Cancer treatment

Abstract

A carborane-comprising porphyrin of Formula (1) is provided for use in cancer therapy that extends the period of time between the doses required while the patient is undergoing radiation therapy. The compound can be given not more often than once every 2 or more weeks, avoiding repeated administration, while radiation therapy can continue regularly. ##STR00001##

Claims

1. A method of treating cancer, comprising administering a compound of the formula (1) as defined below to a patient and repeatedly irradiating the patient, wherein a single dose of the compound is administered not more than once every two weeks: ##STR00004## wherein: R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are selected from an electron withdrawing group, NO.sub.2, NH.sub.2, halogen or a substituent represented by the following formula ##STR00005## wherein Y can be on the ortho, meta or para position on the phenyl rings, and is selected from hydrogen, hydrocarbyl, non-aromatic carbocyclic, non-aromatic heterocyclic, aryl, alkylaryl, arylalkyl; or a hydrocarbyl, non-aromatic carbocyclic, non-aromatic heterocyclic, aryl, alkylaryl or an arylalkyl group substituted with 1 to 4 hydrophilic groups selected from hydroxy, alkoxy, C(O)OR.sup.5, SOR.sup.6, SO.sub.2R.sup.6, nitro, amido, ureido, carbamato, SR.sup.7, NR.sup.8R.sup.9 or poly-alkyleneoxide; or a substituent represented by formula (3)
X(CR.sup.10R.sup.11).sub.rZ(3); provided that at least one of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 is the substituent represented by formula (2) wherein Y represents formula (3); wherein: X is selected from oxygen or sulfur; R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9, R.sup.10 and R.sup.11 are selected from hydrogen and C.sub.1 to C.sub.4 hydrocarbyl; Z is a carborane cluster comprising at least two carbon atoms and at least three boron atoms, or at least one carbon atom and at least five boron atoms, within a cage structure; r is 0 or an integer from 1 to 20; a represents an integer from 1 to 4; and provided also that at least one of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 is an electron withdrawing group, NO.sub.2, NH.sub.2 or halogen; and M is selected from two hydrogen ions, a single monovalent metal ion, two monovalent metal ions, a divalent metal ion, a trivalent metal ion, a tetravalent metal ion, a pentavalent metal ion or a hexavalent metal ion, wherein the porphyrin-metal complex derived from a single monovalent metal ion is charge-balanced by a counter cation, and the porphyrin-metal complex derived from a trivalent, tetravalent, pentavalent or hexavalent metal ion is charge-balanced by an appropriate number of counter anions, dianions or trianions.

2. The method of claim 1, wherein the single dose is administered not more often than once every 3 to 12 weeks.

3. The method of claim 1, wherein the single dose is administered not more often than once every 4 to 9 weeks.

4. The method of claim 1, wherein the single dose is administered not more often than once every 5 to 8 weeks.

5. The method of claim 1, wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4 are selected from NO.sub.2, halogen and Formula (2).

6. The method of claim 1, wherein two of R.sup.1, R.sup.2, R.sup.3, R.sup.4 are NO.sub.2 and two of R.sup.1, R.sup.2, R.sup.3, R.sup.4 are Formula (2).

7. The method of claim 1, wherein R.sup.1 and R.sup.3 are NO.sub.2.

8. The method of claim 1, wherein R.sup.2 and R.sup.4 are Formula (2).

9. The method of claim 1, wherein Y is in the meta position, M is a divalent metal ion, R.sup.10 and R.sup.11 are hydrogen, r is 1 to 6 and a is 1 or 2.

10. The method of claim 1, wherein Z comprises 2 carbon atoms and 10 boron atoms within a cage structure.

11. The method of claim 1, wherein the compound is copper meso-5, 15-bis[3-[(1,2-dicarba-closo-dodecaboranyl)methoxy]phenyl]-meso-10,20-dinitroporphyrin.

12. The method of claim 1, comprising intra-tumoural administration of the compound.

13. The method of claim 1, comprising irradiating the patient approximately daily.

14. A method of treating cancer, comprising administering a compound of the formula (1) as defined in claim 1 to a patient and repeatedly irradiating the patient, wherein a single dose of the compound is administered for the entire course of the treatment.

15. The method claim 14, wherein the entire course of treatment takes between 1 and 16 weeks.

16. The method claim 14, wherein the entire course of treatment takes between 3 and 12 weeks.

17. The method of claim 14, wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4 are selected from NO.sub.2, halogen and Formula (2).

18. The method of claim 14, wherein two of R.sup.1, R.sup.2, R.sup.3, R.sup.4 are NO.sub.2 and two of R.sup.1, R.sup.2, R.sup.3, R.sup.4 are Formula (2).

