Platinum (IV) Complex with Increased Anti-tumor Efficacy

Abstract

The invention relates to a new platinum (IV) complex with substantially increased antitumor efficacy. The invention further discloses a process for preparing of said complex and a pharmaceutical composition for the therapy of tumor diseases containing said complex.

Claims

1. A platinum (IV) complex with “cis-trans-cis” configuration of the ligands of the formula (III): ##STR00018##

2. A process for preparing the platinum (IV) complex according to claim 1 by the reaction of “cis-trans-cis” PtCl.sub.2(OH).sub.2(NH.sub.3,1-adamantylamine) with 1-adamantylcarbonyl chloride and an amine in a non-polar aprotic solvent.

3. The process according to claim 2, wherein the non-polar aprotic solvent is 1,4-dioxane.

4. The process according to claim 2, wherein the amine is pyridine or trialylamine.

5. The process according to claim 2, wherein the stoichiometric ratio of pyridine to 1-adamantyl-carbonyl chloride is from 1 to 2 parts pyridine to 1 part 1-adamantylcarbonyl chloride.

6. A platinum (IV) complex with “cis-trans-cis” configuration of the ligands of the formula (III): ##STR00019## for use in a method to treat tumor diseases.

7. A pharmaceutical composition for the therapy of tumor diseases containing the platinum (IV) complex according to claim 1 and at least one lipophilic and pharmaceutically acceptable additive.

8. The pharmaceutical composition of claim 7, in which composition the content of the platinum (IV) complex according to claim 1 is 0.5 to 50% by weight based on the total weight of the composition.

9. The pharmaceutical composition according to claim 7, wherein the additive is stearoyl macrogol-32 glycerides.

10. The process according to claim 3, wherein the amine is pyridine or trialkylamine.

11. The process according to claim 3, wherein the stoichiometric ratio of pyridine to 1-adamantyl-carbonyl chloride is from 1 to 2 parts pyridine to 1 part 1-adamantylcarbonyl chloride.

12. The process according to claim 4, wherein the stoichiometric ratio of pyridine to 1-adamantyl-carbonyl chloride is from 1 to 2 parts pyridine to 1 part 1-adamantylcarbonyl chloride.

13. A method for treating a tumor disease in a patient affected by such disease comprising administering an effective anti-tumor amount of the compound of claim 6 in a pharmaceutically acceptable vehicle.

14. A method according to claim 14, wherein the vehicle is lipophilic.

15. The pharmaceutical composition of claim 7, in which composition the content of the platinum (IV) complex according to claim 1 is 0.5 to 50% by weight based on the total weight of the composition.

16. The pharmaceutical composition according to claim 7, wherein the additive is stearoyl macrogol-32 glycerides.

17. A method according to claim 16, wherein the effective amount of composition of claim 1 is 0.5 to 5.0% by weight of the total composition.

Description

EXAMPLE 1

Synthesis of Platinum (IV) Complexes According to the Formula (II) and (III)

a) Synthesis of Key Intermediates “c-t-c” PtCl.SUB.2.(OH).SUB.2.(NH.SUB.3., Alkyl- or Cykloalkylamine or Polycykloalkylamine)

[0034] The synthesis was carried out according to general procedure described in the U.S. Pat. No. 6,503,943, example 2a, column 4, line 45 and further.

b) Synthesis of “c-t-c” PtCl.SUB.2.(Alkylcarboxylato).SUB.2.(NH.SUB.3., Alkyl- or Cycloalkylamine or Polycycloalkylamine), i.e. the Platinum (IV) Complexes According to the Formula (II)

[0035] The synthesis was carried out according to the general procedure described in EP 0 328 274, examples 1 to 5, page 4.

c) Synthesis of TU-31, i.e. “c-t-c” PtCl.SUB.2.(1-Adamantylcarboxylato).SUB.2.(NH.SUB.3.,1-Adamantylamine)

[0036] The synthesis was carried in the absence of light 1.0 g of “c-t-c” PtCl.sub.2OH(NH.sub.3,1-adamantylamine) with purity 99% (2.1 mmol), 20 ml of 1,4-dioxane with purity >99%, 1.05 ml of pyridine with purity>99% (12.9 mmol) and 2.2 g of 1-adamantanecarbonyl chloride with purity >95% (10.5 mmol) were stirred 3 hours at room temperature. The resulting mixture was allowed to stand at room temperature for 8 hours. Precipitated TU-31 was separated by filtration, washed repeatedly by water and 1,4-dioxane and then it was dried in vacuum at 45° C. The yield of the TU-31 was 1.43 g (86% based on the theory) and the purity was 98.6% (by HPLC).

