Regulatory submission: NDA submitted February 2026 and approved October 2026

“The application for approval was submitted to the FDA in early February.” (opens the source at this quote in a new tab)

“Pritelivir met its primary endpoint in the pivotal Phase 3 PRIOH-1 trial in immunocompromised patients with refractory HSV infections, and Aicuris submitted a New Drug Application to the FDA in Q1 of 2026.” (opens the source at this quote in a new tab)

Field	Quoted record
Drug name	“Hovilpri”
Active ingredient	“pritelivir”
Approval date	“10/9/2026”

Launch: Anticipated before the end of 2026

“HOVILPRI is expected to be available in the United States before the end of 2026.” (opens the source at this quote in a new tab)

“Commercial availability is coming soon!” (opens the source at this quote in a new tab)
“NOW APPROVED” (opens the source at this quote in a new tab)

FDA approval on 9 October 2026

“FDA has approved Hovilpri (pritelivir) tablets for adults with weakened immune systems (i.e., immunocompromised patients) who have mucocutaneous lesions caused by herpes simplex virus (HSV) infection and have not responded to other therapies (acyclovir, valacyclovir, or famciclovir).” (opens the source at this quote in a new tab)

Field	Quoted record
Drug name	“Hovilpri”
Active ingredient	“pritelivir”
Approval date	“10/9/2026”
FDA-approved use on approval date	“To treat adults with weakened immune systems who have mucocutaneous lesions caused by herpes simplex virus infection and have not responded to other therapies”

“Tokyo – October 9, 2026 – Asahi Kasei Therapeutics, Inc., the global specialty pharmaceutical business of Tokyo-based Asahi Kasei, with U.S. and European business headquarters in Cary, North Carolina, today announced that the U.S. Food and Drug Administration (FDA) has approved HOVILPRI® (pritelivir) 100 mg tablets for the treatment of mucocutaneous lesions caused by herpes simplex virus (HSV) infection that is refractory (with or without documented resistance) to treatment with acyclovir, valacyclovir, or famciclovir in immunocompromised adults.” (opens the source at this quote in a new tab)

“Initial U.S. Approval: 2026” (opens the prescribing information at this quote)
“Revised: 10/2026” (opens the prescribing information at this quote)
“This Patient Information has been approved by the U.S. Food and Drug Administration.” (opens the prescribing information at this quote)
“Issued: 10/2026” (opens the prescribing information at this quote)

Evidence supporting approval

“The efficacy of Hovilpri was evaluated in a randomized, open-label, comparator-controlled, superiority trial (PRIOH-1 Phase 3 Trial, Part C; NCT 03073967) in immunocompromised participants with mucocutaneous HSV infection who did not respond to treatment with acyclovir, valacyclovir, or famciclovir.” (opens the source at this quote in a new tab)
“A total of 101 immunocompromised adults were randomly assigned and treated with Hovilpri or the investigator’s choice of available treatments.” (opens the source at this quote in a new tab)
“By 28 days, all lesions were healed in 63% of patients receiving Hovilpri, compared with 34% of patients receiving one of the other medications.” (opens the source at this quote in a new tab)

“The safety of HOVILPRI was evaluated in 206 adults treated with HOVILPRI and an additional 100 healthy adult participants exposed to HOVILPRI in clinical trials.” (opens the prescribing information at this quote)
“The efficacy of HOVILPRI was further evaluated in Parts D and F of Trial PRIOH-1, which had a non-randomized, open-label, single-arm design to assess the efficacy and safety of HOVILPRI (400 mg loading dose on Day 1 followed by 100 mg once daily).” (opens the prescribing information at this quote)

“The approval is supported by results from PRIOH-1 Part C, the pivotal Phase 3 randomized, open-label, comparator-controlled superiority trial in immunocompromised adults with mucocutaneous HSV infection that was refractory, with or without documented resistance, to acyclovir, valacyclovir, or famciclovir.” (opens the source at this quote in a new tab)

Expedited programs named at approval

“Hovilpri received priority review for this indication.” (opens the source at this quote in a new tab)

“Pritelivir was granted Fast Track designation by the FDA along with Breakthrough Therapy designation and the New Drug Application received Priority Review.” (opens the source at this quote in a new tab)

