The News

Diatos Launches Two International Multi-center Phase II Clinical Trials for DTS-201 in Prostate and Breast Cancer

05/08/2008

Paris, France, 5 August 2008 – Diatos SA, an international biopharmaceutical company focusing on the research, development and commercialization of targeted anti-cancer drugs, announced today the recruitment of the first patient into Phase II clinical trials for DTS-201, a peptidic prodrug of doxorubicin. Two international trials will evaluate the safety and efficacy of DTS-201 as a second line therapy for patients with hormone refractory prostate cancer and as first line therapy in human epidermal growth factor receptor-2 (HER2/neu)-negative metastatic breast cancer.

DTS-201 Prostate Cancer Phase II Trial
The first patient has been treated in the clinical Phase II study of DTS-201 for hormone refractory prostate cancer patients. It is an open-label, multi-center, single-arm study conducted in eight investigational centers in Italy, France and Belgium. The world class expert in prostate cancer, Professor Cora Sternberg of the Dipartimento di oncologia medica at the Azienda Ospedaliera San Camillo and Forlanini in Rome is the Coordinating Investigator for the study. The primary objective of the study is to determine a reduction in Prostate Specific Antigen (PSA). Safety, time to PSA progression, tumor response for measurable lesions (using the RECIST criteria), duration of response, progression free survival and overall survival will be evaluated as secondary objectives.
                                
DTS-201 Breast Cancer Phase II Trial
The primary objective of this pilot Phase II study will be to assess the overall objective response rate of DTS-201 in locally advanced and metastatic breast cancer. Safety, duration of response and progression free survival (PFS) will be assessed as secondary objectives. Four breast cancer centers have been opened in the Republic of South Africa to undertake this open-label breast cancer study lead by Professor Lydia Mary Dreosti from the Pretoria Academic Hospital.

DTS-201 is a doxorubicin prodrug developed for the targeted treatment of several solid cancers, including chemo-resistant tumors. The prodrug is activated by enzymes selective for the tumor environment. At ASCO 2007, Diatos presented Phase I clinical trial data demonstrating DTS-201 to be well tolerated and able to deliver much higher doses of doxorubicin than previously possible. The DTS-201 Phase I trial also indicated promising early signs of efficacy.

President & CEO of Diatos Dr. John Tchelingerian, PhD, commented on today’s announcement, “The initiation of these international DTS-201 Phase II trials marks an important milestone, not only for the progress in development of this targeted doxorubicin prodrug since it was in-licensed at a preclinical stage from our partner Medarex, but also as a validation of the maturity and clinical relevance of Diatos’ Tumor Selective Prodrug platform technology”.

According to Diatos’ Chief Medical Officer Dr. Jamal Gasmi, MD, “The simultaneous assessment of DTS-201 in breast and prostate cancer reflects our confidence in our prodrug’s potential to treat many types of solid cancers, including tumors which are currently not treated with or are not sensitive to doxorubicin.”
 

About DTS-201
DTS-201 consists of doxorubicin, a marketed cytotoxic agent effective against a wide variety of solid tumors, conjugated to a proprietary first generation peptide similar to the company’s second generation Tumor-Selective Prodrug (TSP) technology. The product was discovered in 1996 by Pr André Trouet and his team at the Université Catholique de Louvain, Belgium and in-licensed from Medarex Inc in April 2003 for exclusive EU rights. DTS-201 is also known as Super-Leu-Dox or CPI-0004Na in the USA. DTS-201 completed Phase I clinical studies in Belgium and France in October 2007.
DTS-201 is a prodrug designed to preferentially deliver doxorubicin to tumors as opposed to normal tissues. It consists of the tetrapeptide N-succinyl-β-alanyl-L-leucyl-L-alanyl-L-leucine covalently linked to the aminoglycoside portion of doxorubicin. The DTS-201 concept is based on the inactivation of doxorubicin by the coupling of a tetrapeptidic sequence that prevents cellular uptake. DTS-201 is stable in blood but cleavable by some specific peptidases present in the tumor environment. Preclinical studies have demonstrated that DTS-201 was less toxic in vivo models than free doxorubicin and significantly more effective in a wide panel of human tumor xenograft models.

Tumor Selective Prodrug (TSP) technology
Capitalising on its breakthrough with DTS-201 in the clinic, Diatos is currently utilising its patented TSP technology platform to create families of novel and robust prodrugs of a wide range of pharmacologically active drugs, including small molecules and proteins. The technology enables the conjugation of specifically designed second generation peptides with cancer drugs. The resulting new molecules are inactive while circulating in the body and activated in a tumor microenvironment. The molecules are cleaved by tumor-specific peptidases (enzymes) overproduced and released by tumor cells (CD-10 and TOP), thereby releasing the pharmacologically active form of the anti-cancer molecules to target cancer cells.

About Diatos
Diatos is a biopharmaceutical company dedicated to the research, development and commercialization of innovative anti-cancer drugs with enhanced tumor targeting or improved biodistribution. Diatos is expanding its portfolio of drug candidates with new compounds that utilize its Vectocell® delivery technology or its Tumor-Selective Prodrug (TSP) technology as well as with in-licensed candidate and marketed cancer therapies. Diatos is headquartered in Paris, France and operates subsidiaries in Belgium and the United States of America.

About Diatos’ other portfolio products
> DaunoXome®, a liposomal formulation of widely used cancer drug daunorubicin, improves the biodistribution of daunorubicin and fosters its sustained release in the blood, which potentially allows the administration of higher doses than with non-liposomal formulations. DaunoXome is marketed in Kaposi’s sarcoma and is being re-launched in acute leukaemia in Europe. DaunoXome was in-licensed from Gilead Sciences, Inc.
>  DTS-301, a paclitaxel depot formulation in the polymer gel ReGel®, releases paclitaxel, a widely used cancer drug, directly to the tumor site, avoiding systemic side effects. DTS-301 is in Phase II clinical stage in head and neck cancers and was in-licensed from Protherics PLC.
> DTS-108 is a prodrug of SN38, the active metabolite of the widely-used cancer drug irinotecan, and is based on Diatos' Vectocell® technology. DTS-108 aims to increase the efficacy of SN38 while reducing the toxic effects of irinotecan. DTS-108 is in preclinical development.
For further information please visit: www.diatos.com

Diatos is a registered trademark of Diatos SA, Paris, France.

Contacts:

Media

College Hill Life Sciences
Justine Lamond / John McIntyre / Cosima Zerdik
Tel: +44 (0)20 7866 7857
E-mail: diatos@collegehill.com 
 Investors

Diatos SA
President & CEO
Dr John Tchélingérian
Tel: + 33 (0)1 53 80 93 40
Email:Jtchelingerian@diatos.com