19. The method of claim 14, wherein R.sup.1 and R.sup.3 are NO.sub.2.

20. The method of claim 14, wherein R.sup.2 and R.sup.4 are Formula (2).

21. The method of claim 14, wherein Y is in the meta position, M is a divalent metal ion, R.sup.10 and R.sup.11 are hydrogen, r is 1 to 6 and a is 1 or 2.

22. The method of claim 14, wherein Z comprises 2 carbon atoms and 10 boron atoms within a cage structure.

23. The method of claim 14, wherein the compound is copper meso-5, 15-bis[3-[(1,2-dicarba-closo-dodecaboranyl)methoxy]phenyl]-meso-10,20-dinitroporphyrin.

24. The method of claim 14, comprising intra-tumoural administration of the compound.

25. A method of treating cancer, comprising administering a single dose of a compound of the formula (1) as defined in claim 1 to a patient and repeatedly irradiating the patient, wherein a therapeutically effective amount of X-ray sensitizing compound is retained in the tumour tissue after administration of a single dose of the compound for a clinically relevant period to allow a course of radiation therapy for the clinically relevant period, wherein the clinically relevant period is any period during which radiation therapy can still be given to the patient or needs to be given to the patient to treat the cancer.

26. The method of claim 25 wherein the clinically relevant period is between 1 and 16 weeks.

27. The method of claim 25 wherein the clinically relevant period is between 4 and 9 weeks.

28. The method of claim 25, comprising intra-tumoural administration of the compound.

29. A method of imaging a tumour, comprising administration of a compound of formula (I) as defined in claim 1 not more often than once every 2 weeks, and imaging the tumour two or more times.

30. The method of claim 29, comprising intra-tumoural administration of the compound.

Description

(1) Examples of the present invention will now be described with reference to the following figures in which:

(2) FIG. 1 shows boron concentrations in liver and tumour of mice at the time of euthanasia irradiated with 32 Gy X-rays;

(3) FIG. 2 shows a Kaplan-Meier graph of SCCVII squamous cell carcinomas implanted in the thighs of C3H mice treated with X-rays alone (32 Gy) or with 150 mg/kg MTL005 injected one day prior to irradiations. Mice were euthanized when the tumour volume reached 500 mm.sup.3; and

(4) FIG. 3 shows normalized average tumour volumes over time after irradiation.

EXAMPLE 1

(5) Formulations containing a compound of the invention were prepared with the following components and are as is set out in Table 1 below:

(6) TABLE-US-00001 TABLE 1 Solvent (% Co-Solvent (% Formu- Concentration v/v of total v/v of total lation of MTL-005 vehicle volume) vehicle volume) 1 50 mg/ml DMA (80%) Polysorbate 20 (20%) 2 50 mg/ml DMA (80%) Solutol HS15 (20%) 3 50 mg/ml DMA (80%) Macrogol 300 (20%) 4 50 mg/ml DMA (80%) .sup.Tetraglycol (20%) 5 50 mg/ml DMA (60%) .sup.Tetraglycol (40%) 6 50 mg/ml DMA (80%) Polysorbate 20 (10%) & Macrogol 300 (10%) 7 50 mg/ml DMA (80%) Polysorbate 20 (10%) & Propylene glycol (10%).sup. 8 50 mg/ml DMA (80%) Polysorbate 20 (10%) & .sup.Tetraglycol (10%) 9 50 mg/ml DMA (80%) Solutol HS15 (10%) & Macrogol 300 (10%) 10 50 mg/ml DMA (80%) Solutol HS15 (10%) & .sup.Tetraglycol (10%) 11 75 mg/ml DMA (90%) Solutol HS15 (10%) 12 75 mg/ml DMA (80%) Solutol HS15 (20%) 13 75 mg/ml DMA (70%) Solutol HS15 (30%) 14 75 mg/ml DMA (70%) Solutol HS15 (20%) & Macrogol 300 (10%) 15 50 mg/ml DMA (70%) Solutol HS15 (30%) 16 50 mg/ml DMA (70%) Solutol HS15 (20%) & Macrogol 300 (10%)

EXAMPLE 2

(7) Animal Tumour Model

(8) SCCVII murine squamous cell carcinoma cells were cultured in D-MEM enriched with 10% fetal bovine serum, 1% penicillin/streptomycin and 1% L-glutamine. Only passages 1-3 were used to initiate tumours. Cells (210.sup.5 in 0.05 mL of medium) were then implanted sc into the left thighs of 20-25 g female C3H mice (Charles River Laboratories, Wilmington, Mass.).

(9) 9% CRM Formulation

(10) MTL005 supplied by Cambridge Major Laboratory (Batch CS08-119A and assayed at 98% purity by % area) was used to make three 15 mL batches of 3 mg/mL formulations (MX4-33). The final concentration assayed by HPLC was 2.80 mg/mL copper meso-5,15-bis[3-[(1,2-dicarba-closo-dodecaboranyl)methoxy]phenyl]-meso-10,20-dinitroporphyrin (MTL005) with 97% purity by HPLC.

