Data From Satraplatin SPARC Phase 3 Trial In Patients With Hormone-Refractory Prostate Cancer Progressing After Initial Chemotherapy

Main Category: Prostate / Prostate Cancer
Also Included In: Urology / Nephrology;  Cancer / Oncology
Article Date: 03 Jun 2008 - 1:00 PDT

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GPC Biotech AG (Frankfurt Stock Exchange: GPC, NASDAQ: GPCB) announced the presentation of the overall survival results from the double-blind, randomized satraplatin Phase 3 registrational trial, the SPARC trial (Satraplatin and Prednisone Against Refractory Cancer). The data were presented at the 44th Annual Meeting of the American Society for Clinical Oncology (ASCO) in Chicago. The SPARC trial evaluated satraplatin plus prednisone versus placebo plus prednisone in 950 patients with hormone-refractory prostate cancer (HRPC) that had progressed after initial chemotherapy.

While data presented previously did show a statistically significant improvement in the progression-free survival endpoint, the trial did not achieve the endpoint of overall survival (p=0.80, log rank analysis) for the intent-to-treat (ITT) population. The median was 61.3 weeks for the satraplatin arm compared to 61.4 weeks for the control group, and the hazard ratio, stratified by the pre-specified randomization factors1, was 0.98 (95% CI: 0.84, 1.15). The median in the patient group previously treated with docetaxel (Taxotere®) was 66.1 weeks for the satraplatin arm compared to 62.9 weeks for the control arm. The stratified hazard ratio was 0.91 (95% CI: 0.72, 1.14).

When adjusted for the three pre-specified prognostic factors which showed statistically significant imbalances between the two treatment arms (lactate dehydrogenase, hemoglobin and alkaline phosphatase), the hazard ratio for the ITT group was 0.88 (95% CI: 0.74, 1.03). Importantly, when adjusted for the three significant prognostic factors, there was a positive trend observed in those patients who had progressed after receiving docetaxel, with a hazard ratio of 0.78 (95% CI: 0.61, 0.99).

"There is a need for new therapies for patients with hormone-refractory prostate cancer whose disease has progressed after initial chemotherapy treatment," said A. Oliver Sartor, M.D., Piltz Endowed Professor of Cancer Research and Professor of Medicine and Urology, Tulane Medical School, and one of the principal investigators of the SPARC trial. "While satraplatin did not improve overall survival in the intent-to-treat population, there was a positive trend observed in patients who progressed after Taxotere treatment when adjusted for significant prognostic factors. Additionally, I believe that satraplatin has been shown to be a well tolerated treatment that has demonstrated an important benefit for patients by showing a statistically significant improvement in progression-free survival, as well as pain, tumor and PSA response rates in the overall patient population."

Of note, a significant number of patients received additional cancer therapies after they progressed in the SPARC trial. In the control arm, 68.6% of patients received some form of third-line therapy, including chemotherapy, immunotherapy and other treatments, versus 61.7% of patients in the satraplatin arm. In the control arm, 52.4% of patients received chemotherapy compared to 44.7% in the satraplatin arm, and 24.4% of patients in the control arm were treated with Taxotere following progression in the SPARC trial compared to 18.3% in the satraplatin arm. Taxotere is considered the standard of care in the first-line treatment of HRPC patients in the United States and many countries in Europe.

Safety findings in the SPARC trial were consistent with previous clinical studies involving satraplatin. Myelosuppression (decrease in the production of blood cells by the bone marrow) was the most common adverse reaction associated with satraplatin therapy, with 98.9% of patients in the satraplatin arm experiencing myelosuppression of any grade. A total of 22.6% of patients in the satraplatin arm experienced grade 3 or 4 thrombocytopenia; 14.5% had grade 3 or 4 leucopenia; 22.3% had grade 3 or 4 neutropenia and 11.9% experienced grade 3 or 4 anemia. Gastrointestinal toxicities of any grade were the most frequent non-hematological adverse events (occurring in 59.5% of the patients receiving satraplatin). A total of 7.8% of patients in the satraplatin arm experienced grade 3 or 4 gastrointestinal toxicities, including nausea (1.4%), vomiting (1.6%), diarrhea (1.9%) and constipation (1.9%). Additionally, 5% or less of patients in the satraplatin arm experienced grade 3 or 4 fatigue (1.9%), grade 3 or 4 infections (4.3%) and pulmonary/respiratory grade 3 or 4 toxicities (3.3%).

About Satraplatin

Satraplatin, an investigational drug, is a member of the platinum family of compounds. Platinum-based drugs are a critical part of modern chemotherapy treatments and are used to treat a wide variety of cancers. All platinum drugs currently on the market require intravenous administration. Satraplatin is an oral compound that clinical trial patients are able to take at home. A Marketing Authorization Application for satraplatin in combination with prednisone is currently under review in Europe for the treatment of hormone-refractory prostate cancer patients whose prior chemotherapy has failed. A decision on the filing by the European regulators is expected in the second half of 2008. Celgene Corporation is responsible for the regulatory filings for satraplatin and its development and commercialization for Europe and certain other territories. GPC Biotech also has a license agreement with Yakult Honsha Co. Ltd. under which Yakult has exclusive commercialization rights to satraplatin for Japan and is taking the lead in developing the drug in that territory. GPC Biotech in-licensed satraplatin from Spectrum Pharmaceuticals, Inc. in 2002.

About GPC Biotech

GPC Biotech AG is a publicly traded biopharmaceutical company focused on anticancer drugs. GPC Biotech's lead product candidate is satraplatin, an oral platinum compound. The Company has various anti-cancer programs in research and development that leverage its expertise in kinase inhibitors. GPC Biotech AG is headquartered in Martinsried/Munich (Germany) and has a wholly owned U.S. subsidiary in Princeton, New Jersey. For additional information, please visit GPC Biotech's Web site at http://www.gpc-biotech.com.

This press release contains forward-looking statements, which express the current beliefs and expectations of the management of GPC Biotech, including statements about the efficacy and safety of satraplatin. Such statements are based on current expectations and are subject to risks and uncertainties, many of which are beyond our control, that could cause future results, performance or achievements to differ significantly from the results, performance or achievements expressed or implied by such forward-looking statements. Actual results could differ materially depending on a number of factors, and we caution investors not to place undue reliance on the forward-looking statements contained in this press release. Satraplatin may not be approved for marketing in a timely manner, if at all. We direct you to GPC Biotech's Annual Report on Form 20-F for the fiscal year ended December 31, 2006 and other reports filed with the U.S. Securities and Exchange Commission for additional details on the important factors that may affect the future results, performance and achievements of GPC Biotech. Forward-looking statements speak only as of the date on which they are made and GPC Biotech undertakes no obligation to update these forward-looking statements, even if new information becomes available in the future.

Satraplatin has not been approved by the FDA in the U.S., the EMEA in Europe or any other regulatory authority and no conclusions can or should be drawn regarding its safety or effectiveness. Only the relevant regulatory authorities can determine whether satraplatin is safe and effective for the use(s) being investigated.

Taxotere® is a registered trademark of Aventis Pharma S.A.

1 The three pre-specified randomization factors for the SPARC trial were: 1) performance status at study entry, 2) present pain intensity at study entry, and 3) type of disease progression on first line therapy (PSA or symptomatic).

GPC Biotech

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