAGM
GAGSVSVRGIAGMRKAMEKGVVVIRSTRTGNGIVPPDEELPGLVSDSLNP
AHARILLMLALTRTSDPKVIQEYFHTY
[0055] The term "comprising the sequence of SEQ ID NO:1" means that
the amino-acid sequence of the protein may not be strictly limited
to SEQ ID NO:1 but may contain additional amino-acids.
[0056] In a particular embodiment, the protein is the
L-asparaginase of Erwinia chrysanthemi having the sequence of SEQ
ID NO: 1. In another embodiment, the L-asparaginase is from Erwinia
chrysanthemi NCPPB 1066 (Genbank Accession No. CAA32884,
incorporated herein by reference in its entirety), either with or
without signal peptides and/or leader sequences.
[0057] Fragments of the protein of SEQ ID NO:1 are also comprised
within the definition of the protein used in the conjugate of the
invention. The term "a fragment of SEQ ID NO:1" means that the
sequence of the polypeptide may include less amino-acid than SEQ ID
N01 but still enough amino-acids to confer L-aminohydrolase
activity.
[0058] It is well known in the art that a polypeptide can be
modified by substitution, insertion, deletion and/or addition of
one or more amino-acids while retaining its enzymatic activity. For
example, substitution of one amino-acid at a given position by a
chemically equivalent amino-acid that does not affect the
functional properties of a protein is common. Substitutions may be
defined as exchanges within one of the following groups:
[0059] Small aliphatic, non-polar or slightly polar residues: Ala,
Ser, Thr, Pro, Gly
[0060] Polar, negatively charged residues and their amides: Asp,
Asn, Glu, Gln
[0061] Polar, positively charged residues: His, Arg, Lys
[0062] Large aliphatic, non-polar residues: Met, Leu, Ile, Val,
Cys
[0063] Large aromatic residues: Phe, Tyr, Trp.
[0064] Thus, changes that result in the substitution of one
negatively charged residue for another (such as glutamic acid for
aspartic acid) or one positively charged residue for another (such
as lysine for arginine) can be expected to produce a functionally
equivalent product.
[0065] The positions where the amino-acids are modified and the
number of amino-acids subject to modification in the amino-acid
sequence are not particularly limited. The skilled artisan is able
to recognize the modifications that can be introduced without
affecting the activity of the protein. For example, modifications
in the N- or C-terminal portion of a protein may be expected not to
alter the activity of a protein under certain circumstances. With
respect to asparaginases, in particular, much characterization has
been done, particularly with respect to the sequences, structures,
and the residues forming the active catalytic site. This provides
guidance with respect to residues that can be modified without
affecting the activity of the enzyme. All known L-asparaginases
from bacterial sources have common structural features. All are
homotetramers with four active sites between the N- and C-terminal
domains of two adjacent monomers (Aghaipour et al., Biochemistry 40
(2001) 5655-5664, incorporated herein by reference in its
entirety). All have a high degree of similarity in their tertiary
and quaternary structures (Papageorgiou et al., FEBS J. 275 (2008)
4306-4316, incorporated herein by reference in its entirety). The
sequences of the catalytic sites of L-asparaginases are highly
conserved between Erwinia chrysanthemi, Erwinia carotovora, and E.
coli L-asparaginase II (Papageorgiou et al., FEBS J. 275 (2008)
4306-4316). The active site flexible loop contains amino acid
residues 14-33, and structural analysis show that Thr15, Thr95,
Ser62, Glu63, Asp96, and Ala120 contact the ligand (Papageorgiou et
al., FEBS J. 275 (2008) 4306-4316). Aghaipour et al. have conducted
a detailed analysis of the four active sites of Erwinia
chrysanthemi L-asparaginase by examining high resolution crystal
structures of the enzyme complexed with its substrates (Aghaipour
et al., Biochemistry 40 (2001) 5655-5664). Kotzia et al. provide
sequences for L-asparaginases from several species and subspecies
of Erwinia and, even though the proteins have only about 75-77%
identity between Erwinia chrysanthemi and Erwinia carotovora, they
each still have L-asparaginase activity (Kotzia et al., J.
Biotechnol. 127 (2007) 657-669, incorporated herein by reference in
its entirety). Moola et al. performed epitope mapping studies of
Erwinia chrysanthemi 3937 L-asparaginase and were able to retain
enzyme activity even after mutating various antigenic sequences in
an attempt to reduce immunogenicity of the asparaginase (Moola et
al., Biochem. J. 302 (1994) 921-927, incorporated herein by
reference in its entirety). Each of the above-cited articles is
herein incorporated by reference in its entirety. In view of the
extensive characterization that has been performed on
L-asparaginases, one of skill in the art could determine how to
make fragments and/or sequence substitutions while still retaining
enzyme activity.
Polymers for Use in the Conjugate
[0066] Polymers are selected from the group of non-toxic water
soluble polymers such as polysaccharides, e.g. hydroxyethyl starch,
poly amino acids, e.g. poly lysine, polyester, e.g., polylactic
acid, and poly alkylene oxides, e.g., polyethylene glycol
(PEG).
[0067] Polyethylene glycol (PEG) or mono-methoxy-polyethyleneglycol
(mPEG) is well known in the art and comprises linear and branched
polymers. Examples of some polymers, particularly PEG, are provided
in the following, each of which is herein incorporated by reference
in its entirety: U.S. Pat. No. 5,672,662; U.S. Pat. No. 4,179,337;
U.S. Pat. No. 5,252,714; US Pat. Appl. Publ. No. 2003/0114647; U.S.
Pat. No. 6,113,906; U.S. Pat. No. 7,419,600; and PCT Publ. No.
WO2004/083258.
[0068] The quality of such polymers is characterized by the
polydispersity index (PDI). The PDI reflects the distribution of
molecular weights in a given polymer sample and is calculated from
the weight average molecular weight divided by the number average
molecular weight. It indicates the distribution of individual
molecular weights in a batch of polymers. The PDI has a value
always greater than 1, but as the polymer chains approach the ideal
Gauss distribution (=monodispersity), the PDI approaches 1.
[0069] The polyethylene glycol has advantageously a molecular
weight comprised within the range of about 500 Da to about 9,000
Da. More specifically, the polyethylene glycol (e.g, mPEG) has a
molecular weight selected from the group consisting of polyethylene
glycols of 2000 Da, 2500 Da, 3000 Da, 3500 Da, 4000 Da, 4500 Da,
and 5000 Da. In a particular embodiment, the polyethylene glycol
(e.g., mPEG) has a molecular weight of 5000 Da.
Method for Preparing the Conjugate
[0070] For subsequent coupling of the polymer to proteins with
L-asparagine aminohydrolase activity, the polymer moiety contains
an activated functionality that preferably reacts with amino groups
in the protein. In one aspect, the invention is directed to a
method of making a conjugate, the method comprising combining an
amount of polyethylene glycol (PEG) with an amount of
L-asparaginase in a buffered solution for a time period sufficient
to covalently link the PEG to the L-asparaginase. In a particular
embodiment, the L-asparaginase is from Erwinia species, more
specifically Erwinia chrysanthemi, and more specifically, the
L-asparaginase comprising the sequence of SEQ ID NO:1. In one
embodiment, the PEG is monomethoxy-polyethylene glycol (mPEG).
[0071] In one embodiment, the reaction between the polyethylene
glycol and L-asparaginase is performed in a buffered solution. In
some particular embodiments, the pH value of the buffer solution
ranges between about 7.0 and about 9.0. The most preferred pH value
ranges between about 7.5 and about 8.5, e.g., a pH value of about
7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, or 8.5. In a
particular embodiment, the L-asparaginase is from Erwinia species,
more specifically Erwinia chrysanthemi, and more specifically, the
L-asparaginase comprising the sequence of SEQ ID NO:1.
[0072] Furthermore, PEGylation of L-asparaginase is performed at
protein concentrations between about 0.5 and about 25 mg/mL, more
specifically between about 2 and about 20 mg/mL and most
specifically between about 3 and about 15 mg/mL. For example, the
protein concentration is about 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 mg/mL. In a particular
embodiment, the PEGylation of L-asparaginase at these protein
concentrations is of Erwinia species, more specifically Erwinia
chrysanthemi, and more specifically, the L-asparaginase comprising
the sequence of SEQ ID NO:1.
[0073] At elevated protein concentration of more than 2 mg/mL the
PEGylation reaction proceeds rapidly, within less than 2 hours.
Furthermore, a molar excess of polymer over amino groups in
L-asparaginase of less than about 20:1 is applied. For example, the
molar excess is less than about 20:1, 19:1, 18:1, 17:1, 16:1, 15:1,
14:1, 13:1, 12:1, 11:1, 10:1, 9:1, 8:1, 7.5:1, 7:1, 6.5:1, 6:1,
5.5:1, 5:1, 4.5:1, 4:1, 3.5:1, 3:1, 2.5:1, 2:1, 1.5:1, or 1:1. In a
specific embodiment the molar excess is less than about 10:1 and in
a more specific embodiment, the molar excess is less than about
8:1. In a particular embodiment, the L-asparaginase is from Erwinia
species, more specifically Erwinia chrysanthemi, and more
specifically, the L-asparaginase comprising the sequence of SEQ ID
NO:1.
