GB2144744A

GB2144744A - 4'-halo-anthracycline glycosides

Info

Publication number: GB2144744A
Application number: GB08420237A
Authority: GB
Inventors: Antonino Suarato; Sergio Penco; Fernando Giuliani; Federico Arcamone
Original assignee: Farmitalia Carlo Erba SRL
Current assignee: Pfizer Italia SRL
Priority date: 1983-08-11
Filing date: 1984-08-09
Publication date: 1985-03-13
Also published as: FI843110A; NL8402477A; SE8404005L; BE900336A; IT1209576B; FI843110A0; AT384226B; FI78109C; ATA253884A; HUT35691A; AU563396B2; SE8404005D0; FI78109B; DE3428945A1; AU3168584A; GB2144744B; DK381884D0; ZA846147B; CA1250833A; GB8321676D0

Abstract

<IMAGE> Compounds of the above formula (X=H or OH, R1=H, OH or OCH3, R2=Br, Cl or F) and their acid addition salts are useful as antitumour agents. Those in which X=H may be prepared by an exchange reaction between a 4'-epi-4'-O-trifluoromethanesulphonyl-N-protected-daunorubicin (or a corresponding 4-demethyl or 4-demethoxy derivative) and (C4H9)4NCl, (C4H9)4NBr or CsF. Those in which X=OH are prepared from those in which X=H by bromination and reaction with aqueous sodium formate.

Description

SPECIFICATION 4'-Halo-anthracycline glycosides The invention relates to 4'-halo-anthracycline glycosides, to a process for their preparation and to pharmaceutical compositions containing them.

The invention provides anthracycline glycosides having the general formula A

wherein X represents a hydrogen atom or a hydroxy group, R1 represents a hydrogen atom or a hydroxy or a methoxy group and R2 represents a bromine, chlorine or fluorine atom. Pharmaceutically acceptable acid addition salts of these anthracycline glycosides are also included in the invention.

The compounds of the invention in which X represents a hydrogen atom may be prepared by an exchange reaction between a compound of the general formula 2 wherein R1 is as above defined and R3 represents an amino protecting group and a fluoride, chloride or bromide, followed by deprotection of the resultant compound of the general formula 3. This process is illustrated by the Reaction Scheme below. The compounds of the invention in which X represents a hydroxy group may be prepared from the corresponding compounds according to the invention in which X represents a hydrogen atom by bromination followed by treatment of the resultant 1 4-bromo derivative with aqueous sodium formate, according to the procedure described in United States Patent Specification No. 3803124. These processes are within the scope of the invention.

When R2 represents a bromine or chlorine atom, the exchange reaction is preferably between the compound 2 and tetra (n-butyl) ammonium bromide or chloride respectively, and the amine protecting group R3 is preferably a trifluoroacetyl group. The deprotection reaction may then be a mild alkaline hydrolysis, for example with 0.1 N aqueous sodium hydroxide solution. When R2 represents a fluorine atom, the exchange reaction is preferably between the compound 2 and caesium fluoride, and the amine protecting group R3 is preferably a trichloroethoxycarbonyl group. The deprotection reaction may then be a hydrogenation, for example with zinc dust and acetic acid. The exchange reaction may be carried out in an organic solvent such as methylene chloride or acetonitrile.

The starting materials 2 are either known compounds, for example 4'-epi-4'-O-trifluoromethanesulphonyl N-trifluoroacetyl-daunorubicin (2: R1=OCH3, R3=COCF3 : see European Patent Application No. 8117618.1), are readily prepared from known 4'-epi-daunorubicin derivatives by reaction with trifluoromethanesulphonic anhydride.

The compounds according to the invention and their pharmaceutically acceptable acid addition salts are useful as antitumour agents. They may be used in the same way as the parent compounds, daunorubicin and doxorubicin, to treat various murine experimental tumours such as L1210, P388 and P388/04.

Preliminary screening tests suggest that the compounds according to the invention are in some cases more active than the parent compounds. Accordingly the invention further provides a pharmaceutical composition comprising an anthracycline glycoside according to the invention or a pharmaceutically acceptable acid addition salt thereof in admixture with a pharmaceutically acceptable diluent or carrier.

