U.S. patent application number 10/664670 was filed with the patent office on 2004-04-08 for actinium-225 complexes and conjugates for targeted radiotherapy.
Invention is credited to Frank, R. Keith, Kiefer, Garry E., Simon, Jaime.
Application Number | 20040067924 10/664670 |
Document ID | / |
Family ID | 23039179 |
Filed Date | 2004-04-08 |
United States Patent
Application |
20040067924 |
Kind Code |
A1 |
Frank, R. Keith ; et
al. |
April 8, 2004 |
Actinium-225 complexes and conjugates for targeted radiotherapy
Abstract
.sup.225Ac complexes comprising a functionalized
polyazamacrocyclic chelant compound of the formula I hereinbelow: 1
G is independently hydrogen or 2 each Q is independently hydrogen,
(CHR.sup.5).sub.pCO.sub.2R or
(CHR.sup.5).sub.pPO.sub.3R.sup.6R.sup.7 or 3 Q.sup.1 is hydrogen,
(CHR.sup.5).sub.wCO.sub.2R or (CHR.sup.5).sub.wPO.sub-
.3R.sup.6R.sup.7; each R is independently hydrogen, benzyl or
C.sub.1-C.sub.4 alkyl; R.sup.6 and R.sup.7 are independently H,
C.sub.1-C.sub.6 alkyl or (C.sub.1-C.sub.2 alkyl)phenyl; each
R.sup.5 is independently hydrogen; C.sub.1-C.sub.4 alkyl or
(C.sub.1-C.sub.2 alkyl)phenyl; with the proviso that at least two
of the sum of Q and Q.sup.1 must be other than hydrogen; A is CH,
N, C--Br, C--Cl, C--SO.sub.3H, C--OR.sup.8,
C--OR.sup.9N.sup.+--R.sup.10X.sup.-, or 4 Z and Z.sup.1
independently are CH, N, C--SO.sub.3H, N.sup.+--R.sup.10X.sup.-,
C--CH.sub.2--OR.sup.8 or C--C(O)--R.sup.11; R.sup.8 is H,
C.sub.1-C.sub.5 alkyl, benzyl, or benzyl substituted with at least
one R.sup.12; R.sup.9 is C.sub.1-C.sub.16 alkylamino; R.sup.10 is
C.sub.1-C.sub.16 alkyl, benzyl, or benzyl substituted with at least
one R.sup.12; R.sup.11 is --O--(C.sub.1-C.sub.3 alkyl), OH or
NHR.sup.13; R.sup.12 is H, NO.sub.2, NH.sub.2, isothiocyanato,
semicarbazido, thiosemicarbazido, maleimido, bromoacetamido or
carboxyl; R.sup.13 is C.sub.1-C.sub.5 alkyl; X and Y are each
independently hydrogen or may be taken with an adjacent X and Y to
form an additional carbon-carbon bond; n is 0 or 1; m is an integer
from 0 to 10 inclusive; p is 1 or 2; r is 0 or 1; w is 0 or 1; with
the proviso that n is only 1 when X and/or Y form an additional
carbon-carbon bond, and the sum of r and w is 0 or 1; L is a
linker/spacer group covalently bonded to, and replaces one hydrogen
atom of one of the carbon atoms to which it is joined, said
linker/spacer group being represented by the formula 5 wherein: s
is an integer of 0 or 1; t is an integer of 0 to 20 inclusive;
R.sup.1 is H or an electrophilic or nucleophilic moiety which
allows for covalent attachment to a biological carrier, or
synthetic linker which can be attached to a biological carrier, or
precursor thereof; and Cyc represents a cyclic aliphatic moiety,
aromatic moiety, aliphatic heterocyclic moiety, or aromatic
heterocyclic moiety, each of said moieties optionally substituted
with one or more groups which do not interfere with binding to a
biological carrier; with the proviso that when R.sup.1 is H, the
linkage to the biological carrier is through one of Q or Q.sup.1;
and with the proviso that when R.sup.1 is other than H, at least
one of Q and Q.sup.1 must be
(CHR.sup.5).sub.pPO.sub.3R.sup.6R.sup.7; and with further proviso
that when Q is (CHR.sup.5).sub.pCO.sub.2R, Q.sup.1 is
(CHR.sup.5).sub.wCO.sub.- 2R, R is H, R.sup.5 is H, and R.sup.1 is
H, then the sum of m, n, p, r, s, t, and w is greater than 1; or
pharmaceutically acceptable salts thereof; complexed with
.sup.225Ac
Inventors: |
Frank, R. Keith; (Lake
Jackson, TX) ; Simon, Jaime; (Angleton, TX) ;
Kiefer, Garry E.; (Lake Jackson, TX) |
Correspondence
Address: |
THE DOW CHEMICAL COMPANY
INTELLECTUAL PROPERTY SECTION
P. O. BOX 1967
MIDLAND
MI
48641-1967
US
|
Family ID: |
23039179 |
Appl. No.: |
10/664670 |
Filed: |
September 18, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10664670 |
Sep 18, 2003 |
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10085930 |
Feb 27, 2002 |
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6670456 |
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60272288 |
Feb 28, 2001 |
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Current U.S.
