WO2009135939A2

WO2009135939A2 - Depsipeptide for use in cancer therapy

Info

Publication number: WO2009135939A2
Application number: PCT/EP2009/055604
Authority: WO
Inventors: Pablo Manuel AVILÉS MARÍN; María del Carmen CUEVAS MARCHANTE; Gilles Vassal
Original assignee: Pharma Mar, S.A.
Priority date: 2008-05-09
Filing date: 2009-05-08
Publication date: 2009-11-12
Also published as: WO2009135939A3

Abstract

Methods for treating cancer by using compound PM02734, in particular, for treating Ewing's sarcoma, osteosarcoma and rhabdomyosarcoma and medulloblastoma are provided.

Description

DEPSIPEPTIDE FOR USE IN CANCER THERAPY

The present invention relates to the treatment of cancers and, in particular, to the effective treatment of medulloblastoma or a sarcoma selected from Ewing's sarcoma, osteosarcoma and rhabdomyosarcoma by using the depsipeptide compound PM02734.

BACKGROUND OF THE INVENTION

Cancer develops when cells in a part of the body begin to grow out of control. Although there are many kinds of cancer, they all arise from out-of-control growth of abnormal cells. Cancer cells can invade nearby tissues and can spread through the bloodstream and lymphatic system to other parts of the body. There are several main types of cancer. Carcinoma is a malignant neoplasm, which is an uncontrolled and progressive abnormal growth, arising from epithelial cells . Epithelial cells cover internal and external surfaces of the body, including organs, lining of vessels, and other small cavities. Sarcoma is cancer arising from cells in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. Leukemia is cancer that arises in blood-forming tissue such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the bloodstream. Lymphoma and multiple myeloma are cancers that arise from cells of the immune system.

In addition, cancer is invasive and tends to infiltrate the surrounding tissues and give rise to metastases. It can spread directly into surrounding tissues and also may be spread through the lymphatic and circulatory systems to other parts of the body.

Many treatments are available for cancer, including surgery and radiation for localised disease, and chemotherapy. However, the efficacy of available treatments for many cancer types is limited, and new, improved forms of treatment showing clinical benefits are needed. This is especially true for those patients presenting with advanced and/ or metastatic disease and for patients relapsing with progressive disease after having been previously treated with established therapies which become ineffective or intolerable due to acquisition of resistance or to limitations in administration of the therapies due to associated toxicities.

As mentioned above, sarcomas are cancers that arise from the cells that hold the body together. Specifically, they arise from cells related to muscles, nerves, bones, adipose tissue, tendons, cartilage, or other forms of connective tissues. Sarcomas can be grouped into two general types: soft tissue sarcoma (STS) and primary bone sarcoma, each of which has different staging.

Sarcomas occur infrequently, representing 1-2% of all adult cancers. However, sarcomas are disproportionately common in children, with an incidence of 7-15% of paediatric malignancies (mainly under age 15), of which rhabdomyosarcoma is the most common, representing nearly 50% of STSs for this age range, with an incidence rate of 4.6 per million. Data from Surveillance Epidemiology End Results (SEER) program (1975-1995) reveal that approximately 10,000 new cases and 4,000 deaths from sarcoma occur in the United States each year.

The term soft tissue refers to tissues that connect, support, or surround other structures and organs of the body. Soft tissue includes muscles, tendons (bands of fiber that connect muscles to bones), fibrous tissues, fat, blood vessels, nerves, and synovial tissues (tissues around joints). Malignant (cancerous) tumors that develop in soft tissue are called sarcomas. There are many different sub-types of STSs. They are grouped together because they share certain microscopic characteristics, produce similar symptoms, and are generally treated in similar ways. The most common or illustrative STSs sub-types are the following:

- Liposarcoma. This adipocytic neoplasm is the most common sub-type of STS, representing approximately 20% of STS in the United States.

Several types of liposarcoma are recognized, including well- differentiated liposarcoma, myxoid liposarcoma, round-cell liposarcoma, dedifferentiated liposarcoma, and pleomorphic liposarcoma.

- Leiomyosarcoma. This is a malignant tumor composed of cells showing distinct smooth muscle features.

