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Last update 27 Feb 2026

Valacyclovir Hydrochloride

Last update 27 Feb 2026

Overview

R&D Status

Clinical Result

Translational Medicine

Overview

Basic Info

SummaryValacyclovir Hydrochloride, sold under the brand name Valtrex, is an antiviral drug that was first approved in the USA in 1995. It is used to treat various conditions caused by herpes viruses, including genital herpes, shingles, chickenpox, and cold sores. Valacyclovir Hydrochloride works by inhibiting the activity of DNA polymerase, a viral enzyme essential for the replication of herpes viruses. This medication is the hydrochloride salt of the L-valyl ester of the antiviral drug acyclovir, and its chemical name is L-valine, 2-[(2-amino-1,6-dihydro-6-oxo9H-purin-9-yl)methoxy]ethyl ester, monohydrochloride. Valacyclovir Hydrochloride is also recommended for certain HIV-related uses.

Drug Type

Small molecule drug

Synonyms

L-Valine ester with 9-((2-hydroxyethoxy)methyl)guanine, L-Valine, 2-((2-amino-1,6-dihydro-6-oxo-9H-purin-9-yl)methoxy)ethyl ester, Talavir

+ [38]

Target

DNA polymerase x Viral enzyme

Action

inhibitors

Mechanism

DNA polymerase inhibitors(DNA polymerase inhibitors), Viral enzyme inhibitors

Therapeutic Areas

Infectious DiseasesEye DiseasesMouth and Tooth Diseases+ [2]

Active Indication

Cytomegalovirus InfectionsHerpes Zoster OphthalmicusHerpes Simplex+ [5]

Inactive Indication

Glioblastoma MultiformeHepatitis C, ChronicHigh grade glioma+ [3]

Originator Organization

GSK Plc

Active Organization

GSK Plc

Livzon Group Livzon Pharmaceutical FactoryGlaxoSmithKline KK

+ [2]

Inactive Organization

Glaxo Wellcome SA

Candel Therapeutics, Inc.

License Organization

AFT Pharmaceuticals Ltd.

Hyloris Pharmaceuticals SAQliniq B V

Drug Highest PhaseApproved

First Approval Date

United States (23 Jun 1995),

ChickenpoxHerpes GenitalisHerpes Labialis+ [1]

Regulation-

Structure/Sequence

Molecular FormulaC13H21ClN6O4

InChIKeyZCDDBUOENGJMLV-QRPNPIFTSA-N

CAS Registry124832-27-5

166

Clinical Trials associated with Valacyclovir Hydrochloride

NCT07346144

/ Not yet recruitingPhase 1/2

A Phase I/II Study of an AAV-1 Mediated Dual-Payload Gene Therapy in Patients With High Grade Glioma

The goal of this clinical trial is to first define the Safety and Optimal Biological Dose (OBD) of study drug TGX-007 and to then further investigate the safety and efficacy in patients with newly diagnosed or recurrent Glioblastoma.
TGX-007 is a gene therapy drug delivered by a harmless adeno-associated virus (AAV) vector which delivers two combined therapeutic payloads to enable killing of proliferative cells and activation of an anti-tumour immune response. One is herpes simplex virus thymidine kinase (HSV-tk), which converts the pro-drug valaciclovir into an active drug that can kill tumour cells and the other is interleukin 12 (IL-12), which activates the body's immune system to recognise and fight the tumour.
Patients newly diagnosed with glioblastoma suitable for standard of care surgery and chemoradiotherapy or patients with recurrent glioblastoma suitable for further surgery may be eligible for the study. Patients will receive TGX-007 by a direct intratumoural injection and will then take the pro-drug valacyclovir orally for up to 21 days before proceeding to standard of care surgery.
The study is split into two phases. Phase I will treat patients at different dose levels of TGX-007 to identify the Optimal Biological Dose that will be used to further expand the study into Phase II. Phase II will expand the number of patients treated at the selected OBD to investigate how effective TGX-007 is at treating newly diagnosed and recurrent GBM.
Approximately 68 people aged 18-70 will take part in the study.

Start Date01 Mar 2026

Sponsor / Collaborator

Trogenix Ltd.

NCT06914479

/ Not yet recruitingPhase 1IIT

A Phase 1 Study of a Combined Cytotoxic and Immune-Stimulatory Therapy in Pediatric and Young Adult Patients With Recurrent, Primary Malignant Brain Tumors

This phase I trial tests the safety, side effects and best dose of AdV-HSV1-TK and AdV-Flt3L in combination with valacyclovir for the treatment of patients with primary cancerous (malignant) brain tumors that can be removed by surgery (resectable) and that have come back after a period of improvement (recurrent). AdV-HSV1-TK and AdV-Flt3L use a virus modified in the laboratory to kill tumor cells and stimulate the immune system to recognize the tumor cells as "invaders" which can lead to tumor shrinkage. For this process to work, an oral anti-herpes medication called valacyclovir is also needed. Giving AdV-HSV1-TK, AdV-Flt3L and valacyclovir may be safe, tolerable and/or effective in treating patients with resectable, recurrent primary malignant brain tumors.