Class: |
514/184 ;
424/1.11; 534/11 |
Current CPC
Class: |
A61K 51/0497 20130101;
A61K 51/0482 20130101; A61P 35/00 20180101 |
Class at
Publication: |
514/184 ;
534/011; 424/001.11 |
International
Class: |
C07F 005/00; A61K
031/555; A61K 051/00 |
Claims
What is claimed is:
1. An Actinium-225 complex comprising a functionalized
polyazamacrocyclic chelant compound of the formula I, hereinbelow:
22G is independently hydrogen or 23each Q is independently
hydrogen, (CHR.sup.5).sub.pCO.sub.- 2R or
(CHR.sup.5).sub.pPO.sub.3R.sup.6R.sup.7 or 24Q.sup.1 is hydrogen,
(CHR.sup.5).sub.wCO.sub.2R or
(CHR.sup.5).sub.wPO.sub.3R.sup.6R.sup.7; each R is independently
hydrogen, benzyl or C.sub.1-C.sub.4 alkyl; R.sup.6 and R.sup.7 are
independently H, C.sub.1-C.sub.6 alkyl or (C.sub.1-C.sub.2
alkyl)phenyl; each R.sup.5 is independently hydrogen;
C.sub.1-C.sub.4 alkyl or (C.sub.1-C.sub.2 alkyl) phenyl; with the
proviso that at least two of the sum of Q and Q.sup.1 must be other
than hydrogen; A is CH, N, C--Br, C--Cl, C--SO.sub.3H, C--OR.sup.8,
C--OR.sup.9N.sup.+--R.sup.10X.sup.-, or 25Z and Z.sup.1
independently are CH, N, C--SO.sub.3H, N.sup.+--R.sup.10X--,
C--CH.sub.2--OR.sup.8 or C--C(O)--R.sup.11; R.sup.8 is H,
C.sub.1-C.sub.5 alkyl, benzyl, or benzyl substituted with at least
one R.sup.12; R.sup.9 is C.sub.1-C.sub.16 alkylamino; R.sup.10 is
C.sub.1-C.sub.16 alkyl, benzyl, or benzyl substituted with at least
one R.sup.12; R.sup.11 is --O--(C.sub.1-C.sub.3 alkyl), OH or
NHR.sup.13; R.sup.12 is H, NO.sub.2, NH.sub.2, isothiocyanato,
semicarbazido, thiosemicarbazido, maleimido, bromoacetamido or
carboxyl; R.sup.13 is C.sub.1-C.sub.5 alkyl; X and Y are each
independently hydrogen or may be taken with an adjacent X and Y to
form an additional carbon-carbon bond; n is 0 or 1; m is an integer
from 0 to 10 inclusive; p is l or 2; r is O or 1; w is O or 1; with
the proviso that n is only 1 when X and/or Y form an additional
carbon-carbon bond, and the sum of r and w is 0 or 1; L is a
linker/spacer group covalently bonded to, and replaces one hydrogen
atom of one of the carbon atoms to which it is joined, said
linker/spacer group being represented by the formula 26 wherein: s
is an integer of 0 or 1; t is an integer of 0 to 20 inclusive;
R.sup.1 is H or an electrophilic or nucleophilic moiety which
allows for covalent attachment to a biological carrier, or
synthetic linker which can be attached to a biological carrier, or
precursor thereof; and Cyc represents a cyclic aliphatic moiety,
aromatic moiety, aliphatic heterocyclic moiety, or aromatic
heterocyclic moiety, each of said moieties optionally substituted
with one or more groups which do not interfere with binding to a
biological carrier; with the proviso that when R.sup.1 is H, the
linkage to the biological carrier is through one of Q or Q.sup.1;
and with the proviso that when R.sup.1 is other than H, at least
one of Q and Q.sup.1 must be
(CHR.sup.5).sub.pPO.sub.3R.sup.6R.sup.7; and with further proviso
that when Q is (CHR.sup.5).sub.pCO.sub.2R, Q.sup.1 is
(CHR.sup.5).sub.wCO.sub.- 2R, R is H, R.sup.5 is H, and R.sup.1 is
H, then the sum of m, n, p, r, s, t, and w is greater than 1; or
pharmaceutically acceptable salt thereof; complexed with
.sup.225Ac
2. A conjugate comprising the complex of claim 1 covalently
attached to a biological carrier.
3. The conjugate according to claim 2 wherein the biological
carrier is a protein, antibody, antibody fragment, hormone,
peptide, growth factor, antigen or hapten.
4. The complex of claim 1 wherein R.sup.1 is H, NO.sub.2, NH.sub.2,
isothiocyanato, semicarbazido, thiosemicarbazido, maleimido,
bromoacetamido or carboxyl.
