Ascenta Therapeutics Inc., of Malvern, Pa., reported preliminary results from its Phase II study showing that AT-101 can be safely administered in combination with docetaxel and prednisone in men with docetaxel refractory, castrate-resistant prostate cancer. Investigators also observed clinical responses, based on both prostate-specific antigen (PSA) levels and RECIST criteria, including four patients with a confirmed partial response (defined as a PSA decline of 50 percent or greater). Data were presented at the American Society of Clinical Oncology Genitourinary Cancers Symposium in Orlando, Fla. AT-101 is a pan-Bcl-2 inhibitor that also is in testing for non-small-cell lung cancer.
Biotech AG, of Munich, Germany, said data from the double-blind, randomized satraplatin Phase III trial, the SPARC trial (Satraplatin and Prednisone Against Refractory Cancer) showed it warrants additional testing in prospectively designed trials in docetaxel-refractory prostate cancer patients. When stratified and adjusted for the three prespecified prognostic factors, which showed statistically significant imbalances between the two treatment arms (lactate dehydrogenase, hemoglobin and alkaline phosphatase), there was a positive trend toward better overall survival for the patients treated with satraplatin observed in three groups: those patients who had progressed after receiving docetaxel - hazard ratio 0.78 (95 percent CI: 0.61, 0.99); the R1 group - hazard ratio 0.65 (95 percent CI: 0.47, 0.90); and the R2 group - hazard ratio 0.69 (95 percent CI: 0.49, 0.96). Data were presented at the American Society of Clinical Oncology's Genitourinary Cancer Symposium in Orlando, Fla.
Cell Genesys Inc., of South San Francisco, said results from further analyses of VITAL-1, its terminated Phase III trial, which compared GVAX immunotherapy for prostate cancer to Taxotere (docetaxel) chemotherapy plus prednisone, had some upside. The final Kaplan-Meier survival curves for the two treatment arms suggested a late favorable effect on patient survival compared to chemotherapy. Additionally, the data suggested that patients with Halabi-predicted survival greater than or equal to 18 months may have a more favorable response to the immunotherapy. Additionally, a further analyses of VITAL-2, the company's second Phase III trial of GVAX for prostate cancer used in combination with Taxotere. VITAL-2, which compared GVAX for prostate cancer in combination with Taxotere to Taxotere plus prednisone "was prematurely terminated" in August 2008 following the recommendation of the trial's monitoring committee, which observed an imbalance in deaths between the two treatment arms. Updated analyses show no significant toxicities in the GVAX plus Taxotere arm that could explain the imbalance, the company said. Eighty-five percent of deaths were reported as due to prostate cancer in both arms, and there was no trend in the causes of death in the remaining patients. Those observations were consistent with the hypothesis that the decision to omit concomitant prednisone in the GVAX immunotherapy treatment arm to avoid the immunosuppressive effects of prednisone may have contributed to an unfavorable outcome compared to the combination of chemotherapy and prednisone, Cell Genesys said. Additionally, it said, further analyses of VITAL-2 "have indicated that the imbalance in deaths between the two treatment arms has decreased from 20 deaths as reported at that the time of the IDMC's initial analysis . . . to nine deaths at the time of the final analysis" in December 2008. Data were presented at the American Society of Clinical Oncology's Genitourinary Cancer Symposium in Orlando, Fla. (See BioWorld Today, Oct. 17, 2008, and Aug. 28, 2008.)
Cougar Biotechnology Inc., of Los Angeles, announced positive results from ongoing Phase II trials of CB7630 (abiraterone acetate). In one presentation, data on 31 evaluable patients in a trial of abiraterone acetate plus prednisone in chemotherapy-naïve castration-resistant prostate cancer (CRPC) patients not exposed to ketoconazole showed 24 (77 percent) experienced a decline in prostate-specific antigen (PSA) levels of greater than 30 percent, 22 (71 percent) experienced a PSA decline of greater than 50 percent and eight (26 percent) experienced PSA declines of greater than 90 percent. For those patients, the median time to PSA progression has not yet been reached, with patients continuing to be treated for 10+ months. Another trial on identification of an androgen-withdrawal responsive phenotype in CRPC patients treated with abiraterone acetate showed that of the 50 evaluable patients, 24 (48 percent) experienced a confirmed decline in PSA levels of greater than 50 percent. In addition, six patients (12 percent) experienced PSA declines of greater than 90 percent.