Priority review and PDUFA target date

“Wuppertal, Germany, April 16, 2026 – Aicuris Anti-infective Cures AG (“Aicuris”) today announced that the U.S. Food and Drug Administration (FDA) has granted Priority Review for the New Drug Application (NDA) filed for pritelivir.” (opens the source at this quote in a new tab)
“The submission is based on initial results from the pivotal Phase 3 trial in which pritelivir met its registrational Phase 3 primary endpoint for the treatment of refractory herpes simplex virus (HSV) infection, with or without resistance (R±R), in immunocompromised patients.” (opens the source at this quote in a new tab)
“The FDA has set a Prescription Drug User Fee Act (PDUFA) Target Date in the fourth quarter of 2026.” (opens the source at this quote in a new tab)
“If approved, pritelivir would become the first new treatment for HSV in more than two decades.” (opens the source at this quote in a new tab)

“FDA has granted Priority Review for the pritelivir New Drug Application. Prescription Drug User Fee Act (PDUFA) target date is Q4 2026” (opens the source at this quote in a new tab)

NDA submission: plans announced before the filing

“These results will form the basis for regulatory filings with the FDA and globally.” (opens the source at this quote in a new tab)
“We plan to rapidly advance our New Drug Application submission to the FDA, and we look forward to presenting a comprehensive analysis of these positive results at a medical conference next year,” (opens the source at this quote in a new tab)
“In July, the last patient was enrolled in the Phase 3 pivotal trial, the outcomes of which are expected to serve as a basis for filing for marketing authorization in 2026.” (opens the source at this quote in a new tab)

“PreNDA meeting in 2H2025” (opens the source at this quote in a new tab)
“Topline data of ongoing pivotal study expected in 2H2025” (opens the source at this quote in a new tab)
“US launch YE2026 by Aicuris sales team” (opens the source at this quote in a new tab)
“Breakthrough designation allows active dialog with US FDA” (opens the source at this quote in a new tab)

NDA submission: company assessment of the likelihood of approval, February 2026

“Pritelivir has received Breakthrough Therapy designation from the U.S. Food and Drug Administration (FDA).” (opens the source at this quote in a new tab)
“In addition, the Phase 3 study has demonstrated efficacy and safety compared to conventional treatments. Based on this, we see a very high likelihood of approval.” (opens the source at this quote in a new tab)

Breakthrough therapy designation, June 2020

“WUPPERTAL, GERMANY / ACCESSWIRE / June 5, 2020 / AiCuris Anti-infective Cures GmbH, a leading company in the discovery and development of drugs against infectious diseases, today announced that the Company has been granted Breakthrough Therapy designation by the U.S. Food and Drug Administration (FDA) for oral pritelivir, AiCuris' lead candidate for the treatment of acyclovir-resistant mucocutaneous herpes simplex virus (HSV) infections in immunocompromised adults.” (opens the source at this quote in a new tab)
“Breakthrough Therapy designation is intended to accelerate the development and review of a potential therapy for a serious or life-threatening disease, with clinical evidence of substantial improvement over existing options.” (opens the source at this quote in a new tab)
“Based on early results AiCuris is in close communication with the FDA and preparing to add a pivotal Phase 3 part to this trial as a basis for NDA submission.” (opens the source at this quote in a new tab)

“Notably, pritelivir received a Breakthrough Therapy designation in 2020 from the FDA, and Aicuris supports expanded access to treatment for eligible patients.” (opens the source at this quote in a new tab)

Fast track designation, 2017

“In 2017, AiCuris was granted Fast Track designation by the U.S. Food and Drug Administration (FDA) for pritelivir for the treatment of acyclovir-resistant mucocutaneous HSV infections in immunocompromised adults.” (opens the source at this quote in a new tab)

“AiCuris’ Pritelivir has now secured FDA endorsement in the form of a Fast Track Designation in immuno-compromised patients.” (opens the source at this quote in a new tab)
“Now, the FDA has Fast Tracked the drug for patients with weakened immune systems.” (opens the source at this quote in a new tab)