5. The complex according to claim 1 wherein the functionalized
chelant is a compound of formula II 27 wherein: each Q is
independently hydrogen, (CHR.sup.5).sub.pCO.sub.2R or
(CHR.sup.5).sub.pPO.sub.3R.sup.6R.sup.7 or 28Q.sup.1 is hydrogen,
(CHR.sup.5).sub.wCO.sub.2R or
(CHR.sup.5).sub.wPO.sub.3R.sup.6R.sup.7; each R is independently
hydrogen, benzyl or C.sub.1-C.sub.4 alkyl; R.sup.6 and R.sup.7 are
independently H, C.sub.1-C.sub.6 alkyl or (C.sub.1-C.sub.2 alkyl)
phenyl; each R.sup.5 is independently hydrogen; C.sub.1-C.sub.4
alkyl or (C.sub.1-C.sub.2 alkyl)phenyl; with the proviso that at
least two of the sum of Q and Q.sup.1 must be other than hydrogen;
X and Y are each independently hydrogen or may be taken with an
adjacent X and Y to form an additional carbon-carbon bond; n is 0
or 1; m is an integer from 0 to 10 inclusive; p is l or 2; r is O
or 1; w is O or 1; with the proviso that n is only 1 when X and/or
Y form an additional carbon-carbon bond, and the sum of r and w is
0 or 1; L is a linker/spacer group covalently bonded to, and
replaces one hydrogen atom of one of the carbon atoms to which it
is joined, said linker/spacer group being represented by the
formula 29 wherein: s is an integer of 0 or 1; t is an integer of 0
to 20 inclusive; R.sup.1 is H or an electrophilic or nucleophilic
moiety which allows for covalent attachment to a biological
carrier, or synthetic linker which can be attached to a biological
carrier, or precursor thereof; and Cyc represents a cyclic
aliphatic moiety, aromatic moiety, aliphatic heterocyclic moiety,
or aromatic heterocyclic moiety, each of said moieties optionally
substituted with one or more groups which do not interfere with
binding to a biological carrier; with the proviso that when R.sup.1
is H, the linkage to the biological carrier is through one of Q or
Q.sup.1; and with the proviso that when R.sup.1 is other than H, at
least one of Q and Q.sup.1 must be
(CHR.sup.5).sub.pPO.sub.3R.sup.6R.sup.7; and with further proviso
that when Q is (CHR.sup.5).sub.pCO.sub.2R, Q.sup.1 is
(CHR.sup.5).sub.wCO.sub.- 2R, R is H, R.sup.5 is H, and R.sup.1 is
H, then the sum of m, n, p, r, s, t, and w is greater than 1; or
pharmaceutically acceptable salt thereof.
6. The complex according to claim 1 wherein the functionalized
chelant is a compound of formula III 30 wherein: each Q is
independently hydrogen, (CHR.sup.5).sub.pCO.sub.2R or
(CHR.sup.5).sub.pPO.sub.3R.sup.6R.sup.7 or 31Q.sup.1 is hydrogen,
(CHR.sup.5).sub.wCO.sub.2R or
(CHR.sup.5).sub.wPO.sub.3R.sup.6R.sup.7; each R is independently
hydrogen, benzyl or C.sub.1-C.sub.4 alkyl; R.sup.6 and R.sup.7 are
independently H, C.sub.1-C.sub.6 alkyl or (C.sub.1-C.sub.2 alkyl)
phenyl; each R.sup.5 is independently hydrogen; C.sub.1-C.sub.4
alkyl or (C.sub.1-C.sub.2 alkyl)phenyl; with the proviso that at
least two of the sum of Q and Q.sup.1 must be other than hydrogen;
X and Y are each independently hydrogen or may be taken with an
adjacent X and Y to form an additional carbon-carbon bond; n is 0
or 1; m is an integer from 0 to 10 inclusive; p is l or 2; r is O
or 1; w is O or 1; with the proviso that n is only 1 when X and/or
Y form an additional carbon-carbon bond, and the sum of r and w is
0 or 1; L is a linker/spacer group covalently bonded to, and
replaces one hydrogen atom of one of the carbon atoms to which it
is joined, said linker/spacer group being represented by the
formula 32 wherein: s is an integer of 0 or 1; t is an integer of 0
to 20 inclusive; R.sup.1 is H or an electrophilic or nucleophilic
moiety which allows for covalent attachment to a biological
carrier, or synthetic linker which can be attached to a biological
carrier, or precursor thereof; and Cyc represents a cyclic
aliphatic moiety, aromatic moiety, aliphatic heterocyclic moiety,
or aromatic heterocyclic moiety, each of said moieties optionally
substituted with one or more groups which do not interfere with
binding to a biological carrier; with the proviso that when R.sup.1
is H, the linkage to the biological carrier is through one of Q or
Q.sup.1; and with the proviso that when R.sup.1 is other than H, at
least one of Q and Q.sup.1 must be
(CHR.sup.5).sub.pPO.sub.3R.sup.6R.sup.7; and with further proviso
that when Q is (CHR.sup.5).sub.pCO.sub.2R, Q.sup.1 is
(CHR.sup.5).sub.wCO.sub.- 2R, R is H, R.sup.5 is H, and R.sup.1 is
H, then the sum of m, n, p, r, s, t, and w is greater than 1; or a
pharmaceutically acceptable salt thereof.
7. A conjugate according to claim 2 comprising the .sup.225Ac
complex of DOTA
(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid)
covalently attached via amide linkage to a biological carrier.
8. A conjugate according to claim 2 comprising the .sup.225Ac
complex of
2-(p-isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraa-
cetic acid covalently attached to a biological carrier.
9. A pharmaceutical formulation comprising the .sup.225Ac conjugate
of claim 2 and a pharmaceutically acceptable carrier.
10. The formulation of claim 9 wherein the pharmaceutically
acceptable carrier is a liquid.
11. A method of therapeutic treatment of a mammal having cancer
which comprises administering to said mammal a therapeutically
effective amount of the formulation of claim 9.
Description
[0001] This application is a divisional of U.S. application Ser.
No. 10/085,930 filed Feb. 27, 2002 which claimed the benefit of
U.S. Provisional Application No. 60/272,288 filed Feb. 28,
2001.
[0002] This invention relates to actinium-225 (.sup.225Ac)
complexes with fuctionalized chelants, their conjugates and their
use for targeted radiotherapy.
