WO2005063276A1

WO2005063276A1 - Methods and compositions using gonadotropin hormone releasing hormone

Info

Publication number: WO2005063276A1
Application number: PCT/IB2004/004276
Authority: WO
Inventors: Hervé PORCHET; Eija Lundstrom; Catherine Curdy; Marie-Anne Bardet
Original assignee: Debiopharm S.A.
Priority date: 2003-12-23
Filing date: 2004-12-23
Publication date: 2005-07-14

Abstract

The present invention relates to compositions comprising two sustained release formulations, the first being capable of releasing a gonadotropin releasing hormone composition and the second an estrogenic composition. The compositions of the invention can be employed for an improved androgen deprivation therapy of prostate cancer, in which therapy loss of bone mineral density and the occurrence and severity of hot flushes are minimized through the maintenance of a minimally adequate estrogen level.

Description

ETHODS AND COMPOSITIONS USING GONADOTROPIN HORMONE RELEASING HORMONE

Gonadotropin hormone releasing hormone (GnRH) agonist and antagonist analogs have been used to treat benign gynaecological disorders including premenstrual syndrome and androgen-dependent cancer of the prostate. GnRH is also known as luteinizing hormone releasing hormone. GnRH is secreted by the hypothalamus in the pituitary portal system in a pulsating fashion. Because the hormone has a half-life of the order of minutes, the pituitary gland is exposed to pulses of hormone. This exposure results in the secretion of the gonadotropins, i.e., luteinizing hormone (LH) and follicle-stimulating hormone (FSH). In men LH acts on the Leydig cells of the testes, stimulating the secretion of testosterone. FSH is responsible for spermatogenesis. Testosterone appears to feedback-inhibit secretion of GnRH and reduce the sensitivity of the pituitary to the hormone. In women FSH acts on the ovaries, stimulating secretion of estrogen. The main functions of LH in women are to support follicular maturation and to trigger ovulation at mid-follicular cycle. Like testosterone, estrogen appears to be capable of feedback inhibition of GnRH secretion and action.

Administration of potent agonists of GnRH was found to cause an initial flare-up of LH and FSH release that is followed by a complete down-regulation of GnRH receptor in the pituitary. As a consequence, LH and FSH are no longer released, and sex hormones are reduced to oophorectomized levels in women and orchiectomized or castrate levels in men, respectively. The development of high-dose depot formulations of GnRH agonists permitted sustained inhibition of sex steroid production and ease of drug administration. Typically, prostate cancer is initially androgen-dependent and only in late stages becomes androgen-independent. Various methods of androgen ablation therapy were practiced, either as the only therapy or in conjunction with other treatment modalities such as surgery, external beam radiation therapy, brachytherapy, etc. A regime of high doses of the semi-synthetic estrogenic compound diethylstilbesterol, orally administrated, was one of the earliest non- surgical options for the treatment of prostate cancer. This therapy was equally as effective in mediating remission as orchiectomy. Unfortunately, effective concentrations of the oral estrogenic compound caused cardiovascular complications, including oedema and deep vein thrombosis. Diethylstilbesterol therapy was discontinued when GnRH agonist and antagonist analogs became available that essentially lacked cardiovascular toxicity.

While GnRH agonists are clinically equally as effective in inducing prostate cancer remission as orchiectomy, the gold standard of treatment efficacy, their use is accompanied by important other toxicities, including fatigue, weight gain, depression, bone loss, anaemia, muscle atrophy, gynecomastia, hot flushes, loss of cognitive function, and decrease in high-density lipoprotein. Hellerstedt and Pienta. CA Cancer J Clin 2002; 52: 154-179. Perhaps, the complications that most severely affect quality of life are loss of bone mineral density and hot flushes.

Because testosterone is the main circulating sex hormone in men it was long assumed that the increased bone turnover and loss of bone mineral density in castrated men or in prostate cancer patients treated with GnRH agonist or antagonist analogs was due to the absence of this hormone. However, recent observational studies suggested, surprisingly, that bone mineral density in men correlated better with estrogen levels than with testosterone levels. Khosla et al. J Clin Endocrinol Metab 2002 ; 87 : 1443-1450. An interventional study showed that estrogen supplementation prevented the GnRH-induced reduction in bone formation markers as well as the increase in bone resorption markers in elderly men treated with a GnRH agonist. Falahiti-Nini et al. J Clin Invest 2000; 106 : 1553-1560. Finally, another study showed that specific inhibition of aromatase activity also resulted in a significant increase in bone resorption markers and a decrease in bone formation markers. Taxel et al. J Clin Endocrinol Metab 2001 ; 86 : 2869-2874.