Biological activity tests The compounds of Examples 1,2 and 3 below were tested in vitro in comparison with daunorubicin (DNR) and doxorubicin (DX) against HeLa cells, P388 cells sensitive to DX and P388 cells resistant to DX (P388/DX).

Results are reported in Table 1. All the new derivatives appear to be more cytotoxic than their parent compound against HeLa and P388 cells sensitive to DX. This increased cytotoxicity is, however, much more pronounced if we consider the activity of these compounds against P388/DX. Here a 100 to 250 fold increase in cytotoxicity, in respect to the parent drug, can be noticed with these derivatives. In vivo the compounds have been tested against three different experimental leukemias. The antitumour activity obtained against ascitic P388 leukemia is reported in Table 2. The activity shown by the compound of Example 3 is roughly equal to that of DNR, while the other DNR derivative, the compound of Example 1, has an antitumour activity definitely superior to that of DNR.

The compound of Example 2 at the maximal tolerated dose (4.15 mg/kg) has about the same activity as DX.

All the new compounds show activity against P388/DX leukemia, as reported in Table 3, while DNR and DX have no efficacy. The three new compounds have been also tested after i.v. administration against disseminated Gross leukemia, and the results are reported in Table 4. In this system the compound of Example 3 is as active as DNR, while the compound of Example 1 appears more active than the parent compound. The compound of Example 2 shows about the same efficacy as DX. Two of these compounds have also been tested after oral administration showing an interesting activity, whereas DNR and DX are not active when given orally.

TABLE 1 C yto toxic activity Compound ID50(ngiml) HeLa+ P388++ P3881DX++ DNR 12.3 2.8 980 Example 1 6.8 0.5 4 Example 3 5.8 2.4 8.8 DX 12.5 4.25 1250 Example 2 3 0.2 7 + colony inhibition test after 24 hours exposure to the drugs ++ cytotoxicity evaluated after 48 hours exposure to the drugs Data from several experiments.

TABLE 2 Effect against P388 ascitic leukemiaa Compound doseb TICa LTSd toxice (mglkg) % deaths DNR 2.9 165,155 0/20 0/20 4.4 170,135 0/18 0/18 6.6 130,115 0/20 12/20 Example 1 2.9 145 0/10 0/10 4.4 160 0/10 0/10 66 195 0/10 0/10 10 280 3/10 0/10 Example 3 2.9 130 0/10 0/10 4.4 155 0/10 0/10 6.6 145 0/10 0/10 10 85 0/8 6/8 DX 4.4 215 0/10 0/10 6.6 235 0/10 0/10 10 335 4/10 0/10 Example 2 2.4 200 0/10 0/10 2.88 230 0/10 0/10 3.46 210 0/10 0/10 4.15 325 4/10 1/10 Experiments were performed in CDF1 mice, inoculated with 106 leukemia cells ip.

Treatment ip on day 1 after tumour inoculum.

Median survival time of treated mice/median survival time of controls x 100.

d Long term survivors ( > 60 days).

e Evaluated on the basis of autoptic findings.

TABLE 3 Effect against P388/DX ascitic leukemiaa Compound doseb TIC toxic (mg/kg) % deaths DNR 4.4 91 0/10 6.6 87 0/10 Example 1 4.4 143 0/10 10 143 0/10 Example 3 6.6 148 0/10 10 122 3/10 DX 6.6 108 1/20 10 117 1/20 Example 2 2.88 122 0/20 3.46 125 0/20 4.15 137 1/20 a Experiments were performed in BDF1 mice inoculated with 106 cells ip.

treatment ip on day 1 after tumour inoculum.

Median survival time of treated mice/median survival time of controls x 100.

d-Evaluated on the basis of autoptic findings.

TABLE 4 Effect against Gross leukemiaa Compound route doseb TIC: toxicd ofadmi- Imglkgl /0 deaths nistr.

DNR iv 10 142,138 2/18 15 183,185 1/18 22.5 217,92 9/18 Example 1 iv 10 217 0/10 15 150 6/9 22.5 100 9/9 Example 3 iv 6.6 185 0/10 10 115 7/10 15 77 10/10 oral 6.6 154 0/10 10 169 0/10 15 92 7/8 DX iv 10 183 0/10 13 225 0/10 16.9 242 0/10 Example 2 iv 4.05 233 0/10 5.27 258 0/10 6.85 242 3/10 oral 4.05 114 0/10 5.27 157 0/10 a Experiments were performed in C3H mice, inoculated with 2 x 106 leukemia cells iv.

b Treatment iv or orally on day 1 after tumour inoculum.

c Median survival time of treated mice/median survival time of controls 100.

d Evaluated on the basis of autoptic findings.

