New Data from Several Satraplatin Clinical Trials in Solid Tumors Presented at 44th ASCO Annual Meeting

 

"We are pleased that data from several satraplatin clinical trials evaluating satraplatin in combination with a variety of widely used cancer treatments were selected for presentation at this year's ASCO Annual Meeting," said Bernd R. Seizinger, M.D., Ph.D., Chief Executive Officer of GPC Biotech.  "The information gained from these studies is helpful to GPC Biotech and others as we plan new trials with this active oral platinum-based compound."

 

The following are summaries of the highlighted presentations.

The primary objective of this study was to determine the maximum tolerated dose (MTD) of satraplatin and docetaxel (Taxotere®) in patients with advanced solid tumors when docetaxel was administered every three weeks.  Twenty-three patients were enrolled in the study.  The patient population was heavily pre-treated, with a median of two prior cytotoxic chemotherapy regimens. The recommended Phase II dose was satraplatin at 40mg/m2/day given on days 1-5 and docetaxel at 60mg/m2 given on day 1 of a three-week cycle, without G-CSF, and satraplatin at 50mg/m2/day given on days 1-5 and docetaxel at 70mg/m2 given on day 1 of a three-week cycle with G-CSF. G-CSF is used to promote the recovery of white blood cells. The most commonly reported adverse event was neutropenia (decrease in white blood cells) in 22% of patients, followed by anemia, diarrhea and fatigue.    Preliminary data show encouraging activity in men with high-grade androgen independent prostate cancer. As a result, this combination is currently being further explored in men with chemo-naïve, androgen independent prostate cancer.   

The primary objective of this study was to determine the MTD and Phase 2 recommended dose for satraplatin administered sequentially with capecitabine (Xeloda®).  Thirty-seven patients with a variety of solid tumors were treated in the study.  The MTD and recommended dose for Phase 2 was satraplatin at 70 mg/m2 and capecitabine at 1000 mg/m2/BID (twice daily). Hematological toxicity was the main dose-limiting toxicity.  In the 34 patients who were evaluated, there were three confirmed partial responses - two in platinum-sensitive ovarian cancer and one in prostate cancer patients, as well as six stable disease in prostate cancer patients.  These preliminary results suggest that the sequential administration of satraplatin and capecitabine may represent a well tolerated and convenient oral treatment for patients with advanced solid tumors.

Phase I study of oral platinum with concurrent radiation therapy in non small cell lung cancer -   Hak Choy, MD (Abstract #7560)

The objectives of this study were to determine the dose-limiting toxicities, MTD and recommended Phase 2 dose of satraplatin in combination with radiation therapy for patients with non-small cell lung cancer (NSCLC). Fifteen patients were enrolled in the study.  The recommended Phase 2 dose for this patient population is 30 mg/d each day of radiation treatment.  Dose limiting toxicities were Grade 3 pneumonia and Grade 3 elevated liver function. Of the eleven evaluable patients, eight had partial responses and three had stable disease.  These results suggest therapeutic synergy of satraplatin in combination with radiation for the treatment of NSCLC and provide a rationale for future studies with this combination.

 

Data from this oral presentation are discussed in a separate press release issued by GPC Biotech on June 2, 2008.

 

The Company also reported that data from two other satraplatin clinical trials, as well as in vitro data in multiple myeloma with the RGB-286638 kinase inhibitor, were published in the ASCO Annual Meeting Proceedings.

 

Cirstea, Diana et al, "Pleiotropic Activity of the Novel Cyclin-Dependent Kinase Inhibitor RGB 286638 Predicts Therapeutic Potential in Multiple Myeloma."  Researchers assessed the effect of RGB-286638, a novel broad-spectrum kinase inhibitor, on inhibiting tumor growth in conventional drug-sensitive and drug-resistant multiple myeloma cell lines and primary tumor cells from multiple myeloma patients.  The results demonstrated that RGB-286638 induces multiple myeloma cell death via the inhibition of cyclin-dependent kinase/cyclin complexes and cell cycle progression. In vivo studies are ongoing to assist in the design of clinical testing for RGB-286638 in multiple myeloma.

 

Spigel, D R et al, "Phase II Trial of Satraplatin (S) and Paclitaxel (P) in First-Line Advanced Non-Small Cell Lung Cancer (NSCLC) Treatment: Final Results."  This abstract reviewed the final results from the Phase 2 trial evaluating satraplatin plus paclitaxel (Taxol®) in patients with NSCLC.  Thirty-eight patients with newly-diagnosed NSCLC were enrolled in the study, and 28 patients were evaluable.  One complete response and six partial responses were observed (25.9% overall response rate).  The regimen was well tolerated and associated with limited Grade 3/4 toxicity when satraplatin was administered at 70 mg/m2 on days 1-5 every 28 days.  The results indicate that satraplatin appears to have activity that is similar to other platinum agents when combined with paclitaxel in first-line NSCLC treatment.    

Wisinski, K B et al, "A phase I study of the oral platinum agent satraplatin (S) with capecitabine (C) in patients (pts) with advanced solid malignancies." This abstract discussed results from a Phase 1 study evaluating the combination of satraplatin and capecitabine administered concurrently.  Twenty-two patients were enrolled in the study.  The dose-limiting toxicities were predominantly Grade 3/4 thrombocytopenia.  The MTD for satraplatin was 100 mg/m2 on days 1-5. No responses were observed, and there was significant toxicity when these two compounds were administered together. [Abstract on data from trial evaluating sequential administration of satraplatin with capecitabine discussed earlier in this release.]

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. 

 

RGB-286638 is a novel, broad-spectrum kinase inhibitor.  The compound has been shown in vitro to lead to the inhibition of the cell cycle, targeting all relevant cyclin-dependent kinases, and to the induction of apoptosis (programmed cell death).  RGB-286638 also inhibits other major kinases that are important in controlling the proliferation of cancer cells.  In a range of pre-clinical models in both solid and liquid tumors, this small molecule resulted in tumor regression and increased survival.  The program is expected to enter the clinic during 2008.  Clinical trials are planned in both solid and hematological tumors in Europe and the U.S.

 

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.

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