The invention relates to compositions comprising a first sustained release formulation of a gonadotropin hormone releasing hormone (abbreviated GnRH herein) composition capable of releasing the GnRH composition during a period of at least about one month at a rate sufficient to induce and maintain chemical castration of a male patient, and a second sustained release formulation of an estrogenic composition capable of maintaining for said period a serum level sufficient to reduce the enhanced loss of bone mineral density and/or the hot flushes that are normally caused by the administration of a GnRH composition that chemically castrates a male patient.

Preferably, the first sustained release formulation of a composition of the invention releases a GnRH composition at a rate of between about 10 and about 1 ,000 μg per day.

Preferably, the second sustained release formulation of the invention releases an estrogenic composition at a rate between about 5 and 100 μg of estradiol equivalent per day, preferably at a rate not exceeding about 50 μg of estradiol equivalent per day.

In a different embodiment of the invention the composition is not limited by reference to chemical castration of a male patient. It is defined as comprising a first sustained release formulation of a GnRH composition capable of releasing the GnRH composition for a period of at least about one month at an average rate between about 10 and 1 ,000 μg per day and a second sustained release formulation of an estrogenic composition capable of releasing during said period the estrogenic composition at a rate between about 5 and 100 μg of estradiol equivalent per day, preferably at a rate not exceeding about 50 μg of estradiol equivalent per day.

In the compositions of the invention, the GnRH composition of the first sustained release formulation is selected from the group consisting of GnRH, agonists of GnRH, antagonists of GnRH and mixtures thereof. Preferably, the GnRH composition is a GnRH agonist selected from the group consisting of leuprorelin, goserelin, triptorelin, buserelin, nafarelin, deslorelin, histerelin, gonadorelin, and salts and/or mixtures thereof. The estrogenic composition present in the second sustained release formulation is a polyester of a phosphorous acid and an estrogenic compound containing at least two hydroxyl groups. Said polyester contains at least two recurrent moieties. Preferably, said polyester contains between 3 to 80 recurrent moieties, preferably between 3 and 15 recurrent moieties. Preferably, said phosphorous acid is selected from a phosphoric acid, i.e. orthophosphoric acid and metaphosphoric acid, thiophosphoric acid, phosphonic acid, and said hydroxyl group-containing estrogenic compound is selected from the group consisting of dienestrol, diethylstilbestrol, estetrol, estradiol, estradiol, (3α,17β)-estr-4-ene-3, 17-diol, estriol, ethinylestradiol, hexestrol, and raloxifene.

In preferred compositions, the GnRH composition of the first sustained release formulation is triptorelin or a salt thereof, and the estrogenic composition of the second sustained release formulation is a polyester of a phosphoric acid and estradiol.

In most preferred compositions the GnRH composition of the first sustained release formulation is triptorelin, or a salt thereof, that is released at a rate of about 100 μg per day, and the estrogenic composition of the second sustained release formulation is a polyester of a phosphoric acid and estradiol, said second sustained release formulation releasing estradiol at a rate between about 5 and 100 μg per day, preferably at a rate not exceeding about 50 μg per day.

The invention further relates to a method for the treatment of prostate cancer, involving administration to a prostate cancer patient of a composition comprising a first sustained release formulation of a GnRH composition capable of releasing the GnRH composition during a period of at least about one month at a rate sufficient to induce and maintain chemical castration of a male patient, and a second sustained release formulation of an estrogenic composition capable of maintaining for said period a serum level sufficient to reduce the enhanced loss of bone mineral density and/or the hot flushes that are normally caused by the administration of a GnRH composition that chemically castrates a male patient. The invention relates also to the use of a composition comprising a first sustained release formulation of a GnRH composition, and a second sustained release formulation of an estrogenic composition for the preparation of a medicament capable of maintaining for said period a serum level sufficient to reduce the enhanced loss of bone mineral density and/or the hot flushes that are normally caused by the administration of a GnRH composition that chemically castrates a male patient capable to induce and maintain chemical castration of a male patient and to reduce the enhanced loss of bone mineral density and/or the hot flushes that are normally caused by the administration of a GnRH composition that chemically castrates a male patient, said first sustained release formulation of a GnRH composition being capable of releasing the GnRH composition during a period of at least about one month at a rate sufficient to induce and maintain chemical castration of a male patient, and a second sustained release formulation of an estrogenic composition being capable of maintaining for said period a serum level sufficient to reduce the enhanced loss of bone mineral density and/or the hot flushes that are normally caused by the administration of a GnRH composition that chemically castrates a male patient.

Preferably, the first sustained release formulation of a composition administered to a prostate cancer patient releases a GnRH composition at a rate of between about 10 and about 1 ,000 μg per day, and the second sustained release formulation releases an estrogenic composition at a rate between about 5 and 100 μg of estradiol equivalent per day, preferably at a rate not exceeding about 50 μg of estradiol equivalent per day.

