Innovative Herpes Simplex Virus Therapy Candidate Presents Phase 3 Data

As of February 2026, the U.S. Food and Drug Administration (FDA) has not yet approved any vaccine for the herpes simplex virus (HSV). However, several candidates are currently undergoing clinical trials.

These efforts aim to tackle the global impact of HSV-1 and HSV-2 infections, which cause oral and genital herpes in millions of people annually.

Unfortunately, the FDA states that there is currently no cure for HSV infections.

However, antiviral medications can help shorten the duration of herpes outbreaks. A significant advancement in HSV treatment is currently attracting attention.

AiCuris Anti-infective Cures AG is set to present detailed results from its pivotal Phase 3 clinical trial of pritelivir as a late-breaking oral presentation at the Tandem Meetings 2026, held February 4-7 in Salt Lake City, Utah.

Pritelivir, a novel oral helicase-primase inhibitor, targets both HSV-1 and HSV-2 by blocking viral DNA synthesis through a mechanism distinct from traditional nucleoside analogs like acyclovir or valacyclovir.

This unique mode of action makes it effective against strains resistant to current standard therapies, addressing a critical unmet need—particularly in immunocompromised patients, where resistant or refractory HSV infections can lead to severe complications and limited treatment options.

The PRIOH-1 trial focused on immunocompromised individuals with acyclovir-refractory (and sometimes foscarnet-resistant) mucocutaneous HSV infections. In October 2025, AiCuris announced that pritelivir met its primary endpoint, demonstrating statistically significant superiority in lesion healing compared to the investigator's choice of standard-of-care treatments (such as foscarnet, cidofovir, or topical options).

Superiority was shown for treatment up to 28 days (p=0.0047), with even stronger results extending to 42 days (p<0.0001).

Earlier Phase 2 data supported a favorable safety profile, and pritelivir has held an FDA Breakthrough Therapy designation for this indication since 2020. AiCuris expects to file for FDA marketing authorization in 2026, potentially offering the first new HSV therapy in decades that is active against resistant strains.

Full abstracts will be released on February 4, 2026, and will be available via the conference website here. 

This development highlights progress in managing HSV complications in high-risk groups, even as preventive vaccines remain further on the horizon. Ongoing research and presentations like this at major conferences continue to drive hope for improved options against this widespread virus.