[0074] The number of PEG moieties which can be coupled to the
protein will be subject to the number of free amino groups and,
even more so, to which amino groups are accessible for a PEGylation
reaction. In a particular embodiment, the degree of PEGylation
(i.e., the number of PEG moieties coupled to amino groups on the
L-asparaginase) is within a range from about 10% to about 100% of
free and/or accessible amino groups (e.g., about 10%, 15%, 20%,
25%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100%). 100% PEGylation
of accessible amino groups (e.g., lysine residues and/or the
N-terminus of the protein) is also referred to herein as "maximally
PEGylated." One method to determine the modified amino groups in
mPEG-r-crisantaspase conjugates (degree of PEGylation) is a method
described by Habeeb (A.F.S.A. Habeeb, "Determination of free amino
groups in proteins by trinitrobenzensulfonic acid", Anal. Biochem.
14 (1966), p. 328, incorporated herein by reference in its
entirety). In one embodiment, the PEG moieties are coupled to one
or more amino groups (wherein amino groups include lysine residues
and/or the N-terminus) of the L-asparaginase. In a particular
embodiment, the degree of PEGylation is within a range of from
about 10% to about 100% of total or accessible amino groups (e.g.,
lysine residues and/or the N-terminus), e.g., about 10%, 15%, 20%,
25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%,
90%, 95% or 100%. In a specific embodiment, about 40%, 45%, 50%,
55%, 60%, 65%, 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%,
92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% of the total amino
groups (e.g., lysine residues and/or the N-terminus) are coupled to
a PEG moiety. In another specific embodiment, about 40%, 41%, 42%,
43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%,
56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%,
70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%,
83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%,
96%, 97%, 98%, 99%, or 100% of the accessible amino groups (e.g.,
lysine residues and/or the N-terminus) are coupled to a PEG moiety.
In a specific embodiment, 40-55% or 100% of the accessible amino
groups (e.g., lysine residues and/or the N-terminus) are coupled to
a PEG moiety. In some embodiments, the PEG moieties are coupled to
the L-asparaginase by a covalent linkage. In a particular
embodiment, the L-asparaginase is from Erwinia species, more
specifically Erwinia chrysanthemi, and more specifically, the
L-asparaginase comprising the sequence of SEQ ID NO:1.
[0075] In one embodiment, the conjugate of the invention can be
represented by the formula
Asp-[NH--CO--(CH2)x-CO--NH-PEG]n
wherein Asp is a L-asparaginase protein, NH is the NH group of a
lysine residue and/or the N-terminus of the protein chain, PEG is a
polyethylene glycol moiety and n is a number of at least 40% to
about 100% of the accessible amino groups (e.g., lysine residues
and/or the N-terminus) in the protein, all being defined above and
below in the examples, x is an integer ranging from 1 to 8 (e.g.,
1, 2, 3, 4, 5, 6, 7, 8), preferably 2 to 5 (e.g., 2, 3, 4, 5). In a
particular embodiment, the L-asparaginase is from Erwinia species,
more specifically Erwinia chrysanthemi, and more specifically, the
L-asparaginase comprising the sequence of SEQ ID NO:1.
[0076] Other methods of PEGylation that can be used to form the
conjugates of the invention are provided, for example, in U.S. Pat.
No. 4,179,337, U.S. Pat. No. 5,766,897, U.S. Pat. Appl. Publ. No.
US 2002/0065397A1, and U.S. Pat. Appl. Publ. No. US 2009/0054590A1,
each of which is herein incorporated by reference in its
entirety.
[0077] Specific embodiments include proteins having substantial
L-Asparagine aminohydrolase activity and polyethylene glycol,
selected from the group of conjugates wherein:
(A)
[0078] the protein has at least 90% homology of structure with the
L-asparaginase from Erwinia chrysanthemi as disclosed in SEQ ID
NO:1 [0079] the polyethylene glycol has a molecular weight of about
5000 Da, [0080] the protein and polyethylene glycol moieties are
covalently linked to the protein by amide bonds, and [0081] about
100% of the accessible amino groups (e.g., lysine residues and/or
the N-terminus) or about 80-90%, in particular, about 84%, of total
amino groups (e.g., lysine residues and/or the N-terminus) are
linked to a polyethylene glycol moiety.
(B)
[0081] [0082] the protein has at least 90% homology with the
L-asparaginase from Erwinia chrysanthemi as disclosed in SEQ ID
NO:1 [0083] the polyethylene glycol has a molecular weight of about
5000 Da, [0084] the protein and polyethylene glycol moieties are
covalently linked to the protein by amide bonds, and [0085] about
40% to about 45%, and in particular about 43% of the accessible
amino groups (e.g., lysine residues and/or the N-terminus), or
about 36% of the total amino groups (e.g., lysine residues and/or
the N-terminus) are linked to a polyethylene glycol moiety.
(C)
[0085] [0086] the protein has at least 90% homology with the
L-asparaginase from Erwinia chrysanthemi as disclosed in SEQ ID
NO:1 [0087] the polyethylene glycol has a molecular weight of about
2000 Da, [0088] the protein and polyethylene glycol moieties are
covalently linked to the protein by amide bonds, and [0089] about
100% of the accessible amino groups (e.g., one or more lysine
residues and/or the N-terminus) or about 80-90%, in particular,
about 84% of total amino groups (e.g., lysine residues and/or the
N-terminus) are linked to a polyethylene glycol moiety.
(D)
[0089] [0090] the protein has at least 90% homology with the
L-asparaginase from Erwinia chrysanthemi as disclosed in SEQ ID
NO:1 [0091] the polyethylene glycol has a molecular weight of about
2000 Da, [0092] the protein and polyethylene glycol moieties are
covalently linked to the protein by amide bonds, and [0093] about
50% to about 60%, and in particular about 55% of the accessible
amino groups (e.g., lysine residues and/or the N-terminus) or about
47% of the total amino groups (e.g., lysine residues and/or the
N-terminus) are linked to a polyethylene glycol moiety.
L-Asparaginase-PEG Conjugates
[0094] Conjugates of the invention have certain advantageous and
unexpected properties compared to unmodified L-asparaginases,
particularly compared to unmodified Erwinia L-asparaginases, more
particularly compared to unmodified L-asparaginase from Erwinia
chrysanthemi, and more particularly compared to unmodified
L-asparaginase having the sequence of SEQ ID NO:1.
[0095] In some embodiments, the conjugate of the invention reduces
plasma L-asparagine levels for a time period of at least about 12,
24, 48, 72, 96, or 120 hours when administered at a dose of 5 U/kg
body weight (bw) or 10 .mu.g/kg (protein content basis). In other
embodiments, the conjugate of the invention reduces plasma
L-asparagine levels to undetectable levels for a time period of at
least about 12, 24, 48, 72, 96, 120, or 144 hours when administered
at a dose of 25 U/kg bw or 50 .mu.g/kg (protein content basis). In
other embodiments, the conjugate of the invention reduces plasma
L-asparagine levels for a time period of at least about 12, 24, 48,
72, 96, 120, 144, 168, 192, 216, or 240 hours when administered at
a dose of 50 U/kg bw or 100 .mu.g/kg (protein content basis). In
another embodiment, the conjugate of the invention reduces plasma
L-asparagine levels to undetectable levels for a time period of at
least about 12, 24, 48, 72, 96, 120, 144, 168, 192, 216, or 240
hours when administered at a dose ranging from about 10,000 to
about 15,000 IU/m.sup.2 (about 20-30 mg protein/m.sup.2). In a
particular embodiment, the conjugate comprises L-asparaginase from
Erwinia species, more specifically Erwinia chrysanthemi, and more
specifically, the L-asparaginase comprising the sequence of SEQ ID
NO:1. In a particular embodiment, the conjugate comprises PEG
(e.g., mPEG) having a molecular weight of less than or equal to
about 5000 Da. In a more particular embodiment, at least about 40%
to about 100% of accessible amino groups (e.g., lysine residues
and/or the N-terminus) are PEGylated.
[0096] In one embodiment, the conjugate comprises a ratio of mol
PEG/mol monomer of about 4.5 to about 8.5, particularly about 6.5;
a specific activity of about 450 to about 550 U/mg, particularly
about 501 U/mg; and a relative activity of about 75% to about 85%,
particularly about 81% compared to the corresponding unmodified
L-asparaginase. In a specific embodiment, the conjugate with these
properties comprises an L-asparaginase from Erwinia species, more
specifically Erwinia chrysanthemi, and more specifically, the
L-asparaginase comprising the sequence of SEQ ID NO:1, with
PEGylation of approximately 40-55% accessible amino groups (e.g.,
lysine residues and/or the N-terminus) with 5000 Da mPEG.
[0097] In one embodiment, the conjugate comprises a ratio of mol
PEG/mol monomer of about 12.0 to about 18.0, particularly about
15.1; a specific activity of about 450 to about 550 U/mg,
particularly about 483 U/mg; and a relative activity of about 75 to
about 85%, particularly about 78% compared to the corresponding
unmodified L-asparaginase. In a specific embodiment, the conjugate
with these properties comprises an L-asparaginase from Erwinia
species, more specifically Erwinia chrysanthemi, and more
specifically, the L-asparaginase comprising the sequence of SEQ ID
NO:1, with PEGylation of approximately 100% accessible amino groups
(e.g., lysine residues and/or the N-terminus) with 5000 Da
mPEG.
[0098] In one embodiment, the conjugate comprises a ratio of mol
PEG/mol monomer of about 5.0 to about 9.0, particularly about 7.0;
a specific activity of about 450 to about 550 U/mg, particularly
about 501 U/mg; and a relative activity of about 80 to about 90%,
particularly about 87% compared to the corresponding unmodified
L-asparaginase. In a specific embodiment, the conjugate with these
properties comprises an L-asparaginase from Erwinia species, more
specifically Erwinia chrysanthemi, and more specifically, the
L-asparaginase comprising the sequence of SEQ ID NO:1, with
PEGylation of approximately 40-55% accessible amino groups (e.g.,
lysine residues and/or the N-terminus) with 10,000 Da mPEG.