In the compositions administered according to the method of the invention, the GnRH composition of the first sustained release formulation is selected from the group consisting of GnRH, agonists of GnRH, antagonists of GnRH and mixtures thereof. Preferably, the GnRH composition is a GnRH agonist selected from the group consisting of leuprorelin, goserelin, triptorelin, buserelin, nafarelin, deslorelin, histerelin, gonadorelin, and salts and/or mixtures thereof. The estrogenic composition present in the second sustained release formulation is selected from a group consisting of a polyester of a phosphorous acid and an estrogenic compound containing at least two hydroxyl groups. Said polyester contains at least two recurrent moieties. Preferably, said polyester contains between 3 to 80 recurrent moieties, preferably between 3 and 15 recurrent moieties. Preferably, said phosphorous acid is selected from a phosphoric acid, i.e. orthophosphoric acid and metaphosphoric acid, thiophosphoric acid, phosphonic acid, and said hydroxyl group-containing estrogenic compound is selected from the group consisting of dienestrol, diethylstilbestrol, estetrol, estradiol, estradiol, (3α,17β)-estr-4-ene-3,17-diol, estriol, ethinylestradiol, hexestrol, and raloxifene. In preferred compositions administered according to the method of the invention, the GnRH composition of the first sustained release formulation is triptorelin, or a salt thereof, that is released at a rate of about 100 μg per day, and the estrogenic composition of the second sustained release formulation is a polyester of a phosphoric acid and estradiol, said second sustained release formulation releasing estradiol at a rate between about 5 and 100 μg per day, preferably at a rate not exceeding about 50 μg per day.

In a more detailed presentation, the present invention relates to novel compositions and the use of these compositions to treat hormone-responsive prostate cancer without eliciting the severe side effects characteristic of prior art hormone ablation therapies. The compositions of the invention comprise two sustained release formulations, the first comprising a gonadotropin hormone releasing hormone (GnRH) composition and the second an estrogenic composition, that are administered to a patient simultaneously. The first formulation and the second formulation may be combined at the time of administration or may be joined at the time of manufacture. Typically, the sustained release formulations of the invention are effective for a period of at least about one month. The period of effectiveness may be as long as one year. Formulations that are even longer-lasting are considered as being within the scope of the present invention. Preferably, the compositions of the invention are designed for treatment periods of one to three months, after which periods the compositions are re-administered. It is understood that the scope of the present invention includes any modification the clinician may conceive regarding the schedule of administration of first formulation and the second formulation in order to reach the respective steady-state of serum concentrations.

The first sustained release formulation comprises a GnRH composition. A number of compounds were described that inhibit secretion of gonadotropins and, consequently, the secretion of androgens in men and estrogens in women. In men estrogens are derived from testosterone by the aromatase reaction. GnRH compositions include both agonist and antagonist analogs of GnRH as well as GnRH itself. GnRH compositions of the invention may also consist of mixtures of the latter compounds. GnRH antagonists act by competing with GnRH for GnRH receptor in the pituitary gland. Normally, GnRH is secreted in a pulsating fashion. Because of the high turnover of the hormone, GnRH receptors are exposed to waves of GnRH signalling release of LH and FSH. In the presence of high and continuous concentrations of a GnRH agonist, after an initial burst of LH and FSH release, the signalling pathway is shut down through down-regulation of GnRH receptor, resulting in reduction of LH and FSH release. Within a period of several months, LH and FSH release are completely suppressed, and estrogen and testosterone concentrations reach oophorectomized levels in women and orchiectomized or castrate levels in men, respectively. In the presence of such minimal levels of testosterone and estrogen, feedback inhibition of GnRH no longer occurs. Consequently, GnRH release is maximal. This release pattern assists the maintenance of GnRH receptor down-modulation. Well-known GnRH agonists include leuprorelin, goserelin, triptorelin, buserelin, nafarelin, deslorelin, histrelin, gonadorelin and salts thereof. A well-known GnRH antagonist is abarelix.