- Angiosarcoma. This is a rare and clinically highly variable cancer of blood vessels. Angiosarcoma can start anywhere in the body, but the most common place to arise is in the head and neck area, breast (frequently several years after radiation and surgery for breast cancer), bone, or other vital organs such as liver and spleen.

- Kaposi Sarcoma. This is also a form of blood vessel sarcoma. Kaposi sarcoma is one of the rare forms of cancer caused by a virus, KSHV or HHV-8, which escapes control of the immune system as seen in patients with HIV or in elderly patients, typically living in the areas around the Mediterranean Sea.

- Gastrointestinal Stromal Tumor (GIST). This is the most common sarcoma of the gastrointestinal tract. The tumor can originate anywhere from the esophagus to the rectum, but most often comes from the stomach or small intestine. Uncommonly, GIST arises elsewhere in the abdomen outside of the gastrointestinal tract.

- Dermatofibrosarcoma Protuberans (DFSP). This is a tumor of the skin, which is a rare type of sarcoma with low-to-intermediate grade malignancy. It compromises less than 0.1% of all cancers and about 1% of all STSs. DFSP tumors occur in the dermis layer of the skin and can invade deeper subcutaneous tissue, such as fat, fascia, and muscle.

- Alveolar Soft-Part Sarcoma. It is a very rare, slow growing, highly angiogenic (vessel-forming) tumor that can occur in any age group. - Rhabdomyosarcoma. This is the most common malignant soft tissue tumor of children and young adults, and it is an uncommon tumor in adults over the age of 30. The malignant cells of this tumor have features characteristic of developing skeletal muscle. Although rhabdomyosarcoma can appear in the extremities, it is more frequently seen in other areas: the head and neck region, the vaginal area in females, the testicular area in males, or the bladder and prostate.

- Synovial Sarcoma. It most commonly affects adolescents and young adults in age 15-40. It originates from mesenchymal cells, but not from the synovium as the name implies. It can spread to other part of body mainly through blood circulation, sometimes through lymph node.

- Neuroblastoma. It is a cancer that forms in the nerve tissue. It usually begins in the adrenal glands, but it may also begin in the neck, chest or spinal cord. The cancer often begins in early childhood, and sometimes before a child is born.

On the other hand, bone consists of cartilaginous, osteoid, and fibrous tissue and bone marrow elements. Each tissue can give rise to benign or malignant spindle cell tumors. Malignant tumors arising from the skeletal system are rare, representing just 0.001 % of all new cancers. Osteosarcoma and Ewing's sarcoma, the two most common bone tumors, occur during childhood and adolescence . Other mesenchymal (spindle cell) neoplasms that characteristically arise after skeletal maturity, fibrosarcoma, chondrosarcoma, and malignant fibrous histiocytoma (MFH), are less common.

Another tumor type highly frequent in children is medulloblastoma, which is the most common childhood malignant brain tumor, accounting for 16% of all paediatric brain tumors. The peak incidence of medulloblastoma is between 3 and 4 years of age, and the tumor is rare in adults; it comprises approximately 1% of all primary brain tumors. For adult medulloblastoma the peak age is between 20 and 35 years, after which the incidence steadily declines.

Medulloblastoma is a highly malignant primary brain tumor that originates in the cerebellum or posterior fossa. Originally considered to be a glioma, medulloblastoma is now known to be of the family of cranial primitive neuroectodermal tumors (PNET). This tumor type has the propensity of spreading throughout the Central Nervous System, and systemic metastases of this tumor, especially to bone, also have been recognized.

More information about these tumor types can be found in the medical literature such as in the handbook Cancer. Principles & Practice of Oncology, 7th ed. Philadelphia, Pa: Lippincott Williams & Wilkins, 2005.

