New Oral Therapy Pritelivir Shows Promise for Treating HSV in Immunocompromised Patients

The drug demonstrates superior lesion healing compared to current treatments, with a favorable safety profile.

Published on Feb. 11, 2026

Got story updates? Submit your updates here. ›

A new oral therapy called pritelivir was significantly more effective against herpes simplex virus (HSV) than standard treatments for immunocompromised patients with refractory infections, according to data from a study of 101 individuals. Pritelivir was able to achieve complete lesion healing within 28 days in 62.7% of patients, compared to only 34% for the comparison treatments. The drug also had fewer adverse events related to kidney problems, electrolyte issues, and treatment discontinuations.

Why it matters

Treatment options for HSV types 1 and 2 in immunocompromised patients are limited, and the current standard-of-care therapies like foscarnet can have significant side effects that lead many patients to discontinue treatment. Pritelivir offers a new mechanism of action that targets the HSV helicase-primase complex, blocking viral DNA and showing activity against acyclovir- and foscarnet-resistant strains. If approved, pritelivir could provide a much-needed new option for this vulnerable patient population.

The details

In the study, researchers randomized 101 immunocompromised patients aged 16 or older with HSV mucocutaneous infection to receive either oral pritelivir or the investigator's choice of IV foscarnet, IV or topical cidofovir, or topical imiquimod for up to 28 days. The patients were immunocompromised due to organ transplant, oncology/autoimmune conditions, or HIV. Most had refractory HSV, and over a quarter had acyclovir-resistant infections. The primary endpoint of complete lesion healing within 28 days was achieved by 62.7% of pritelivir patients compared to 34% of the comparison group.

  • The study findings were presented at the Tandem Meeting of the American Society for Transplantation and Cellular Therapy and CIBMTR in February 2026.

The players

Pritelivir

A new oral therapy that targets the HSV helicase-primase complex, blocking viral DNA and showing activity against acyclovir- and foscarnet-resistant strains of HSV.

Cynthia Wat, MD

Chief medical officer for Aicuris, the manufacturer of pritelivir.

Shirin A. Mazumder, MD

An infectious diseases specialist and associate professor at the University of Tennessee Health Science Center in Memphis, Tennessee.

Got photos? Submit your photos here. ›

What they’re saying

“The results are consistent with pritelivir's novel mechanism of action targeting the helicase-primase complex, so activity against acyclovir- and foscarnet-resistant strains was expected, and initial clinical activity has been demonstrated in otherwise healthy adults with genital HSV-2 infection.”

— Cynthia Wat, MD, Chief medical officer, Aicuris (Medscape Medical News)

“Alternative therapy options are critical in the treatment of HSV infections, especially for immunocompromised hosts, as antiviral resistance to standard therapy tends to be higher in this group with prolonged use.”

— Shirin A. Mazumder, MD, Infectious diseases specialist and associate professor, University of Tennessee Health Science Center (Medscape Medical News)

“If approved, pritelivir offers a treatment option with a favorable safety profile and superior efficacy. Since it is administered orally, it also offers a convenience in administration compared to the IV antivirals currently available.”

— Shirin A. Mazumder, MD, Infectious diseases specialist and associate professor, University of Tennessee Health Science Center (Medscape Medical News)

What’s next

The company is preparing a regulatory filing, with a New Drug Application in the works, so clinicians should watch for labeling, approved indications, and guidance on dosing and monitoring.

The takeaway

Pritelivir represents a promising new oral therapy for treating HSV infections in immunocompromised patients, offering superior efficacy, a favorable safety profile, and more convenient administration compared to current IV treatments. If approved, it could help address an unmet need for this vulnerable patient population.