A variety of sustained release formulations of GnRH agonists were developed and are commercially available. Examples of commercial sustained release formulations of GnRH agonists include Lupron Depot 3.75 mg, Lupron Depot - 3 7.5 mg, and Lupron Depot - 4 30 mg of TAP Pharmaceuticals Inc. of Lake Forrest, IL. Lupron Depot 3.75 mg comprises 3.75 mg leuprorelin acetate, 0.65 mg gelatin, 33.1 mg DL-lactic and glycolic acids co-polymer, and 6.6 mg D-mannitol. The accompanying diluent contains 7.5 mg carboxymethylcellulose sodium, 75 mg mannitol, 1.5 mg polysorbate 80, water, USP, and glacial acetic acid. Lupron Depot - 3 Month 22.5 mg and Lupron Depot - 4 Month 30 mg are formulations for intramuscular injection at respectively three months intervals comprising 22.5 mg leuprorelin acetate in polylactide microspheres and four months intervals. U.S. Pat. Nos. 4,728,721 ; 4,849,228; 5,330,767; 5,476,663; 5,480,656; 5,575,987; 5,631 ,020; 5,643,607; 5,716,640; 5,814,342; 5,823,997; 5,980,488; 6,036,976. Other sustained release formulations of leuprorelin acetate include Eligard formulations (respectively 7.5 mg, 22.5 mg, and 30 mg) by Atrix Laboratories and Viadur, a 12-months formulation by ALZA Corporation. Zoladex 3.6 mg and 10.8 mg are one-month and three-months depot formulations, respectively, of goserelin acetate marketed by AstraZeneca. The Zoladex 3.6 mg formulation comprises goserelin acetate in an amount corresponding to 3.6 mg of goserelin in 13.3-14.3 mg D,L-lactic and glycolic acids co-polymer. Decapeptyl distributed by Ferring Corp. and Ipsen-Beaufour is a depot formulation of triptorelin acetate or pamoate. The one-month formulation of Decapetyl includes 3.75 mg triptorelin encapsulated in polylactide co-glycolide microcapsules. Similar sustained release formulations of triptorelin pamoate have been approved in the U.S. by the Food and Drug Administration and will be distributed by Watson Laboratories under the trade names Trelstar and those formulations are distributed in Europe under the name Pamorelin. Trelstar is available as one-month or three- months sustained release formulation (Trelstar Depot 3.75 mg, Trelstar 11.25 mg). Trelstar Depot 3.75 mg is a sterile, lyophilised biodegradable microgranule formulation supplied as a single dose vial containing triptorelin pamoate (3.75 mg of triptorelin peptide), 170 mg poly-d,l-lactide-co-glycolide, 85 mg mannitol, 30 mg carboxymethylcellulose sodium and 2 mg polysorbate 80. For injection, the formulation is suspended in 2 ml water and injected intramuscularly. Trelstar 11.25 mg is a similar formulation containing triptorelin pamoate (11.25 mg of triptorelin peptide), 145 mg poly-d,l-lactide-co-glycolide, 85 mg mannitol, 30 mg carboxymethylcellulose sodium and 2 mg polysorbate 80. The formulation is suspended in 2 ml water and injected intramuscularly. Similar formulations are described in U.S. Pat. Nos. 5,134,122, 5,192,741 and 5,225,205. These patents are incorporated herein in their entirety by this reference.

Analogous sustained release formulation of GnRH, a GnRH agonist, a GnRH antagonist or mixtures thereof can be used in the compositions of the invention. Such sustained release formulations may be based on biodegradable and/or biocompatible polymers other than the polylactide-glycolide co-polymers present in the above-described commercial formulations, including ethylene vinyl acetate, polyanhydrides, polyglycolic acid, collagen, polyorthoesters and polylactic acid. These and other polymers as well as methods for preparing appropriate formulations using such polymers are well known to those skilled in the art. While the first sustained release formulation of the present invention is preferably a depot formulation of triptorelin pamoate such as the Trelstar formulations, other sustained release formulations of an agonist or antagonist of GnRH, or of GnRH itself, could also be employed. Any depot formulation that continuously releases an agonist or antagonist of GnRH or GnRH at a rate sufficient to cause down- regulation of GnRH receptor and reduction of sex hormone concentrations to oophorectomized levels in women and orchiectomized or castrate levels in men, respectively, would be suitable for use with the present invention. While the exact rate of release may vary with the nature of the GnRH agonist (including GnRH) or antagonist used, the nature of the formulation, and the mode of administration, a suitable first sustained release formulation will release a GnRH agonist or antagonist at a rate of between about 10 and 1 ,000 μg per day.

Release of agonist or antagonist of GnRH from a first sustained release formulation will produce the well-known side effects of GnRH agonist/antagonist therapy. To counteract these side effects, in particular loss on bone mineral density and hot flushes in prostate cancer patients, the compositions of this invention comprise a second sustained release formulation that releases an estrogenic composition. Observational studies indicate that loss of bone mineral density in men may not occur if the serum level of bioavailable estradiol is at or above about 11 pg/ml. Khosla et al. J Clin Endocrinol Metab 2002; 87: 1443-1450. Taking into account the increased level of sex hormone binding globulin in elderly men, this corresponds to a total serum estradiol level of minimally about 30 pg/ml. Estrogenic compositions delivered by the second sustained release formulations include a polyphosphoric ester of both natural and non-natural estrogenic compounds containing at least two hydroxyl groups. The preferred estrogenic compounds is estradiol (chemical name: β-estra-1 ,3,5(10)-triene-3, 17-diol; CAS RN: 50-28-2). Polyphosphoric ester of a number of estrogenic compounds have been described in the 50's and 60's by Diczfalusy et al., in particular in Endocrinology, (1954), 54, 471 , in Acta Chem. Scand. (1958), 12, 1675, in U.S. Pat. No. 2,928,849. A pharmaceutical preparation comprising a polymeric ester of phosphoric acid and estradiol was developed and is currently commercially available and distributed in Switzerland by Pfizer under the trade name Estradurin. It has been named in the "Compendium Suisse des Medicaments" as "Estrogene-depόt". Such a polymeric ester is known under the names of Polyestradiol phosphate, Estradiol phosphate polymer, and PEP. The Registry Number and present name attributed by the Chemical Abstracts Service to this polymeric ester are respectively 28014-46-2 and "(17β)-Estra-1 ,3,5(10)-triene-3,17-diol, polymer with phosphoric acid". The above-mentioned pharmaceutical preparation is described in the

