New Data From Satraplatin Phase 3 Trial In Second-Line Castrate-Refractory Prostate Cancer Presented At 2009 ASCO Annual Meeting

Main Category: Prostate / Prostate Cancer
Also Included In: Cancer / Oncology;  Clinical Trials / Drug Trials
Article Date: 04 Jun 2009 - 1:00 PDT

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GPC Biotech AG (FRANKFURT: GPC) (XETRA: GPC) announced that data from the double- blind, randomized satraplatin Phase 3 trial, the SPARC trial (Satraplatin and Prednisone Against Refractory Cancer), were presented at the 2009 American Society for Clinical Oncology (ASCO) Annual Meeting in Orlando, Florida. The SPARC trial evaluated satraplatin plus prednisone versus placebo plus prednisone in 950 patients with castrate-refractory prostate cancer (CRPC) who had progressed after initial chemotherapy. The data presented are retrospective analyses of the SPARC trial evaluating correlations between overall survival (OS) and pain at baseline, pain progression, and progression-free survival (PFS) at three months.

One presentation ("Use of pain at baseline and pain progression to predict overall survival in patients with docetaxel pretreated metastatic castration-refractory prostate cancer: results from the SPARC trial," Sartor et al, Abstract #5148), analyzed the docetaxel-pretreated population (n=488) in two separate ways:

-- The first analysis compared OS in those patients who had no pain (Present Pain Intensity (PPI) score less than or equal to 1) vs. those with pain (PPI greater than or equal to 2) at time of entry to the trial.

-- The second analysis compared OS in those patients who experienced pain progression versus progression by pre-specified measures other than pain (as judged by the blinded Independent Review Committee (IRC)).

Shorter OS time was observed in docetaxel-pretreated patients who had pain at baseline compared to those who did not. The median survival of patients with baseline pain (n=178) was 44 weeks versus 72 weeks for patients without baseline pain (n=287) [stratified hazard ratio: 0.59 (95% CI: 0.48-0.74), stratified log-rank p less than 0.0001]. The IRC found that 414 docetaxel-pretreated patients (84.8%) progressed as of the data cutoff date for the SPARC study. Of these, the median survival of patients showing pain progression (n=196) was 47 weeks, compared to 71 weeks for non-pain progressors (n=292) [stratified hazard ratio: 0.71 (95% CI: 0.57-0.87), stratified log-rank p=0.0022]. Thus, pain at baseline, as well as pain progression, were prognostic indicators of OS in the docetaxel-pretreated patient population.

A second presentation ("Correlation of progression-free survival and overall survival in men with metastatic castration-resistant prostate cancer who failed first-line chemotherapy: results from the SPARC trial," Halabi et al, Abstract #5150) evaluated whether PFS at three months was predictive of OS and explored the statistical dependencies between PFS and OS. Of the 853 men alive at three months post-randomization, 477 (56%) had already progressed. The median survival for this group was 34.5 weeks versus 78.7 weeks in men who had not progressed at the same three months timepoint. [hazard ratio: 2.16 (95% CI=1.84-2.55), p-value less than 0.001]. The dependence between PFS and OS was 0.29 (95% confidence limits=0.24-0.33, p-value less than 0.00001). Thus PFS at three months was predictive of OS. Additional studies will be needed to assess the clinical relevance of the individual components of progression as defined in the SPARC trial to OS.

Data from other Phase I and Phase II clinical trials evaluating satraplatin in combination with other cancer therapeutic drugs were published in the 2009 ASCO Annual Meeting Proceedings:
- Phase II trial of bevacizumab and oral satraplatin and prednisone in docetaxel pretreated metastatic castrate resistant prostate cancer - Vaishampayan et al (Abstract #e16028).
- Dose finding study of the combination of satraplatin and gemcitabine in patients with advanced solid tumors - Di Paola et al (Abstract #e13534).
- A phase I study investigating the combination of orally bioavailable platinum and nonparticle albumin-bound paclitaxel in advanced solid tumors - Deshpande et al (Abstract #e13501).

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. GPC Biotech has a license agreement with Yakult Honsha Co. Ltd. under which Yakult has exclusive commercialization rights to satraplatin for Japan. GPC Biotech is currently in discussions with Yakult regarding further development and registrational efforts for satraplatin. GPC Biotech in-licensed satraplatin from Spectrum Pharmaceuticals, Inc.

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GPC Biotech