[0003] The use of radionuclides complexed with suitable chelants,
as well as their conjugates (that is, such complexes covalently
attached to a biologically active carrier, e.g., protein) for
diagnosis of cancer and/or therapeutic treatment of cancer in
mammals is known. These biochemically engineered molecules provide
the tumor specificity and the radioisotope provides potent
cytotoxicity. See, for example, U.S. Pat. Nos. 4,897,254;
5,342,925; 5,435,990; 5,652,361; 5,696,239; and 5,756,065.
[0004] It has been recognized that antibody-targeted alpha
particles would allow extraordinarily potent, single cell-specific
killing with minimal toxicity to normal cells or the patient. The
use of alpha particles as an alternative to more traditional
classes of radiation is derived from the particle's kinetic
characteristics and the radioactive half-life of their source
isotope, as well as from the properties of the target-selective
carrier moiety for the source isotope. The use of alpha-emitting
radionuclides is highly desirable for the following reasons: (a) a
single atom can kill a cell making them hundreds to thousands of
times more potent than even the most potent toxins or drugs; (b)
the range of alpha particles is only about 50 microns, so that
adjacent tissues are not harmed; (c) the chelated atoms on fully
human or humanized antibodies are unlikely to be immunogenic and
can be repeatedly dosed; (d) the radioactive atoms decay to
harmless stable atoms; (e) killing can occur from inside or outside
of the cell; (f) killing is by apoptosis and by double stranded DNA
breaks and repair is not likely.
[0005] Specific cytotoxic effects of "alpha particle-emitting
radioimmunoconjugates" have been demonstrated in several
experimental systems. Specific in vitro cell-killing has been
demonstrated against a human epidermoid cell line using .sup.213Bi-
and .sup.225Ac-containing immunoconjugates, see, for example,
Kaspersen et al, Nuclear Medicine Communications, Vol. 15, pp.
468-476 (1995). Efficient and specific cell kill by the
.sup.212Bi-labeled anti-Tac (CD25) monoclonal antibody has been
demonstrated against an adult T-cell leukemia cell line in vitro,
see, for example, R. W. Kozak et al, Proc. Natl. Acad. Sci. USA,
Vol. 83, pp. 474-478 (1986). In other experiments, mice inoculated
intraperitoneally with the murine tumor line EL-4 were cured of
their ascites after intraperitoneal injection of 150 .mu.Ci of a
.sup.212Bi-labeled antibody conjugate, see, for example, R. M.
Macklis et al, Science, Vol. 240, pp. 1024-1026 (1988).
[0006] Potential for use of .sup.225Ac in radiotherapy of cancer
has also been recognized due to its favorable properties. This
isotope decays with a radioactive half-life of 10 days into a
cascade of short lived alpha- and beta-emitting isotopes. See, for
example, M. W. Geerlings et al, Nuclear Medicine Communications,
Vol. 14, pp. 121-125 (1993) and Kaspersen et al, Nuclear Medicine
Communications, Vol. 15, pp. 468-476 (1995). However, the use of
.sup.225Ac in radioimmunotherapy has been hampered due to its
toxicity and lack of a suitable carrier which will deliver it to
the targeted cells.
[0007] In an effort to reduce the toxicity of .sup.225Ac, numerous
chelating agents such as, for example,
1,4,7,10-tetra-azacyclododecane-1,- 4,7,10-tetraacetic acid (DOTA),
diethylenetriaminepentaacetic acid (DTPA),
ethylene-diaminetetracetic acid (EDTA),
1,4,7,10,13-pentaazacyclopentadec- ane-1,4,7,10,13-pentaacetic acid
(PEPA), and 1,4,7,10,13,16-hexaazacyclohe-
xadecane-1,4,7,10,13,16-hexaacetic acid (HEHA) have been complexed
with .sup.225Ac and evaluated in vivo for toxicity and stability.
However, the toxicity of these complexes has proved to be still
substantial.
[0008] G. J. Beyer et al, Isotoperpraxis, Vol. 26, pp. 111-114
(1990), has evaluated the in vivo uptake of .sup.225Ac-citrate and
compared it to .sup.169Yb-citrate. This study has found that
.sup.225Ac-citrate had more efficient blood clearance, greater
liver uptake, and lower bone uptake than .sup.169Yb-citrate.
[0009] G. J. Beyer et al, Nucl. Med. & Biol., Vol. 24, pp.
367-372 (1997), has evaluated EDTMP
(ethylenediaminetetra-methylenephosphonic acid) as a chelant for
.sup.225Ac. The study has found that EDTMP, depending on its
concentration, reduces the liver uptake. However, the liver uptake
of .sup.225Ac-EDTMP is still substantial and excretion of
.sup.225Ac-EDTMP is poor. The study has also suggested that greater
efficacy in endoradionuclide therapy of bone metastasis can be
expected with the use of .sup.225Ac-EDTMP due to the
alpha-radiation.
[0010] K. A. Deal et al, J. Med. Chem., Vol 42, pp. 298-2992
(1999), has evaluated biodistribution of a number of .sup.225Ac
chelates. It has been observed that the structure of the chelant
has a dramatic effect on the biodistribution of .sup.225Ac. HEHA
(1,4,7,10,13,16-hexaazacyclohexadecan- e-1,4,7,10,13,16-hexaacetic
acid) was the largest macrocyclic chelant. .sup.225Ac readily
formed a complex with HEHA. Exceptional in vivo stability and
reduced toxicity has been observed for .sup.225Ac-HEHA. This has
been attributed to the large size and macrocyclic effect of
HEHA.