"Compendium Suisse des Medicaments" as being a preparation of a hydrosoluble polymerised estradiol with a long acting effect, the polymerised chain comprising around 13 molecules of estradiol, each of these molecules being linked together by a phosphoric group. After intramuscular administration of polyestradiol phosphate, phosphatases induce hydrolytic degradation of polyestradiol phosphate and estradiol is slowly released in the body. Once steady-state is obtained, estradiol is released on a long term period at constant rates. For instance, with one administration per month, steady-state is generally obtained after 6 to 12 months and estradiol concentrations are proportional to the amount of administrated polyestradiol phosphate.

Examples of other estrogenic compounds that can be used according to the present invention include dienestrol, diethyl-stilbestrol, estetrol, estradiol, estradiol, (3α,17β)-estr-4-ene-3,17-diol, estriol, ethinylestradiol, hexestrol.

Because the potencies and pharmacokinetic properties of these estrogenic compounds are widely different, average molecular weight of the polyphosphoric esters and administrated doses will vary widely depending of the amounts of concentrations of released compounds to be reached. For the purposes of this invention, amounts and concentrations of estrogenic compositions are defined by their equivalence to amounts and concentrations of estradiol. Equivalence means similarity of desirable biological effects achieved, e.g., reduction in loss of bone mineral density and/or reduction in frequency and severity of hot flushes in prostate cancer patients undergoing hormone ablation therapy.

Additional estrogenic compounds include estrogen receptor modulators (SERM) such as raloxifene. Because of the selectivity of these compositions, their use in a second sustained release formulation of this invention may only produce some but not all of the beneficial effects resulting from estradiol administration. For example, raloxifene, toremifene and tamoxifen can be expected to slow bone resorption but not to reduce (but, possibly, to enhance) the incidence and severity of hot flushes. Estrogenic compositions also include so-called ANGELS (Activators of Non-Genotropic Estrogen-like Signalling) compounds that were described in patent application PCT/US02/18544. ANGELS compounds are small molecules that mimic the non-genotropic effects of estrogen and androgen but substantially lack their genotropic effects. A preferred ANGELS compound is (3α,17β)-estr- 4-ene-3,17-diol (CAS RN: 35950-87-9) that was shown to reverse bone loss in mouse models. Kousteni et al. 2002. Science 298, 843-846.

Estrogens are well known to increase the probability of cardiovascular events, in particular oedema and deep venous thrombosis. This realization was an important reason why diethylstilbesterone therapy was abandoned for GnRH agonist therapies. Analogous observations were made for estrogen replacement therapies for postmenopausal women. Although the toxicity of estrogens to prostate cancer patients may be mitigated to some extent if the route of administration of the hormone is changed from oral to parenteral, there still may be a significant remainder risk associated with the administration of elevated doses of estrogens.

To effectively counteract the negative side effects of GnRH administration without unnecessarily increasing the risk associated with high levels of estrogens, the second sustained release formulation releases an estrogenic composition at a low rate that is calculated to be only sufficient to provide a serum estrogen level equivalent to about 15 pg/ml to about 50 pg/ml of estradiol. Because of biological differences between subjects, the actual serum estradiol or estradiol equivalent level achieved by administration of the second sustained release formulation may vary between about 10 pg/ml and about 100 pg/ml.

Sustained release formulations generally show a bimodal kinetics of drug release, comprising an initial slight burst of release that is followed by a prolonged phase of sustained release at a considerably lower rate. A preferred second sustained release composition of this invention displays a release profile that approaches unimodality. Because of the absence of an important initial burst of drug release from this second sustained release formulation, estrogen concentrations will never greatly exceed target levels. The calculated ideal rate of release of estrogenic composition is equivalent to about 25 μg/day of estradiol (clearance x desired serum level or increase in serum level). The maximal rate of release of estrogenic composition during the first days following administration of the second slow release formulation will be equivalent to about 50 μg estradiol per day. As a consequence of these narrowly defined release characteristics of the second sustained release formulation, the risk associated with a high estrogen level will be kept to a minimum.

The commercially available pharmaceutical preparation comprising polyestradiol phosphate is available under its lyophilisate form and it contains additives such as nicotinamide as a co-adjuvant, and mepivacaine as a local anaesthetic. Before administration, solution is reconstituted by addition of an appropriate amount of solvent, for instance water as ppi grade.