PM02734 ((4S)-MeHex-D-Val-L-Thr-L-Val-D-Val-D-Pro-L-Orn-D- αZZo-Ile-cydo(D-αZZo-Thr-D-αZZo-Ile-D-Val-L-Phe-Z-Dhb-L-Val)) is a depsipeptide related to the family of kahalalide compounds. This compound is the subject of WO 2004/035613 and has the following structure:

Kahalalide compounds are cyclic depsipeptides which were originally isolated from a Hawaiian herbivorous marine species of mollusk, Elysia rufescens, and its diet, the green alga Briopsis sp. Kahalalides A-G were described by Hamann et al. (J. Am. Chem. Soc. 1993, 1 15, 5825-5826 and J. Org. Chem. 1996, 61 , 6594-6600) and many of them show activity against cancer and AIDS-related opportunistic infections. Some other natural kahalalide compounds have been also disclosed such as Kahalalide H and J by Scheuer et al. (J. Nat. Prod. 1997, 60, 562-567), Kahalalide O by Scheuer et al. (J. Nat. Prod. 2000, 63(1), 152- 154), Kahalalide K by Kan et al. (J. Nat. Prod. 1999, 62(8), 1 169- 1 172).

PM02734 has shown significant improved efficacy in in vivo cancer models with respect to those activities observed with kahalalide compounds of natural origin. PM02734 has demonstrated in vitro antitumor activity against a broad spectrum of tumor types such as leukemia, melanoma, breast, colon, ovary, pancreas, lung, and prostate, and has shown significant in vivo activity in xenografted murine models using human tumor cell types such as breast, prostate, and melanoma. Additionally, in US 60/ 98 1 ,43 1 , PM02734 was evaluated in combination with EGFR tyrosine kinase inhibitors, specifically Erlotinib, for the treatment of lung cancer.

More information on PM02734 and other kahalalide compounds, their uses, formulations and synthesis can be found in the patent applications EP 610078, WO 2004/035613, WO 01 /58934, WO 2005/023846, WO 2004/075910, WO 03/033012, WO 02/36145, WO 2005/ 103072, US 60/981 ,431 , and EP 08380078.9. We incorporate by specific reference the content of each of these application texts. It is an object of the present invention to provide new and improved forms of treatment of Ewing's sarcoma, osteosarcoma, rhabdomyosarcoma and medulloblastoma by using PM02734.

It is another object of the present invention to provide new uses in cancer therapy for PM02734.

SUMMARY OF THE INVENTION

We have established for the first time that PM02734 has antitumor activity against Ewing's sarcoma, osteosarcoma, rhabdomyosarcoma and medulloblastoma, and therefore it can be successfully used in the treatment of these diseases.

Thus, this invention is directed to pharmaceutical compositions, kits, methods for the treatment of Ewing's sarcoma, osteosarcoma, rhabdomyosarcoma and medulloblastoma using PM02734, and uses of PM02734 in the manufacture of a medicament for the treatment of Ewing's sarcoma, osteosarcoma, rhabdomyo sarcoma and medulloblastoma.

In accordance with one aspect of this invention, we provide for the use of PM02734, or a pharmaceutical acceptable salt thereof, in the treatment of a tumor selected from Ewing's sarcoma, osteosarcoma, rhabdomyosarcoma and medulloblastoma.

In a related embodiment, the invention further provides for the use of PM02734, or a pharmaceutically acceptable salt thereof, in the preparation of a medicament for the treatment of a tumor selected from Ewing 's s arcoma, o steo sarco ma, rhabdomyo sarco ma and medulloblastoma. In a further aspect, the invention provides PM02734, or a pharmaceutically acceptable salt thereof, for use in the treatment of a tu m o r s e l e c t e d fr o m Ewing 's sarcoma, o ste o sarcoma , rhabdomyosarcoma and medulloblastoma.

In another aspect, the present invention is also directed to a pharmaceutical composition comprising PM02734, or a pharmaceutical acceptable salt thereof, and a pharmaceutically acceptable carrier or excipient, to be used in the treatment of a tumor selected from Ewing's sarcoma, osteosarcoma, rhabdomyosarcoma and medulloblastoma.

The present invention additionally provides a method for treating any mammal, notably a human, affected by a tumor selected from Ewing's sarcoma, osteosarcoma, rhabdomyosarcoma and medulloblastoma, comprising administering to the affected individual a therapeutically effective amount of PM02734, or a pharmaceutical acceptable salt thereof.

In a further aspect of the present invention, a medical kit for administering PM02734 is provided, comprising printed instructions for administering PM02734 according to the uses and methods of treatment set forth herein, and a pharmaceutical composition comprising PM02734, or a pharmaceutical acceptable salt thereof, and a pharmaceutically acceptable carrier or excipient.

