A new antiviral drug, pritelivir, has demonstrated significant efficacy in treating herpes simplex virus (HSV) in immunocompromised patients, according to results presented at the Conference on Retroviruses and Opportunistic Infections in Denver this week. The phase 3 trial showed that 62.7% of patients receiving pritelivir experienced complete lesion healing, compared to 34% in a control group receiving standard care.
The study, involving 101 adults with HSV infections that were resistant or unresponsive to other treatments, utilized a randomized, controlled, open-label design. Participants received either a 400 mg loading dose of pritelivir followed by 28 days of 100 mg daily treatment, or a control regimen chosen by their physician – including intravenous foscarnet, intravenous or topical cidofovir, or topical imiquimod. The treatment difference in lesion healing was 28.7 percentage points, a statistically significant result.
“There is indeed a high medical demand for effective and well-tolerated treatment options for immunocompromised people having refractory herpes simplex infection, including people living with HIV,” said Jean-Michel Molina, MD, PhD, who presented the study findings. Pritelivir’s mechanism of action, inhibiting the viral helicase-primase complex, differs from traditional treatments like acyclovir, and may overcome resistance. Unlike acyclovir, pritelivir does not require viral enzyme activation and can prevent infection in unaffected cells, according to Molina.
The U.S. Food and Drug Administration (FDA) has granted pritelivir Breakthrough Therapy designation, expediting its development and review process. Aicuris, the drug’s developer, anticipates submitting an application for FDA approval in the first quarter of 2026.
Globally, the World Health Organization estimates that 42 million new genital herpes infections occur annually among individuals aged 15 to 49, with a new infection occurring every second. According to Aicuris, pritelivir represents the first potential new oral antiviral treatment for HSV in over two decades.
Cynthia Wat, MD, Chief Medical Officer at Aicuris, stated that the results “mark a pivotal moment for patients with refractory HSV infections, supporting pritelivir’s potential to redefine the standard of care for patients at high risk of morbidity and mortality.”