Polyestradiol phosphate may be prepared by chemical synthesis following the instructions given in U.S. Pat. No. 2,928,849. Chemical reaction and work-up conditions may be monitored by the person skilled in the art in order to obtained batches satisfying to criteria of the present invention. Quality of the production may be assessed by relying upon the rules based on a biological duration test and a ³¹ P NMR analysis and given by Thelin et al. in Chemometrics and Intelligent Laboratory Systems, (1995), 27, 135-145. The first formulation and the second formulation may be combined at the time of administration or may be joined at the time of manufacture. In the latter case, it may be recommended, due in particular to differences between each individual patient in the rate of estradiol metabolism caused by e.g. differences in age, body weight or composition, alcohol consumption or smoking, or drug interaction, to provide the clinician with a series of combinations with an appropriate amount of the second formulation for a given amount of the first formulation. For instance, two different polyestradiol phosphate doses combined with the same dose of triptorelin, may be proposed, one releasing an estrogenic composition equivalent to 5-50 μg and 50-100 μg estradiol per day, respectively. This would allow to reach in each individual patient a serum estrogen level equivalent to about 10-100 pg/ml of estradiol. As the sustained release formulations of the invention are effective for a period of at least about one month and the period of effectiveness may be as long as one year, the following combinations comprising respectively triptorelin pamoate and polyestradiol phosphate are proposed:

When the first formulation comprising triptorelin pamoate and the second formulation comprising polyestradiol phosphate are combined at the time of administration, commercially available preparations may be used. As both available preparations need to be reconstituted prior use as an injectable preparation, the same solvent may be used thus allowing a single injection. The first formulation comprising triptorelin pamoate and the second formulation comprising polyestradiol phosphate may also be joined at the time of manufacture following the appropriate amount as mentioned above. For instance, polyestradiol phosphate used as raw material may be dispersed in an appropriate aqueous medium at a pH comprised between 5.5 and 8.0, preferably between 6.0 and 7.8 and the homogeneous mixture obtained may be subsequently added to the triptorelin sustained release formulation and the obtained mixture is then lyophilised. The composition of the present invention and its properties are presented in more details in the following examples and the drawing in which:

- Fig. 1 represents estradiol kinetic profiles as obtained with formulation of Example 1 ;

- Fig. 2 represents estradiol kinetic profile as obtained with composition of Example 3; and

- Fig. 3 represents triptorelin release profiles as obtained with the composition of Example 3.

The composition of the present invention and its use are presented in the following Examples.

Example 1 : Preparation of a formulation comprising polyestradiol phosphate (Combination 1)

In a first vial containing 80 mg of polyestradiol phosphate (Estradurin^®, marketed product), 2 ml of water for injection are added. The vial is shacked vigorously until complete dissolution

Example 2: Preparation of a combination in which the first and second formulations are combined at the time of administration (Combination2)

Both formulations are reconstituted ex-temporis. In a first vial containing 80 mg of polyestradiol phosphate (Estradurin^®, marketed product), 2 ml of water for injection are added. The vial is shacked vigorously until complete dissolution. 1 ml of that solution and 1 ml of water for injection are injected in a second vial containing the triptorelin formulation "3-months" (12 mg triptorelin per vial) and the vial is shaken in order to obtain a homogeneous suspension ready for injection.

Example 3: Preparation of a combination in which the first and second formulations are combined at the time of manufacture (Combination 3)

A first formulation of microgranules of triptorelin pamoate was prepared according to the following method.

Approximately 12 wt% of triptorelin pamoate was mixed with approximately 88 wt% PLGA 75:25 in a ball mill, at room temperature. The given mixture was duly homogenized, subjected to a progressive compression and simultaneously to a progressive heating, before extruded at a temperature of approximately 110°C. The extrudate was cut into pellets and ground at a temperature of about -100°C. The microgranules obtained after grinding were sieved below 180 microns.

The second formulation was obtained by dissolving polyestradiol phosphate in a phosphate buffer pH 7.8 medium at a concentration of 20 mg/ml.

The final combination was obtained by adding polyestradiol phosphate solution to triptorelin pamoate microgranules in order to have a dose of 12 mg of triptorelin and 40 mg of polyestradiol phosphate per vial. After homogenisation, the obtained suspension was frozen and lyophilised. The product is finally sterilized by gamma radiation.

Example 4: Preparation of a combination in which the first and second formulations are combined at the time of manufacture (Combination 4)

A formulation of microgranules of triptorelin pamoate was prepared according to the method described in Example 3. Polyestradiol phosphate was dispersed in an aqueous medium pH around 6.4 at a concentration of 20 mg/ml. The final combination was prepared by adding polyestradiol phosphate dispersion to triptorelin pamoate microgranules in order to have a dose of 12 mg of triptorelin and 40 mg of polyestradiol phosphate per vial. After homogenisation, the suspension obtained is frozen and lyophilised. The product is finally sterilized by gamma radiation.