[0099] In one embodiment, the conjugate comprises a ratio of mol
PEG/mol monomer of about 11.0 to about 17.0, particularly about
14.1; a specific activity of about 450 to about 550 U/mg,
particularly about 541 U/mg; and a relative activity of about 80 to
about 90%, particularly about 87% compared to the corresponding
unmodified L-asparaginase. In a specific embodiment, the conjugate
with these properties comprises an L-asparaginase from Erwinia
species, more specifically Erwinia chrysanthemi, and more
specifically, the L-asparaginase comprising the sequence of SEQ ID
NO:1, with PEGylation of approximately 100% accessible amino groups
(e.g., lysine residues and/or the N-terminus) with 10,000 Da
mPEG.
[0100] In one embodiment, the conjugate comprises a ratio of mol
PEG/mol monomer of about 6.5 to about 10.5, particularly about 8.5;
a specific activity of about 450 to about 550 U/mg, particularly
about 524 U/mg; and a relative activity of about 80 to about 90%,
particularly about 84% compared to the corresponding unmodified
L-asparaginase. In a specific embodiment, the conjugate with these
properties comprises an L-asparaginase from Erwinia species, more
specifically Erwinia chrysanthemi, and more specifically, the
L-asparaginase comprising the sequence of SEQ ID NO:1, with
PEGylation of approximately 40-55% accessible amino groups (e.g.,
lysine residues and/or the N-terminus) with 2,000 Da mPEG.
[0101] In one embodiment, the conjugate comprises a ratio of mol
PEG/mol monomer of about 12.5 to about 18.5, particularly about
15.5; a specific activity of about 450 to about 550 U/mg,
particularly about 515 U/mg; and a relative activity of about 80 to
about 90%, particularly about 83% compared to the corresponding
unmodified L-asparaginase. In a specific embodiment, the conjugate
with these properties comprises an L-asparaginase from Erwinia
species, more specifically Erwinia chrysanthemi, and more
specifically, the L-asparaginase comprising the sequence of SEQ ID
NO:1, with PEGylation of approximately 100% accessible amino groups
(e.g., lysine residues and/or the N-terminus) with 2,000 Da
mPEG.
[0102] In other embodiments, the conjugate of the invention has an
increased potency of at least about 10 times, 20 times, 30 times,
40 times, 50 times, 60 times, 70 times, 80 times, 90 times, or 100
times after a single injection compared to the corresponding
unmodified L-asparaginase. In a specific embodiment, the conjugate
with these properties comprises an L-asparaginase from Erwinia
species, more specifically Erwinia chrysanthemi, and more
specifically, the L-asparaginase comprising the sequence of SEQ ID
NO:1. In a particular embodiment, the conjugate comprises PEG
(e.g., mPEG) having a molecular weight of less than or equal to
about 5000 Da. In a more particular embodiment, at least about 40%
to about 100% of accessible amino groups (e.g., lysine residues
and/or the N-terminus) are PEGylated.
[0103] In one aspect the conjugate of the invention has a
pharmacokinetic profile according to the following parameters:
TABLE-US-00003 Parameter Definition A.sub.max Maximal residual
enzyme activity t.sub.Amax Time to A.sub.max after test item
exposure d.sub.Amax Maximal duration of A.sub.max or A above
zero
[0104] The half-life time of the residual enzyme activity in plasma
is derived from the following formula:
t 1 2 = - In 2 .times. t In ( c t c 0 ) ##EQU00001##
Mean:
[0105] where t.sub.1/2 is the half-life, t is the time point,
c.sub.t is the residual plasma activity at the time point and
c.sub.0 the residual plasma activity at the beginning. Area under
the curve (AUC) is calculated using a pharmacokinetics software
program, e.g., SigmaPlot Version 11.
[0106] In one embodiment, the conjugate of the invention has a
single-dose pharmacokinetic profile according to the following,
specifically wherein the conjugate comprises mPEG at molecular
weight of less than or equal to 2000 Da and an L-asparaginase from
Erwinia species, more specifically Erwinia chrysanthemi, and more
specifically, the L-asparaginase comprising the sequence of SEQ ID
NO:1: [0107] A.sub.max: about 150 U/L to about 250 U/L; [0108]
T.sub.Amax: about 4 h to about 8 h, specifically about 6 h; [0109]
d.sub.Amax: about 220 h to about 250 h, specifically, about 238.5 h
(above zero, from about [0110] 90 min to about 240 h); [0111] AUC:
about 12000 to about 30000; and [0112] t.sub.1/2: about 50 h to
about 90 h.
[0113] In one embodiment, the conjugate of the invention has a
single-dose pharmacokinetic profile according to the following,
specifically where the conjugate comprises mPEG at molecular weight
of less than or equal to 5000 Da and an L-asparaginase from Erwinia
species, more specifically Erwinia chrysanthemi, and more
specifically, the L-asparaginase comprising the sequence of SEQ ID
NO:1: [0114] A.sub.max: about 18 U/L to about 250 U/L; [0115]
T.sub.Amax: about 1 h to about 50 h; [0116] d.sub.Amax: about 90 h
to about 250 h, specifically, about 238.5 h (above zero, from about
90 min to about 240 h); [0117] AUC: about 500 to about 35000; and
[0118] t.sub.1/2: about 30 h to about 120 h.
[0119] In one embodiment, the conjugate of the invention results in
a similar level of L-asparagine depletion over a period of time
(e.g., 24, 48, or 72 hours) after a single dose compared to an
equivalent quantity of protein of pegaspargase. In a specific
embodiment, the conjugate comprises an L-asparaginase from Erwinia
species, more specifically Erwinia chrysanthemi, and more
specifically, the L-asparaginase comprising the sequence of SEQ ID
NO:1. In a particular embodiment, the conjugate comprises PEG
(e.g., mPEG) having a molecular weight of less than or equal to
about 5000 Da. In a more particular embodiment, at least about 40%
to about 100% of accessible amino groups (e.g., lysine residues
and/or the N-terminus) are PEGylated, more particularly about
40-55% or 100%.
[0120] In one embodiment, the conjugate of the invention has a
longer t.sub.1/2 than pegaspargase administered at an equivalent
protein dose. In an a specific embodiment, the conjugate has a
t.sub.1/2 of at least about 50, 52, 54, 56, 58, 59, 60, 61, 62, 63,
64, or 65 hours at a dose of about 50 .mu.g/kg (protein content
basis). In another specific embodiment, the conjugate has a
t.sub.1/2 of at least about 30, 32, 34, 36, 37, 38, 39, or 40 hours
at a dose of about 10 .mu.g/kg (protein content basis). In another
specific embodiment, the conjugate has a t.sub.1/2 of at least
about 100 to about 200 hours at a dose ranging from about 10,000 to
about 15,000 IU/m.sup.2 (about 20-30 mg protein/m.sup.2).
[0121] In one embodiment, the conjugate of the invention has a mean
AUC that is at least about 2, 3, 4 or 5 times greater than
pegaspargase at an equivalent protein dose.
[0122] In one embodiment, the conjugate of the invention does not
raise any significant antibody response for a particular period of
time after administration of a single dose, e.g, greater than about
1 week, 2 weeks, 3 weeks, 4, weeks, 5 weeks, 6 weeks, 7 weeks, 8
weeks, 9 weeks, 10 weeks, 11 weeks, 12 weeks, etc. In a particular
embodiment the conjugate of the invention does not raise any
significant antibody response for at least 8 weeks. In one example,
"does not raise any significant antibody response" means that the
subject receiving the conjugate is identified within art-recognized
parameters as "antibody-negative." Antibody levels can be
determined by methods known in the art, for example ELISA or
surface plasmon resonance (SPR-Biacore) assays (Zalewska-Szewczyk
et al., Clin. Exp. Med. (2009) 9:113-116; Avramis et al.,
Anticancer Research 29 (2009) 299-302, each of which is
incorporated herein by reference in its entirety). Conjugates of
the invention may have any combination of these properties.
Methods of Treatment and Use of the Conjugate
[0123] The conjugates of the invention can be used in the treatment
of a disease treatable by depletion of asparagine. For example, the
conjugate is useful in the treatment or the manufacture of a
medicament for use in the treatment of acute lymphoblastic leukemia
(ALL) in both adults and children, as well as other conditions
where asparagine depletion is expected to have a useful effect.
Such conditions include, but are not limited to the following:
malignancies, or cancers, including but not limited to hematologic
malignancies, non-Hodgkin's lymphoma, NK lymphoma, pancreatic
cancer, Hodgkin's disease, acute myelocytic leukemia, acute
myelomonocytic leukemia, chronic lymphocytic leukemia,
lymphosarcoma, reticulosarcoma, and melanosarcoma. Representative
non-malignant hematologic diseases which respond to asparagine
depletion include immune system-mediated blood diseases, e.g.,
infectious diseases such as those caused by HIV infection (i.e.,
AIDS). Non-hematologic diseases associated with asparagine
dependence include autoimmune diseases, for example rheumatoid
arthritis, SLE, autoimmune, collagen vascular diseases, AIDS, etc.