Start Date01 Jan 2026

Sponsor / Collaborator

Rogel Cancer Center: University of Michigan

NCT07294547

/ RecruitingNot ApplicableIIT

Non-Inferiority Assessment of Valacyclovir Versus Valganciclovir as Prophylaxis Against CMV and EBV Viremia in Kidney Transplant Recipients: A Single-Center Prospective Randomized Pilot Study.

Opportunistic CMV viremia (primary infection or reactivation) is usually managed by taking prophylactic medication for both adult and pediatric kidney transplant patients. Most hospitals prescribe valganciclovir for this purpose but valacyclovir has also been used. The most unfavorable side effect of valganciclovir is bone marrow suppression which can be troublesome for kidney transplant patients who are already immunosuppressed. We aim to assess the non-inferiority of valacyclovir compared with valganciclovir in this study.

Start Date27 Nov 2025

Sponsor / Collaborator

National Taiwan University Hospital

100 Clinical Results associated with Valacyclovir Hydrochloride

100 Translational Medicine associated with Valacyclovir Hydrochloride

100 Patents (Medical) associated with Valacyclovir Hydrochloride

1,877

Literatures (Medical) associated with Valacyclovir Hydrochloride

01 Feb 2026·JOURNAL FRANCAIS D OPHTALMOLOGIE

Corticosteroid-responsive optic neuritis associated with acute retinal necrosis due to Herpes simplex virus type 2 in a pediatric patient

Article

Author: Montero-Garcia, A ; Díaz-Cascajosa, J ; Verdú-Reyes, A ; Cobo-De-Nadal, M ; Pérez-Garcia, G

PURPOSE:

Optic neuritis (ON) associated with acute retinal necrosis (ARN) has traditionally been considered a complication resulting from direct viral infiltration of the optic nerve. Although it is currently treated with intravenous acyclovir, the appropriate dosage and duration of treatment in the pediatric population remain unclear, and no standardized effective treatment has been established in clinical guidelines.

METHODS:

A 14-year-old boy was referred for panuveitis in the right eye (RE), with a visual acuity (VA) of hand motions. Fundus examination revealed intense vitritis, and PCR testing was positive for HSV-2. Empirical treatment with intravenous (IV) acyclovir and intravitreal foscarnet was initiated; however, the patient developed peripheral ARN with multiple retinal detachments that required surgery, leaving silicone oil tamponade in place, and was maintained on oral valacyclovir prophylaxis. Fourteen months later, he presented with discomfort in the left eye (LE), where an active focus of ARN was identified, leading to a diagnosis of bilateral ARN. Despite urgent treatment with IV acyclovir and an intravitreal foscarnet injection, the disease progressed in the LE, and four days later, the patient developed optic neuritis associated with ARN, with VA of light perception. Since the LE was the only functional eye, high-dose intravenous methylprednisolone boluses were started.

RESULTS:

One month later, the optic disc edema had significantly improved, and VA had improved to counting fingers. Currently, the patient has shown a remarkable recovery, with VA improving to 20/32.

CONCLUSIONS:

These positive outcomes may suggest new therapeutic possibilities and highlight the possibility that HSV-2 may trigger an intense inflammatory or autoimmune response that could be the primary cause of ON, rather than direct infection of the optic nerve, as previously believed. Importantly, in our case, high-dose corticosteroid therapy was initiated at the onset of optic neuritis, after several days of antiviral therapy, which supports the safety of corticosteroid administration at this stage. To our knowledge, this case and two other cases of ON associated with herpetic encephalitis in the literature represent the first instances treated with corticosteroid boluses, all of which showed significant improvement.

06 Jan 2026·CURRENT HIV RESEARCH

A Mucoadhesive In situ Gel of Valaciclovir Xanthan Gum Nanoparticles for Genital Herpes Management

Article

Author: Sudheer, Preethi ; Basavaraju, Prakruthi Manjula

Background::

Valaciclovir, a prodrug of acyclovir, is used to treat herpes simplex virus infections. The pharmacokinetics of the drug, namely, low oral bioavailability and short half-life, demands an alternative drug delivery system. Since the drug normally targets virus-infected cells and is metabolized into active acyclovir, its therapeutic effect can be achieved through both local and systemic action when administered vaginally. The innate physiological characteristics of the vagina limit long-term drug availability in the vaginal region.