Example 5: Phamacokinetics studies

The aim of this experimental study was to follow the estradiol and/or triptorelin serum release following a single intramuscular injection of formulation and combinations in the rat.

1. Animals and administration of formulations

Under mild ether anaesthesia, male Sprague Dawley orchidectomized rats were given an intramuscular injection (i.m.) of the formulation of Example 1 and the combination of Example 3, in the posterior thigh muscle. Six animals were studied per group. The day before the injection of the formulation (Day 0), a reference blood sample was collected. Each injection was carried out on Day 1 at time TO. This was considered as the reference time for the following blood samples.

2. Blood sampling

Two blood samples were then collected on Day 1 , the first one 1 hour after injection (T0+1 h00) and the second one 6 hours after injection (T0+6h00). On the following days, i.e. from Day 2 to Day 42, blood samples was collected at the same time as that chosen for TO. Blood samples were collected in all groups until day 42. For the animals treated with the three-month formulation, additional weekly blood samples were taken until Day 91. At each time point, approximately 1.5 ml of blood were collected from the retro-orbital sinus (right or left eye) using hematocrit capillaries

3. Assays

Serum estradiol and/or triptorelin were measured in the serum of treated animals by Radio-lmmuno-Assay (RIA). 4. Results

4.1 Formulation as obtained in Example 1

Fig. 1 reports the kinetic profile of the estradiol release of formulation of Example 1 in rat serum. This profile shows a very slight burst effect occurring at a maximum of 4600 pmol/l during the first day. Then, the estradiol level in serum reach a plateau at least for the next following 42 days.

A similar kinetic profile is expected to be achieved in man.

4.2 Combined formulation as obtained in Example 3

Fig. 2 reports the kinetic profile of estradiol releases of combined formulation of Example 3 in rat serum during 92 days following a single intramuscular injection. This profile is very similar to the one as obtained with formulation of Example 1 and a control curve, not shown on Fig 2, demonstrates that the presence of triptorelin seems to have no effect on the release of estradiol.

Fig. 3 reports the triptorelin profile of serum triptorelin release in rat serum following the IM injection of combined formulation of Example 3 in rat serum during 92 days following a single intramuscular injection. A control curve, not shown on Fig 3, demonstrates that the presence of polyestradiol phosphate seems to have no effect on the release of triptorelin.

Example 6: Effects of the combined formulation on treatment on bone mineral densities, hot flushes, testosterone serum levels and prostate specific antigen level in a patient suffering from advanced prostate cancer.

A single IM injection of the combination of triptorelin (11.25 mg) and polyestradiol phosphate (40 mg) was administered once every 12 weeks over 48 weeks into the buttocks of a GnRH analog naϊve patient suffering from advanced prostate cancer.

Results: Bone mineral density (BMP)

No accelerated bone loss was detected. At 48 weeks, there was only a 0.52% decrease in BMD at lumbar spine and 0.45% decrease in total hip BMD compared to baseline.

Hot flushes

The mean number of hot flushes daily was in average 5 and the mean severity of hot flushes based on a visual analog scale (from 1 to 10) was 4.0.

Serum testosterone levels

The patient had achieved chemical castration (serum testoterone < 1.735 nmol/L) at Day 29 and remained castrated between Days 29 and day 336 (48 weeks).

Serum PSA levels The PSA concentration decreased from 46.0 mg/L at baseline to 1.2 mg/L at 48 weeks.

Example 7: A study comparing the effects of a sustained release triptorelin (alone) and the combined formulation triptorelin+polvestradiol phosphate treatments on bone mineral density, hot flushes, testosterone serum levels and prostate specific antigen in men receiving GnRH agonist therapy for prostate cancer

140 men suffering from advanced prostate cancer without bone metastases are randomised to receive every 12 weeks IM injections of either triptorelin pamoate 11.25 mg alone or combined with a dose of 40 mg of polyestradiol phosphate, 70 patients per treatment arm. In both arms triptorelin are in a sustained release (PLGA) formulation. The patients are followed over a 48-week period.

All patients are started on calcium and vitamin D supplements one month before start of the study drug treatment in order to prevent bone loss due to calcium or vitamin D deficiency.

The bone mineral density (BMD) is measured at the baseline and at 48 weeks. The incidence and severity of hot flushes are measured at the baseline and monthly using a patient diary. The serum testosterone and prostate specific antigen (PSA) levels are measured at the baseline and at regular intervals.

Results: Bone mineral density

At 48 weeks there is a 2.6% decrease in BMD at lumbar spine and 3.4 % decrease in total hip in the triptorelin alone arm, whereas there is only a 0.5% decrease in BMD at both sites with triptorelin+polyestradiol phosphate treatment. The mean difference in bone loss after 48 weeks between triptorelin+polyestradiol phosphate and triptorelin alone groups is found as 2.1% at lumbar spine and 2.9% at total hip (statistically significant), with a standard deviation of 4.3 in the change from baseline.