Other autoimmune diseases include osteoarthritis, Issac's syndrome,
psoriasis, insulin dependent diabetes mellitus, multiple sclerosis,
sclerosing panencephalitis, systemic lupus erythematosus, rheumatic
fever, inflammatory bowel disease (e.g., ulcerative colitis and
Crohn's disease), primary billiary cirrhosis, chronic active
hepatitis, glomerulonephritis, myasthenia gravis, pemphigus
vulgaris, and Graves' disease. Cells suspected of causing disease
can be tested for asparagine dependence in any suitable in vitro or
in vivo assay, e.g., an in vitro assay wherein the growth medium
lacks asparagine. Thus, in one aspect, the invention is directed to
a method of treating a disease treatable in a patient, the method
comprising administering to the patient an effective amount of a
conjugate of the invention. In a specific embodiment, the disease
is ALL. In a particular embodiment, the conjugate used in the
treatment of a disease treatable by asparagine depletion comprises
an L-asparaginase from Erwinia species, more specifically Erwinia
chrysanthemi, and more specifically, the L-asparaginase comprising
the sequence of SEQ ID NO:1. In a particular embodiment, the
conjugate comprises PEG (e.g., mPEG) having a molecular weight of
less than or equal to about 5000 Da. In a more particular
embodiment, at least about 40% to about 100% of accessible amino
groups (e.g., lysine residues and/or the N-terminus) are PEGylated,
more particularly about 40-55% or 100%.
[0124] In one embodiment, treatment with a conjugate of the
invention will be administered as a first line therapy. In another
embodiment, treatment with a conjugate of the invention will be
administered as a second line therapy in patients, particularly
patients with ALL, where objective signs of allergy or
hypersensitivity, including "silent hypersensitivity," have
developed to other asparaginase preparations, in particular, the
native Escherichia coli-derived L-asparaginase or its PEGylated
variant (pegaspargase). Non-limiting examples of objective signs of
allergy or hypersensitivity include testing "antibody positive" for
an asparaginase enzyme. In a specific embodiment, the conjugate of
the invention is used in second line therapy after treatment with
pegaspargase. In a more specific embodiment, the conjugate used in
second line therapy comprises an L-asparaginase from Erwinia
species, more specifically Erwinia chrysanthemi, and more
specifically, the L-asparaginase comprising the sequence of SEQ ID
NO:1. In a more specific embodiment, the conjugate further
comprises PEG (e.g., mPEG) having a molecular weight of less than
or equal to about 5000 Da, more specifically about 5000 Da. In an
even more specific embodiment, at least about 40% to about 100% of
accessible amino groups (e.g., lysine residues and/or the
N-terminus) are PEGylated, more particularly about 40-55% or
100%.
[0125] In another aspect, the invention is directed to a method for
treating acute lymphoblastic leukemia comprising administering to a
patient in need of the treatment a therapeutically effective amount
of a conjugate of the invention. In a specific embodiment,
treatment will be administered at a dose ranging from about 1500
IU/m.sup.2 to about 15,000 IU/m.sup.2, typically about 10,000 to
about 15,000 IU/m.sup.2 (about 20-30 mg protein/m.sup.2), at a
schedule ranging from about twice a week to about once a month,
typically once per week or once every other week, as a single agent
(e.g., monotherapy) or as part of a combination of chemotherapy
drugs, including, but not limited to glucocorticoids,
corticosteroids, anticancer compounds or other agents, including,
but not limited to methotrexate, dexamethasone, prednisone,
prednisolone, vincristine, cyclophosphamide, and anthracycline. As
an example, patients with ALL will be administered the conjugate of
the invention as a component of multi-agent chemotherapy during 3
chemotherapy phases including induction, consolidation or
intensification, and maintenance. In a specific example, the
conjugate is not administered with an asparagine synthetase
inhibitor (e.g., such as set forth in PCT Pub. No. WO 2007/103290,
which is herein incorporated by reference in its entirety). In
another specific example, the conjugate is not administered with an
asparagine synthetase inhibitor, but is administered with other
chemotherapy drugs. The conjugate can be administered before,
after, or simultaneously with other compounds as part of a
multi-agent chemotherapy regimen. In a particular embodiment, the
conjugate comprises L-asparaginase from Erwinia species, more
specifically Erwinia chrysanthemi, and more specifically, the
L-asparaginase comprising the sequence of SEQ ID NO:1. In a
particular embodiment, the conjugate comprises PEG (e.g., mPEG)
having a molecular weight of less than or equal to about 5000 Da.
In a more particular embodiment, at least about 40% to about 100%
of accessible amino groups (e.g., lysine residues and/or the
N-terminus) are PEGylated, more particularly about 40-55% or
100%.
[0126] In a specific embodiment, the method comprises administering
a conjugate of the invention at an amount of about 1 U/kg to about
25 U/kg (e.g., about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 U/kg) or an
equivalent amount thereof (e.g., on a protein content basis). In a
more specific embodiment, the conjugate is administered at an
amount selected from the group consisting of about 5, about 10, and
about 25 U/kg. In another specific embodiment, the conjugate is
administered at a dose ranging from about 1,000 IU/m.sup.2 to about
20,000 IU/m.sup.2 (e.g., 1,000 IU/m.sup.2, 2,000 IU/m.sup.2, 3,000
IU/m.sup.2, 4,000 IU/m.sup.2, 5,000 IU/m.sup.2, 6,000 IU/m.sup.2
7,000 IU/m.sup.2, 8,000 IU/m.sup.2, 9,000 IU/m.sup.2, 10,000
IU/m.sup.2, 11,000 IU/m.sup.2, 12,000 IU/m.sup.2 13,000 IU/m.sup.2
14,000 IU/m.sup.2, 15,000 IU/m.sup.2, 16,000 IU/m.sup.2, 17,000
IU/m.sup.2, 18,000 IU/m.sup.2, 19,000 IU/m.sup.2, or 20,000
IU/m.sup.2). In another specific embodiment, the conjugate is
administered at a dose that depletes L-asparagine to undetectable
levels using methods and apparatus known in the art for a period of
about 3 days to about 10 days (e.g., 3, 4, 5, 6, 7, 8, 9, or 10
days) for a single dose. In another embodiment, the method
comprises administering a conjugate of the invention that elicits a
lower immunogenic response in a patient compared to an unconjugated
L-asparaginase. In another embodiment, the method comprises
administering a conjugate of the invention that has a longer in
vivo circulating half-life after a single dose compared to the
unconjugated L-asparaginase. In one embodiment, the method
comprises administering a conjugate that has a longer t.sub.112
than pegaspargase administered at an equivalent protein dose. In an
a specific embodiment, the method comprises administering a
conjugate that has a t.sub.1/2 of at least about 50, 52, 54, 56,
58, 59, 60, 61, 62, 63, 64, or 65 hours at a dose of about 50
.mu.g/kg (protein content basis). In another specific embodiment,
the method comprises administering a conjugate that has a t.sub.1/2
of at least about 30, 32, 34, 36, 37, 37, 39, or 40 hours at a dose
of about 10 .mu.g/kg (protein content basis). In another specific
embodiment, the method comprises administering a conjugate that has
a t.sub.1/2 of at least about 100 to about 200 hours at a dose
ranging from about 10,000 to about 15,000 IU/m.sup.2 (about 20-30
mg protein/m.sup.2). In one embodiment, the method comprises
administering a conjugate that has a mean AUC that is at least
about 2, 3, 4 or 5 times greater than pegaspargase at an equivalent
protein dose. In another embodiment, the method comprises
administering a conjugate of the invention that has a greater AUC
value after a single dose compared to the unconjugated
L-asparaginase. In a particular embodiment, the conjugate comprises
L-asparaginase from Erwinia species, more specifically Erwinia
chrysanthemi, and more specifically, the L-asparaginase comprising
the sequence of SEQ ID NO:1. In a particular embodiment, the
conjugate comprises PEG (e.g., mPEG) having a molecular weight of
less than or equal to about 5000 Da. In a more particular
embodiment, at least about 40% to about 100% of accessible amino
groups (e.g., lysine residues and/or the N-terminus) are PEGylated,
more particularly about 40-55% or 100%.
[0127] The incidence of relapse in ALL patients following treatment
with L-asparaginase remains high, with approximately 10-25% of
pediatric ALL patients having early relapse (e.g., some during
maintenance phase at 30-36 months post-induction) (Avramis and
Panosyan, Clin. Pharmacokinet. (2005) 44:367-393). If a patient
treated with E. coli-derived L-asparaginase has a relapse,
subsequent treatment with E. coli preparations could lead to a
"vaccination" effect, whereby the E. coli preparation has increased
immunogenicity during the subsequent administrations. In one
embodiment, the conjugate of the invention may be used in a method
of treating patients with relapsed ALL who were previously treated
with other asparaginase preparations, in particular those who were
previously treated with E. coli-derived asparaginases.
[0128] In some embodiments, the uses and methods of treatment of
the invention comprise administering an L-asparaginase conjugate
having properties or combinations of properties described herein
above (e.g., in the section entitled "L-asparaginase PEG
conjugates") or herein below.
Compositions, Formulations, and Routes of Administration
[0129] The invention also includes a pharmaceutical composition
comprising a conjugate of the invention. In a specific embodiment
the pharmaceutical composition is contained in a vial as a
lyophilized powder to be reconstituted with a solvent, such as
currently available native L-asparaginases, whatever the bacterial
source used for its production (Kidrolase.RTM., Elspar.RTM.,
Erwinase.RTM. . . . ). In another embodiment, the pharmaceutical
composition is a "ready to use" solution, such as pegaspargase
(Oncaspar.RTM.) enabling, further to an appropriate handling, an
administration through, e.g., intramuscular, intravenous (infusion
and/or bolus), intra-cerebroventricular (icy), sub-cutaneous
routes.