Objective::

This study aimed to propose a nanoparticle-loaded in situ gel as a drug delivery system to achieve both local and systemic effects of the drug.

Methods::

Ionotropic gelation-high-speed homogenization was adopted to prepare xanthan gum nanoparticles, where crosslinking agents consisted of a combination of sodium citrate and alu-minium chloride. Design Expert Software V13 was used to screen the formulation and processing variables. The nanoparticles were characterized by particle size, zeta potential, morphology, drug loading, and in vitro drug release. The selected nanoparticles were combined with 20% w/v polox-amer 407 and 2% w/v HPMC to produce an in situ mucoadhesive gel, and ex vivo drug permeation was established.

Results::

Drug loading ranged from 79.92±0.11 to 95.52±0.11%. During the 12-hour investiga-tion, drug release was promising. The optimum formula exhibited a zeta potential of -18.6 mV and an average particle size of 117.0 nm. The optimized nanoparticle permeability coefficient was fourfold higher than that of the drug-embedded gel. The in situ gel's adhesion strength (0.784 N) revealed adequate mucoadhesive properties.

Conclusion::

Nanoparticulate mucoadhesive gels are a promising approach for the management of genital herpes infection.

03 Jan 2026·Cureus Journal of Medical Science

Herpes Zoster of the Larynx: A Diagnostic and Therapeutic Challenge

Article

Author: Bessa, Simão ; Lousan, Nuno ; Nogueira, Noémi ; Ferreira, Joana ; Bernardo, Teresa

Herpes zoster of the larynx is an exceptionally rare condition that may mimic more common causes of laryngitis. Reactivation of varicella-zoster virus in the vagus nerve can lead to odynophagia, dysphonia, and dysphagia, often without the typical cutaneous rash. Early recognition is essential, as delayed diagnosis may result in serious complications, including postherpetic neuralgia, persistent dysphagia, chronic voice impairment, and even laryngeal paralysis. We describe a 66-year-old woman on long-term low-dose corticosteroid therapy who presented with acute odynophagia, dysphagia, dysphonia, and fever. Flexible nasopharyngolaryngoscopy revealed supraglottic vesicles localized to the right hemilarynx, extending to the epiglottis and arytenoid region, with ipsilateral sensory loss. Serological testing confirmed varicella-zoster virus infection. The patient was treated with valacyclovir and gabapentin, with resolution of odynophagia and mucosal lesions at one month, though mild dysphagia persisted. Laryngeal herpes zoster represents a diagnostic challenge due to its rarity, overlapping symptoms with other forms of laryngitis, and the brief window of opportunity in which vesicular lesions are visible. The scarcity of reported cases underscores the importance of maintaining a high index of suspicion, particularly in immunosuppressed patients. Early antiviral therapy is crucial to reduce complications, while endoscopic evaluation plays a key role in timely recognition.

128

News (Medical) associated with Valacyclovir Hydrochloride

26 Feb 2026

·www.biospace.com

Pritelivir Demonstrates Superior Efficacy in People Living with HIV with Refractory HSV in Phase 3 PRIOH-1

