pritelivir (AIC316) / AiCuris, Veloxis, Asahi Kasei Therapeutics - LARVOL DELTA

Efficacy and Safety of Pritelivir vs Foscarnet for the Treatment of Acyclovir-Refractory Herpes Simplex Virus Infection in Immunocompromised Adults: A Randomized, Open-Label Phase 2 Trial. (PubMed, Open Forum Infect Dis) - "In Part B, the median time to healing was 19.0 days, with a 63% healing rate. Pritelivir demonstrated encouraging efficacy and favorable safety in immunocompromised adults with limited treatment options, supporting Phase 3 evaluation for the treatment of refractory HSV infection in this population."

Clinical • Journal • P2 data • Herpes Simplex • Infectious Disease

Pritelivir for treatment of resistant/refractory HSV in stem cell transplant patients: Real-world experience from a single centre tertiary hospital (TTS 2026) - "Salvage therapies including foscarnet and cidofovir, are limited by nephrotoxicity, cytopenias, and the need for intravenous administration...Pritelivir, a novel first-in-class helicase-primase inhibitor that blocks viral DNA synthesis, offers activity against aciclovir- and foscarnet-resistant HSV...Case 1: A 68-year-old female allogeneic HSCT recipient for pre-B acute lymphoblastic leukaemia developed refractory perianal HSV-2 ulcers despite high-dose valaciclovir, IV foscarnet, and topical imiquimod... In a phase 3 trial, pritelivir demonstrated superior healing of refractory/ resistant HSV lesions compared to standard therapies. Although optimal durations of pritelivir could not be completed in our cases due to transplant related morbidity, there was evidence of initial clinical improvement. Early consideration of pritelivir may help mitigate significant morbidity associated with refractory or resistant HSV ulceration."

Clinical • Real-world • Real-world evidence • Acute Lymphocytic Leukemia • B Acute Lymphoblastic Leukemia • Bone Marrow Transplantation • Graft versus Host Disease • Hematological Disorders • Hematological Malignancies • Herpes Simplex • Immunology • Infectious Disease • Leukemia • Myelodysplastic Syndrome • Septic Shock • Transplantation

Reduced Healthcare Resource Utilization (HCRU) with Pritelivir Compared to Investigator's Choice Therapy (ICT) in Immunocompromised (IC) Patients Treated for Refractory Herpes Simplex Virus (HSV): Phase 3 PRIOH-1 Study (IDWeek 2026) - No abstract available

Clinical • HEOR • P3 data • Herpes Simplex • Infectious Disease

Early Access Program (EAP) Experience of Pritelivir in the Treatment of Acyclovir- and Foscarnet-Refractory Herpes Simplex Virus (HSV) Infection in Immunocompromised (IC) Patients (IDWeek 2026) - No abstract available

Clinical • Herpes Simplex • Infectious Disease

Impact of Acid-Reducing Agents on the Pharmacokinetics of Pritelivir, a Novel Oral Herpes Simplex Virus (HSV) Helicase-Primase Inhibitor (IDWeek 2026) - No abstract available

PK/PD data • Herpes Simplex • Infectious Disease

Pritelivir for refractory HSV infections in immunocompromised adults (IDWeek 2026) - No abstract available

Clinical • Herpes Simplex • Infectious Disease

Treatment of Herpes simplex encephalitis with the helicase-primase inhibitor pritelivir in an immunocompromised patient. (PubMed, NPJ Antimicrob Resist) - "After 1.5 months, while still on valacyclovir prophylaxis, HSE relapsed, confirmed by Magnetic Resonance Imaging (MRI) and HSV1 DNA detection in cerebrospinal fluid (CSF). Following transient response to acyclovir and foscarnet, combined pritelivir/acyclovir treatment was initiated in this comatose patient with cerebral edema and necrosis...Pritelivir plasma and CSF concentrations exceeded the 50% effective concentration for HSV1. This case highlights the potential of pritelivir for treating HSE."

