Satraplatin Slows Progression of Refractory Prostate Ca

ORLANDO—Satraplatin, an investigational oral platinum agent, given in combination with prednisone, slows the progression of hormone-refractory prostate cancer, according to the phase III Satraplatin and Prednisone Against Refractory Cancer (SPARC) trial presented at the 2007 Prostate Cancer Symposium (abstract 145). At 28 months of follow-up, satraplatin/prednisone reduced the risk of disease progression by 33%, compared with prednisone alone, in men with prostate cancer refractory to prior treatment with docetaxel (Taxotere)-based or non-docetaxel chemotherapy, said Daniel Petrylak, MD, associate professor of medicine, Columbia University College of Physicians and Surgeons.

The SPARC researchers randomized 950 men with hormone-refractory prostate cancer in a 2:1 fashion to receive satraplatin (80 mg/m²/d for 5 days) plus an antiemetic and prednisone or prednisone plus a placebo and a placebo antiemetic. Progression was a composite of two or more new lesions according to RECIST criteria, fractures, bone surgery, initiation of bisphosphonates, weight loss greater than 10%, increased pain as documented by increased use of pain-relieving medications, or death. The vast majority of progression events were based on radiological and pain progressions.

Since SPARC was designed in 2003 before FDA approval of docetaxel for refractory prostate cancer, patients were allowed to have prior chemotherapy with docetaxel or mitoxantrone. Bisphosphonate use could also be continued.

The median time to progression was 11.1 weeks for the satraplatin group, compared with 9.7 weeks for the placebo group (HR 0.67, P = .0000003).

Satraplatin was well tolerated, Dr. Petrylak reported. Less than 5% of patients had grade 3-4 hematologic toxicities. As expected, patients on satraplatin had more neutropenia, but of the 20% of satraplatin patients with neutropenia, just 0.6% developed neutropenic fevers.

Prior chemotherapy did not affect the efficacy of satraplatin, Dr. Petrylak said. "About half the patients had prior docetaxel as their chemotherapeutic treatment, but their median time to progression and progression-free survival were identical to those who did not, so it did not matter what prior chemotherapy these patients received," he said.

These findings suggest that satraplatin/prednisone could become a valuable second-line treatment option for hormone-refractory prostate cancer, Dr. Petrylak concluded. "This is significant, because there is currently no standard second-line therapy for these patients," he said.

Further data on the trial's primary endpoint, overall survival, will be presented at the annual meeting of the American Society of Clinical Oncology in Chicago this June, he added.

GPC Biotech, the company that developed satraplatin, will be going before the FDA for approval of the drug with hopes of a launch sometime later this year, Dr. Petrylak said. He disclosed that he owns equity in GPC Biotech, and receives funding and acts as a consultant for the company.