The U.S. Food and Drug Administration grants Priority Review to pritelivir, a novel HSV therapy from Aicuris Anti-infective Cures AG, backed by Phase 3 data in immunocompromised patients.
Written By: Dr. Anuja Badgujar, BDS
Reviewed By: Pharmacally Editorial Team
The U.S. Food and Drug Administration has granted Priority Review to the New Drug Application for pritelivir, an investigational antiviral from Aicuris Anti-infective Cures AG, for the treatment of refractory herpes simplex virus (HSV) infections in immunocompromised patients. The agency has set a PDUFA target date in the fourth quarter of 2026, placing the drug on track to potentially become the first new HSV therapy in more than two decades if approved.
Clinical Trial Evidence
The submission is supported by data from the pivotal Phase 3 PRIOH-1 trial (NCT03073967), where pritelivir met its primary endpoint, demonstrating superior lesion healing compared with investigator’s choice therapy in patients with refractory HSV infection, including those with antiviral resistance.
Updated findings to be presented at the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) 2026 Congress provide additional context on durability and depth of response. Extended treatment up to 42 days was associated with higher complete lesion healing rates, with more than 80% of patients on pritelivir achieving full resolution compared with just over 40% on standard therapies, alongside a marked reduction in viral burden and faster time to undetectable virus in lesions.
The antiviral effect was consistent across key immunocompromised subgroups, including transplant recipients, patients with hematologic malignancies, and individuals living with HIV, suggesting broad applicability in high-risk populations.
Safety Profile
At the same time, pritelivir showed a favorable tolerability profile, with substantially lower discontinuation rates than comparator therapies and adverse events largely limited to manageable gastrointestinal and neurological symptoms.
Larry Edwards CEO of Aicuris said the Priority Review marks a key step toward bringing pritelivir to patients with high unmet need, noting that it could become the first new HSV treatment in over 20 years if approved, and highlighting the company’s ongoing collaboration with the U.S. Food and Drug Administration and Asahi Kasei.
The PRIOH-1 trial enrolled a clinically diverse population reflective of real-world practice, randomizing patients to receive either oral pritelivir or existing therapies such as foscarnet or cidofovir, with treatment durations of up to 28 days and optional extension based on response. Additional non-randomized cohorts further supported the safety and efficacy findings.
How Pritelivir Works
Pritelivir’s differentiation lies in its mechanism as a helicase-primase inhibitor, targeting viral DNA replication through a pathway distinct from nucleoside analog antivirals. This allows activity against strains resistant to standard treatments, a persistent challenge in immunocompromised patients who often experience severe, recurrent, and treatment-refractory HSV infections.
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About the Writer
Dr. Anuja Badgujar, BDS is a dentist with expertise in US healthcare data and medical data annotation. With four years of experience handling US healthcare datasets, she brings strong domain knowledge and precision to her work. She is also deeply passionate about medical writing, with a focus on translating complex medical information into clear and structured content.