Journal • Bone Marrow Transplantation • CNS Disorders • Herpes Simplex • Infectious Disease • Transplantation

Helicase-primase inhibitors as next-generation anti-HSV agents: from current clinical status to structure-activity relationships and patent coverage. (PubMed, Expert Opin Ther Pat) - "With amenamevir already approved for the treatment of VZV and HSV in Japan and with pritelivir's granted breakthrough therapy designation and priority review for the treatment of acyclovir-resistant HSV infections in immunocompromised patients, other companies have also expressed interest in small-molecule helicase-primase inhibitors (HPIs)...In parallel, the availability of several cryo-electron microscopy structures of the helicase-primase complex has enabled structure-based and computer-aided drug design, facilitating the exploration of alternative scaffolds beyond the established chemotypes. The potential opportunities and limitations of the current HPIs, as well as the different dosage forms, are discussed."

Journal • Review • Herpes Simplex • Herpes Zoster • Infectious Disease • Varicella Zoster

Elucidation of DNA Primase as a Drug Target in Leishmania donovani: Structure-Guided Inhibitor Identification and Biochemical Validation. (PubMed, Chem Biol Drug Des) - "Moreover, kinetic studies showed that Pritelivir and EGCG exhibit competitive and uncompetitive inhibition, respectively, for both NTP and DNA substrates. Pritelivir effectively disrupted the L. donovani cell cycle, and the replication mechanism in treated promastigotes showed irregular shapes and short flagella."

Journal • Infectious Disease

Highlights from JAAD Reviews: Herpes Simplex Virus - New Weapons Against an Old Foe. (PubMed, J Am Acad Dermatol) - No abstract available

Journal • Herpes Simplex

Preliminary embryo-fetal developmental toxicity study of pritelivir in CD1-IGS mice. (PubMed, Sci Rep) - "Placenta-to-maternal plasma and fetus-to-maternal plasma concentration ratios in mice were 0.4 and 0.2, respectively, indicating transfer but not accumulation of pritelivir in the fetoplacental compartment. Taken together, our findings support further preclinical studies of pritelivir for its use in pregnancy."

Journal • Preclinical • Herpes Simplex

Diagnosis and management of acyclovir-resistant herpes simplex virus for the dermatologist. (PubMed, J Am Acad Dermatol) - No abstract available

Journal • Herpes Simplex

SUCCESSFUL HEMATOPOIETIC STEM CELL TRANSPLANTATION FOR ACYCLOVIR-RESISTANT HSV INFECTION IN DOCK-8 DEFICIENCY (ESPID 2026) - "HSV viremia persisted for 14 days despite acyclovir therapy, necessitating addition of Foscarnet, after which viremia cleared; viral resistance testing confirmed high-level Acyclovir/Cidofovir resistance...While novel treatments like Pritelivir was explored, progressive ocular deterioration and anticipated delay in drug procurement led to the risky decision to proceed with matched sibling donor hematopoietic stem cell transplantation for definitive immune reconstitution...Learning Points/Discussion The increasing prevalence of HSV resistance among immunocompromised patients presents a significant clinical challenge given the restricted arsenal of available antiviral agents, coupled with the potential toxicity and questionable effectiveness of current therapeutic options. Hematopoietic stem cell transplantation facilitates restoration of competent T-cell populations critical for infection control through correction of the primary immunologic defect."

Herpes Simplex • Infectious Disease

Structural insights into inhibition mechanism of the helicase-primase complex from human herpesvirus 1. (PubMed, Cell Chem Biol) - "Here, cryo-EM structures of the HHV1 (α-subfamily) HPC bound to single-stranded DNA and two clinical inhibitors, amenamevir and pritelivir, are reported. Combined molecular dynamics and fragment molecular orbital analyses explain the α-subfamily selectivity and distinct antiviral spectra of these drugs. These findings provide a structural framework to guide the development of novel inhibitors targeting β- and γ-subfamily herpesviruses."

