AEterna Zentaris’ stock dropped over 65% after initial Phase III efficacy results of its benign prostatic hyperplasia (BPH) treatment, cetrorelix pamoate, failed to show a statistically significant improvement. Safety data from a separate trial were good, and the firm will thus continue two more planned efficacy studies.
The North American efficacy trial called Z-033 was a double-blind, multicenter efficacy study conducted in 53 sites in the U.S. and Canada with eight additional sites in Europe and involved 667 patients. Patients in treatment arm A were administered cetrorelix by intramuscular (IM) injection at weeks 0, 2, 26, and 28. Those in arm B received IM injection at weeks 0, 2, and 26 followed by placebo at week 28. Patients in treatment arm C received placebo injections at weeks 0, 2, 26, and 28. All patients were followed up to week 52.
Patients completing this 52-week study will continue into an open-label extension, sponsored by sanofi-aventis, where patients receive the same dosing regimen of cetrorelix by IM injection at weeks 52, 54, 78, and 80. They will be followed up to week 90.
Another multicenter Phase III efficacy study called Z-036 for which patient recruitment was completed in October 2008, involves 420 patients, mainly in Europe. Patients in this randomized placebo-controlled study with open-label extension will receive cetrorelix according to similar dosing regimens used in the first efficacy study Z-033. Results are scheduled to be disclosed during the fourth quarter of this year.
The primary endpoint for both North American and European efficacy studies is absolute change in IPSS between baseline and week 52. Other efficacy endpoints include additional measures of BPH symptom progression and the need for BPH-related surgery. Safety endpoints include changes in sexual function. Other important endpoints include plasma changes in levels of testosterone and assessment of other adverse events.