[0011] Although various chelating agents were suggested and
evaluated as carriers for .sup.225Ac, up to now .sup.225Ac has not
been successfully chelated to an antibody and no successful
therapeutic use of .sup.225Ac in animals or humans has been
reported, presumably due to its inherent toxicity and/or stability
problems of its complexes.
[0012] It would be desirable to provide complexes comprising
.sup.225Ac and functionalized chelants which are kinetically and
thermodynamically inert for use in therapeutic applications.
[0013] It would also be desirable to provide conjugates of such
.sup.225Ac complexes with a biological carrier. The biological
carrier in these conjugates would provide the tumor specificity and
the .sup.225Ac isotope would provide potent cytotoxicity.
[0014] Another desirable property of these conjugates includes
physiological compatibility which would permit the .sup.225Ac
complex, if separated from its targeting, conjugated biological
carrier in vivo, to be soluble in physiological fluids and thus be
rapidly eliminated from the body.
[0015] The present invention is directed to .sup.225Ac complexes
and their conjugates with a biological carrier. The .sup.225Ac
complexes and conjugates of the present invention are useful for
the treatment of cancer in mammals, especially humans.
[0016] More specifically, the present invention is directed to
.sup.225Ac complexes comprising a functionalized polyazamacrocyclic
chelant compound of the formula I hereinbelow: 6
[0017] G is independently hydrogen or 7
[0018] each Q is independently hydrogen, (CHR.sup.5).sub.pCO.sub.2R
or (CHR.sup.5).sub.pPO.sub.3R.sup.6R.sup.7 or 8
[0019] Q.sup.1 is hydrogen, (CHR.sup.5).sub.wCO.sub.2R or
(CHR.sup.5).sub.wPO.sub.3R.sup.6R.sup.7;
[0020] each R is independently hydrogen, benzyl or C.sub.1-C.sub.4
alkyl;
[0021] R.sup.6 and R.sup.7 are independently H, C.sub.1-C.sub.6
alkyl or (C.sub.1-C.sub.2 alkyl)phenyl;
[0022] each R.sup.5 is independently hydrogen; C.sub.1-C.sub.4
alkyl or (C.sub.1-C.sub.2 alkyl)phenyl;
[0023] with the proviso that at least two of the sum of Q and
Q.sup.1 must be other than hydrogen;
[0024] A is CH, N, C--Br, C--Cl, C--SO.sub.3H, C--OR.sup.8,
C--OR.sup.9N.sup.+--R.sup.10X.sup.-, or 9
[0025] Z and Z.sup.1 independently are CH, N, C--SO.sub.3H,
N.sup.+--R.sup.10X.sup.-, C--CH.sub.2--OR.sup.8 or
C--C(O)--R.sup.11;
[0026] R.sup.8 is H, C.sub.1-C.sub.5 alkyl, benzyl, or benzyl
substituted with at least one R.sup.12;
[0027] R.sup.9 is C.sub.1-C.sub.16 alkylamino;
[0028] R.sup.10 is C.sub.1-C.sub.16 alkyl, benzyl, or benzyl
substituted with at least one R.sup.12;
[0029] R.sup.11 is --O--(C.sub.1-C.sub.3 alkyl), OH or
NHR.sup.13;
[0030] R.sup.12 is H, NO.sub.2, NH.sub.2, isothiocyanato,
semicarbazido, thiosemicarbazido, maleimido, bromoacetamido or
carboxyl;
[0031] R.sup.13 is C.sub.1-C.sub.5 alkyl;
[0032] X and Y are each independently hydrogen or may be taken with
an adjacent X and Y to form an additional carbon-carbon bond;
[0033] n is 0 or 1;
[0034] m is an integer from 0 to 10 inclusive;
[0035] p is l or 2;
[0036] r is O or 1;
[0037] w is O or 1;
[0038] with the proviso that n is only 1 when X and/or Y form an
additional carbon-carbon bond, and the sum of r and w is 0 or
1;
[0039] L is a linker/spacer group covalently bonded to, and
replaces one hydrogen atom of one of the carbon atoms to which it
is joined, said linker/spacer group being represented by the
formula 10
[0040] wherein:
[0041] s is an integer of 0 or 1;
[0042] t is an integer of 0 to 20 inclusive;
[0043] R.sup.1 is H or an electrophilic or nucleophilic moiety
which allows for covalent attachment to a biological carrier, or
synthetic linker which can be attached to a biological carrier, or
precursor thereof; and
[0044] Cyc represents a cyclic aliphatic moiety, aromatic moiety,
aliphatic heterocyclic moiety, or aromatic heterocyclic moiety,
each of said moieties optionally substituted with one or more
groups which do not interfere with binding to a biological
carrier;
[0045] with the proviso that when R.sup.1 is H, the linkage to the
biological carrier is through one of Q or Q.sup.1; and with the
proviso that when R.sup.1 is other than H, at least one of Q and
Q.sup.1 must be (CHR.sup.5).sub.pPO.sub.3R.sup.6R.sup.7; and with
further proviso that when Q is (CHR.sup.5).sub.pCO.sub.2R, Q.sup.1
is (CHR.sup.5).sub.wCO.sub.- 2R, R is H, R.sup.5 is H, and R.sup.1
is H, then the sum of m, n, p, r, s, t, and w is greater than
1;
[0046] or a pharmaceutically acceptable salts thereof; complexed
with .sup.225Ac.
[0047] Even more specifically, the present invention is directed to
.sup.225Ac complexes comprising a functionalized polyazamacrocyclic
chelant compound of the formula II, III, IV or V hereinbelow:
11
[0048] wherein the substituents are as defined above.
