{"id":53453,"date":"2026-03-09T07:45:56","date_gmt":"2026-03-09T07:45:56","guid":{"rendered":"https:\/\/i-base.info\/htb\/?p=53453"},"modified":"2026-03-24T11:21:28","modified_gmt":"2026-03-24T11:21:28","slug":"pritelivir-active-against-drug-resistant-herpes-in-phase-3-study","status":"publish","type":"post","link":"https:\/\/i-base.info\/htb\/53453","title":{"rendered":"CROI 2026: Pritelivir active against drug-resistant herpes in phase 3 study"},"content":{"rendered":"
\"\"<\/div>\n

Simon Collins, HIV i-Base<\/strong><\/p>\n

Drug resistance to HSV types 1 and 2 and other outbreaks of refractory herpes is a painful and difficult condition. Developing effective and tolerable options remains a high unmet need and particularly affects people who are immunocompromised, including people living with HIV.<\/strong><\/p>\n

CROI 2026 included phase 3 results using the investigational direct-acting antiviral compound pritelivir, presented in an oral presentation by Jean-Michel Molina from H\u00f4pitaux de Paris. Pritelivir is bioavailable with a long half-life (60 hours), enabling once-daily oral dosing and is sensitive to HSV with drug resistance to acyclovir and foscarnet.<\/p>\n

The open-label PRIOH-1 study randomised (1:1) 101 people with refractory or drug-resistant HSV-1\/2 to either daily oral pritelivir or investigational chosen standard of care (foscarnet IV, cidofovir IV or topical imiquimod) for 28 days (or extended to 42 days) with further 28-day follow-up. Pritelivir used an initial 400 mg loading dose on day 1, with subsequent 100 mg daily dosing.<\/p>\n

The primary endpoint was complete lesion healing at day 28.<\/p>\n

The sample size was based on expected 85% efficacy with pritelivir and 60% with foscarnet.<\/p>\n

Underlying immunocompromised status often included multiple causes and was related to HIV in 38%, cancer in 75%, stem cell transplant in 40%, autoimmune disease in 29% and solid organ transplant in 4%.<\/p>\n

Characteristics of the HIV subgroup (n=38) included mean age 48, 76% men, 50% Black with mean CD4 of 330 cells\/mm3 (IQR: 143 to 514). All were on ART but viral load results were not given.<\/p>\n

With the HIV subgroup, 23 were randomised to pritelivir and 15 to SoC and there were 1 vs 6 discontinuations, respectively, mainly due to poor tolerability or non-response.<\/p>\n

Results at day 28 in the overall study and HIV subgroup were 63% vs 28% (p=0.004) and 67% vs 21% (p=0.027), respectively, both showing pritelivir to have significantly superior efficacy.<\/p>\n

Benefits were reported irrespective of baseline resistance to acyclovir, although small numbers didn\u2019t reach statistical significance.<\/p>\n

Overall, of the nine participants who failed in the pritelivir arm, drug resistance results at failure were only available for 2\/9, one of whom showed pritelivir-associated new mutation detected at day 36.<\/p>\n

comment<\/h3>\n

Pritelivir is being developed by German manufacturer AiCuris Anti-infective Cures and top-level results from the PRIOH-1 trial were released \u00a0in October 2025, reporting continued efficacy in the 42-day analysis (p=0.0001). [2]<\/strong><\/p>\n

The US FDA has designated pritelivir for a breakthrough indication, with submission of a New Drug Indication expected by 1Q 2026.<\/strong><\/p>\n

Longer-term data presented at future meetings will include some cases of lesion recurrence after discontinuation of pritelivir, indicating longer treatment might be needed for some people.<\/strong><\/p>\n

Tolerability was reported as being good (some headache and nausea) with the only early discontinuation due to elevated ALT in a participant on multiple comedications.<\/strong><\/p>\n

The main drug interactions involve needing to separate dosing of proton pump inhibitors by at least two hours. [3]<\/strong><\/p>\n

An expanded access programme (EAP) is available to provide pritelivir to people with treatment resistant HSV-1\/2 who are immunocompromised, can’t participate in a clinical trial and have no approved treatment options. [4]<\/strong><\/p>\n

References<\/p>\n

    \n
  1. Molina JM et al. Pritelivir for Refractory HSV Infections in Immunocompromised Patients: Results of a Phase III Trial. CROI 2026, Denver. Oral abstract 196.<\/li>\n
  2. Phase 3 trial confirms superior efficacy of oral pritelivir for refractory HSV in immunocompromised patients. (16 October 2025).
    \nhttps:\/\/www.aicuris.com\/press-release\/aicuris-announces-pritelivir-met-primary-endpoint-in-immunocompromised-herpes-simplex-virus-infected-patients-in-phase-3-pivotal-trial<\/a><\/li>\n
  3. ClinicalTrials.gov. Potential Influence of Esomeprazole on the Pharmacokinetics of Pritelivir.
    \n    https:\/\/clinicaltrials.gov\/study\/NCT05513625<\/a><\/li>\n
  4. ClinicalTrials.gov. Expanded Access Intermediate Size Treatment Protocol: Pritelivir for Immunocompromised Subjects with Treatment Resistant Herpes Simplex Virus Type 1 or 2.
    \n    https:\/\/clinicaltrials.gov\/study\/NCT05844436<\/a><\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"

    Simon Collins, HIV i-Base Drug resistance to HSV types 1 and 2 and other outbreaks of refractory herpes is a painful and difficult condition. Developing effective and tolerable options remains a high unmet need and particularly affects people who are …<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4,31],"tags":[346],"class_list":["post-53453","post","type-post","status-publish","format-standard","hentry","category-conference-reports","category-opportunistic-infections-coinfections-and-complications","tag-croi-2026"],"_links":{"self":[{"href":"https:\/\/i-base.info\/htb\/wp-json\/wp\/v2\/posts\/53453","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/i-base.info\/htb\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/i-base.info\/htb\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/i-base.info\/htb\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/i-base.info\/htb\/wp-json\/wp\/v2\/comments?post=53453"}],"version-history":[{"count":4,"href":"https:\/\/i-base.info\/htb\/wp-json\/wp\/v2\/posts\/53453\/revisions"}],"predecessor-version":[{"id":53611,"href":"https:\/\/i-base.info\/htb\/wp-json\/wp\/v2\/posts\/53453\/revisions\/53611"}],"wp:attachment":[{"href":"https:\/\/i-base.info\/htb\/wp-json\/wp\/v2\/media?parent=53453"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/i-base.info\/htb\/wp-json\/wp\/v2\/categories?post=53453"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/i-base.info\/htb\/wp-json\/wp\/v2\/tags?post=53453"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}