In a subgroup analysis of people living with HIV enrolled in PRIOH-1, pritelivir demonstrated superior lesion healing, achieving 61% complete lesion healing compared with 20% receiving investigator’s choice therapy (ICT) with an adjusted treatment difference of 37% (p = 0.027) in people living with HIV with refractory HSV infections The results were presented as a late-breaking oral presentation at the Conference on Retroviruses and Opportunistic Infections (CROI), which focuses on key clinical and scientific innovations in human retrovirus-associated diseases like HIV Wuppertal, Germany, February 25, 2026 - Aicuris Anti-infective Cures AG (“Aicuris”) today announced superior efficacy results from a subgroup analysis of its pivotal Phase 3 trial (PRIOH-1) evaluating pritelivir vs. investigator’s choice in people living with HIV with refractory herpes simplex virus (HSV) infection. The results were presented as a late-breaking oral presentation at the Conference on Retroviruses and Opportunistic Infections (CROI) on February 25, 2026, in Denver, USA. People living with HIV face a higher risk of severe, refractory HSV infections due to weakened immunity. HSV-2 also increases HIV acquisition risk, and co-infection can cause aggressive, prolonged, painful lesions and may accelerate HIV progression. Repeated antiviral use for treatment of HSV recurrence increases the risk of resistance, underscoring the urgent need for more effective HSV therapies for this vulnerable population. “Patients living with HIV who develop refractory HSV infections with or without acyclovir resistance often present with prolonged, atypical, and clinically challenging disease courses,” said Professor Jean-Michel Molina, University of Paris Cité, Department of Infectious Diseases, Saint-Louis and Lariboisière Hospitals APHP, Paris France , a principal investigator in the PRIOH-1 study who made the presentation at CROI. “The subgroup analysis from this Phase 3 trial provides important evidence that pritelivir can achieve meaningful lesion healing in this population, using an oral treatment option. These data add an important piece to our understanding of how refractory HSV can be managed in people living with HIV.” In the subgroup, people living with HIV represented 37.6% (38/101) of all immunocompromised patients enrolled in the PRIOH-1 Phase 3 trial and had a mean CD4 cell count of 334.8 cells/mm³. Among these patients, 81.6% (31/38) had refractory HSV (no clinical improvement in HSV lesions after ≥ 7 days of treatment), and 18.4% (7/38) had laboratory-confirmed acyclovir resistance. 40% of the study cohort had another underlying immunosuppressive condition. Similar to other subgroups, pritelivir achieved superior lesion healing of 61% (14/23) within up to 28 days of treatment, compared with 20% (3/15) for ICT, with an adjusted treatment difference of 37%, p = 0.027 [95%CI 7.6, 66.8] (post-hoc analysis). The majority (96%) of people living with HIV completed pritelivir treatment compared with 60% in the investigator’s choice treatment group. “People living with HIV often experience more complex clinical manifestations of HSV, which can make infections particularly difficult to treat,” said Cynthia Wat, CMO of Aicuris . “As an antiviral with a novel mechanism of action, pritelivir has shown efficacy in the treatment of refractory HSV infections with or without resistance (R±R) and may offer an important option for people living with HIV facing severe, refractory HSV disease.” Aicuris announced positive efficacy and favorable safety results for pritelivir at the 2026 Tandem Meetings earlier this month. The global, controlled, open-label comparative trial (PRIOH-1, NCT03073967 / Eudra-CT 2023-510088-37-00 ) included 101 randomized patients and 56 non-randomized patients with R±R HSV infection, including patients living with HIV, hematopoietic stem-cell and solid organ transplant patients, and patients with malignancies, autoimmune or inflammatory disorders. Patients were treated with either oral pritelivir or ICT (IV foscarnet, IV/topical cidofovir, or topical imiquimod). Pritelivir demonstrated a favorable safety and tolerability profile. It was associated with fewer renal, electrolyte events and drug-related TEAE discontinuations (2.0%) compared with ICT (20.0%). The most common TEAEs that occurred while receiving pritelivir were headache (13.7%), diarrhea (11.8%), nausea (7.8%), decreased appetite (7.8%), vomiting (5.9%) and dizziness (5.9%). About Herpes Simplex Virus Herpes Simplex Virus (HSV) includes two types, HSV-1 and HSV-2, both of which cause lifelong infections. HSV-1 most commonly causes labial herpes, typically presenting as cold sores, while HSV-2 is the primary cause of genital herpes. HSV infections are characterized by recurrent, painful lesions and sores and, in severe cases, can lead to complications such as encephalitis, meningitis, disseminated disease, keratitis and neonatal herpes. HSV infections represent a substantial global public health burden. According to the World Health Organization, an estimated 3.8 billion people under the age of 50, or 64% of the global population, were infected with HSV-1 in 2020. 520 million people aged 15 to 49 were living with HSV-2. The disease burden is particularly high in immunocompromised patients, who are at increased risk of more severe, more frequent and treatment-refractory HSV infections. About Pritelivir Pritelivir, a novel helicase-primase inhibitor developed by Aicuris, targets both HSV-1 and HSV-2. These viruses are responsible for genital, oral, or disseminated infections with increasing severity and limited treatment options, particularly in immunocompromised patients where being treatment refractory or resistant to existing antivirals is a significant clinical challenge. Unlike traditional antivirals, pritelivir blocks viral DNA synthesis by inhibiting the helicase-primase complex, a mechanism distinct from marketed nucleoside analogues. Because of this distinct mode of action, pritelivir is active against strains resistant to nucleoside analog and foscarnet based therapies. 1 Earlier clinical trials in immunocompetent and immunocompromised individuals showed a favorable safety pro early signals of clinical efficacy compared to standard of care treatments like valacyclovir and foscarnet. Based on these results, pritelivir was granted FDA Breakthrough Therapy designation. In October 2025, Aicuris announced that pritelivir met its primary endpoint in the pivotal Phase 3 trial. About Aicuris Aicuris is meeting the needs of the growing population of immunocompromised people who require precise therapies to effectively treat infection. Our flagship product, PREVYMIS ® , marketed by our partner MSD, prevents CMV in a defined group of transplant recipients. Our pivotal Phase 3 candidate, pritelivir, aims to address refractory HSV infections in a broad population of patients with weakened immune systems. For immunocompromised people, an otherwise manageable infection can mean life or death. Aicuris, with its expertise and growing pipeline, is committed to providing therapeutic solutions for them now and in the future. Contact: Aicuris Anti-infective Cures AG Email: info@aicuris.com Trophic Communications Dr. Stephanie May and Anja Heuer Phone: +49 171 1855 682 Email: aicuris@trophic.eu 1 Sallée, L. and Boutolleau, D. (2024), Management of Refractory/Resistant Herpes Simplex Virus Infections in Haematopoietic Stem Cell Transplantation Recipients: A Literature Review. Rev Med Virol, 34: e2574. Attachment CROI PR