[0049] The present invention is also directed to a conjugate
comprising the aforementioned .sup.225Ac complex covalently
attached to a biological carrier.
[0050] The present invention is also directed to a conjugate
comprising the .sup.225Ac complex of DOTA
(1,4,7,10-tetraazacyclododecane-1,4,7,10-t- etraacetic acid)
covalently attached via amide linkage to a biological carrier.
[0051] The present invention also includes formulations comprising
the conjugates of this invention and a pharmaceutically acceptable
carrier, especially formulations where the pharmaceutically
acceptable carrier is a liquid.
[0052] The present invention is also directed to a method of
therapeutic treatment of a mammal having cancer which comprises
administering to said mammal a therapeutically effective amount of
the formulation of this invention.
[0053] Surprisingly, the .sup.225Ac complexes and conjugates of
this invention are relatively stable (that is, do not easily
dissociate) and some display rapid clearance from the whole body
and some non-target organs, such as liver and kidney. Additionally,
the alpha particle-emitting .sup.225Ac complexes and conjugates of
this invention are expected to have several advantages over beta
particle-emitting cytotoxic agents including higher energy and more
potent emissions, less hazardous waste, expected lower effective
dose, the potential for outpatient treatment, better retention at
the target sites, and higher target to non-target radiation
ratios.
[0054] As used herein, the term ".sup.225Ac complex" refers to a
polyazamacrocyclic functionalized chelant compound of formula I
complexed with .sup.225Ac radionuclide.
[0055] As used herein, the term ".sup.225Ac conjugate" refers to
.sup.225Ac complex of the present invention that is covalently
attached to a biological carrier.
[0056] As used herein, the term "mammal" means animals that nourish
their young with milk secreted by mammary glands, preferably
humans.
[0057] As used herein, the term "biological carrier" refers to any
protein, antibody, antibody fragment, hormone, peptide, growth
factor, antigen, hapten or any other carrier which functions in
this invention to recognize a specific biological target site.
Antibody and antibody fragment refers to any polyclonal,
monoclonal, chimeric, human, mammalian, single chains, dimeric and
tetrameric antibody or antibody fragment. Such biological carrier,
when attached to a functionalized complex, serves to carry the
attached .sup.225Ac ion to specific targeted tissues. The term
"antibody" refers to any polyclonal, monoclonal, chimeric antibody
or heteroantibody. Preferably the antibodies used in the .sup.225Ac
conjugates of the present invention are monoclonal antibodies
having high specificity for the desired cancer cells. Antibodies
used in the present invention may be directed against, for example,
cancer, tumors, leukemias, autoimune disorders involving cells of
the immune system, normal cells that need to be ablated such as
bone marrow and prostate tissue, virus infected cells including
HIV, mycoplasma, differentiation and other cell membrane antigens,
patogen surface antigens and any biologically active molecules.
Some examples of antibodies are HuM195 (anti-CD33), CC-11, CC-46,
CC-49, CC-49 F(ab').sub.2, CC-83, CC-83 F(ab').sub.2, and B72.3.
Particularly preferred antibody for use in the practice of the
present invention is HuM195. Antibody fragment includes Fab
fragments and F(ab').sub.2 fragments, and any portion of an
antibody having specificity toward a desired epitope or epitopes.
The antibodies which may be used in the .sup.225Ac conjugates of
the present invention can be prepared by techniques well known in
the art. Highly specific monoclonal antibodies can be produced by
hybridization techniques well known in the art, see, for example,
Kohler and Milstein, Nature, 256, 495-497 (1975); and Eur. J.
Immunol., 511-519 (1976).
[0058] As used herein, "pharmaceutically acceptable salt" means any
salt of a compound of formula I which is sufficiently non-toxic to
be useful in therapy of mammals. Representative of those salts,
which are formed by standard reactions, from both organic and
inorganic sources include, for example, sulfuric, hydrochloric,
phosphoric, acetic, succinic, citric, lactic, maleic, fumaric,
palmitic, cholic, palmoic, mucic, glutamic, d-camphoric, glutaric,
glycolic, phthalic, tartaric, formic, lauric, steric, salicylic,
methanesulfonic, bensenesulfonic, sorbic, picric, benzoic, cinnamic
and other suitable acids. Also included are salts formed by
standard reactions from both organic and inorganic sources such as
ammonium, alkali metal ions, alkaline earth metal ions, and other
similar ions. Preferred are the salts of the compounds of formula I
where the salt is potassium, sodium, ammonium, or mixtures
thereof.
[0059] As used herein, the term "therapeutically effective amount"
means an amount of the .sup.225Ac conjugate that produces a
therapeutic effect on the disease treated. The therapeutically
effective amount will vary depending on the mammal, the .sup.225Ac
conjugate and the method of its administration (for example, oral
or parenteral). A person of ordinary skill in the art can determine
the therapeutically effective amount of the .sup.225Ac
conjugate.
[0060] In the practice of the present invention the .sup.225Ac
conjugate may be administered per se or as a component of a
pharmaceutically acceptable formulation.
[0061] Thus, the present invention may be practiced with the
.sup.225Ac conjugate being provided in pharmaceutical formulation,
both for veterinary and for human medical use. Such pharmaceutical
formulations comprise the active agent (the .sup.225Ac conjugate)
together with a physiologically acceptable carrier, excipient or
vehicle therefore. The carrier(s) must be physiologically
acceptable in the sense of being compatible with the other
ingredient(s) in the formulation and not unsuitably deleterious to
the recipient thereof. The .sup.225Ac conjugate is provided in a
therapeutically effective amount, as described above, and in a
quantity appropriate to achieve the desired dose.