Hot flushes 74% of the patients in both treatment arms experienced hot flushes. The mean number of hot flushes daily is 7 in the triptorelin alone group and 5 in the triptorelin+polyestradiol phosphate arm. The mean severity of hot flushes based on a visual analog scale (from 1 to 10) is 6.3 in the triptorelin alone arm and 4.3 in the triptorelin+polyestradiol phosphate arm.

Serum testosterone levels

The mean percentage of patients achieving castration (serum testoterone

< 1.735 nmol/L) at Day 29 is 94.3% in the triptorelin alone arm, and 95.1% in the triptorelin+polyestradiol phosphate group. The mean percentage of patients maintaining castration between Day 29 and Day 336 is 98.0% in the triptorelin alone group and 98.1% in the triptorelin+polyestradiol phosphate group. The mean differences between the treatment groups are not significant.

Serum PSA levels Reduction in PSA levels by Day 336 vs. baseline was 97.1% in the triptorelin alone group and 97.3% in the triptorelin+estradiol group, respectively.

Claims

1. A composition comprising: a first sustained release formulation of a gonadotropin hormone releasing hormone composition capable of releasing the gonadotropin hormone releasing hormone composition during a period of at least about one month at a rate sufficient to induce and maintain chemical castration of a male patient, and a second sustained release formulation of an estrogenic composition capable of maintaining for said period a serum level sufficient to reduce the enhanced loss of bone mineral density and/or the hot flushes that are normally caused by the administration of a GnRH composition that chemically castrates a male patient.

2. The composition according to claim 1 , characterised in that said second sustained release formulation is a polyester of a phosphorous acid and an estrogenic compound containing at least two hydroxyl groups.

3. The composition according to claim 2, characterised in that the chemical structure of said polyester comprises between 3 to 80 recurrent moieties.

4. The composition according to claim 2, characterised in that said phosphorous acid is selected from a phosphoric acid, thiophosphoric acid, phosphonic acid.

5. The composition according to claim 2, characterised in that said hydroxyl group-containing estrogenic compound is selected from the group consisting of dienestrol, diethylstilbestrol, estetrol, estradiol, estradiol, (3α,17β)-estr-4-ene-3,17- diol, estriol, ethinylestradiol, hexestrol, and raloxifene.

6. The composition according to claim 2, characterised in that said polyester is a polymeric ester of phosphoric acid and estradiol.

7. The composition according to any of claim 1 or claim 2, characterised in that the second sustained release formulation of the invention releases an estrogenic composition at a rate between about 5 and 100 μg of estradiol equivalent per day.

8. The composition according to any of the previous claims, characterised in that the first sustained release formulation of a gonadotropin hormone releasing hormone composition is capable of releasing the gonadotropin hormone releasing hormone composition at a rate between about 10 and 1 ,000 μg per day.

9. The composition according to any of the previous claims, characterised in that the gonadotropin hormone releasing hormone composition of the first sustained release formulation is selected from the group consisting of gonadotropin hormone releasing hormone, agonists of gonadotropin hormone releasing hormone, antagonists of gonadotropin hormone releasing hormone and mixtures thereof.

10. The composition according to claim 9, characterised in that the gonadotropin hormone releasing hormone composition of the first sustained release formulation is an agonist of gonadotropin hormone releasing hormone selected from the group consisting of leuprorelin, goserelin, triptorelin, buserelin, nafarelin, deslorelin, histerelin, gonadorelin, and salts and/or mixtures thereof.

11. The composition according to any of the previous claims, characterised in that the gonadotropin hormone releasing hormone composition is triptorelin or a salt thereof and the estrogenic composition is polyestradiol phosphate.

12. Method for the treatment of prostate cancer comprising: administration to a patient suffering from prostate cancer a first sustained release formulation of a gonadotropin hormone releasing hormone composition capable of releasing the gonadotropin hormone releasing hormone composition during a period of at least about one month at a rate sufficient to induce and maintain chemical castration of a male patient, and simulltaneously administrating to the patient a second sustained release formulation of an estrogenic composition capable of maintaining for said period a serum level sufficient to reduce the enhanced loss of bone mineral density and/or the hot flushes that are normally caused by the administration of a GnRH composition that chemically castrates a male patient.

13. Use of a composition according to any of the preceding claims for the preparation of a medication capable of maintaining for said period a serum level sufficient to reduce the enhanced loss of bone mineral density and/or the hot flushes that are normally caused by the administration of a GnRH composition that chemically castrates a male patient capable to induce and maintain chemical castration of a male patient and to reduce the enhanced loss of bone mineral density and/or the hot flushes that are normally caused by the administration of a GnRH composition that chemically castrates a male patient.