Phase 3Clinical ResultBreakthrough TherapyQualified Infectious Disease Product

05 Feb 2026

·www.einpresswire.com

GARM Clinic Introduces HSV Immunotherapy Protocol to Help Patients Break the Cycle of Recurrent Outbreaks

Three-phase treatment offers patients with HSV infections an alternative to perpetual antiviral management ROATAN, BAY ISLANDS, HONDURAS, February 5, 2026 / EINPresswire.com / -- GARM Clinic , a specialized medical facility focused on advanced regenerative, longevity, and immunotherapy treatments, announced today the availability of a three-phase immunotherapy protocol for patients with recurrent herpes simplex virus (HSV-1 and HSV-2) infections. The treatment, which has been administered to hundreds of patients over 13 years of clinical application, offers an immune-based approach aiming to achieve sustained viral suppression for patients who have not responded adequately to conventional antiviral therapy or for patients who do not wish to take antivirals on a long term basis. An estimated 1 in 3 adults worldwide lives with either HSV1 or HSV2. For many, antiviral medications such as valacyclovir and acyclovir provide adequate symptom control. However, long term use of these drugs may not be a desirable option due to decreased efficacy over time and unpleasant side effects in some patients. Even on an antiviral regimen, a significant subset of patients continues to experience frequent outbreaks—monthly, bi-weekly, or near-constant—despite daily suppressive therapy. These patients often also report neurological symptoms including chronic pain, paresthesia, and insomnia that physicians frequently dismiss or misattribute. For this population, conventional treatment represents a cycle with no end: outbreak, medication, brief relief, outbreak again. Quality of life remains compromised indefinitely. The immunotherapy protocol now available at GARM Clinic in Roatan works through a fundamentally different mechanism than antiviral medication. Rather than suppressing viral replication during active outbreaks, the treatment retrains the immune system's response to the virus. Administered in three phases over 10-12 weeks, the treatment aims to achieve sustained latency—long-term suppression of viral reactivation rather than perpetual symptom management. Clinical experience over 13 years has demonstrated a 50-90% reduction in outbreak frequency across the patient population, with many patients achieving extended periods of complete latency. Neurological symptoms associated with recurrent outbreaks have also shown significant improvement, often beginning after the first administration. Individual results vary, and proper medical evaluation is required to determine candidacy. "For patients experiencing frequent HSV outbreaks, conventional treatment can feel like a life sentence of symptom management, discomfort, and shame," said Heather Terry, CEO at GARM Clinic. "This immunotherapy protocol offers something different—not a cure, but a genuine opportunity to try to break the cycle and achieve the sustained suppression that antivirals alone haven't provided. We're proud to make this option available to patients who've been told nothing more can be done." The protocol is designed for patients with confirmed HSV-1 and/or HSV-2 who wish to re-alert the immune system to the virus, allowing the immune system to do its job at suppressing outbreaks, instead of trying to manage the symptoms with antivirals. Furthermore, patients with frequent recurrent outbreaks who have not achieved adequate symptom control with antiviral therapy may well achieve latency and relief with the immunotherapy treatment. It is important to note the treatment is not a cure—the virus remains in the body permanently—and is not appropriate for all patients. GARM Clinic conducts thorough medical evaluations via telemedicine to determine candidacy before treatment. Importantly, recent research has identified causation between recurrent HSV infections and an elevated risk of cognitive decline and Alzheimer's disease, with some studies indicating up to 2.5 times higher risk in affected individuals. While more research is needed, suppressing recurrent viral reactivation may potentially reduce the chronic neuroinflammatory burden associated with frequent outbreaks. The HSV immunotherapy protocol is available now at GARM Clinic's Roatán facility. Patients interested in determining their candidacy may request an evaluation at www.garmclinic.com or contact hsvsolution@garmclinic.com. ABOUT GARM CLINIC For twelve years, GARM Clinic has been providing advanced regenerative, longevity and immunotherapy treatments in its specialized medical facility located in Roatán, Bay Islands, Honduras. GARM provides access to high quality, evidence-based, safe and effective therapies not yet available in the United States. The clinic serves international patients seeking alternatives to conventional treatment approaches for chronic and acute conditions, as well as patients seeking safe, cutting edge longevity treatments such as specialized cell and gene therapies. For more information, visit www.garmclinic.com . This treatment is not approved by the U.S. Food and Drug Administration. It is not a cure for HSV; the virus remains in the body permanently. Individual results vary. This press release is for informational purposes only and does not constitute medical advice. Patients should consult with qualified medical professionals to determine if this treatment is appropriate for their individual circumstances. GARM Clinic GARM Clinic +1 305-848-0144 info@garmclinic.com Visit us on social media: LinkedIn Instagram Facebook YouTube TikTok X Legal Disclaimer: EIN Presswire provides this news content "as is" without warranty of any kind. We do not accept any responsibility or liability for the accuracy, content, images, videos, licenses, completeness, legality, or reliability of the information contained in this article. If you have any complaints or copyright issues related to this article, kindly contact the author above.