EXAMPLE 2

Preparation of a Pharmaceutical Composition of TU-31, i.e. “c-t-c” PtCl.SUB.2.(1-Adamantylcarboxylato).SUB.2 .(NH.SUB.3.,1-Adamantylamine) with Gelucire 50/13

[0037] 1.0 g of TU-31 and 4.0 g of Gelucire 50/13 were heated to 65° C. to create a yellow melt. This melt was poured into polypropylene mold and cooled 1 hour at −18° C. Solid composition was then mechanically grated into particles, each weighing approximately 5 mg and containing 20% by weight of the TU-31. The grated composition was filed into hydroxypropyl methyl cellulose capsules with a dosage 1.0 g of the composition containing 200 mg of the active substance per each capsule.

EXAMPLE 3

Determination of In Vitro Cytotoxicity IC.SUB.50 .of Prepared Platinum (IV) Complexes

Abbreviation of Used Compounds

[0038] DMSO: dimethyl sulfoxide
PBS: phosphate buffered saline
XTT: 2,3-bis-(2-methoxy-4-nitro-5-sulphophenyl)-2H-tetrazolium-5-carboxanilide salt
PMS: N-methyl-dibenopyrazinmethylsulfate
FBS: fetal bovine serum
NEAA: non-essential amino acids

L-glu: L-glutamine

DMEM: Dulbecco's Modified Eagle's Medium (SigmaAldrich)

[0039] PMS: phenazine methosulfate

Tested Compounds:

Platinum (IV) Complexes According to the Specification in the Tables

Used Tumor Cell Lines:

[0040] MCF-7 breast adenocarcinoma
CaCo-2 colon adenocarcinoma
HL60 promyelotic leukaemia
A2780/cis ovarian carcinoma cisplatin resistant
LNCaP prostate cancer
COR-L23 lung carcinoma
Cultivation's conditions: 37° C., 5% CO.sub.2
Growth medium: DMEM, 10% FBS, 2 mM L-glut., NEAA 100×

Working Procedure:

[0041] Tested compounds were dissolved in DMSO and diluted by PBS to tested concentration range just before addition to cell lines in wells. PBS was used as a positive control, DMSO in final concentration 20% was used as a negative control. All concentrations of compounds were assayed in triplicates. Each determination was carried out twice and was blinded for experimenter. Testing was conducted on a 96-well plate. Dosage of tumor cells was about 2.5×10.sup.4 cells per well, dosage of growth medium was 100 μl per well. After 24 hours, the growth medium was suck off and 80 μl of fresh growth medium and 20 μl of solution with different concentration of the tested substance were added to wells. After 72 hours, the medium was suck off and 100 μl of a solution of Optimem reagent containing XTT and PMS were added to wells. After another 4 hours, the absorbance was measured at 450 nm (reference was at 630 nm). Results as ICs, were evaluated from the graph of normalized viability of cells plotted against the logarithm of the concentration of the substance.

EXAMPLE 4

Study of a Dependence of IC of Platinum (IV) Complexes According to the Formula (II) on the Structure and Lipophility of the Equatorial Aminoligand A.SUB.2., Wherein the R.SUB.1 .Group is Methyl

[0042] Platinum (IV) complexes according to the formula (U) where R.sub.1 group is methyl and A.sub.2 group is different amino-compound were prepared according to the example 1. Tumor cell lines MCF-7 (breast adenocarcinoma) and CaCo-2 (colon adenocarcinoma) were used. IC.sub.50 were measured according to procedure in the example 3. Commercially available cisplatin and oxaliplatin were used as reference compounds. The results are shown in the Table 1.

TABLE-US-00001 TABLE 1 A study of dependence of IC.sub.50 of platinum (IV) complexes according to the formula (II) on the structure and lipophility of the equatorial aminoligand A.sub.2, R.sub.1 group is methyl IC.sub.50 (μmol) No. of Pt(IV) R.sub.1 group in axial The equatorial MCF-7 tumor CaCo-2 tumor complex ligands aminoligand A.sub.2 cell line cell line 1. CH.sub.3— NH.sub.3 137.0 56.1 2. CH.sub.3— [00004] 168.0 71.3 3. (Satraplatin) CH.sub.3— [00005] 27.2 12.7 4. (LA-12) CH.sub.3— [00006] 9.6 9.3 5. CH.sub.3— [00007] 18.3 109.4 6. CH.sub.3— [00008] 45.5 39.3 7. CH.sub.3— [00009] 317.8 478.5 8. CH.sub.3— [00010] 9.5 104.6 9. CH.sub.3— [00011] 45.6 14.0 10. — Reference-Cisplatin 53.4 70.5 Pt(II) complex 11. — Reference-Oxaliplatin 46.5 55.7 Pt(II) complex