[0130] Conjugates of the invention, including compositions
comprising conjugates of the invention (e.g., a pharmaceutical
composition) can be administered to a patient using standard
techniques. Techniques and formulations generally may be found in
Remington's Pharmaceutical Sciences, 18th ed., Mack Publishing Co.,
Easton, Pa., 1990 (herein incorporated by reference).
[0131] Suitable dosage forms, in part, depend upon the use or the
route of entry, for example, oral, transdermal, transmucosal, or by
injection (parenteral). Such dosage forms should allow the
therapeutic agent to reach a target cell or otherwise have the
desired therapeutic effect. For example, pharmaceutical
compositions injected into the blood stream preferably are
soluble.
[0132] Conjugates and/or pharmaceutical compositions according to
the invention can be formulated as pharmaceutically acceptable
salts and complexes thereof. Pharmaceutically acceptable salts are
non-toxic salts present in the amounts and concentrations at which
they are administered. The preparation of such salts can facilitate
pharmaceutical use by altering the physical characteristics of the
compound without preventing it from exerting its physiological
effect. Useful alterations in physical properties include lowering
the melting point to facilitate transmucosal administration and
increasing solubility to facilitate administering higher
concentrations of the drug. The pharmaceutically acceptable salt of
an asparaginase may be present as a complex, as those in the art
will appreciate.
[0133] Pharmaceutically acceptable salts include acid addition
salts such as those containing sulfate, hydrochloride, fumarate,
maleate, phosphate, sulfamate, acetate, citrate, lactate, tartrate,
methanesulfonate, ethanesulfonate, benzenesulfonate,
p-toluenesulfonate, cyclohexylsulfamate, and quinate.
Pharmaceutically acceptable salts can be obtained from acids,
including hydrochloric acid, maleic acid, sulfuric acid, phosphoric
acid, sulfamic acid, acetic acid, citric acid, lactic acid,
tartaric acid, malonic acid, methanesulfonic acid, ethanesulfonic
acid, benzenesulfonic acid, p-toluenesulfonic acid,
cyclohexylsulfamic acid, fumaric acid, and quinic acid.
[0134] Pharmaceutically acceptable salts also include basic
addition salts such as those containing benzathine, chloroprocaine,
choline, diethanolamine, ethylenediamine, meglumine, procaine,
aluminum, calcium, lithium, magnesium, potassium, sodium, ammonium,
alkylamine, and zinc, when acidic functional groups, such as
carboxylic acid or phenol are present. For example, see Remington's
Pharmaceutical Sciences, supra. Such salts can be prepared using
the appropriate corresponding bases.
[0135] Pharmaceutically acceptable carriers and/or excipients can
also be incorporated into a pharmaceutical composition according to
the invention to facilitate administration of the particular
asparaginase. Examples of carriers suitable for use in the practice
of the invention include calcium carbonate, calcium phosphate,
various sugars such as lactose, glucose, or sucrose, or types of
starch, cellulose derivatives, gelatin, vegetable oils,
polyethylene glycols, and physiologically compatible solvents.
Examples of physiologically compatible solvents include sterile
solutions of water for injection (WFI), saline solution and
dextrose.
[0136] Pharmaceutical compositions according to the invention can
be administered by different routes, including intravenous,
intraperitoneal, subcutaneous, intramuscular, oral, topical
(transdermal), or transmucosal administration. For systemic
administration, oral administration is preferred. For oral
administration, for example, the compounds can be formulated into
conventional oral dosage forms such as capsules, tablets, and
liquid preparations such as syrups, elixirs, and concentrated
drops.
[0137] Alternatively, injection (parenteral administration) may be
used, e.g., intramuscular, intravenous, intraperitoneal, and
subcutaneous injection. For injection, pharmaceutical compositions
are formulated in liquid solutions, preferably in physiologically
compatible buffers or solutions, such as saline solution, Hank's
solution, or Ringer's solution. In addition, the compounds may be
formulated in solid form and redissolved or suspended immediately
prior to use. For example, lyophilized forms of the conjugate can
be produced. In a specific embodiment, the conjugate is
administered intramuscularly. In another specific embodiment, the
conjugate is administered intravenously.
[0138] Systemic administration can also be accomplished by
transmucosal or transdermal means. For transmucosal or transdermal
administration, penetrants appropriate to the barrier to be
permeated are used in the formulation. Such penetrants are well
known in the art, and include, for example, for transmucosal
administration, bile salts, and fusidic acid derivatives. In
addition, detergents may be used to facilitate permeation.
Transmucosal administration, for example, may be through nasal
sprays, inhalers (for pulmonary delivery), rectal suppositories, or
vaginal suppositories. For topical administration, compounds can be
formulated into ointments, salves, gels, or creams, as is well
known in the art.
[0139] The amounts of the conjugate to be delivered will depend on
many factors, for example, the IC.sub.50, EC.sub.50, the biological
half-life of the compound, the age, size, weight, and physical
condition of the patient, and the disease or disorder to be
treated. The importance of these and other factors to be considered
are well known to those of ordinary skill in the art. Generally,
the amount of the conjugate to be administered will range from
about 10 International Units per square meter of the surface area
of the patient's body (IU/m.sup.2) to 50,000 IU/m.sup.2, with a
dosage range of about 1,000 IU/m.sup.2 to about 15,000 IU/m.sup.2
being preferred, and a range of about 6,000 IU/m.sup.2 to about
15,000 IU/m.sup.2 being more preferred, and a range of about 10,000
to about 15,000 IU/m.sup.2 (about 20-30 mg protein/m.sup.2) being
particularly preferred to treat a malignant hematologic disease,
e.g., leukemia. Typically, these dosages are administered via
intramuscular or intravenous injection at an interval of about 3
times weekly to about once per month, typically once per week or
once every other week during the course of therapy. Of course,
other dosages and/or treatment regimens may be employed, as
determined by the attending physician.
[0140] In particular embodiments, the conjugate and/or
pharmaceutical composition or formulation to be administered as
described herein comprises L-asparaginase from Erwinia species,
more specifically Erwinia chrysanthemi, and more specifically, the
L-asparaginase comprising the sequence of SEQ ID NO:1. In a
particular embodiment, the conjugate comprises L-asparaginase from
Erwinia species, more specifically Erwinia chrysanthemi, and more
specifically, the L-asparaginase comprising the sequence of SEQ ID
NO:1. In a particular embodiment, the conjugate comprises PEG
(e.g., mPEG) having a molecular weight of less than or equal to
about 5000 Da. In a more particular embodiment, at least about 40%
to about 100% of amino groups (e.g., lysine residues and/or the
N-terminus) are PEGylated.
EXAMPLES
Example 1
Preparation of Recombinant Crisantaspase
[0141] The recombinant bacterial strain used to manufacture the
naked recombinant Erwinia chrysanthemi L-asparaginase protein (also
referred to herein as "r-crisantaspase") was an E. coli BL21 strain
with a deleted ansB gene (the gene encoding the endogenous E. coli
type II L-asparaginase) to avoid potential contamination of the
recombinant Erwinia chrysanthemi L-asparaginase with this enzyme.
The deletion of the ansB gene relies on homologous recombination
methods and phage transduction performed according to the three
following steps: 1) a bacterial strain (NM1100) expressing a
defective lambda phage which supplies functions that protect and
recombine electroporated linear DNA substrate in the bacterial cell
was transformed with a linear plasmid (kanamycin cassette)
containing the kanamycin gene flanked by an FLP recognition target
sequence (FRT). Recombination occurs to replace the ansB gene by
the kanamycin cassette in the bacterial genome, resulting in a
.DELTA.ansB strain; 2) phage transduction was used to integrate the
integrated kanamycin cassette region from the .DELTA.ansB NM1100
strain to the ansB locus in BL21 strain. This results in an E. coli
BL21 strain with a deleted ansB gene and resistant to kanamycin; 3)
this strain was transformed with a FLP-helper plasmid to remove the
kanamycin gene by homologous recombination at the FRT sequence. The
genome of the final strain (BL21 .DELTA.ansB strain) was sequenced,
confirming full deletion of the endogenous ansB gene.
[0142] The E. coli-optimized DNA sequence encoding for the mature
Erwinia chrysanthemi L-asparaginase fused with the ENX signal
peptide from Bacillus subtilis was inserted into an expression
vector. This vector allows expression of recombinant Erwinia
chrysanthemi L-asparaginase under the control of hybrid T5/lac
promoter induced by the addition of Isopropyl
.beta.-D-1-thiogalactopyranoside (IPTG) and confers resistance to
kanamycin.
[0143] BL21 .DELTA.ansB strain was transformed with this expression
vector. The transformed cells were used for production of the
r-crisantaspase by feed batch glucose fermentation in Reisenberg
medium. The induction of the cell was done 16 h at 23.degree. C.
with IPTG as inducer. After cell harvest and lysis by
homogenization in 10 mM sodium phosphate buffer pH6 5 mM EDTA
(Buffer A), the protein solution was clarified by centrifugation
twice at 15000 g, followed by 0.45 .mu.m and 0.22 .mu.m filtration
steps. The recombinant Erwinia chrysanthemi L-asparaginase was next
purified using a sequence of chromatography and concentration
steps. Briefly, the theoretical isoelectric point of the Erwinia
chrysanthemi L-asparaginase (7.23) permits the recombinant enzyme
to adsorb to cation exchange resins at pH6. Thus, the recombinant
enzyme was captured on a Capto S column (cation exchange
chromatography) and eluted with salt gradient in Buffer A.