The invention is illustrated by the following Examples.

Example 1 4'-Deoxy-4'-bromodaunorubicin (A: X=H, R1=OCH3, R2=Br) 2 g of tetra (n-butyl) ammonium bromide was added to a solution of 4.0 g of 4'-epi-4'-O-trifluoromethane-sulphonyl-N-trifluoroacetyidaunorubicin (2: R1=OCH3, R3=COCF3) in 80 ml of anhydrous methylene dichloride. After 1 hour at room temperature the reaction mixture was washed with water and the organic phase evaporated in vacuo. The residue was purified on silica gel, using the mixture methylene dichloride:acetone as eluent, to give 3.5 g of 4'-deoxy-4'-bromo-N-trifluoro-acetyidaunorubicin, m.p. 1300C; FD,MS 685 (M+), TLC on Kieselgel plates (Merck F 254) using the solvent system methylene dichloride:acetone (10:1 by volume) Rf 0.5.To a solution of 3 g of 4'-deoxy-4'-bromo-N-trif luoro-acetyldau norubicin in 20 ml of acetone, 160 ml of 0.1 N aqueous sodium hydroxide solution was added. After 4 hours at 0 C, the solution was adjusted to pH 8.6 with 0.1 N hydrochloric acid and extracted with methylene dichloride. The solvent was evaporated off, affording a residue that was converted by treatment with methanolic hydrogen chloride into the hydrochloride (2.2 g, m.p. 180"C with decomposition, TLC on Kieselgel plates (Merck F 254) using the solvent system methylene dichloride:methanol :water:acetic acid (80:20:7:3 by volume) Rf 0.32.

Example 2 4'-Deoxy-4'-bromodoxorubicin (A: X=OH, R1=OCH3, R2=Br) 2 g of 4'-deoxy-4'-bromodaunorubicin, prepared as described in Example 1, was dissolved in a mixture of methanol and dioxan. The solution was treated, as described in United States Patent Specification No. 3803124, first with bromine to give the 14-bromo-derivative and then with aqueous sodium formate to give 4'-deoxy-4'-bromo-doxorubicin. This was converted into its hydrochloride by treatment with methanolic hydrogen chloride. m.p. 1700C (with decomposition), FD-MS 605 (M+), TLC on Kieselgel plates (Merck F 254) using the solvent system methylene dichloride:methanol:water:acetic acid (80:20:7:3 by volume) Rf 0.20.

Example 3 4'-Deoxy-4'-chlorodaunborubicin (A: X=H, R1 OCH3, R2=C1) The treatment of 4'-epi-4'-Otrifluoromethanesulphonyl-N-trifluoroacetyldaunorubicin (2, R1=OCH3, R3=COCF3) with tetra (n-butyl) ammonium chloride, following the procedure described in Example 1, afforded 4'-deoxy-4'- chlorodaunorubicin, m.p. 175"C with decomposition, FD-MS 545 (M+), TLC on Kieselgel plates (Merck F 254) using the solvent system methylene dichloride:methanol :water:acetic acid (80:20:7:3) by volume) Rf 0.32.

Example 4 4'-Deoxy-4'-chlorodoxorubicin (A: X=OH, R1=OCH3, R2=CI) Following the procedure described in Example 2, 4'-deoxy-4'-chlorodaunorubicin was converted into 4'-deoxy-4'-chlorndoxorubicin, isolated as its hydrochloride, m.p. 1800C (with decomposition), FC-MS: 561 (M+), TLC on Kieselgel plates (Merck F 254) using the solvent system methylene dichloride:methanol :water:acetic acid (80:20:7:3 by volume) Rf 0.2.

