Whether or not FDA is copacetic with the mITT analysis is something that will be revealed next month. Auxilium did not pursue a Special Protocol Assessment (SPA) with FDA to cover the design of the Xiaflex studies.
Xiaflex treatment causes a lot of side effects. Let's take a look at the most common adverse events reported in the two studies:
This is a list that will make any man wince: Penile hematomas, pain, swelling and hemmorrhage were all reported at vastly higher rates in the Xiaflex arm of the study compared to sham injections.
Weighed against the modest efficacy, the risk profile of Xiaflex is troublesome. Even if approved, it's hard to envision scenarios under which the drug is widely used in men with Peyronie's.
One more safety slide looking at serious adverse events (as if the list above wasn't serious?):
Note the three cases of "penile fracture" or "rupture" reported in Xiaflex-treated patients. No such fractures occurred in men treated with sham injections.
All three cases of penile fracture occurred during intercourse. One patient had sex within the 14-day period following a Xiaflex treatment when he was supposed to abstain. A second man's penile fracture was blamed on a "mis-thrust" during sex; while the third occurred during "vigorous intercourse."
All three penile ruptures were surgically repaired successfully.
The FDA approves drugs when the benefit outweighs risks. For Xiaflex, the benefit-risk equation is a tough call. Efficacy is modest at best and comes with significant side effects. Some men with Peyronie's are helped by Xiaflex, but does the drug do enough to be approved?
After looking at the data and the way the studies were conducted and analyzed, I say no. Close, but no.
-- Reported by Adam Feuerstein in Boston.