DETAILED DESCRIPTION OF THE INVENTION

The term "treating", as used herein, unless otherwise indicated, means reversing, alleviating, inhibiting the progress of, or preventing the disorder or condition to which such term applies, or one or more symptoms of such disorder or condition. The term "treatment", as used herein, unless otherwise indicated, refers to the act of treating as "treating" is defined immediately above.

As mentioned above, PM02734 ((4S)-MeHex-D-Val-L-Thr-L- VaI-D- Val-D-Pro-L-Orn-D-allo-Ile-cyclolD-allo-Thr-D-αZZo-Ile-D-Val-L-Phe-Z- Dhb-L-Val)) is a depsipeptide with the following structure:

The term "PM02734" is intended here to cover any pharmaceutically acceptable salt, solvate, hydrate, prodrug, or any other compound which upon administration to the patient is capable of providing (directly or indirectly) the compound as described herein. The preparation of salts, solvates, hydrates, and prodrugs can be carried out by methods known in the art.

Pharmaceutically acceptable salts can be synthesized from the parent compound, which contains a basic or acidic moiety, by conventional chemical methods. Generally, such salts are, for example, prepared by reacting the free acid or base forms of these compounds with a stoichiometric amount of the appropriate base or acid in water or in an organic solvent or in a mixture of the two. Generally, nonaqueous media like ether, ethyl acetate, ethanol, isopropanol or acetonitrile are preferred. Examples of the acid addition salts include mineral acid addition salts such as, for example, hydrochloride, hydrobromide, hydroiodide, sulphate, nitrate, phosphate, and organic acid addition salts such as, for example, acetate, trifluoroacetate, maleate, fumarate, ci trate , oxalate , suc ci nate , tartrate , m al ate , m and e l ate , methanesulphonate and p-toluenesulphonate. Examples of the alkali addition salts include inorganic salts such as, for example, sodium, potassium, calcium and ammonium salts, and organic alkali salts such as, for example, ethylenediamine, ethanolamine, N, N- dialkylenethanolamine, triethanolamine and basic aminoacids salts.

Any compound that is a prodrug of PM02734 is within the scope and spirit of the invention. The term "prodrug" is used in its broadest sense and encompasses those derivatives that are converted in vivo to PM02734. The prodrug can hydrolyze, oxidize, or otherwise react under biological conditions to provide PM02734. Examples of prodrugs include, but are not limited to, derivatives and metabolites of PM02734 that include biohydrolyzable moeities such as biohydrolyzable amides, biohydrolyzable esters, biohydrolyzable carbamates, biohydrolyzable carbonates, biohydrolyzable ureides, and biohydrolyzable phosphate analogues. Prodrugs can tipically be prepared using well-known methods, such as those described by Burger "Medicinal Chemistry and Drug Discovery 6th ed. (Donald J. Abraham ed. , 2001 , Wiley) and "Design and Applications of Prodrugs" (H. Bundgaard ed., 1985, Harwood Academic Publishers).

In addition, any drug referred to herein may be in crystalline form either as free compound or as solvates (e.g. hydrates) and it is intended that both forms are within the scope of the present invention. Methods of solvation are generally known within the art. PM02734 for use in accordance of the present invention may be prepared following a synthetic process such as those disclosed in WO 2004/035613, WO 2005/ 103072, WO 01 /58934, and WO 2005/023846, which are incorporated herein by reference.

Pharmaceutical compositions of PM02734, or of a pharmaceutically acceptable salt thereof, that can be used include solutions, suspensions, emulsions, lyophilized compositions, etc., with suitable excipients for intravenous administration. For further guidance on pharmaceutical compositions of PM02734, or a pharmaceutically acceptable salt thereof, see for example the formulations described in WO 2004/035613, which is incorporated herein by reference in its entirety.

Administration of PM02734, or a pharmaceutically acceptable salt thereof, or pharmaceutical compositions comprising the compound is preferably by intravenous infusion. Infusion times of up to 72 hours can be used, more preferably between 30 minutes and 24 hours, with either about 30 minutes, about 3 hours or about 24 hours most preferred. Short infusion times which allow treatment to be carried out without an overnight stay in hospital are especially desirable. However, infusion may be around 24 hours or even longer if required.

