FIELD OF THIS INVENTION

The present invention relates to the use of the isolated l-enantiomer of centchro¬ man (3,4-trans-2,2-dimethyl-3-phenyl-4-[4-(2-(pyrrolidin-1 -yl)ethoxy)phenyl]-7- methoxychroman) or pharmaceutically acceptable salts thereof for the treatment of patients suffering from breast cancer and prophylaxis hereof. The present in- vention also embraces pharmaceutical compositions comprising the l-enantiomer of centchroman or pharmaceutically acceptable salts thereof and methods of using above mentioned compounds and their pharmaceutical compositions.

BACKGROUND OF THIS INVENTION

Breast cancer is the most common malignant tumor and the leading cause of cancer death in women. It causes approximately 20% of the cancer deaths among women. However, in spite of many years of intensive research and new types of treatment the age-adjusted death rate from breast cancer in the western world has virtually remained stable over the past 30 years. The term " breast cancer" implies a carcinoma arising in the ductal and glandular structures of the breast. Breast cancer is rare in women who have been castrated; oophorectomy before 35 years of age reduces the risk to one third. Women who have their first child before the age of 1 8 years have only one third the risk compared with those whose first child is delayed until age 30. Growth of breast cancer is associated with the presence of estrogen. A course of treatment of breast cancer is, therefore, ablation of the estrogen source by ovariectomy or hysterectomy. An alternative to this surgical approach is endocrine therapy whereby an estrogen antagonist is used to deplete estrogen concentration at the target site.

Centchroman is a non-steroidal compound known to have antiestrogenic activity. It is in use in India as an oral contraceptive (see, for example, Salman et al., U.S. Patent Specification No. 4,447,622; Singh et al., Acta Endocrinol. (Copenh) 1__ ( 1 9921, 444 - 450; Grubb, 2 (1 991 ), 491 - 495; Sankaran et al., Contraception 9 ( 1 974), 279 - 289; Indian Patent Specification No. 1 291 87). Centchroman has also been investigated as an anti-cancer agent for treatment of advanced breast cancer (Misra et al., ]ni. J. Cancer 43 (1 989), 781 - 783). Recently, centchroman as a racemate has been found as a potent cholesterol lowering pharmaceutical expressed by a significant decrease of the serum concentrations (S.D. Bain et al., J.Min.Bon.Res. 9. (1 994), 394). However, it has never been disclosed that the isolated l-enantiomer of centchroman is use¬ ful for treatment of breast cancer.

There remains today a need in the art for compositions and methods that are useful and safe in the treatment or prophylaxis of breast cancer.

One object of the present invention is to provide compounds which can effecti¬ vely be used in the treatment or prophylaxis of breast cancer.

DETAILED DESCRIPTION OF THIS INVENTION

The present invention relates to the use of the isolated l-enantiomer of centchro- man (3,4-trans-2,2-dimethyl-3-phenyl-4-[4-(2-(pyrrolidin-1 -yl)ethoxy)phenyl]-7- methoxychroman) or pharmaceutically acceptable salts thereof for the manufac¬ ture of a pharmaceutical composition for the treatment or prophylaxis of breast cancer.

3,4-diarylchromans are prepared according to known methods, such as those disclosed in U .S. Patent Specification No. 3,340,276 to Carney et al., U.S. Patent Specification No. 3,822,287 to Bolger, and Ray et al., J. ed.Chem. 1_\

( 1 976), 276 - 279, the contents of which are incorporated herein by reference. Conversion of the cis isomer to the trans configuration by means of an organo- metallic base-catalyzed rearrangement is disclosed in U.S. Patent Specification No. 3,822,287. The optically active d- and l-enantiomers may be prepared as disclosed by Salman et al. in U.S. Patent Specification No. 4,447,622

(incorporated herein by reference) by forming an optically active acid salt which is subjected to alkaline hydrolysis to produce the desired enantiomer.