ImmunotherapyClinical Study

05 Feb 2026

·www.biospace.com

Aicuris Presents Positive Phase 3 Data for Pritelivir in Immunocompromised Patients with Refractory Herpes Simplex Virus at TANDEM

Pritelivir met its primary endpoint of superior lesion healing, achieving a 62.7% lesion healing rate compared to 34.0% with standard-of-care therapies (investigator’s choice), resulting in an adjusted treatment difference of 28.4% (p = 0.0047) Pritelivir demonstrated a favorable safety and tolerability profile, with fewer treatment-emergent adverse events and drug-related discontinuations compared to investigator’s choice Aicuris is on track to submit a New Drug Application (NDA) to the U.S. FDA in Q1 of 2026 The 2026 Tandem Meetings cover the latest research and breakthroughs in the evolving field of hematopoietic cell transplantation (HCT), cellular therapy and gene therapy Wuppertal, Germany, February 5, 2026 - Aicuris Anti-infective Cures AG (“Aicuris”) today announced positive results from its pivotal Phase 3 trial (PRIOH-1, NCT03073967 ), evaluating pritelivir in immunocompromised patients with refractory herpes simplex virus (HSV) infections, with or without resistance (R±R). Pritelivir, a novel small molecule antiviral targeting the helicase-primase complex of HSV, demonstrated superior efficacy and a favorable safety and tolerability pro to investigator’s choice therapy (ICT). The results will be presented by study investigator Genovefa Papanicolaou, MD, in an Oral Late Breaker presentation at the 2026 Tandem Meetings on February 7, 2026, in Salt Lake City, USA. As announced in October 2025, the trial met its primary efficacy endpoint and demonstrated favorable safety and tolerability results. Pritelivir achieved a clinically meaningful and statistically significant superiority in lesion healing of 62.7% compared to 34.0% for ICT, with an adjusted treatment difference of 28.4% (p = 0.0047). Pritelivir was associated with fewer drug-related treatment-emergent adverse events (TEAEs), including renal, electrolyte and drug-related TEAEs, leading to discontinuations compared with ICT (2.0% vs. 20% respectively). The most common TEAEs were headache, diarrhea, nausea, decreased appetite, vomiting and dizziness with a ≥5% incidence. “Current therapeutic options for hematopoietic cell transplant patients with refractory or resistant herpes simplex viral infection are limited by poor response rates, significant toxicities, and the burden of daily intravenous infusions in a healthcare setting,” said Genovefa Papanicolaou, MD, Clinical Director of Infectious Disease Service at Memorial Sloan Kettering Cancer Center and Professor at Weill Cornell College of Medicine . Pritelivir addresses a critical unmet medical need for an oral agent offering statistically superior and clinically meaningful lesion healing with fewer side effects. It has the potential to significantly improve both clinical outcomes and quality of life for these vulnerable patients.” “For more than two decades, there has been no innovation in antiviral medicines for HSV, leaving clinicians with limited treatment options for patients who do not respond to existing antivirals. By targeting an essential step in the virus’s replication process, pritelivir offers a novel approach that can overcome current antiviral resistance,” Cynthia Wat, MD, CMO of Aicuris , added. “Together, these results mark a pivotal moment for patients with refractory HSV infections, supporting pritelivir’s potential to redefine the standard of care for patients at high risk of morbidity and mortality. We look forward to bringing it swiftly to those with few effective and well tolerated alternatives.” The global, controlled, open-label comparative trial ( NCT03073967 / Eudra-CT 2023-510088-37-00 ) randomized and treated a total of 101 immunocompromised patients with R±R HSV infection, including transplant recipients (hematopoietic stem-cell and solid organ), patients with malignancies, autoimmune or inflammatory disorders, and patients with an HIV infection. An additional 56 patients were treated in the non-randomized part of the trial. Participants received either oral pritelivir (100 mg daily, 400 mg loading dose on the first day of therapy) or ICT (IV foscarnet, IV/topical cidofovir or topical imiquimod) for up to 28 days, with the option to extend treatment to 42 days, if lesion improvement was observed. About Herpes Simplex Virus Herpes Simplex Virus (HSV) includes two types, HSV-1 and HSV-2, both of which cause lifelong infections. HSV-1 most commonly causes labial herpes, typically presenting as cold sores, while HSV-2 is the primary cause of genital herpes. HSV infections are characterized by recurrent, painful lesions and sores and, in severe cases, can lead to complications such as encephalitis, meningitis, disseminated disease, keratitis and neonatal herpes. HSV infections represent a substantial global public health burden. According to the World Health Organization, an estimated 3.8 billion people under the age of 50, or 64% of the global population, were infected with HSV-1 in 2020. 520 million people aged 15 to 49 were living with HSV-2. The disease burden is particularly high in immunocompromised patients, who are at increased risk of more severe, more frequent and treatment-refractory HSV infections. About Pritelivir Pritelivir, a novel helicase-primase inhibitor developed by Aicuris, targets both HSV-1 and HSV-2. These viruses are responsible for genital, oral, or disseminated infections with increasing severity and limited treatment options, particularly in immunocompromised patients where being treatment refractory or resistant to existing antivirals is a significant clinical challenge. Unlike traditional antivirals, pritelivir blocks viral DNA synthesis by inhibiting the helicase-primase complex, a mechanism distinct from marketed nucleoside analogues. Because of this distinct mode of action, pritelivir is active against strains resistant to nucleoside analog-and foscarnet based therapies. 1 Earlier clinical trials in immunocompetent and immunocompromised individuals showed a favorable safety pro early signals of clinical efficacy compared to standard of care treatments like valacyclovir and foscarnet. Based on these results, pritelivir was granted FDA Breakthrough Therapy designation. In October 2025, Aicuris announced that pritelivir met its primary endpoint in the pivotal Phase 3 trial. The company expects to marketing authorization with the U.S. FDA in Q1 of 2026. About Aicuris Aicuris is meeting the needs of the growing population of immunocompromised people who require precise therapies to effectively treat infection. Our flagship product, PREVYMIS ® , marketed by our partner MSD, prevents CMV in a defined group of transplant recipients. Our pivotal Phase 3 candidate, pritelivir, aims to address refractory HSV infections in a broad population of patients with weakened immune systems. For immunocompromised people, an otherwise manageable infection can mean life or death. Aicuris, with its expertise and growing pipeline, is committed to providing therapeutic solutions for them now and in the future. Contact: Aicuris Anti-infective Cures AG info@aicuris.com Trophic Communications Dr. Stephanie May and Anja Heuer Phone: +49 171 1855 682 Email: aicuris@trophic.eu 1 Sallée, L. and Boutolleau, D. (2024), Management of Refractory/Resistant Herpes Simplex Virus Infections in Haematopoietic Stem Cell Transplantation Recipients: A Literature Review. Rev Med Virol, 34: e2574. Attachment Tandem Data PR

