Cougar Biotechnology’s once-daily oral drug CB7630 (abiraterone acetate), based on recently announced trial results, appears o have some efficacy at two stages of the standard treatment path for androgen independent prostate cancer — either before or after chemotherapy.

A UK Phase I/II trial of CB7630 reports positive signs among a small number of patients enrolled so far in a trial for AIPC men who have never taken chemotherapy but have taken LHRH analogues and multiple other hormonal therapies, including antiandrogens, diethylstilboestrol and dexamethasone. In addition, a Phase II trial ongoing at several US centers and in the UK indicates that CB7630 may benefit some patients who have used up Taxotere (docetaxel) chemotherapy.

CB7630 (abiraterone acetate) is reported to have “minimal toxicity” (as yet no maximum tolerated dose has been reached). Among the small numbers of patients treated so far, benefits include lowering of PSA’s, some tumor shrinkage, and some pain reduction. In one of the trials, out of “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.”

The company says CB7630 “has the potential to be used by both urologists who treat patients with second line hormonal therapies and by medical oncologists who treat patients in the second line chemotherapy setting…” To that end, the company chose to announce results at AACR, aiming the presentation toward oncologists, and again at AUA:

Cougar Biotechnology Announces Interim Phase II Results Confirm
Efficacy of CB7630 in Both Chemotherapy Naïve and Chemotherapy
Refractory Prostate Cancer Patients April 17 (posted May 31) 2007.

Cougar . . . Presentation of Positive CB7630 (abiraterone acetate)
Clinical Data at AUA Annual Meeting May 21 (posted May 31), 2007

For three UK and US trials ongoing see:
clinicaltrials.gov/ct/search?term=CB7630&submit=Search