[0062] The formulations include those suitable for parenteral
(including subcutaneous, intramuscular, intraperitoneal, and
intravenous), oral, rectal, topical, nasal, or ophthalmic
administration. Formulations may be prepared by any methods well
known in the art of pharmacy. Such methods include the step of
bringing the .sup.225Ac conjugate into association with a carrier,
excipient or vehicle therefore. In general, the formulation may be
prepared by uniformly and intimately bringing the .sup.225Ac
conjugate into association with a liquid carrier, a finely divided
solid carrier, or both, and then, if necessary, shaping the product
into desired formulation. In addition, the formulations of this
invention may further include one or more accessory ingredient(s)
selected from diluents, buffers, binders, disintegrants, surface
active agents, thickeners, lubricants, preservatives, and the like.
In addition, a treatment regime might include pretreatment with
non-radioactive carrier.
[0063] Injectable formulations of the present invention may be
either in suspensions or solution form. In the preparation of
suitable formulations it will be recognized that, in general, the
water solubility of the salt is greater than the acid form. In
solution form the complex (or when desired the separate components)
is dissolved in a physiologically acceptable carrier. Such carriers
comprise a suitable solvent, preservatives such as free radical
quenching agents, for example, ascorbic acid, benzyl alcohol or any
other suitable molecule, if needed, and buffers. Useful solvents
include, for example, water, aqueous alcohols, glycols, and
phosphonate or carbonate esters. Such aqueous solutions contain no
more than 50 percent of the organic solvent by volume.
[0064] Injectable suspensions are compositions of the present
invention that require a liquid suspending medium, with or without
adjuvants, as a carrier. The suspending medium can be, for example,
aqueous polyvinylpyrrolidone, inert oils such as vegetable oils or
highly refined mineral oils, polyols, or aqueous
carboxymethylcellulose. Suitable physiologically acceptable
adjuvants, if necessary to keep the complex in suspension, may be
chosen from among thickeners such as carboxymethylcellulose,
polyvinylpyrrolidone, gelatin, and the alginates. Many surfactants
are also useful as suspending agents, for example, lecithin,
alkylphenol, polyethyleneoxide adducts, naphthalenesulfonates,
alkylbenzenesulfonates, and polyoxyethylene sorbitane esters.
[0065] In the context of the present invention the terms
"functionalized chelant" and "bifunctional chelant" are used
interchangeably and refer to compounds which have the dual
functionality of sequestering metal ions plus the ability to
covalently bind a biological carrier having specificity for tumor
cell epitopes or antigens. Such compounds are of great utility for
therapeutic and diagnostic applications when they are, for example,
complexed with radioactive metal ions and covalently attached to a
specific antibody. These types of complexes have been used to carry
radioactive metals to tumor cells which are targeted by the
specificity of the attached antibody [see, for example, Mears et
al., Anal. Biochem. 142, 68-74 (1984); Krejcarek et al., Biochem.
And Biophys. Res. Comm. 77, 581-585 (1977)].
[0066] The polyazamacrocyclic functionalized chelant compounds of
formulas II, III, IV and V useful in the practice of the present
invention are known in the art. See, for example, U.S. Pat. Nos.
5,435,990; 5,652,361; 5,428,139; 5,480,990; and 5,739,294.
[0067] The polyazamacrocyclic functionalized chelants of formula I
useful in the practice of the present invention can be prepared by
known methods. General synthetic approach to a twelve-membered
macrocyclic, bifunctional chelant of the present invention as
represented by formula II involves monofuctionalization of a
free-base macrocycle (for example, 1,4,7,10-tetraazacyclododecane)
at only one of the nitrogen atoms with an appropriate electrophile
(for example, any appropriately substituted alpha-halocarboxylic
acid ester). This electrophile must possess a suitable linker
moiety which would allow covalent attachment of bifunctional ligand
to a biological carrier. Various synthetic routes to functionalized
chelants of formula II have been described in U.S. Pat. Nos.
5,435,990; 5,652,361, both incorporated herein by reference.
[0068] General synthetic approach to a twelve-membered macrocyclic,
bifunctional chelant of the present invention as represented by
formula III is more complex and involves synthesis of a
backbone-functionalized macrocycle. Various synthetic routes to
functionalized chelants of formula III have been described in J. K.
Moran, et al, Bioconjugate Chem., 6(3), 296-301 (1995); O. Renn, et
al, Bioconjugate Chem., 3(6), 563-9 (1992).
[0069] General synthetic approach to a macrocyclic, bifunctional
chelant of the present invention as represented by formula IV
involves functionalization of the base macrocycle (for example,
3,6,9,15-tetraazabicyclo[9.3.1]-pentadeca-1(15),11,13-triene) with
chelating and/or linking functionalities. Various synthetic routes
to functionalized chelants of formula IV have been described in
U.S. Pat. Nos. 5,428,139; 5,480,990; and 5,739,294.
[0070] General synthetic approach to a twelve-membered macrocyclic,
bifunctional chelant of the present invention as represented by
formula V involves the use of functionalized moieties in the
formation of the twelve-membered tetraazamacrocycle in order to
accomplish backbone substitution. Various synthetic routes to
functionalized chelants of formula V can be envisioned by
substituting these moieties into the schemes presented in U.S. Pat.