Phase 3Clinical ResultBreakthrough Therapy

100 Deals associated with Valacyclovir Hydrochloride

External Link

KEGG	Wiki	ATC	Drug Bank
D00398	Valacyclovir Hydrochloride	J05AB11	DB00577

R&D Status

Approved

10 top approved records.

to view more data

Indication	Country/Location	Organization	Date
Cytomegalovirus Infections	Australia	Sun Pharma ANZ Pty Ltd.	09 Jul 2009
Herpes Zoster Ophthalmicus	Australia	Sun Pharma ANZ Pty Ltd.	09 Jul 2009
Herpes Simplex	China	Livzon Group Livzon Pharmaceutical Factory	01 Jan 1996
Chickenpox	United States	GSK Plc	23 Jun 1995
Herpes Genitalis	United States	GSK Plc	23 Jun 1995
Herpes Labialis	United States	GSK Plc	23 Jun 1995
Herpes Zoster	United States	GSK Plc	23 Jun 1995

Developing

10 top R&D records.

to view more data

Indication	Highest Phase	Country/Location	Organization	Date
HIV Infections	Phase 3	United States	Glaxo Wellcome SA	01 Jun 1999
HIV Infections	Phase 3	Canada	Glaxo Wellcome SA	01 Jun 1999
Hepatitis C, Chronic	Phase 2	United States	GSK Plc	01 Apr 2012
Glioblastoma Multiforme	Phase 2	United States	Candel Therapeutics, Inc.	01 Mar 2007
High grade glioma	Phase 2	United States	Candel Therapeutics, Inc.	01 Mar 2007
Resectable Lung Non-Small Cell Carcinoma	Phase 1	United States	Candel Therapeutics, Inc.	04 May 2017
Pancreatic adenocarcinoma	Phase 1	United States	Candel Therapeutics, Inc.	01 Aug 2008
Virus Diseases	Preclinical	Belgium	Hyloris Pharmaceuticals SA	28 Dec 2023

