Peyronie’s disease is characterized by a plaque or hard lump that occurs on the penis. It begins as a localized inflammation, which progresses to a hardened scar that reduces flexibility and causes the penis to bend during erection. This causes pain on erection and in some circumstances may prevent sexual intercourse altogether. Aside from the physical consequences, depression and loss of self-esteem are common in men with Peyronie’s disease. It is currently believed that Peyronie’s disease is caused by vascular trauma or injury to the penis. Peyronie’s disease is most common in men over 50 years, and the incidence increases with age.
Generally, Peyronie’s disease is treated by urologists. There are no approved drug therapies for Peyronie’s disease. Surgical treatment may be an option for some patients, although complications as well as loss of penile length can occur. Xiaflex is injected intralesionally into the affected area in an in-office procedure with the intent to soften the scar tissue and reduce the curvature of the penis. This is expected to improve sexual function and minimize the negative psychosocial aspects of the disease.
Clinical Trial Results
The first phase II trials, sponsored and monitored by BioSpecifics Technologies Corp., licensor of Xiaflex, with follow up and data analysis conducted by Auxilium, showed promising results. Both studies were open label and up to 12 months in duration. The trials were conducted to evaluate the efficacy and tolerability of Xiaflex in the treatment of Peyronie's disease. Clinical success was defined as change from baseline in deviation angle of at least 25%.
In Study A (n=25), three injections of Xiaflex, each administered on a separate day, were given over seven to ten days. Patients received a second series of three injections 12 weeks later. Patients were evaluated at three, six, and nine months post-last injection. The mean baseline deviation angle was 52.8°. With respect to deviation angle, clinical success was achieved at three and six months with 58% and 53% of patients, respectively.
The best results were achieved with a three-treatment series of three injections each in Study B (n=10). In Study B, patients received three injections of Xiaflex administered one per day, separated by at least one day each, over a one-week timeframe. Patients received two additional series of three injections, each spaced six weeks apart. The mean baseline deviation angle was 50.2°. At nine month follow up (post-first injections), 25% or greater reduction in deviation angle was achieved in eight out of nine patients who completed the study (89%, 1 patient had 24% reduction in deviation angle). Based on the investigator's global assessment, 67% of subjects were very much improved or much improved after treatment with Xiaflex.
The most common adverse events reported in both studies were local administration site reactions that were mild or moderate in severity, non-serious, and resolved in time without medical attention.