Journal • CNS Disorders • Epstein-Barr Virus Infections • Immunology

Aicuris…Presents New Phase 3 Data at ESCMID 2026 (The Manila Times) - "Tended treatment up to 42 days; among patients who continued therapy, 82.4% of those treated with pritelivir achieved complete lesion healing compared with 42.0% with investigator’s choice therapy (ICT), resulting in an adjusted treatment difference of 40.2%; Pritelivir treatment significantly reduced viral replication and viral burden, shortening the median time to undetectable HSV in lesions to 9 days compared with 21 days with ICT (p = 0.0581)"

P3 data • Herpes Simplex

Aicuris Receives FDA Priority Review for Pritelivir NDA (The Manila Times) - " The U.S. Food and Drug Administration has granted Priority Review for Aicuris’ New Drug Application for pritelivir, a novel helicase primase inhibitor developed to treat refractory herpes simplex virus infections, with or without resistance (R±R), in immunocompromised patients; The Prescription Drug User Fee Act (PDUFA) Target Date is in Q4 2026; The submission is based on positive pivotal Phase 3 data demonstrating superior complete lesion healing and a favorable safety profile compared to investigator’s choice therapy "

FDA filing • PDUFA • Priority review • Herpes Simplex • Infectious Disease

PRITELIVIR DEMONSTRATED SUPERIOR EFFICACY COMPARED TO INVESTIGATOR'S CHOICE TREATMENT FOR REFRACTORY HERPES SIMPLEX VIRUS INFECTIONS IN IMMUNOCOMPROMISED PATIENTS: PRIOH-1, PHASE 3 SAFETY AND EFFICACY (EBMT 2026) - P3 | " In this randomized (1:1), controlled, open label trial, 101 IC patients (≥16 years) with R±R HSV mucocutaneous infection received oral pritelivir (100 mg daily; 400 mg loading dose) or ICT (IV foscarnet, IV/topical cidofovir, or topical imiquimod) for up to 28 days, extendable to 42 days. Eligibility criteria included hematopoietic cell transplant, solid organ transplant, HIV, malignancy, or chronic use of immunosuppressive treatment with refractory/clinical failure (defined as no clinical improvement of lesions after ≥7 days of standard of care nucleoside analogue therapy or confirmed acyclovir resistance)... Pritelivir met the Phase 3 primary endpoint, demonstrating statistically superior efficacy compared with ICT, with a favorable safety and tolerability profile. These findings support pritelivir as a promising oral agent to address the unmet needs of refractory HSV infections in IC patients.Table 1 Incidence of TEAEs (≥ 10%): Pritelivir vs...."

Clinical • P3 data • Herpes Simplex • Human Immunodeficiency Virus • Immunology • Infectious Disease • Primary Immunodeficiency • Solid Organ Transplantation

ACICLOVIR-RESISTANT HERPES SIMPLEX VIRUS IN PEDIATRIC PATIENTS UNDERGOING ALLOGENEIC HAEMATOPOIETIC STEM CELL TRANSPLANT: A CASE SERIES (EBMT 2026) - "All patients were treated with second-line antivirals (foscarnet and/or cidofovir), and three patients were treated with third-line antivirals (pritelivir). Aciclovir-resistant HSV infection in pediatric HSCT recipients is associated with high morbidity and mortality, limited therapeutic options, and significant treatment-related toxicity. Early recognition, resistance testing, timely initiation of second-line therapy and weaning of immunosuppression are critical for disease control. Emerging therapies, such as helicase-primase inhibitors and adoptive T-cell therapy, hold promise but remain limited by access and pediatric data."

Clinical • Bone Marrow Transplantation • Gastrointestinal Disorder • Genetic Disorders • Graft versus Host Disease • Hematological Disorders • Hematological Malignancies • Herpes Simplex • Immunology • Infectious Disease • Inflammation • Keratitis • Leukemia • Myelodysplastic Syndrome • Ocular Inflammation • Ophthalmology • Pediatrics • Pneumonia • Primary Immunodeficiency • Respiratory Diseases • Sickle Cell Disease • Transplantation • Transplantation Associated Thrombotic Microangiopathy

Positive treatment response of pritelivir achieved in refractory HSV infections in immunocompromised patients, including haematopoietic stem cell and solid organ transplant recipients and oncology patients: PRIOH-1 phase III trial (ESCMID Global 2026) - No abstract available