Clinical Result

Indication

Phase

Evaluation

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Study	Phase	Population	Analyzed Enrollment	Group	Results	Evaluation	Publication Date


Tandem Meetings ASTCT and CIBMTR2026	Not Applicable	Hematopoietic stem cell transplantation	79	Letermovir	lxkdznqygw(oiuecyxnas) = mtkvngvpye rizygllqzd (ydvofxlbov ) View more	Negative	04 Feb 2026
				Valacyclovir	lxkdznqygw(oiuecyxnas) = nmnuoiirch rizygllqzd (ydvofxlbov ) View more
NCT03282916 (Pubmed \| JAMA)	Phase 3	Alzheimer Disease HSV-1 or HSV-2	120	Valacyclovir 4 g/d (HSV Seropositivity + Early Symptomatic Alzheimer Disease)	iiowusfqzg(cnbrtkysls) = pzfyzpcpem rraoyzntrq (mmgsraeybm, 8.80 - 12.91) View more	Negative	17 Dec 2025
				Placebo (HSV Seropositivity + Early Symptomatic Alzheimer Disease)	iiowusfqzg(cnbrtkysls) = xdnvtccuvj rraoyzntrq (mmgsraeybm, 4.88 - 8.97) View more
NCT03282916 (CTgov)	Phase 2	Alzheimer Disease \| Herpes Simplex	120	Valacyclovir (Valacyclovir)	xilpqczxqf(gqhkdawjme) = dymqdxbexx hwzrqvefet (tsgmlqxgdm, 6.6) View more	-	08 Sep 2025
				Placebo (Placebo)	xilpqczxqf(gqhkdawjme) = pnlodfasvz hwzrqvefet (tsgmlqxgdm, 7.6) View more
GlobeNewswire Manual	Not Applicable	Post Acute COVID 19 Syndrome	27	Valacyclovir + Celecoxib + Pulsed Paxlovid	flahpaahkn(kzfvzaoakf): P-Value = <0.0001 View more	Positive	04 Sep 2025
				Valacyclovir + Celecoxib
NCT04448392 (CTgov)	Phase 1	Neonatal Herpes	7	Valacyclovir	hlmafrtgaz(btshoppqnw) = bhbsigrfxp fzjevuwsue (bkuvivkufk, 16.8) View more	-	24 Jun 2025
NCT00589875 (BrTK02, CTgov)	Phase 2	Glioblastoma Multiforme \| High grade glioma	52	Radiation therapy+Temozolomide+Valacyclovir+CAN-2409	iggyztxncs = epcfktmgaw mvsyxtszby (waqjxgobrh, degeloelop - kiirnjqcrv) View more	-	03 Apr 2024
NCT05094414 (Pubmed \| Biomedicines) Manual	Phase 1	Overactive bladder syndrome Epstein-Barr virus \| John Cunningham virus \| BK virus ... View more	58	Valacyclovir 500 mg	ujzvmchtrc(hdaughitsl) = qcscylmdru uqpzahlvly (gpfyrjfmyu ) View more	Positive	26 Feb 2024
				Valacyclovir (Control)	krtudbroje(gwphvcfbil) = ogjmwsujrz yxrcigqgjx (xyccgxguod )
NCT02831933 (ENSIGN, CTgov)	Phase 2	Uveal Melanoma \| Advanced Lung Squamous Cell Carcinoma \| metastatic non-small cell lung cancer ... View more	11	SBRT+Nivolumab+Valacyclovir	nkqmzmctjv(hjeuzobfho) = moefrbzrlt qysaidrulq (trsmcpzccy, xrsyjeyesl - rgaeipfgef) View more	-	21 Sep 2023
NCT03699904 (EViSCO, Pubmed \| Chest)	Not Applicable	Pulmonary Disease, Chronic Obstructive	84	Valaciclovir	mltepphcmz(ctttsczlqp) = cgfonodfga hptonilqye (qabaxiajgg ) View more	Positive	01 Apr 2023
				Placebo	ghwjhsfmua(hpiwedybpc) = cjxjhzkblx psrbwwyakh (opfddgthxf )
NCT03004183 (STOMP, CTgov)	Phase 2	metastatic non-small cell lung cancer \| Metastatic Triple-Negative Breast Carcinoma	57	SBRT+ADV/HSV-tk+pembrolizumab+Valacyclovir	noyjisbgoo(gpvafcknsx) = wrxgpduxpk ebelegkeuw (cpudrhcjii, ctngwocxlr - xbmfkpyfko) View more	-	25 Jan 2023

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