Clinical hold imposed by the FDA in May 2013

“On May 9, 2013, the US Food and Drug Administration (FDA) imposed a clinical hold (an order to the sponsor to suspend ongoing investigation), based on hematologic and dermatologic findings such as dry skin, crusty skin lesions, and alopecia in a chronic toxicity study involving monkeys.” (opens the source at this quote in a new tab)
“Because the duration of the clinical hold was uncertain, the sponsor terminated the study on June 24, 2013.” (opens the source at this quote in a new tab)
“The trial was placed on clinical hold by the FDA and terminated by the sponsor based on findings in monkeys in a 39-week toxicity study.” (opens the source at this quote in a new tab)
“These findings included skin related findings such as dry skin, crusty skin lesions, and alopecia as well as anemia (decreases in hemoglobin and in most animals an increase in the percentage of reticulocytes).” (opens the source at this quote in a new tab)
“So far the mechanism of dermatologic and hematologic findings is not understood.” (opens the source at this quote in a new tab)
“However, in the present study participants did not experience any similar adverse events (eg, anemia), although one person developed a rash (hives).” (opens the source at this quote in a new tab)

Clinical hold: status described in December 2016

“Although the clinical trials conducted so far in humans have shown no serious side effects, the U.S. Food and Drug Administration put a hold on the drug’s clinical use in 2013 because of skin and blood abnormalities shown in a concurrent animal trial.” (opens the source at this quote in a new tab)
“The German drug maker AiCuris is working with the FDA to partially lift the hold so that pritelivir can be tested in a new clinical trial on patients who are resistant to drugs in the acyclovir family, which include acyclovir, famciclovir and valacyclovir.” (opens the source at this quote in a new tab)

Clinical hold: date lifted

No evidence found.

PRIOH-1 milestones: first site of the phase 2 part opened in May 2017

“Wuppertal, May 09, 2017 - AiCuris Anti-infective Cures GmbH, a leading company in the discovery and development of drugs against infectious diseases, today announced the opening of the first site in its clinical phase 2 study, PRIOH-1, to evaluate the efficacy and safety of oral pritelivir, a small molecule helicase-primase inhibitor for the treatment of acyclovir-resistant mucocutaneous herpes simplex virus (HSV) infections in immunocompromised adults.” (opens the source at this quote in a new tab)
“The primary endpoint of the study which is planned to include a total of 30 patients at approx. 20 sites in the U.S. is time to lesion healing.” (opens the source at this quote in a new tab)

PRIOH-1 milestones: phase 3 part started in July 2021

“WUPPERTAL, GERMANY / ACCESSWIRE / July 8, 2021 / AiCuris Anti-infective Cures AG, a leading company in the discovery and development of drugs against infectious diseases, today announced the start of pivotal phase 3 development with its proprietary lead compound pritelivir, a novel helicase-primase inhibitor, following encouraging phase 2 interim results achieved in the phase 2 part of its clinical phase 2/3 trial, PRIOH-1.” (opens the source at this quote in a new tab)
“Following the strong results achieved in phase 2, AiCuris directly amended this trial with a pivotal phase 3 part as a basis for NDA submission.” (opens the source at this quote in a new tab)
“The phase 3 part of the trial with a study design based on the phase 2 part will compare lesion healing in a given time frame and is conducted worldwide at up to 70 sites in the US, South America, Europe, and China and plans to enroll 128 patients.” (opens the source at this quote in a new tab)
“First clinical sites are already initiated.” (opens the source at this quote in a new tab)

PRIOH-1 milestones: timelines projected in 2023 and 2024

“Topline data from the ongoing phase 3 trial is expected end of 2024.” (opens the source at this quote in a new tab)

“The study expects to complete patient enrollment in 1H 2025.” (opens the source at this quote in a new tab)
“The results of this trial will serve as a basis for filing for marketing authorization in 2026.” (opens the source at this quote in a new tab)

PRIOH-1 milestones: enrollment completed in July 2025

“Wuppertal, Germany, July 24, 2025 – Aicuris Anti-infective Cures AG today announced the completion of patient enrollment in its pivotal Phase 3 trial, PRIOH-1, evaluating pritelivir for the treatment of refractory and/or treatment resistant herpes simplex virus (HSV) infections in immunocompromised patients.” (opens the source at this quote in a new tab)
“The study recruited 157 participants across 12 countries in Europe, North America and Australia.” (opens the source at this quote in a new tab)
“Topline results are expected for Q4 2025 with a detailed analysis presented at a medical conference in H1 2026.” (opens the source at this quote in a new tab)