Preferably the administration of PM02734 is performed in cycles. In a preferred application method an intravenous infusion of PM02734 is given to the patients the first week of each cycle and the patients are allowed to recover for the remainder of the cycle. The preferred duration of each cycle is of either 1 , 3, or 4 weeks. Multiple cycles can be given as needed. In an alternative dosing protocol, PM02734 is administered for say about 1 hour for 5 consecutive days every 3 or 4 weeks. Other protocols can be devised as variations. For further guidance on PM02734 administration and dosages, see for example WO 2004/035613 which is incorporated herein by reference.

Although guidance for the dosage is given above, the correct dosage of the compound may change according to the particular formulation, the mode of application, and the particular situs, patient and tumor being treated. Other factors like age, body weight, sex, diet, time of administration, rate of excretion, condition of the patient, drug combinations, reaction sensitivities and severity of the disease shall be taken into account. Dose delays and/ or dose reductions and schedule adjustments are performed as needed depending on individual patient condition and tolerance of treatments.

Depending on the type of tumor and the development stage of the disease, anticancer effects of the methods of treatment of the present invention include, but are not limited to, inhibition of tumor growth, tumor growth delay, regression of tumor, shrinkage of tumor, increased time to regrowth of tumor on cessation of treatment, slowing of disease progression, and prevention of metastasis. It is expected that when a method of treatment of the present invention is administered to a patient in need of such treatment, said method of treatment will produce an effect, as measured by, for example, the extent of the anticancer effect, the response rate, the time to disease progression, or the survival rate. In particular, the methods of treatment of the invention are suited for human patients, especially those who are relapsing or refractory to previous chemotherapy. First line therapy is also envisaged.

PM02734 may be used with other drugs to provide a combination therapy in the tre atment of Ewing's sarcoma, osteosarcoma, rhabdomyosarcoma and medulloblastoma. The other drug may form part of the same composition, or be provided as a separate composition for administration at the same time or at different time.

In a preferred embodiment, the methods of the invention are used to treat rhabdomyosarcoma. In another preferred embodiment, the methods of the invention are used to treat Ewing's sarcoma and osteosarcoma. In another preferred embodiment, the methods of the invention are used to treat medulloblastoma.

Therefore in another aspect, the invention provides a method for treating any mammal, notably a human, affected by a tumor selected from Ewing's sarcoma, osteosarcoma, rhabdomyosarcoma and medulloblastoma, comprising administering to the affected individual a therapeutically effective amount of PM02734, or a pharmaceutical acceptable salt thereof. In a preferred embodiment, the methods provided by the present invention are for the treatment of paediatric patients.

In another aspect, the present invention is directed to a medical kit for administering PM02734, comprising printed instructions for administering PM02734 in the treatment of a tumor selected from

Ewing's sarcoma, osteosarcoma, rhabdomyosarcoma and medulloblastoma, and a pharmaceutical composition comprising

PM02734, or a pharmaceutical acceptable salt thereof, and a pharmaceutically acceptable carrier.

In another aspect, the present invention also provides for a pharmaceutical composition comprising PM02734, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier, to be use in the treatment of a tumor selected from Ewing's sarcoma, osteosarcoma, rhabdomyosarcoma and medulloblastoma.

In another aspect, the invention further provides for the use of PM02734, or a pharmaceutically acceptable salt thereof, in the manufacture of a medicament for the treatment of a tumor selected from Ewing's sarcoma, osteosarcoma, rhabdomyosarcoma and medulloblastoma.

In a further aspect, the invention provides PM02734, or a pharmaceutically acceptable salt thereof, for use in the treatment of a tu m o r s e l e c t e d fr o m Ewing's sarcoma, osteosarcoma, rhabdomyosarcoma and medulloblastoma.

The following examples further illustrate the invention. They should not be interpreted as a limitation of the scope of the invention.

To provide a more concise description, some of the quantitative expressions given herein are not qualified with the term "about". It is understood that, whether the term "about" is used explicitly or not, every quantity given herein is meant to refer to the actual given value, and it is also meant to refer to the approximation to such given value that would reasonably be inferred based on the ordinary skill in the art, including equivalents and approximations due to the experimental and/ or measurement conditions for such given value. In addition, unless otherwise stated, where values are given as ranges, the upper and lower values are specifically contemplated as preferred values.

