Inhibition of androgen synthesis results in high response rate in castration resistant prostate cancer
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-naive patients with castration resistant prostate cancer (CRPC), who had progressive disease despite treatment with LHRH analogues and multiple other hormonal therapies. To date, a total of 47 patients have been treated in the Phase I/II trial, including 15 patients treated in the Phase I portion of the trial and 32 patients treated in the Phase II portion of the trial. Of the 38 patients who were evaluable, all of the patients had radiological evidence of metastatic disease. Moreover, all of the patients had previously failed treatment with LHRH analogs and antiandrogens, while 20 patients (53%) had failed treatment with diethylstilboestrol and 19 patients (50%) had failed treatment with steroids.
In her poster and oral presentation, Dr. Alison Reid from The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust in the United Kingdom reported that 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.
In the 38 patients who were evaluable in the Phase I/II trial, 33 patients (87%) experienced a decline in prostate specific antigen (PSA) levels with 23 patients (61%) experiencing a confirmed decline in PSA levels of greater than 50%, and with 10 of the 38 patients (26%) 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.
Currently 21 of the 38 patients (55%) in the Phase I/II trial remain on study and are continuing to be treated with CB7630. For the 38 evaluable patients in the trial, the median time to PSA progression has not been reached and is currently estimated to be 252 days (8.4 months).
Abiraterone, an oral, irreversible CYP450c17 enzyme inhibitor appears to have activity in post-docetaxel castration resistant prostate cancer
The Phase II trial of CB7630 in patients with advanced prostate cancer who have failed docetaxel-based chemotherapy 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 resistant prostate cancer who have failed treatment with androgen deprivation therapy and failed treatment with first line docetaxel-based chemotherapy. To date, a total of 43 patients have been enrolled in the trial.
In his poster and oral presentation, Dr. Gerhardt Attard from The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust in the United Kingdom provided an update on the 30 patients in this Phase II trial who have been treated in the United Kingdom. Of these 30 patients, all of the patients had failed treatment wi th LHRH analogs and antiandrogens, 21 patients (70%) had failed treatment with steroids and 15 patients (50%) had failed treatment with diethylstilboestrol. Moreover, all of the patients in the study had failed treatment with docetaxel and 10 patients (33%) had failed treatment with an additional cytotoxic agent (mitoxantrone, estramustine, vinorelbine, cyclophosphamide).
Of the 30 patients who have been treated, CB7630 was well tolerated with only minimal toxicity in this post-docetaxel population. In the 21 patients who have been in the study for over 3 months, 10 patients (48%) experienced a confirmed decline in PSA levels of greater than 50% and 2 patients (10%) experienced PSA declines of greater than 90%. Of the 12 evaluable patients with measurable tumor lesions, 2 patients (17%) experienced confirmed partial radiological responses (as measured by the RECIST criteria), 1 patient (8%) experienced an unconfirmed partial response and 5 patients experienced ongoing stable disease (including one patient with a minor response). Individual patients treated with CB7630 also experienced improvement in pain and a reduction in opioid use. Twenty-eight of the 43 patients (65%) enrolled in this trial are still receiving treatment with CB7630.
Dr. Arie S. Belldegrun, M.D., FACS, Vice Chairman of the Board of Directors of Cougar Biotechnology, said, "The data on CB7630 presented at the ESMO Conference is important for several reasons. First, not only does it confirm the earlier signal of clinical activity in second line hormonal therapy patients, but it also for the first time demonstrates that CB7630 is capable of impacting time to progression in patients with metastatic disease. The time to progression data presented in the CB7630 trial compares favorably to that which has been reported for other currently used second line hormonal therapies. Second, the data provides additional confirmation of CB7630's activity in second line chemotherapy patients. As both addressable patient populations, including second line hormone therapy candidates and second line chemotherapy candidates, continue to represent significant unmet medical needs in CRPC, we believe that CB7630 has strong 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 ESMO. 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.
Alan H. Auerbach, Chief Executive Officer and President
Mariann Ohanesian, Director of Investor Relations
Russo Partners, LLC
David Schull, +1-212-845-4271
Andreas Marathovouniotis, +1-212-845-4253