(11) Boron and MTL005 Analysis

(12) Direct current plasma-atomic emission spectroscopy [DCP-AES] (ARL/Fisons Model SS-7) was used (detection limit: 0.1 g B/mL) to determine boron concentrations in tissues of individual mice. Samples (50-130 mg) were digested at 60 C. with sulfuric acid:nitric acid (1:1). Triton X-100 and water were added to give final concentrations of 50 mg tissue/mL, 15% total acid v/v and 5% Triton X-100 v/v. The reference standard for MTL005 was assayed using prompt-gamma spectroscopy at the Massachusetts Institute of Technology Reactor Prompt-Gamma Neutron Activation Facility. The concentrations of MTL005 in the EMT-6 tumour and normal tissues can be calculated from the boron concentration of the porphyrin (22.5% boron). It is known that the ether linkages between the porphyrin and carborane cages remain intact in vivo.

(13) Porphyrin Concentration/Formulation/Batch

(14) 2.80 mg/mL MTL005/9% CRM Batch MX4-33.

(15) Administration Protocol and Total Doses

(16) A total dose of 150 mg/kg MTL005 was administered to mice using three intraperitoneal (i.p.) injections over an 8-hour period at 4-h intervals using 0.018 mL/gbw for each injection. Due to the large number of animals to be dosed and irradiated, it was necessary to split the animals into two equally sized groups: Groups A and B. Animals in each Group A were injected on day 7 after tumour implantation, while animals in each Group B were injected on day 8 post tumour implantation. A group of five mice, which was given MTL005, was euthanized at the time of irradiation (24-hour clearance) for boron biodistribution data in tumour, blood, liver, spleen, brain and skin. The liver and tumour of irradiated mice given MTL-005, were also assayed for boron concentration at the time of euthanasia.

(17) Irradiations

(18) Irradiation was carried out 1 day after the final injection of MTL005.

(19) The animals in Group A were irradiated 8 days, and those in Groups B were irradiated 9 days after tumour implantation. Mice were anesthetized (sodium pentobarbital, 60 g/g i.p.) and positioned for irradiation with the tumour-bearing leg extended across a 2-cm diameter collimated irradiation port. Tumours were irradiated using a single dose fraction of 32 gy at a dose-rate of 2.0 Gy/min using a Philips RT-100 set, operating at 100 kVp and 8 mA.

(20) Tumours were measured 2-3 times per week and the mice were killed humanely when the calculated tumour volume (x.sup.2y/2, where x is the shorter surface dimension) exceeded 500 mm.sup.3.

(21) Dosimetry

(22) Dosimetry for X-irradiation was carried out using a thimble ionization chamber applying the 1996 IPEB code of practice.

(23) Biodistribution

(24) Table 2 shows the boron concentrations in various tissues of the mice (meanSD in g/g in various tissues of mice given 150 mg/kg MTL005 in 9% CRM at 1 day after a series of 3 i.p. injections) (n=5).

(25) The boron concentrations from livers of mice given MTL005 ranged from 135-207 g (40-62 days post irradiation) as indicated in FIG. 1. One would have expected boron in tumour to decrease more rapidly with time. There appeared to be a constant tumour boron concentration of 9-22 g/g in the group over the time period. There was no indication that greater survival was correlated to higher tumour boron values.

(26) TABLE-US-00002 TABLE 2 Boron concentration Tissue (g/g) from MXS020 SCCVII Tumour 83.3 17.4 Blood 45.4 12.2 Brain 0.8 0.4 Skin (pinna) 10.3 2.4 Liver 263 32 Spleen 100 18
Radiotherapy

(27) FIG. 2, shows a greater tumour control using MTL-005 than with X-rays alone. Not only were there more controlled tumours but the number of surviving mice was also higher. A Wilcoxon non-parametric two-sample test of the groups at 30 and 62 days showed that there was a significant difference (p=0.09) between the groups at 62 days.

(28) TABLE-US-00003 TABLE 3 Results from irradiated and control groups in SCCVII tumour. Untreated 32 Gy only MTL005 + 32 Gy controls Total mice 12 11* 9 Controlled tumours** 3 6 0 Mice alive at 62 days 1 2 0 with observable tumours % Tumour control 25 54.5 0 *One mouse was omitted from this study due to leg damage and was euthanized on day 48 but no tumour was observed at this time. **Controlled tumours are defined as having a volume of 0 mm.sup.3.

(29) The number of controlled tumours was doubled in the presence of MTL-005 compared to radiation alone at 32 Gy. Further, there is still a significant concentration of active sensitiser in the tumour for days, weeks and months after the single administration of the compound.