EXAMPLES OF THE INVENTION Example 1

Antitumor activity of PM02734 in Ewing's sarcoma, osteosarcoma and rhabdomyosarcoma was evaluated by using a cell line panel comprising 12 human tumor cell lines representative of these tumor types. Table 1 shows a list of the cell lines used in this assay.

Table 1

All cell lines were grown in a qualified incubator at 37°C in a humidified atmosphere with 5% CO2, and were cultured in the following media:

- A637 cells were grown in Dulbecco's Modified Eagle Medium (DMEM), supplemented with glutamine, Fetal Calf Serum (FCS), and Penicillin- Streptomycine-Fungizone (PSF) - EW7, RD-ES, SIM (EW27), RD, RH-30, RMS-YM, and RMS- I cells were grown in RPMI- 1640 medium, supplemented with glutamine, FCS, and PSF

- IOR/OS9, U-2OS, SAOS-2, and MG-63 cells were grown in Iscove's Modified Dulbecco's Medium (IMDM), supplemented with glutamine, FCS, and PSF.

The adherent growing cells were detached from the tissue culture flask or the collagen matrix with a trypsin/ EDTA solution.

The cito toxicity of the test drug was evaluated with the MTS-test, wherein the reduction of the yellow dye 3-(4,5-dimethylthiazol-2-yl)-5- (3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazoliumbromid (MTS) to the blue formazan dye by mitochondrial aldehyde dehydrogenases of viable cells was measured. The formation of the blue formazan correlates to the amount of viable cells.

Cells were inoculated on 96 well microtiter plates with 50 μL complete cell culture medium at plating densities which were dependent on the cell line used. Lower cell densities were required for cell lines with high activity of mitochondrial aldehyde dehydrogenases or short population doubling times, whereas cell lines with low activities of their aldehyde dehydrogenases or long population doubling times were seeded at higher densities. Specifically:

-A637, EW7, RD-ES, SIM (EW27), RD, RH-30, RMS-YM, and RMS- I cells were seeded at a concentration of 50,000 cells/ mL - IOR/OS9 and U-2OS cells were seeded at a concentration of 10,000 cells/ mL - SAOS-2 and MG-63 cells were seeded at a concentration of 15,000 and 20,000 cells/ mL, respectively.

The plates were incubated at 37°C in a humidified atmosphere with 5% CO2 for 24 hours to allow attachment of the adherent cells and resumption of exponential growth. After 24 hours, cells of each cell line were analysed for viability by the MTS-test, in which 20 μL of MTS solution were added to each well and the cells were incubated for additional 3 hours at 37°C, 5% CO₂, 95% air, and 100% relative humidity. After 3 hours the absorbance was read on an automated plate reader at a wavelength 490 nm.

Then, PM02734, in the form of its trifluoroacetate salt, was dissolved in DMSO to a concentration of 2 mg/mL. Further serial log- dilutions of this stock solution were done with complete cell culture medium. PM02734 stock solution was diluted to twice the desired final maximum test concentration (4x10 ², 4x 10 ³, 4xlO ⁴, 4xlO ⁵, 4xlO ⁶, 4xlO^"7, 4xlO ⁸, 4xlO ⁹ mg/mL of PM02734) with the appropriate complete cell culture medium. Due to the stability of PM02734, drug dilution was divided on aliquots for each individual experiment. Thus, additional freezing and thawing of PM02734 was avoided. Aliquots of 50 μL of these different drug dilutions were added to the appropriate microtiter wells already containing 50 μL of medium, resulting in the required final drug concentrations (2x10 ⁹, 2x10 ⁸, 2x10 ⁷, 2x10 ⁶, 2x10" ⁵, 2xlO-⁴, 2xlO-³, 2xlO-² mg/mL of PM02734). Drug free complete cell culture medium served as control. Each concentration was tested on each cell line and at each time point in quadruplate and each experiment was carried out in triplicate.

Following drug addition the plates were incubated for additional 72 hours at 37°C, 5% CO₂, 95% air, and 100% relative humidity. After 72 hours, 20 μL of MTS solution were added to each well and the cells were incubated for additional 3 hours at 37°C, 5% CO₂, 95% air, and 100% relative humidity. After 3 hours the absorbance was read on an automated plate reader at a wavelength 490 nm.