Fractions containing the recombinant enzyme were pooled. The pooled
solution was next purified on Capto MMC column (cation exchange
chromatography) in Buffer A with salt gradient. The eluted
fractions containing Erwinia chrysanthemi L-asparaginase were
pooled and concentrated before protein separation on Superdex 200
pg size exclusion chromatography as polishing step. Fractions
containing recombinant enzymes were pooled, concentrated, and
diafiltered against 100 mM sodium phosphate buffer pH8. The purity
of the final Erwinia chrysanthemi L-asparaginase preparation was
evaluated by SDS-PAGE (FIG. 1) and RP-HPLC and was at least 90%.
The integrity of the recombinant enzyme was verified by N-terminal
sequencing and LC-MS. Enzyme activity was measured at 37.degree. C.
using Nessler's reagent. The specific activity of the purified
recombinant Erwinia chrysanthemi L-asparaginase was around 600
U/mg. One unit of enzyme activity is defined as the amount of
enzyme that liberates 1 .mu.mol of ammonia from L-asparagine per
minute at 37.degree. C.
Example 2
Preparation of 10 kDa mPEG-L-Asparaginase Conjugates
[0144] A solution of L-asparaginase from Erwinia chrysanthemi was
stirred in a 100 mM sodium phosphate buffer at pH 8.0, at a protein
concentration between 2.5 and 4 mg/mL, in the presence of 150 mg/mL
or 36 mg/mL 10 kDa mPEG-NHS, for 2 hours at 22.degree. C. The
resulting crude 10 kDa mPEG-L-asparaginase was purified by size
exclusion chromatography using a Superdex 200 pg column on an Akta
purifier UPC 100 system. Protein-containing fractions were pooled
and concentrated to result in a protein concentration between 2 and
8 mg/mL. Two 10 kDa mPEG-L-asparaginase conjugates were prepared in
this way, differing in their degree of PEGylation as determined by
TNBS assay with unmodified L-asparaginase as a reference, one
corresponding to full PEGylation (100% of accessible amino groups
(e.g., lysine residues and/or the N-terminus) residues being
conjugated corresponding to PEGylation of 78% of total amino groups
(e.g., lysine residues and/or the N-terminus)); the second one
corresponding to partial PEGylation (39% of total amino groups
(e.g., lysine residues and/or the N-terminus) or about 50% of
accessible amino groups (e.g., lysine residues and/or the
N-terminus)). SDS-PAGE analysis of the conjugates is shown in FIG.
2. The resulting conjugates appeared as an essentially homogeneous
band and contained no detectable unmodified r-crisantaspase.
Example 3
Preparation of 5 kDa mPEG-L-Asparaginase Conjugates
[0145] A solution of L-asparaginase from Erwinia chrysanthemi was
stirred in a 100 mM sodium phosphate buffer at pH 8.0, at a protein
concentration of 4 mg/mL, in the presence of 150 mg/mL or 22.5
mg/mL 5 kDa mPEG-NHS, for 2 hours at 22.degree. C. The resulting
crude 5 kDa mPEG-L-asparaginase was purified by size exclusion
chromatography using a Superdex 200 pg column on an Akta purifier
UPC 100 system. Protein-containing fractions were pooled and
concentrated to result in a protein concentration between 2 and 8
mg/mL. Two 5 kDa mPEG-L-asparaginase conjugates were prepared in
this way, differing in their degree of PEGylation as determined by
TNBS assay with unmodified L-asparaginase as a reference, one
corresponding to full PEGylation (100% of accessible amino groups
(e.g., lysine residues and/or the N-terminus) being conjugated
corresponding to PEGylation of 84% of total amino groups (e.g.,
lysine residues and/or the N-terminus)); the second one
corresponding to partial PEGylation (36% of total amino groups
(e.g., lysine residues and/or the N-terminus) or about 43% of
accessible amino groups (e.g., lysine residues and/or the
N-terminus)). SDS-PAGE analysis of the conjugates is shown in FIG.
2. The resulting conjugates appeared as an essentially homogeneous
band and contained no detectable unmodified r-crisantaspase.
Example 4
Preparation of 2 kDa mPEG-L-Asparaginase Conjugates
[0146] A solution of L-asparaginase from Erwinia chrysanthemi was
stirred in a 100 mM sodium phosphate buffer pH 8.0 at a protein
concentration of 4 mg/mL in the presence of 150 mg/mL or 22.5 mg/mL
2 kDa mPEG-NHS for 2 hours at 22.degree. C. The resulting crude 2
kDa mPEG-L-asparaginase was purified by size exclusion
chromatography using a Superdex 200 pg column on an Akta purifier
UPC 100 system. Protein containing fractions were pooled and
concentrated to result in a protein concentration between 2 and 8
mg/mL. Two 2 kDa mPEG-L-asparaginase conjugates were prepared in
this way, differing in their degree of PEGylation as determined by
TNBS assay with unmodified L-asparaginase as reference, one
corresponding to maximum PEGylation (100% of accessible amino
groups (e.g., lysine residues and/or the N-terminus) being
conjugated corresponding to PEGylation of 86% of total amino groups
(e.g., lysine residues and/or the N-terminus)); the second one
corresponding to partial PEGylation (47% of total amino groups
(e.g., lysine residues and/or the N-terminus) or about 55% of
accessible amino groups (e.g., lysine residues and/or the
N-terminus)). SDS-PAGE analysis of the conjugates is shown in FIG.
2. The resulting conjugates appeared as an essentially homogeneous
band and contained no detectable unmodified r-crisantaspase.
Example 5
Activity of mPEG-r-Crisantaspase Conjugates
[0147] L-asparaginase aminohydrolase activity of each conjugate
described in the proceeding examples was determined by
Nesslerization of ammonia that is liberated from L-asparagine by
enzymatic activity. Briefly, 50 .mu.L of enzyme solution were mixed
with 20 mM of L-asparagine in a 50 mM Sodium borate buffer pH 8.6
and incubated for 10 min at 37.degree. C. The reaction was stopped
by addition of 200 .mu.L of Nessler reagent. Absorbance of this
solution was measured at 450 nm. The activity was calculated from a
calibration curve that was obtained from Ammonia sulfate as
reference. The results are summarized in Table 2, below:
TABLE-US-00004 TABLE 2 Activity of mPEG-r-crisantaspase conjugates
mol PEG/ Specific activity Rel. activity Sample * mol monomer **
[U/mg] % 10 kDa mPEG-r-crisantaspase 40% 7.0 543 87 10 kDa
mPEG-r-crisantaspase 100% 14.1 541 87 5 kDa mPEG-r-crisantaspase
40% 6.5 501 81 5 kDa mPEG-r-crisantaspase 100% 15.1 483 78 2 kDa
mPEG-r-crisantaspase 40% 8.5 524 84 2 kDa mPEG-r-crisantaspase 100%
15.5 515 83 r-crisantaspase -- 622 100 * the numbers "40%" and
"100%" indicate an approximate degree of PEGylation of respectively
40-55% and 100% of accessible amino groups (see Examples 2-4,
supra). ** the ratio mol PEG/mol monomer was extrapolated from data
using TNBS assay, that makes the assumption that all amino groups
from the protein (e.g., lysine residues and the N-terminus) are
accessible.
[0148] Residual activity of mPEG-r-crisantaspase conjugates ranged
between 483 and 543 Units/mg. This corresponds to 78-87% of
L-asparagine aminohydrolase activity of the unmodified enzyme.
Example 6
L-Asparagine-Depleting Effect of Unmodified Crisantaspase
[0149] The pharmacodynamic profile of Erwinase.RTM. was determined
in B6D2F1-Hybrids (immune competent, females), Charles River
Germany. Erwinase.RTM. is a commercially available crisantaspase
(L-asparaginase derived from Erwinia chrysanthemi). Briefly, 2
animals per group received a single i.v. injection of 5, 25, 125,
or 250 Units/kg bw Erwinase.RTM. At -1 h pre-dose and at 6 h, 12 h,
24 h, and 48 h post-dose, plasma samples were collected from
orbital sinus and analyzed for plasma levels of L-asparagine.
[0150] Plasma amino acid levels were determined with a PICO-TAG
Amino Acid Analysis Kit (Waters). Briefly, plasma samples were
deproteinised by methanol precipitation. Free amino acids in the
supernatant were derivatised with phenylisothiocyanate and
quantified by RP-HPLC.
[0151] As shown in FIG. 3, the 5 and 25 U/kg doses were not
efficient in depleting L-asparagine levels in mice following iv
administration. Only the 250 U/kg dose induced a complete depletion
over 48 hrs.
[0152] This result illustrates the clinical limitations of
Erwinase.RTM., an unmodified crisantaspase, which needs to be
administered up to 3 times a weeks as painful injections in
patients suffering from ALL, and at high doses resulting in
frequent allergic reactions and immunogenicity.
Example 7
L-Asparagine-Depleting Effect and Plasma L-Asparaginase Activity
Following Single Administration of Six mPEG-r-Crisantaspase
Conjugates
[0153] The pharmacodynamic and pharmacokinetic profiles of 6
different mPEG-r-crisantaspase conjugates was determined in
B6D2F1-Hybrids (immune competent, females), Charles River Germany
The six conjugates tested differed in the molecular size of the PEG
(2, 5 or 10 kDa) and in the degree of PEGylation (maximal vs.
partial PEGylation). Unmodified crisantaspase (Erwinase.RTM.) was
used as a reference. Briefly, 4 animals per group received a single
i.v. injection of 5 Units/kg bw conjugate vs. 250 Units/kg bw
Erwinase.RTM.. At -1 h pre-dose and at 6 h, 24 h, 48 h, 96 h and
192 h after injection, plasma samples were collected from the
orbital sinus of each animal and analyzed for plasma levels of
L-asparagine and residual enzyme activity, respectively.