Clinical • Late-breaking abstract • P3 data • Herpes Simplex • Infectious Disease • Solid Organ Transplantation • Transplantation

In vitro two-way drug–drug interaction study shows no antagonism or potentiation between post-phase III anti-HSV pritelivir and nine licensed anti-HIV drugs (INSTI, NNRTI, NRTI, and CAI) (ESCMID Global 2026) - No abstract available

P3 data • Preclinical • Human Immunodeficiency Virus • Infectious Disease

Pritelivir demonstrated superior lesion healing with extended treatment compared to investigator's choice for refractory herpes simplex virus infection in immunocompromised patients in the PRIOH-1 phase III trial (ESCMID Global 2026) - No abstract available

Clinical • P3 data • Herpes Simplex • Infectious Disease

Pritelivir Demonstrated Superior Efficacy Compared to Investigator's Choice Treatment for Refractory Herpes Simplex Virus Infections In Immunocompromised Patients: PRIOH-1, Phase 3 Safety and Efficacy (TCT-ASTCT-CIBMTR 2026) - "Methods In this randomized (1:1), controlled, open label trial, 101 IC patients (≥16 years) with R±R HSV mucocutaneous infection received oral pritelivir (100 mg daily; 400 mg loading dose) or ICT (IV foscarnet, IV/topical cidofovir, or topical imiquimod) for up to 28 days, extendable to 42 days. Eligibility criteria included hematopoietic cell transplant, solid organ transplant, HIV, malignancy, or chronic use of immunosuppressive treatment with refractory/clinical failure (defined as no clinical improvement of lesions after ≥7 days of standard of care nucleoside analogue therapy or confirmed acyclovir resistance)...Conclusions Pritelivir met the Phase 3 primary endpoint, demonstrating statistically superior efficacy compared with ICT, with a favorable safety and tolerability profile. These findings support pritelivir as a promising oral agent to address the unmet needs of refractory HSV infections in IC patients."

Clinical • Late-breaking abstract • P3 data • Herpes Simplex • Human Immunodeficiency Virus • Immunology • Infectious Disease • Primary Immunodeficiency • Solid Organ Transplantation

Acyclovir-Resistant Herpes Simplex Virus in Pediatric Patients Undergoing Allogeneic Hematopoietic Stem Cell Transplant: A Case Series. (PubMed, Transpl Infect Dis) - "Acyclovir-resistant HSV infection in pediatric HSCT recipients is associated with high morbidity and mortality, limited therapeutic options, and significant treatment-related nephrotoxicity. Early recognition, early resistance testing, prompt initiation of second-line therapy, and weaning of immunosuppression are critical. Emerging therapies, such as helicase-primase inhibitors and adoptive T-cell therapy, hold promise but remain limited by access and pediatric data."

Journal • Bone Marrow Transplantation • Gastrointestinal Disorder • Genetic Disorders • Graft versus Host Disease • Hematological Disorders • Hematological Malignancies • Herpes Simplex • Immunology • Infectious Disease • Keratitis • Leukemia • Myelodysplastic Syndrome • Ocular Inflammation • Oncology • Ophthalmology • Pediatrics • Pneumonia • Primary Immunodeficiency • Respiratory Diseases • Sickle Cell Disease • Transplantation

PRIOH-1: Trial on Efficacy and Safety of Pritelivir Tablets for Treatment of Acyclovir-resistant Mucocutaneous HSV (Herpes Simplex Virus) Infections in Immunocompromised Subjects (clinicaltrials.gov) - P3 | N=158 | Completed | Sponsor: AiCuris Anti-infective Cures AG | Active, not recruiting ➔ Completed

Trial completion • Herpes Simplex • Infectious Disease

Next Generation 3D Printed Multipurpose Intravaginal Ring For Sustained Co-Delivery of Antiretroviral Drugs and A Contraceptive Hormone. (PubMed, Pharm Res) - "Collectively, these results demonstrate that this first-in-line 3D printed MPT IVR has potential to expand preventative choices for young women and girls against HIV, HSV, and unplanned pregnancy."

Journal • Human Immunodeficiency Virus • Infectious Disease