Within the present invention the l-enantiomer of centchroman may be prepared in the form of pharmaceutically acceptable salts, especially acid-addition salts, in¬ cluding salts of organic acids and mineral acids. Examples of such salts include salts of organic acids such as formic acid, fumaric acid, acetic acid, propionic acid, glycolic acid, lactic acid, pyruvic acid, oxalic acid, succinic acid, malic acid, tartaric acid, citric acid, benzoic acid, salicylic acid and the like. Suitable inorga- nic acid-addition salts include salts of hydrochloric, hydrobromic, sulphuric and phosphoric acids and the like. The acid addition salts may be obtained as the direct products of compound synthesis. In the alternative, the free base may be dissolved in a suitable solvent containing the appropriate acid, and the salt isolated by evaporating the solvent or otherwise separating the salt and solvent.

The l-enantiomer of centchroman and its salts are useful within human and vete¬ rinary medicine, for example, in the treatment of patients suffering from breast cancer. For use within the present invention, the l-enantiomer of centchroman or its pharmaceutically acceptable salts are formulated with a pharmaceutically acceptable carrier to provide a medicament for parenteral, oral, nasal, rectal, subdermal or intradermal or transdermal administration according to conventional methods. Formulations may further include one or more diluents, fillers, emulsi¬ fiers, preservatives, buffers, excipients, etc. and may be provided in such forms as liquids, powders, emulsions, suppositories, liposomes, transdermal patches, controlled release, dermal implants, tablets, etc. One skilled in this art may for¬ mulate the l-enantiomer of centchroman or a pharmaceutically acceptable salt thereof in an appropriate manner, and in accordance with accepted practices,

such as those disclosed in Remington's Pharmaceutical Sciences. Gennaro, ed., Mack Publishing Co., Easton, PA, 1 990

Oral administration is preferred. Thus, the active l-enantiomer of centchroman or a pharmaceutically acceptable salt thereof is prepared in a form suitable for oral administration, such as a tablet or capsule. Typically, a pharmaceutically acceptable salt of the l-enantiomer of centchroman is combined with a carrier and moulded into a tablet. Suitable carriers in this regard include starch, sugars, dicalcium phosphate, calcium stearate, magnesium stearate and the like. Such compositions may further include one or more auxiliary substances, such as wetting agents, emulsifiers, preservatives, stabilizers, colouring additives, etc.

Pharmaceutical compositions containing a compound of the l-enantiomer of centchroman or a pharmaceutically acceptable salt thereof is administered one or more times per day or week. An effective amount of such a pharmaceutical composition is the amount that provides a clinically significant effect against breast cancer. Such amounts will depend, in part, on the particular condition to be treated, age, weight, and general health of the patient, and other factors evi¬ dent to those skilled in the art. A typical daily dose will contain a non-toxic dosage range of from about 0 001 to about 75 mg/kg patient per day of a compound of the present invention

The pharmaceutical compositions containing the l-enantiomer of centchroman or a pharmaceutically acceptable salt thereof may be administered in unit dosage form one or more times per day or week. In the alternative, they may be pro¬ vided as controlled release formulations suitable for dermal implantation. Im¬ plants are formulated to provide release of active compound over the desired period of time, which can be up to several years. Controlled-release formulations are disclosed by, for example, Sanders et al., J.Pharm.Sci. 23. ( 1 964), 1 294 - 1 297, 1 984; U.S. Patent Specification No 4,489,056; and U.S. Patent Specifi¬ cation No. 4,21 0,644, which are incorporated herein by reference.

The present invention is further illustrated by the following examples which, however, are not to be construed as limiting the scope of protection.

The features disclosed in the foregoing description and in the following examples may, both separately and in any combination thereof, be material for realising the invention in diverse forms thereof.

EXAMPLES

Test

Between 1 5 and 45 nude (thymus deficient) mice are ovariectomized under phe- nobarbital anaesthesia. After one week recovery an estrogen sensitive human tumor cell line (MCF7, mammary cancer fibroblast 7) is serially transplanted to each of these animals. Subsequently the mice are treated with either placebo (negative control), 1 7-beta-estradiol (positive control), or the test compound. Oestrogen stimulated tumor growth is assessed by measurement of tumor size twice weekly for a dosing period of approximately 8 weeks.