Xiapex is a mixture of two collagenases produced by the bacterium Clostridium histolyticum. The two enzymes have complementary substrate specificity, as they cleave interstitial collagen at different sites. The product is injected directly into a Peyronie's plaque, causing collagen lysis and plaque disruption.
Approval for use of Xiapex in Peyronie's disease was based on the results of two identical studies (IMPRESS I and IMPRESS II) involving 832 men with penile curvature deformity of at least 30 degrees. Participants were randomised to undergo up to four treatment cycles with Xiapex (n=551) or placebo (n=281) at weeks 0, 6, 12 and 18 with follow-up during weeks 24 to 52. Each treatment cycle comprised two injections one to three days apart followed by a penile modelling procedure one to three days after the second injection.
Xiapex significantly improved penile curvature deformity compared with placebo (percent change from baseline to week 52, -34.0% versus -18.2% [p<0.001]) and significantly reduced patient-reported 'bother' (percent change in Bother domain score of Peyronie's Disease Questionnaire from baseline to week 52, -2.8 versus -1.8% for placebo [p=0.0037]).
The most frequently reported adverse events in collagenase-treated men included penile ecchymosis, penile swelling and penile pain. Serious treatment-related adverse events, including corporal rupture and penile haematoma, occurred in six men.
Xiapex is also indicated for the treatment of Dupuytren's contracture in adults with a palpable cord.