Therefore, at the start of the drug incubation (0 hour) and after 72 hours the rate of cell survival was determined by the MTS-test. The optical density of each well was recorded and means, standard deviations (SD) and coefficients of variations (CV) were calculated from triplicate measurements performed for each concentration and each cell line at each time point. The mean extinctions determined for untreated cells at the start of the incubation (Oh = Tz) or of untreated controls after 72 h (control growth = C) served as controls. The means of the ten absorbance measurements: absorbance measurement at time zero = Tz, absorbance measurement of control growth = C, and test growth in the presence of drug at the eight concentration levels = Ti, were used to calculate the percentage growth / cell survival at each of the drug concentrations levels. The percentage growth inhibition compared to control growth (C) was calculated as Ti/ C x 100. Growth inhibition of 50% (GI50) was calculated from (Ti/ C) x 100 = 50, which is the drug concentration that inhibits cell growth by 50%. On the other hand, the percentage of reduced cell viability compared to cell viability at time zero (Tz) was calculated as Ti/Tz x 100. The LC50 (concentration of drug resulting in a 50% reduction in the measured cell viability at the end of the drug treatment as compared to that at the beginning), which indicates a net loss of cells following treatment, was calculated from (Ti/Tz) x 100 = 50.

Table 2 summarizes the mean GI50 and LC50 determined for each cell line after PM02734 exposure for 72 hours.

Table 2

Example 2

Antitumor activity of PM02734 in medulloblastoma was evaluated by using a cell line panel comprising 4 human tumor cell lines representative of medulloblastoma. Specifically, DAOY, D283 MED, D341 MED, and MED-MEB-8A were used. All cell lines were grown in a qualified incubator at 37°C in a humidified atmosphere with 5% CO2, and were cultured in the following media:

- DAOY cells were grown in RPMI- 1640 medium, supplemented with glutamine, FCS, and PSF

- D283 MED, D341 MED, and MED-MEB-8A cells were grown in DMEM, supplemented with glutamine, FCS, and PSF

The adherent growing cells were detached from the tissue culture flask with a trypsin/ EDTA solution.

The citotoxicity of the test drug was evaluated as described in Example 1 by using MTS-test.

Cells were inoculated on 96 well microtiter plates with 50 μL complete cell culture medium at a concentration of 50,000 cells/ mL in the case of DAOY, D283 MED, and MED-MEB-8A cells, and of 100,000- 300,000 cells/mL in the case of D341 MED cells. It was used the same methodology and drug concentrations as those described in Example 1. In addition, GI50 and LC50 were determined as disclosed in Example 1.

Table 3 summarizes the mean GI50 and LC50 determined for each cell line after PM02734 exposure for 72 hours.

Table 3

Claims

Claims:

1. A method for treating any mammal, notably a human, affected by a tu m o r s e l e c t e d fr o m Ewing's sarcoma, osteosarcoma, rhabdomyosarcoma and medulloblastoma, comprising administering to the affected individual a therapeutically effective amount of PM02734 or a pharmaceutical acceptable salt thereof.

2. The method according to claim 1 , wherein the tumor to be treated is Ewing's sarcoma.

3. The method according to claim 1 , wherein the tumor to be treated is rhabdomyosarcoma.

4. The method according to claim 1 , wherein the tumor to be treated is osteosarcoma.

5. The method according to claim 1 , wherein the tumor to be treated is medulloblastoma.

6. The method according to any of the preceding claims, wherein the patient is a human patient.

7. The use of PM02734, or a pharmaceutically acceptable salt thereof, in the manufacture of a medicament for a method according to any of the preceding claims.

8. A pharmaceutical composition comprising PM02734, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier or excipient, to be used in a method according to any of claims 1 to 6.

9. PM02734, or a pharmaceutically acceptable salt thereof, for use in a method according to any of claims 1 to 6.

10. A medical kit for administering PM02734, comprising printed instructions for administering PM02734 in a method according to any of claims 1 to 6, and a pharmaceutical composition comprising PM02734, or a pharmaceutical acceptable salt thereof, and a pharmaceutically acceptable carrier or excipient.