Example 5 4'-Deoxy-4'-fluorodaunorubicin (A: X=H, R1=OCH3, R2=F) To a stirred solution of 26 g of 4'-epi-N-trichloroethoxycarbonyldaunorubicin, described in United States Patent Specification No. 4345068, in 650 ml of anhydrous methylene chloride and 32 ml of anhydrous pyridine, cooled at OOC, was added a solution of 11 ml of trifluoromethanesulphonic snhydride in 140 ml of anhydrous methylene dichloride. The reaction mixture was washed with a cooled 5% aqueous solution of sodium bicarbonate, water, a 0.1 N hydrochloric acid and water in that order. The organic solution, dried over anhydrous sodium sulphate, was used in the following step without further purification.A solution of 2 g of 4'-epi-4'-O-trifluoromethane-sulphonyl-N trichloroethoxycarbonyldaunorubicin in 30 ml of acetonitrile was treated with 0.5 g of caesium fluoride. After 10 minutes at room temperature the mixture was poured into water and extracted with methylene dichloride. The organic phase, dried over anhydrous sodium sulphate, was evaporated to dryness under vacuum. The residue, dissolved in 30 ml of ethanol, was treated with 4 ml of acetic acid and 0.2 g of zinc dust at 0 C. After 1 hour, the mixture, filtered on celite, was diluted with water and extracted with methylene dichloride. The crude product, obtained by evaporating off the solvent under vacuum, was purified by chromatography on a column of silica gel, using methylene chloride as eluent, to give pure 4'-deoxy-4'-fluorodaunorubicin, isolated as its hydrochloride: FD-MS 529 (M+), TLC on Kieselgel plates (Merck F 254) using the solvent system methylene chloride: methanol :water:acetic acid (80:20:7:3 by volume) Rf 0.32.

Example 6 4'-Deoxy-4'-fluorodoxorubicin (A: X=OH, R1=OCH3; R2=F) Following the procedure described in Example 2, 4'-deoxy-4'-fluorodaunorubicin was converted into 4'-deoxy-4'4luorodoxorubicin, isolated as its hydrochloride.

Claims

1. An anthracylcine glycoside having the general formula A as defined herein, or a pharmaceutically acceptable acid addition salt thereof.

2. 4'-Deoxy-4'-bromodaunorubicin.

3. 4'-Deoxy-4'-chlorodaunorubicin.

4. 4'-Deoxy-4'-fluorodaunorubicin.

5. 4'-Deoxy-4'-bromodoxorubicin.

6. 4'-Deoxy-4'-chlorodoxorubicin.

7. 4'-Deoxy-4'4luorodoxoru bicin.

8. A process for the preparation of an anthracycline glycoside having the general formula A wherein R1 and R2 are as defined herein and X represents a hydrogen atom, the process comprising performing an exchange reaction between a compound having the general formula 2 as herein defined and a fluoride, bromide or iodide, and deprotecting the resultant compound having the general formula 3 as herein defined.

9. A process according to claim 8 in which the fluoride is caesium fluoride.

10. A process according to claim 8 in which the bromide is tetra (n-butyl) ammonium bromide.

11. A process according to claim 8 in which the chloride is tetra (n-butyl) ammonium chloride.

12. A process according to any of claims 8 to 11 in which the amine protecting group is a trichloroethoxy-carbonyl group.

13. A process according to claim 12 in which the deprotection reaction is a hydrogenation reaction.

14. A process according to claim 12 or claim 13 in which the deprotection is effected with zinc dust and acetic acid.

15. A process according to any of claims 8 to 11 in which the amine protecting group is a trifluoroacetyl group.

16. A process according to claim 15 in which the deprotection reaction is a mild alkaline hydrolysis.

17. A process according to claim 15 or claim 16 in which the deprotection is effected with 0.1 N aqueous sodium hydroxide solution.

18. A process according to any preceding claim in which the exchange reaction is carried out in methylene dichloride or acetonitrile.

19. A process for the preparation of an anthrancycline glycoside having the general formula A wherein R1 and R2 are as defined herein and X represents a hydroxy group, the process comprising reacting an anthracycline glycoside having the general formula A wherein R1 and R2 are as defined herein and X represents a hydrogen atom with bromine and treating the resultant 14-bromo derivative with an aqueous solution of sodium formate.

20. A process according to claim 8, the process being substantially as described herein with reference to any of Examples 1,3 and 5.

21. A process according to claim 19, the process being substantially as described herein with reference to any of Examples 2,4 and 6.

22. A pharmaceutical composition comprising an anthracycline glycoside according to any of claims 1 to 7 our a pharmaceutically acceptable acid addition saltthereof in admixture with a pharmaceutically acceptable diluent or carrier.