Hovilpri approved as first-in-class treatment for refractory HSV

Clinical takeaway: Consider pritelivir (Hovilpri) for immunocompromised adults with mucocutaneous HSV lesions that fail to respond to acyclovir, valacyclovir, or famciclovir, including cases with documented antiviral resistance.

Refractory HSV infections can be painful, persistent, and difficult to manage in immunocompromised patients, often requiring intravenous therapies such as foscarnet or cidofovir. Pritelivir introduces a new oral treatment option with a distinct helicase-primase inhibition mechanism, potentially reducing reliance on more burdensome IV treatments.

FDA has approved Hovilpri (pritelivir) tablets for the treatment of mucocutaneous lesions caused by herpes simplex virus (HSV) infection that is refractory, with or without documented resistance, to acyclovir, valacyclovir, or famciclovir in immunocompromised adults. The drug is active against both HSV-1 and HSV-2 and represents the first FDA-approved HSV therapy with a novel mechanism of action in nearly three decades.

Approval was supported by the phase 3 PRIOH-1 trial, which enrolled 101 immunocompromised adults with refractory mucocutaneous HSV infection. Participants were randomized to oral pritelivir or investigator's choice treatment, which could include IV foscarnet, IV or topical cidofovir, or topical imiquimod.

The study met its primary endpoint. By day 28, complete lesion healing occurred in 63% of patients receiving pritelivir versus 34% of those receiving investigator's choice therapy, an adjusted treatment difference of 28.4% (95% CI, 9.6-47.3; P=.0047). The advantage widened through day 42, with healing rates of 82% and 42%, respectively.

Adverse reactions were reported less frequently with pritelivir than with comparator therapy (22% vs 54%), and treatment discontinuations due to adverse reactions were also lower (2% vs 20%). Headache was the most commonly reported adverse event.

"As an oral therapy, Hovilpri provides a non-intravenous treatment option for eligible immunocompromised adult patients with refractory HSV infection," the company said in announcing the approval.

Sources: FDA (2026 Oct 9). FDA Approves Drug to Treat Lesions of Herpes Simplex virus; Asahi Kasei Therapeutics (2026 Oct 9). Asahi Kasei Therapeutics Announces FDA Approval of HOVILPRI® (pritelivir) Tablets for Mucocutaneous HSV Lesions Refractory (With or Without Resistance) to Standard Antiviral Treatment in Immunocompromised Adults