A 1-month course of pritelivir reduced genital HSV-2 shedding more than valacyclovir did in a small phase II clinical trial, according to a report published online in JAMA.
Previous phase I studies suggested that oral daily pritelivir was safe and tolerable in the patient population under evaluation (healthy adults with four to nine annual genital HSV-2 recurrences). Researchers performed this randomized, double-blind, crossover trial to assess the drug’s efficacy in 91 adults (mean age 48 years) who had frequent recurrences of genital symptoms and lesions. Study participants at four U.S. clinical research centers received pritelivir or valacyclovir for 28 days, followed by a washout period, then a 28-day course of the other drug, said lead investigator Anna Wald, MD, of the University of Washington and the Fred Hutchinson Cancer Research Center, Seattle, and her associates.
The primary endpoint – the number of swabs that tested positive for HSV-2 relative to the total number of swabs collected – was 2.4% during pritelivir treatment and 5.3% during valacyclovir treatment, a significant difference (relative risk, 0.42). Genital lesions were reported on 1.9% of days during pritelivir treatment, compared with 3.9% of days during valacyclovir treatment (RR, 0.40). In addition, the frequency of subclinical shedding also was significantly lower with pritelivir (1.8% vs. 4.1%), while the percentage of episodes resolving within 24 hours was significantly higher (87% vs. 69%).
The rate and severity of adverse events were similar between the two study groups. There were no serious adverse events or deaths. Compared with valacyclovir, pritelivir was associated with more statistically significant but clinically irrelevant changes in lymphocyte counts and creatinine levels. One patient in each study group developed mild allergic reactions thought to be possibly related to treatment, which resolved upon discontinuation of the study drugs.
AiCuris, maker of pritelivir, supported the study. Dr. Wald reported ties to AiCuris, Amgen, GlaxoSmithKline, Merck, Gilead, Vical, Genocea, and Admedus; her associates reported ties to numerous industry sources.