Cougar Biotechnology Presents Positive CB7630 Clinical Data at AACR Annual Meeting Late-Breaking Clinical Trials Session.

Interim Phase II Results Confirm Efficacy of CB7630 in Both Chemotherapy Naove and Chemotherapy Refractory Prostate Cancer Patients

LOS ANGELES -- Cougar Biotechnology, Inc. (OTCBB:CGRB) today announced that positive Phase I and Phase II data on the Company's prostate cancer drug candidate CB7630 (abiraterone acetate) was presented at the American Association for Cancer Research (AACR) Annual Meeting in Los Angeles, California. The data was presented in two oral presentations as part of a special session, Phase II Proof of Concept Late-Breaking Clinical Trials. These presentations are further detailed below:

Inhibition of androgen synthesis results in a high response rate in castration refractory prostate cancer: A Phase II clinical trial 

The Phase I/II trial of CB7630 was conducted at The Institute of Cancer Research and at The Royal Marsden NHS Foundation Trust in the United Kingdom. In the trial, CB7630 was administered orally, once daily, to chemotherapy-naove patients with castration refractory prostate cancer (CRPC), who had progressive disease despite treatment with LHRH analogues and multiple other hormonal therapies, including antiandrogens, diethylstilboestrol and dexamethasone. To date a total of 38 patients have been treated in the Phase I/II trial, including 15 patients treated in the Phase I portion of the trial and 23 patients treated in the Phase II portion of the trial. In his oral presentation, Dr. Gerhardt Attard from The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust in the United Kingdom reported that in the 38 patients treated in this trial, CB7630 was well tolerated at doses as high as 2000 mg/day with minimal toxicity. Moreover, no dose limiting toxicity has been observed in the trial to date.

Of the 30 patients who were evaluable in the Phase I/II trial, 18 patients (60%) experienced confirmed declines in prostate specific antigen (PSA) levels of greater than 50%, with 10 of the 30 patients (33%) experiencing PSA declines of greater than 90%. Of the 20 evaluable patients with measurable tumor lesions, treatment with CB7630 resulted in partial radiological responses (as measured by the RECIST criteria) in 11 patients (55%), with 7 patients demonstrating ongoing stable disease and 3 patients experienced regressing bone disease. Individual patients treated with CB7630 also experienced improvement in pain and a reduction in opioid use. Circulating tumor cells (CTC) were detected in 14 of 31 patients and changes in CTC counts were shown to correlate with changes in PSA.

Currently 27 (90%) of the 30 patients in the Phase I/II trial remain on study and continue to be treated with CB7630. Of the 15 patients in the Phase I portion of the trial, 12 patients (80%) are still receiving treatment with CB7630, with the average patient having received the drug for over 8.5 months and 4 patients having received the drug for over 12 months.

Abiraterone, an oral, irreversible CYP450c17 enzyme inhibitor appears to have activity in post-docetaxel castration refractory prostate cancer patients

The Phase II trial is being conducted at numerous locations in the United States and United Kingdom. In the trial, CB7630 is administered orally, once daily, to patients with castration refractory prostate cancer who have failed treatment with first line docetaxel based chemotherapy. The oral presentation was made by Dr. Alison H. M. Reid from The Institute of Cancer Research.

To date, 19 patients have been treated in this Phase II trial, with 13 of the patients having been treated for over 3 months. Of the 19 patients who have been treated, CB7630 was well tolerated with only minimal toxicity in this post-docetaxel population. In the 13 patients who have been on study for over 3 months, 8 patients (62%) experienced confirmed declines in PSA levels of greater than 50%, with 2 of the 13 patients (15%) experiencing PSA declines of greater than 90%. All 19 patients in this trial are still receiving treatment with CB7630. Individual patients treated with CB7630 also experienced improvement in pain and a reduction in opioid use. Circulating tumor cells (CTC) were detected in 14 of 19 patients and changes in CTC counts were shown to correlate with changes in PSA.

Dr. Arie S. Belldegrun, M.D., FACS, Vice Chairman of the Board of Directors of Cougar Biotechnology, said, "The data from both trials of CB7630 presented at AACR continues to support the potential role of the drug in the treatment of CRPC. Interestingly, CB7630 showed strong evidence of antitumor activity in patients who were both chemotherapy naove and chemotherapy refractory, both of which represent significant unmet medical needs in prostate cancer. We continue to have strong confidence in CB7630's potential in both of these patient populations." Alan H. Auerbach, Chief Executive Officer and President of Cougar Biotechnology, added, "We are pleased to be able to present data from both of these CB7630 trials at AACR. We look forward to continuing to provide updates on these ongoing trials at future cancer conferences and greatly look forward to the continued development of CB7630 in both the second line hormone therapy and second line chemotherapy settings."

About Cougar Biotechnology

Cougar Biotechnology, Inc. is a Los Angeles-based biotechnology company established to in-license and develop clinical stage drugs, with a specific focus on the field of oncology. Cougar's oncology portfolio includes CB7630, a targeted inhibitor of the 17-alpha hydroxylase/c17,20 lyase enzyme, which is currently being tested in Phase II clinical trials in prostate cancer; CB3304, an inhibitor of microtubule dynamics, which is currently in a Phase I trial in hematological malignancies; and CB1089, an analog of vitamin D, which has been clinically tested in a number of solid tumor types.

Further information about Cougar Biotechnology can be found at www.cougarbiotechnology.com.

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These statements are often, but not always, made through the use of words or phrases such as "anticipates," "expects," "plans," "believes," "intends," and similar words or phrases. These forward-looking statements include, without limitation, statements related to benefits to be derived from Cougar's drug development programs, including the potential advantages of CB7630 and its potential for use in the treatment of CRPC and in second line hormone and chemotherapy treatment settings. Such statements involve risks and uncertainties that could cause Cougar's actual results to differ materially from the anticipated results and expectations expressed in these forward-looking statements. These statements are only predictions based on current information and expectations and involve a number of risks and uncertainties. Actual events or results may differ materially from those projected in any of such statements due to various factors, including the risks and uncertainties inherent in clinical trials, and drug development and commercialization, including the uncertainty of whether results in testing of CB7630 will be predictive of results in later stages of development. For a discussion of these and other factors, please refer to Cougar's annual report on Form 10-KSB for the year ended December 31, 2006, as well as other subsequent filings with the Securities and Exchange Commission. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. This caution is made under the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. All forward-looking statements are qualified in their entirety by this cautionary statement and Cougar undertakes no obligation to revise or update this press release to reflect events or circumstances after the date hereof.