[0154] Plasma amino acid levels were determined with a PICO-TAG
Amino Acid Analysis Kit (Waters). Briefly, plasma samples were
deproteinised by methanol precipitation. Free amino acids in the
supernatant were derivatised with phenylisothiocyanate and
quantified by RP-HPLC.
[0155] Enzyme activity in plasma was determined by a chromogenic
assay. L-aspartic .beta.-hydroxamate (AHA) was used as substrate.
The enzymes hydrolyzed AHA to L-Asp and hydroxylamine, which was
determined at 710 nm after condensation with 8-hydroxyquinoline and
oxidation to indooxine. (Analytical Biochemistry 309 (2002):
117-126, incorporated herein by reference in its entirety).
[0156] As shown in FIG. 4, the, conjugates administered at 5 U/kg
showed an L-asparagine depleting potency at least as good as that
of Erwinase.RTM. 250 U/kg, suggesting that PEGylation increased
potency of the protein by at least 50 times. All conjugates
exhibited similar potency, depleting plasma levels in L-asparagine
for 2 days, except for the 5 kDa-100% conjugate which showed longer
duration of action (96 h=4 days as compared to 48 h=2 days for
other conjugates).
[0157] Thus, increasing the size of the PEG conjugated to the
r-crisantaspase from 2 kDa to 5 kDa resulted in an improved potency
and duration of action. However, surprisingly, increasing the size
of the PEG to 10 kDa did not further improve the potency and
duration of action of the conjugate, it even resulted in a decrease
when compared to the 5 kDa maximally PEGylated conjugate.
[0158] Enzymatic activity was consistent with L-asparagine
depletion. As shown in FIG. 5, the 5 kDa-100% conjugate exhibited
the largest AUC, reflecting a longer half-life. Lower AUCs were
observed with PEG-40% (partially PEGylated) vs. PEG-100% (maximally
PEGylated) conjugates for the 2 kDa and 5 kDa candidates and no
difference was observed for the 10 kDa candidates.
[0159] Consistent with the L-asparagine depletion data, increasing
the molecular size of the PEG conjugated to the r-crisantaspase
from 2 kDa to 5 kDa resulted in a longer circulating L-asparaginase
activity. However, surprisingly, increasing the size of the PEG to
10 kDa did not further improve the in vivo enzymatic activity of
the conjugate, it even resulted in a decrease when compared to the
5 kDa maximally PEGylated conjugate. Also, notably, when
r-crisantaspase was N-terminally monoPEGylated with high molecular
weight (i.e., 40 kDa) mPEG, there was no significant impact on the
in vitro stability of the enzyme toward proteolysis (data not
shown).
Example 8
Dose-Ranging Effects of Two mPEG-r-Crisantaspase Conjugates on
Plasma L-Asparagine
[0160] The pharmacodynamic profile of 2 mPEG-r-crisantaspase
conjugates compared to pegaspargase (Oncaspar.RTM.) was determined
in B6D2F1-Hybrids (immune competent, females), Charles River
Germany The conjugates tested were the 2 kDa maximally (100%)
PEGylated r-crisantaspase and the 5 kDa maximally (100%) PEGylated
r-crisantaspase at 3 doses. Briefly, 8 animals per group received a
single i.v. injection of 5, 25 or 50 Units/kg bw of the
r-crisantaspase conjugates, corresponding to 10, 50 or 100 .mu.g
protein/kg. As a comparative arm, Oncaspar.RTM. was tested at 1
Unit/kg, corresponding to 10 .mu.g protein/kg. At -1 h pre-dose and
at 90 min, 6 h, 24 h, 48 h, 72 h, 96 h, 120 h, 144 h, 192 h and 240
h post-dose plasma samples were collected from orbital sinus and
analyzed for plasma levels of L-asparagine.
[0161] Plasma amino acid levels were determined with a PICO-TAG
Amino Acid Analysis Kit (Waters). Briefly, plasma samples were
deproteinised by methanol precipitation. Free amino acids in the
supernatant were derivatised with phenylisothiocyanate and
quantified by RP-HPLC.
[0162] The dose-related effects of the conjugates on plasma
L-asparagine levels are shown in FIG. 6. As shown in FIGS. 6A and
6B, both conjugates were highly efficient in depleting circulating
L-asparagine. For the 2 kDa 100% conjugate, total depletion was
observed over 3, 6 and at least 10 days at the 5 U, 25 U and 50
U/kg doses, respectively. For the 5 kDa 100% conjugate, total
depletion was observed over 3, 10 and 10 days at the 5 U, 25 U and
50 U/kg doses, respectively. For both conjugates tested, the 5, 25
and 50 U/kg doses tested corresponded to 10, 50 and 100 .mu.g/kg on
a protein content basis, which is a very low amount of protein when
compared to other available L-asparaginase preparations. Indeed,
250 U/kg Erwinase.RTM. corresponds to approximately 520 .mu.g/kg,
and 1 U/kg Oncaspar.RTM. corresponds approximately to 10 .mu.g/kg
(protein content basis). FIG. 6C shows that the administration of
an equivalent quantity of protein (10 .mu.g/kg) of either the 2
kDa-100% conjugate, the 5 kDa-100% conjugate or Oncaspar.RTM.
resulted in a similar L-asparagine depletion over 72 hrs.
Example 9
Pharmacokinetic Profiles of Two mPEG-r-Crisantaspase Conjugates
[0163] The pharmacokinetic profile of mPEG-r-crisantaspase
conjugates was determined in B6D2F1-Hybrids (immune competent,
females), Charles River Germany The conjugates tested were the 2
kDa maximally (100%) PEGylated r-crisantaspase and the 5 kDa
maximally (100%) fully PEGylated r-crisantaspase at 3 doses.
Unmodified crisantaspase (Erwinase.RTM.) at 250 U/kg and
Oncaspar.RTM. at 1 U/kg were also tested as controls. Briefly, 8
animals per group received a single i.v. injection of 5, 25 or 50
Units/kg bw of each mPEG-r-crisantaspase conjugate compared to
Erwinase.RTM. and Oncaspar.RTM.. At -1 h pre-dose and at 90 min, 6
h, 24 h, 48 h, 72 h, 96 h, 120 h, 144 h, 192 h and 240 h post-dose
plasma samples were collected from orbital sinus and analyzed for
plasma levels of residual enzyme activity.
[0164] Enzyme activity in plasma was determined by a chromogenic
assay. L-aspartic .beta.-hydroxamate (AHA) was used as substrate.
The enzymes hydrolyzed AHA to L-Asp and hydroxylamine, which was
determined at 710 nm after condensation with 8-hydroxyquinoline and
oxidation to indooxine. (Analytical Biochemistry 309 (2002):
117-126).
[0165] For the calculation of the half-life time, exponential
best-fit lines of the respective residual plasma activities were
derived using the MS-excel function tool. Negative activity values
were excluded from the calculation.
TABLE-US-00005 Parameter Definition A.sub.max Maximal residual
enzyme activity t.sub.Amax Time to A.sub.max after test item
exposure d.sub.Amax Maximal duration of A.sub.max or A above
zero
[0166] The half-life time of the residual enzyme activity in plasma
were derived from the following formula using the MS-excel function
tool and the respective formula of the exponential best-fit
lines:
Mean:
[0167] t 1 2 = - In 2 .times. t In ( c t c 0 ) ##EQU00002##
where t.sub.1/2 is the half-life, t is the time point, c.sub.t is
the residual plasma activity at the time point and c.sub.0 the
residual plasma activity at the beginning
[0168] The areas under the curve (AUC) were calculated using
SigmaPlot Version 11. Pharmacokinetic data are summarized in Tables
3 and 4, below, and FIGS. 7-9.
