GPC Biotech, a publicly traded biopharmaceutical company, has reported encouraging data from the double-blind, randomized satraplatin Phase III trial, the Sparc trial.
The Sparc trial evaluated satraplatin plus prednisone versus placebo plus prednisone in 950 patients with androgen-independent or castrate-refractory prostate cancer (CRPC) who had progressed after initial chemotherapy.
Of the 950 patients in the Sparc trial, 488 received first-line docetaxel. As there is no universally accepted definition of docetaxel-refractory CRPC patients, two definitions were adopted based on the literature: R1) disease progression while on docetaxel or within 100 days of the last docetaxel dose; and R2) disease progression while on docetaxel or within 50 days of the last docetaxel dose. Both R1 and R2 patients were randomized to the Sparc trial within 100 days of receiving their last docetaxel dose.
When stratified and adjusted for the three pre-specified prognostic factors which showed statistically significant imbalances between the two treatment, there was a positive trend toward better overall survival for the patients treated with satraplatin observed in the following three groups: in those patients who had progressed after receiving docetaxel – hazard ratio 0.78 (95% CI: 0.61, 0.99); in the R1 group – hazard ratio 0.65 (95% CI: 0.47, 0.90) and in the R2 group – hazard ratio 0.69 (95% CI: 0.49, 0.96). Safety findings in the SPARC trial were consistent with previous clinical studies involving satraplatin.
Daniel Petrylak, one of the principal investigators of the Sparc trial, said: There are currently no approved treatment options for advanced prostate cancer patients once they become refractory to docetaxel. Thus, there is an urgent need for new therapies for these patients.
I am encouraged by the positive trends in overall survival observed in patients refractory to docetaxel when adjusted for significant prognostic factors, along with the treatment’s safety profile. These findings warrant additional testing in prospectively designed trials in docetaxel-refractory CRPC patient populations.