[0043] It follows from the results in the Table 1: [0044] 1. There is no clear relationship between type and lipophility of the equatorial aminoligand A.sub.2 and IC.sub.50. [0045] 2. The best results has the platinum (IV) complex with 1-adamantylamine equatorial ligand which is in accordance with the prior art. [0046] 3. A change of 1-adamantyl skeleton to 3,5-dimethyl-1-adamantyl skeleton results in worsening of antitumor efficacy, probably due to worsening of the symmetry of 1-adamantyl group. A high symmetry of 1-adamantane skeleton like diamonds is probably important in this type of platinum (IV) complexes. [0047] 4. A change of 1-adamantyl skeleton to 2-adamantyl skeleton results also in worsening of antitumor efficacy, probably due to worsening of a space protection of central Pt(IV)-ion. [0048] 5. An increase of distance between 1-adamantane skeleton and central Pt(IV)-ion results in worsening of antitumor efficacy, probably due to worsening of a space protection of central Pt(IV)-ion.

EXAMPLE 5

Study of a Dependence of IC.SUB.50 .of Platinum (IV) Complexes According to the Formula (II) on the Structure and Lipophility of the Group R.SUB.1., Equatorial Aminoligand A.SUB.2 .is 1-Adamantylamine

[0049] Platinum (IV) complexes according to the formula (II) where A.sub.2 is 1-adamantylamine and the R.sub.1 group is different alkyl or 1-adamantyl were prepared according to the example 1. Tumor cell lines MCF-7 (breast adenocarcinoma) and CaCo-2 (colon adenocarcinoma) were used. IC.sub.50 was measured according to procedure in the example 3. The results are shown in the Table 2.

TABLE-US-00002 TABLE 2 A study of dependence of IC.sub.50 of platinum (IV) complexes according to the formula (II) on the structure and lipophility of the axial group R.sub.1, the equatorial aminoligand A.sub.2 is 1-adamantylamine No. of Pt(IV) IC.sub.50 (μmol) complex Ligand A.sub.2 Group R.sub.1 MCF-7 CaCo-2 1. [00012] CH.sub.3— 9.6 9.3 2. [00013] (CH.sub.3).sub.3C— 5.4 4.5 3. [00014] CH.sub.3(CH.sub.2).sub.6— 10.0 10.2 4. [00015] CH.sub.3(CH.sub.2).sub.10— 39.2 67.1 5. [00016] [00017] 4.1 1.9

[0050] It follows from the results in the Table 2: [0051] 1. There is no clear relationship between number of carbon atoms in the aliphatic chain of R.sub.1 group. The LA-12 with methyl group as R.sub.1 had a good results but platinum complex with tert-butyl group as R.sub.1 appears the best among all tested aliphatic chains which is in accordance with the prior are (see EP0328274, the claim 1-3). [0052] 2. 1-Adamantyl group surprisingly exceeds all tested groups R.sub.1 including tert-butyl group.

EXAMPLE 6

Comparison of IC.SUB.50 .of the TU-31, i.e. the Platinum (IV) Complex of the Formula (III), with Referent Platinum (II) Complex Oxaliplatin and the Temporary Best Platinum (IV) Complex LA-12 on the Broader Tumor Cell Line Panel

Tested Tumor Cell Line Panel:

[0053] MCF-7 breast adenocarcinoma
CaCo-2 colon adenocarcinoma
HL60 promyelotic leukaemia
A2780/cis ovarian carcinoma cisplatin resistant
LNCaP prostate cancer
COR-L23 lung carcinoma

TABLE-US-00003 TABLE 3 A comparison of IC.sub.50 of TU-31, that means the platinum (IV) complex of formula (III), with referent platinum (II) complex oxaliplatin and the temporary best platinum (IV) complex LA-12 on the broader tumor cell line panel. Type of IC.sub.50 (μmol) platinum A2780/ complex MCF-7 CaCo-2 HL-60 cis LNCaP COR-L23 Oxaliplatin 46.5 55.7 0.4 >132 0.5 >141 Pt(II)com- plex LA-12 9.6 9.3 0.2 8.6 1.8 6.1 Pt(IV)com- plex TU-31 4.1 1.9 0.1 1.5 4.8 8.0 Pt(IV)com- plex

[0054] It follows from the results in the Table 3: [0055] 1. The TU-31, i.e. the platinum (IV) complex according to invention, exceeds the best platinum (II) complex oxaliplatin and temporary the best platinum (IV) complex LA-12 in four of the six tested cancer cell lines. [0056] 2. Oxaliplatin had better result in the tumor cell line LNCaP where antitumor efficacy is decreased with increased lipophility of the platinum complex.