TABLE-US-00006 TABLE 3 Primary pharmacokinetics of a single
treatment with 250 U/kg bw of Erwinase .RTM., 1 U/kg bw
Pegaspargase (Oncaspar .RTM.), or 2 kDa mPEG-r-crisantaspase 100%
conjugates (residual plasma enzyme activity) 2 kDa/ 2 kDa/ 2 kDa/
Pegaspargase 100% 100% 100% Parameter Erwinase .RTM. 1 U/kg bw 5
U/kg bw 25 U/kg bw 50 U/kg bw A.sub.max 83.9 U/L 6 U/L 14 U/L 153
U/L 208 U/L t.sub.Amax 6 h 90 min 90 min 6 h 6 h d.sub.Amax 18 h
46.5 h 70.5 h 238.5 h 238.5 h above zero from 6 h-24 h 90 min-48 h
90 min-72 h 90 min-240 h 90 min-240 h AUC 1205 222 627 12446 28349
(mean) t.sub.1/2 6 h 28 h 31 h 55 h 85 h
TABLE-US-00007 TABLE 4 Primary pharmacokinetics of a single
treatment with 250 U/kg bw of Erwinase .RTM., 1 U/kg bw
Pegaspargase (Oncaspar .RTM.), or 5 kDa mPEG-r-crisantaspase 100%
conjugates (residual plasma enzyme activity) 5 kDa/ 5 kDa/ 5 kDa/
Pegaspargase 100% 100% 100% Parameter Erwinase .RTM. 1 U/kg bw 5
U/kg bw 25 U/kg bw 50 U/kg bw A.sub.max 83.9 U/L 6 U/L 18 U/L 188
U/L 226 U/L t.sub.Amax 6 h 90 min 90 min 6 h 48 h d.sub.Amax 18 h
46.5 h 94.5 h 238.5 h 238.5 h above zero from 6 h-24 h 90 min-48 h
90 min-96 h 90 min-240 h 90 min-240 h AUC 1205 222 798 19748 33151
(mean) t.sub.1/2 6 h 28 h 38 h 63 h 104 h
[0169] The data show that PEGylation of r-crisantaspase
significantly prolongs half-life when compared to unmodified
crisantaspase, and in a dose-dependent manner (Tables 3 and 4,
FIGS. 7-9). Additionally, when compared at the same dose level,
AUCs measured for the 5 kDa-100% were higher than those observed
for the 2-kDa-100% conjugates. A difference of 21%, 37% and 14%
were consistently found in favor of the 5 kDa-100% conjugate, at
the 5, 25 and 50 U/kg doses, respectively (FIG. 8). The 5 kDa-100%
conjugate also appeared to have a longer half-life than
Oncaspar.RTM. itself when tested at the same dose on a protein
content basis, as shown in FIG. 9 and in the derived
pharmacokinetic parameters shown in Table 4. The superior
pharmacokinetic profiles for the Erwinia conjugates are surprising,
since E. coli-derived L-asparaginase is known to have a longer
half-life in human and in animals than Erwinia chrysanthemi-derived
L-asparaginase (crisantaspase). Hence, a longer half-life would
have logically been predicted for PEGylated E. coli L-asparaginase
(pegaspargase) compared to PEGylated r-crisantaspase. However,
unexpectedly and advantageously, the PEGylated r-crisantaspase has
a longer half-life than pegaspargase.
[0170] Table 5, below, summarizes pharmacokinetic and
pharmacodynamic data gathered from several experiments, including
those described in Examples 7-9 herein, showing that: 1) both the 2
kDa-100% and the 5 kDa-100% conjugates were highly potent in
increasing potency and duration of action of crisantaspase, as
shown by the marked differences observed compared to Erwinase.RTM.;
2) the 5 kDa-100% conjugate was longer-acting than both the 2
kDa-100% conjugate and Oncaspar.RTM., as shown by a longer
half-life observed at all doses tested. In view of the surprisingly
inferior results obtained with the 10 kDa-100% conjugate, these
data suggest that the benefit of PEGylation increases with the size
of the PEG moiety anchored to the crisantaspase up to 5 kDa. The
higher molecular weight PEG did not add further benefit, and, at
least in the case of 10 kDa, might be even be detrimental. This is
unexpected and contrary to results that were seen e.g., when
Holtsberg et al. conjugated varying molecular weights of PEG to
arginine deaminase, another amino acid degrading enzyme isolated
from a microbial source. In those studies pharmacokinetic and
pharmacodynamic function of the arginine deaminase enzyme increased
as the size of the PEG attachment increased from a molecular weight
of 5000 Da to 20,000 Da (Holtsberg, F. W., Journal of Controlled
Release 80 (2002), 259-271), incorporated herein by reference in
its entirety).
TABLE-US-00008 TABLE 5 2 kDA-100% 5 kDA-100% mPEG-r- mPEG-r-
Erwinase .RTM. crisantaspase crisantaspase Oncaspar .RTM. Dose
(.mu.g/kg) 520 10 50 10 50 10 50 Dose (U/kg) 250 5 25 5 25 1 5
T.sub.1/2 (h) 6 31 55 38 63 28 51 Duration of 2 2-3 6 3-4 10+ 3 8+
L-asparagine depletion (days)
[0171] In addition, as seen in more detail below, the
immunogenicity data showed that the 10 kDa-100% exhibited an
unacceptable immunogenicity profile, a major drawback when
considering administering the compound to patients who are allergic
to E. coli L-asparaginase or have developed anti-L-asparaginase
antibodies. In this respect, the 10 kDa-100% conjugate is really
not suitable. The 2 kDa-100% and the 5 kDa-100% are preferable, and
the 5 kDa-100% conjugate is particularly preferable.
Example 10
Immunogenicity
[0172] Immunogenicity of mPEG-r-crisantaspase conjugates was
determined in B6D2F1-Hybrids (immune competent, females), Charles
River Germany Animals were treated twice a week in weeks 1, 2, 3,
4, an 8 by i.v. injection of 250 U/kg bw for Erwinase.RTM. and 5
U/kg bw for all r-crisantaspase conjugates. Serum samples were
collected at -1 h pre-dose and after 1w, 2w, 4w, 6w and 8w from the
orbital sinus. Anti-crisantaspase or anti-mPEG-r-crisantaspase
antibody levels in serum were determined by ELISA. The results are
summarized in FIGS. 10 and 11.
[0173] High titers of anti-crisantaspase antibodies were observed
for Erwinase.RTM. starting at week 2 and were maintained for the
whole study period. In contrast, no significant antibody levels
were observed for r-crisantaspase conjugates (FIG. 10).
[0174] As shown in FIG. 11, the production of anti-conjugate
antibodies remained of low intensity and frequency for the 2 kDa
and 5 kDa mPEG-r-crisantaspase conjugates, and increased with
higher values and frequency for the 10 kDa mPEG-r-crisantaspase
conjugates. No clear difference was noted between the fully and
partially PEGylated conjugates (not shown).
[0175] Thus, these data demonstrated that the PEGylation strategy
that was selected reduced the immunogenicity of the conjugates
compared to the unmodified L-asparaginase, markedly decreasing the
anti-crisantaspase antibody response. However, anti-conjugate
antibodies were detected, especially with the 10 kDa conjugates,
and with a lower intensity with the 2 kDa and 5 kDa conjugates.
[0176] In conclusion, it appears that, up to 5 kDa, PEGylation
succeeded in improving pharmacokinetic profile, potency and
duration of action of r-crisantaspase, while reducing
immunogenicity when compared to the unmodified protein, with a
potency and duration of action increasing with the size of the
polymer used, the 5 kDa mPEG-r-crisantaspase conjugate being
slightly more potent that the 2 kDa mPEG-r-crisantaspase conjugate.
However, further increasing the size of the PEG to 10 kDa failed to
further improve potency and duration of action, as the 10 kDa
mPEG-r-crisantaspase conjugate was less potent in vivo than the 5
kDa mPEG-r-crisantaspase conjugate, despite similar in vitro
potencies. In addition, the 10 kDa mPEG-r-crisantaspase conjugates
exhibited an unacceptable immunogenicity profile, an unexpected
result in view of published results with other proteins.
[0177] While embodiments and applications of the present invention
have been described in some detail by way of illustration and
example, it would be apparent to those of skill in the art that
many additional modifications would be possible without departing
from the inventive concepts contained herein. All references cited
herein are hereby incorporated in their entirety.
Sequence CWU 1
1
11327PRTErwinia chrysanthemi 1Ala Asp Lys Leu Pro Asn Ile Val Ile
Leu Ala Thr Gly Gly Thr Ile1 5 10 15Ala Gly Ser Ala Ala Thr Gly Thr
Gln Thr Thr Gly Tyr Lys Ala Gly 20 25 30Ala Leu Gly Val Asp Thr Leu
Ile Asn Ala Val Pro Glu Val Lys Lys 35 40 45Leu Ala Asn Val Lys Gly
Glu Gln Phe Ser Asn Met Ala Ser Glu Asn 50 55 60Met Thr Gly Asp Val
Val Leu Lys Leu Ser Gln Arg Val Asn Glu Leu65 70 75 80Leu Ala Arg
Asp Asp Val Asp Gly Val Val Ile Thr His Gly Thr Asp 85 90 95Thr Val
Glu Glu Ser Ala Tyr Phe Leu His Leu Thr Val Lys Ser Asp 100 105
110Lys Pro Val Val Phe Val Ala Ala Met Arg Pro Ala Thr Ala Ile Ser
115 120 125Ala Asp Gly Pro Met Asn Leu Leu Glu Ala Val Arg Val Ala
Gly Asp 130 135 140Lys Gln Ser Arg Gly Arg Gly Val Met Val Val Leu
Asn Asp Arg Ile145 150 155 160Gly Ser Ala Arg Tyr Ile Thr Lys Thr
Asn Ala Ser Thr Leu Asp Thr 165 170 175Phe Lys Ala Asn Glu Glu Gly
Tyr Leu Gly Val Ile Ile Gly Asn Arg 180 185 190Ile Tyr Tyr Gln Asn
Arg Ile Asp Lys Leu His Thr Thr Arg Ser Val 195 200 205Phe Asp Val
Arg Gly Leu Thr Ser Leu Pro Lys Val Asp Ile Leu Tyr 210 215 220Gly
Tyr Gln Asp Asp Pro Glu Tyr Leu Tyr Asp Ala Ala Ile Gln His225 230
235 240Gly Val Lys Gly Ile Val Tyr Ala Gly Met Gly Ala Gly Ser Val
Ser 245 250 255Val Arg Gly Ile Ala Gly Met Arg Lys Ala Met Glu Lys
Gly Val Val 260 265 270Val Ile Arg Ser Thr Arg Thr Gly Asn Gly Ile
Val Pro Pro Asp Glu 275 280 285Glu Leu Pro Gly Leu Val Ser Asp Ser
Leu Asn Pro Ala His Ala Arg 290 295 300Ile Leu Leu Met Leu Ala Leu
Thr Arg Thr Ser Asp Pro Lys Val Ile305 310 315 320Gln Glu Tyr Phe
His Thr Tyr 325
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References