Aicuris Reports Positive Phase 2 Results for Pritelivir in Refractory HSV Infections and Favorable Phase 1 Safety Data for AIC468
Key Insights
Pritelivir demonstrated superior lesion healing rates compared to foscarnet in Phase 2 trial, with 93% vs. 57% of patients achieving healing within 28 days of treatment.
The novel helicase-primase inhibitor showed improved safety profile with zero adverse event-related discontinuations compared to 42.9% for foscarnet in immunocompromised patients.
AIC468, an antisense oligonucleotide targeting BK virus, showed favorable safety and pharmacokinetic profile across all dose cohorts in Phase 1 trial.
Aicuris Anti-infective Cures AG presented compelling clinical data at the 2025 ID Week Annual Meeting, showcasing positive Phase 2 results for its lead candidate pritelivir and favorable Phase 1 safety data for AIC468. The presentations underscore the company's progress in developing antiviral therapies for immunocompromised patients with limited treatment options.
Pritelivir Demonstrates Superior Efficacy in Refractory HSV Infections
The Phase 2 study (2023-510088-37-00) compared pritelivir to foscarnet in immunocompromised patients with refractory mucocutaneous HSV infections with or without resistance. In the multi-center trial, 22 patients were randomized 2:1 to receive either pritelivir or foscarnet, with an additional 8 patients treated with pritelivir in a non-randomized arm due to foscarnet resistance or intolerance.
All pritelivir-treated patients received a daily dose of 100mg oral pritelivir for 28 days following an initial 400mg loading dose. The results showed pritelivir achieved numerically improved efficacy compared to foscarnet, with 93% versus 57% of patients achieving lesion healing within 28 days of treatment.
The safety profile also favored pritelivir, with zero adverse event-related discontinuations compared to 42.9% for foscarnet. Dr. Cynthia Wat, Chief Medical Officer of Aicuris, noted that "findings from the pritelivir Phase 2 program were recently confirmed in a positive registrational trial."
Novel Mechanism of Action Addresses Resistance Challenges
Pritelivir represents a distinct therapeutic approach as a helicase-primase inhibitor that targets both HSV-1 (search) and HSV-2. Unlike traditional antivirals, pritelivir blocks viral DNA synthesis by inhibiting the helicase-primase complex (search), a mechanism different from marketed nucleoside analogues. This distinct mode of action makes pritelivir active against viral strains resistant to nucleoside analogs.
The drug has received FDA Breakthrough Therapy Designation based on previous clinical trial results. Following recently announced positive Phase 3 topline results where pritelivir met the primary superiority endpoint, Aicuris remains on track for New Drug Application submission in 2026.
AIC468 Shows Promise for BK Virus Treatment
Aicuris also presented new safety data from its ongoing first-in-human Phase 1 trial (2023-510074-13-00) of AIC468, a novel antisense oligonucleotide designed to treat BK virus reactivation in kidney transplant patients. The randomized, double-blind, placebo-controlled study evaluated subcutaneous doses ranging from 25 mg to 600 mg and an intravenous dose of 200 mg, with weekly subcutaneous dosing over one month also tested.
Across all cohorts, AIC468 demonstrated a favorable safety profile with no evidence of antisense oligonucleotide-related class toxicities, no severe adverse events, no dose-related safety trends, and no treatment discontinuations. The pharmacokinetic characteristics were consistent with expected profiles for a second-generation antisense oligonucleotide.
AIC468 works by blocking viral replication within infected cells through inhibiting splicing of the pre-mRNA that encodes for the virus's large T-antigen (search). This addresses a significant unmet need, as there are currently no approved antiviral therapies targeting BK virus, despite the serious complications it can cause in kidney transplant recipients, including renal dysfunction or graft loss.
Pipeline Advancement and Commercial Preparation
Based on the favorable safety and pharmacokinetic data, Aicuris plans to submit an investigational new drug dossier later in 2025 to initiate a Phase 2 trial for AIC468 in the first half of 2026. The company is simultaneously preparing for commercial launch of pritelivir in the US following the planned NDA submission.
Larry Edwards, Chief Executive Officer of Aicuris, emphasized the company's progress: "Pritelivir stands out as a cornerstone asset with clear potential to change the treatment landscape for HSV in immunocompromised patients. At the same time, we are advancing AIC468 into a patient population with clear unmet need."
The presentations at ID Week 2025 highlight Aicuris's commitment to developing therapeutic solutions for immunocompromised patients, a growing population that faces life-threatening complications from otherwise manageable infections.