Nos. 5,428,139; 5,480,990; and 5,739,294.
[0071] The method of obtaining .sup.225Ac radionuclide is not
critical to the present invention. For example, .sup.225Ac can be
prepared in a cyclotron. .sup.225Ac can be obtained in pure form
from Department of Energy (DOE), U.S.A., and Institute for
Transuranium Elements (ITU), Karlsruhe, Germany.
[0072] When forming the .sup.225Ac complexes of the present
invention, the degree of complexation is advantageously high. As
used herein, the terms "degree of complexation" and "percent
complexation" are used interchangeably and are defined to mean the
percentage of the .sup.225Ac that is successfully complexed with
the bifunctional chelant divided by the total .sup.225Ac used in
the complexation reaction. Preferably, the percent complexation
when making the .sup.225Ac complexes of the present reaction is
greater than 50%, more preferably greater than 70%, even more
preferably greater than 90% and yet even more preferably greater
than 95%, as measured by cation exchange chromatography within 24
hours after complexation.
[0073] The .sup.225Ac conjugates of the present invention can be
prepared by first forming the complex and then attaching to the
biological carrier. Thus, the process involves preparing or
obtaining the ligand, forming the complex with .sup.225Ac and then
adding the biological carrier. Alternatively, the process may
involve first conjugation of the ligand to the biological carrier
and then the formation of the complex with .sup.225Ac. Any suitable
process that results in the formation of the .sup.225Ac conjugates
of this invention is within the scope of the present invention.
EXAMPLES
[0074] Materials
[0075] All materials were from common commercial sources unless
stated otherwise.
[0076] EDTA is ethylenediaminetetraacetic acid.
[0077] Sephadex C-25 resin is a cation exchange resin, sold by
Pharmacia Inc.
[0078] .sup.225Ac was received from Oak Ridge National Laboratory,
Oak Ridge, Tenn., as a solid nitrate salt. It was dissolved in 0.1
M nitric acid and diluted further.
[0079] TMAA (tetramethyl ammonium acetate) is from Lancaster,
Windham, N.H.
[0080] The following examples are provided to further illustrate
the present invention, and should not be construed as limiting
thereof.
Examples 1-5
[0081] Preparation of .sup.225Ac-Chelant Complexes
[0082] Table 1 lists the chelants that were used to form the
complexes in Examples 1-5. Methods known in the art can be employed
to convert these chelants into bifunctional molecules capable of
forming conjugates. For example, the nitro group in chelant 1 can
be reduced to an amine and subsequently converted to an
isothiocyanate; a bifunctional analog of chelant 4 can be prepared
by attaching a linking group to one of the acetate carbons.
1TABLE 1 Chelants used for complexation. Chelant Name 1 12
1-(.alpha.-(2-methoxy-5- nitrophenyl)-acetic acid-4,7,10-methylene-
phosphonic acid tri- methyl ester-1,4,7,10- tetraazacyclododecane 2
13 3,6,9,15-tetraaza- bicyclo-[9.3.1]penta- deca-1(15),11,13-
triene-3,6,9-methyl- enephosphonic acid 3 14 3,6,9,15-tetraaza-
bicyclo-[9.3.1]penta- deca-1(15),11,13- triene-3,6,9-methyl-
enphosphonic acid tributyl ester 4 15 3,6,9,15-tetraaza-
bicyclo-[9.3.1]penta- deca-1(15),11,13- triene-3,6,9-acetic acid 5
16 1,4,7,10-tetraazacyclo- dodecane-1,4,7,10- tetraacetic acid
(DOTA)
[0083] For each example, the complexes were prepared by mixing
0.063 mL of an aqueous solution (20 mM) of chelant with .sup.225Ac
chloride solution (35 .mu.L; 1 .mu.Ci/.mu.L,) in 0.1M HCl. When
complexation was performed at pH=6, the pH of the reaction mixture
was set using 50% tetramethyl ammonium acetate (130 .mu.L, 0.2 M,
pH 6). When complexation was conducted at higher pH, the pH of the
reaction mixture was set with 0.1 M sodium hydroxide. The final
volume of the reaction mixture was 10 0.250 mL.
[0084] Complexation was carried out by incubating the reaction
mixture at 20, 37 or 60.degree. C. for 1, 3 or 24 hours. The
chelant concentration was 5 mM. The degree of complexation was
determined using cation exchange chromatography employing Sephadex
C-25 resin.
[0085] Table 2 summarizes the reaction conditions and the
results.
2TABLE 2 Summary of the reaction conditions and results. Chelant
Temp (.degree. C.) pH Time (h) % complexation 1 17 20 37 60 8 8 8 1
3 1 2 24 1 2 24 96.0 97.9 97.1 98.0 99.0 98.8 99.3 99.9 2 18 20 37
60 8 8 8 1 3 24 1 3 1 24 1 3 24 97.7 98.2 98.1 95.6 97.3 99.5 98.5
98.4 99.2 3 19 20 37 60 8 8 8 1 3 24 1 3 24 1 3 24 97.6 95.1 92.6
93.6 94.8 90.1 92.1 88.5 94.6 4 20 20 37 60 6 6 6 1 3 24 1 3 24 1 3
24 99.9 100.0 98.5 99.9 100.0 99.3 100.0 100.0 99.3 5 21 20 37 60 6
6 6 1 3 24 1 3 24 1 3 24 87.1 95.0 98.6 99.2 99.5 99.1 100.0 99.9
99.1
* * * * *