The US FDA has approved Hovilpri (pritelivir) for mucocutaneous lesions caused by herpes simplex virus (HSV) infection refractory, with or without documented resistance, to acyclovir, valacyclovir, or famciclovir in immunocompromised adults, according to Asahi Kasei Therapeutics.
As noted by Asahi, the approval marks the first HSV therapy with a novel mechanism of action to reach the US market in nearly 30 years. It also gives patients access to an oral alternative to existing treatments for refractory HSV infection, which have often required intravenous administration and can present significant tolerability and treatment-management challenges.
Pritelivir inhibits the HSV helicase-primase complex, blocking viral DNA unwinding and primer synthesis independently of viral thymidine kinase activation, retaining activity against thymidine kinase-deficient strains that resist nucleoside analogs. The drug is formulated as 100 mg oral tablets; the label carries warnings regarding drug interactions with acid-reducing agents, which may reduce pritelivir exposure and risk resistance, and notes that pritelivir is a breast cancer resistance protein (BCRP) inhibitor that may increase plasma concentrations of BCRP substrates.
The approval is supported by Part C of PRIOH-1 (NCT03073967), a Phase III randomized, open-label trial enrolling 101 immunocompromised adults with mucocutaneous HSV refractory to standard antivirals. Complete lesion healing by Day 28 was achieved in 63% of pritelivir-treated participants versus 34% receiving Investigator's Choice treatment, an adjusted difference of 28.4% (p=0.0047), the company reported.