Cougar Biotechnology, Inc. (NASDAQ: CGRB) announced that results from ongoing Phase II clinical trials of Cougar's investigational drug CB7630 (abiraterone acetate) were presented at the ASCO Genitourinary Cancers Symposium that is currently taking place in Orlando, Florida. The data were presented today in two poster presentations. These presentations are further detailed below:

Abiraterone Acetate Plus Prednisone in Chemotherapy Naïve Castration Resistant Prostate Cancer (CRPC) Patients Not Exposed to Ketoconazole: Results of a Multicenter Phase II Study Conducted by the DOD Prostate Cancer Clinical Trial Consortium

A Phase II clinical trial of CB7630 (COU-AA-002) is being conducted by The Prostate Cancer Clinical Trials Consortium, a national clinical research group sponsored by the Department of Defense, with Dr. Charles J. Ryan, Associate Professor of Clinical Medicine at the University of California, San Francisco Comprehensive Cancer Center as the principal investigator. In this Phase II trial, CB7630 in combination with prednisone is administered once daily to chemotherapy-naïve, ketoconazole-naïve patients with castration resistant prostate cancer (CRPC), who had progressive disease despite treatment with LHRH analogues and other hormonal therapies. Twenty-six (79%) of the 33 patients who were enrolled in the trial had radiological evidence of metastatic disease with bone metastases, 15 patients (45%) had lymph node metastases and 2 patients (6%) had visceral metastases.

In his poster presentation, Dr. Ryan presented data on the 31 evaluable patients treated in the trial. Of these patients, 24 (77%) experienced a decline in prostate specific antigen (PSA) levels of greater than 30%, 22 (71%) experienced a PSA decline of greater than 50% and 8 (26%) experienced PSA declines of greater than 90%. For the 31 evaluable patients, the median time to PSA progression has not yet been reached, with patients continuing to be treated for 10+ months.

Of the 33 evaluable patients with tumor lesions that were measurable by the RECIST criteria, treatment with CB7630 resulted in partial radiological responses in 8 patients (24%), stable disease in 13 patients (39%) and progressive disease in 4 patients (12%); 8 patients (24%) are awaiting radiographic disease assessment.

Identification of an Androgen Withdrawal Responsive Phenotype in Castrate Resistant Prostate Cancer (CRPC) Patients Treated with Abiraterone Acetate (COU-AA-BMA)

The COU-AA-BMA clinical trial of CB7630 is being conducted at The University of Texas M.D. Anderson Cancer Center (MDACC) in order to investigate associations between serum and microenvironment (bone marrow) androgen concentrations and response to CB7630. In this Phase II trial, CB7630 in combination with prednisone was administered orally, once daily, to patients with CRPC, who had progressive disease despite treatment with LHRH analogues and multiple other therapies. All of the 53 patients who were enrolled in the trial had radiological evidence of metastatic disease with bone metastases. Forty-two patients (79%) had at least 10 metastatic bone lesions, 7 patients (13%) had visceral metastases and 15 patients (28%) had lymph node metastases. Twenty-eight (53%) of the 53 patients had received prior treatment with ketoconazole and/or diethylstilbesterol and 44 patients (83%) had received prior treatment with chemotherapy, with 28 patients (53%) having received two or more prior chemotherapy regimens before entering the trial.

In her poster presentation, Dr. Eleni Efstathiou from MDACC presented data on the 50 evaluable patients treated in the trial. Of the 50 evaluable patients, 24 patients (48%) experienced a confirmed decline in PSA levels of greater than 50%. In addition, 6 patients (12%) experienced PSA declines of greater than 90%. For the 50 evaluable patients, the median duration of treatment was 41 weeks (10.3 months). Twenty-five (50%) of the 50 patients experienced an improvement in performance status.

Of the 21 patients re-evaluated with radiographic imaging studies after six months of treatment, 4 patients (19%) showed an improvement in their bone scan and 15 patients (71%) showed a stable bone scan. Also, 2 (40%) of 5 patients with lymph node metastases showed a partial radiological response (as measured by the RECIST criteria) and 3 patients (60%) with lymph node metastases showed stable disease after six months of treatment with CB7630. Lastly, 1 of 2 patients with liver metastases demonstrated a partial radiological response (as measured by the RECIST criteria).

Both serum and bone marrow testosterone levels were measured before and after treatment with CB7630. A decline in both serum and bone marrow testosterone levels to below detectable levels (

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