PRIOH-1 milestones: topline results in October 2025

“Wuppertal, Germany, October 16, 2025 – Aicuris Anti-infective Cures AG today announced that the registrational Phase 3 trial (PRIOH-1, NCT03073967) with its lead candidate pritelivir, a first-in-class helicase primase inhibitor for HSV, has met its primary endpoint of superiority (p=0.0047) in lesion healing in patients receiving treatment up to 28 days.” (opens the source at this quote in a new tab)
“Statistical superiority in lesion healing further increased in patients receiving up to 42 days of treatment (p<0.0001).” (opens the source at this quote in a new tab)
“The open-label, comparative trial (NCT03073967 / Eudra-CT 2023-510088-37-00) was conducted in centers across 15 countries and enrolled 158 immunocompromised participants.” (opens the source at this quote in a new tab)

Acquisition of AiCuris by Asahi Kasei: agreement of February 2026

“Asahi Kasei announced it has entered into a definitive agreement to acquire all issued shares of Aicuris Anti-infective Cures AG, a German-based biopharmaceutical company, for approximately €780 million” (opens the source at this quote in a new tab)
“This transaction expands Asahi Kasei’s specialty pharmaceutical platform further into severe infectious diseases and is expected to close in the first quarter of fiscal 2026, subject to customary conditions.” (opens the source at this quote in a new tab)
“The portfolio also enhances Asahi Kasei’s financial profile, combining immediate royalty income from Prevymis® with near-term commercial upside from pritelivir, for which approval is targeted in fiscal 2026.” (opens the source at this quote in a new tab)

“Aicuris today announced that it has entered into a definitive agreement under which Asahi Kasei will acquire all shares of Aicuris through its U.S. subsidiary Veloxis Pharmaceuticals Inc. for a total of €780 million (~$920 million).” (opens the source at this quote in a new tab)

“When the positive results from pritelivir's Phase 3 trial were confirmed in October 2025, Aicuris raised the prospect of an acquisition, and we were swiftly able to express our interest.” (opens the source at this quote in a new tab)

Acquisition of AiCuris by Asahi Kasei: completion in April 2026

“Asahi Kasei, a diversified global company, announced the successful completion of its acquisition of Aicuris Anti-infective Cures AG (Aicuris), a German-based biopharmaceutical company.” (opens the source at this quote in a new tab)
“This includes a consistent royalty stream from Prevymis®; a near-term commercial opportunity with pritelivir, for which the U.S. Food and Drug Administration (FDA) granted Priority Review to the New Drug Application, with a Prescription Drug User Fee Act (PDUFA) target date in the fourth quarter of 2026 and AIC468 as a longer-term growth driver.” (opens the source at this quote in a new tab)
“Asahi Kasei plans to advance Aicuris’s portfolio through its U.S. subsidiary, Veloxis Pharmaceuticals, Inc., an established leader in transplant medicine.” (opens the source at this quote in a new tab)

Patent term and generic entry: company statement, February 2026

“How do you anticipate the timing of generic drug entry?” (opens the source at this quote in a new tab)
“We currently anticipate the patent will remain valid until the mid-2030s.” (opens the source at this quote in a new tab)

Patent coverage described in a 2026 review of helicase-primase inhibitor patents

“Initial patents filed by Bayer between 1999 and 2003 established the foundational chemical space around thiazolyl amide derivatives (Table 7).” (opens the source at this quote in a new tab)
“However, most of these early patents have now expired.” (opens the source at this quote in a new tab)
“A key milestone was the introduction of tablet formulations containing pritelivir salts, with protection in some regions extending into the late 2020s.” (opens the source at this quote in a new tab)
“The most significant intellectual property emerged from patents filed in 2012, which describe both the synthesis and specific crystalline forms of pritelivir, particularly the mesylate monohydrate.” (opens the source at this quote in a new tab)
“This form, along with defined particle size distributions, represents a central element of the current protection strategy and is covered until approximately 2032.” (opens the source at this quote in a new tab)
“Further diversification of solid forms was disclosed in later patents, including the free base hemihydrate and the maleate salt, both of which are associated with pharmaceutical formulations and manufacturing processes and extend protection until around 2037.” (opens the source at this quote in a new tab)
“The definitive crystalline form used in a marketed formulation has not been publicly disclosed.” (opens the source at this quote in a new tab)
“Overall, while the original compound class is no longer protected, the current patent estate for pritelivir is strongly centered on specific crystalline forms, formulation technologies, and methods of manufacture, which together are expected to play a decisive role in the eventual commercial product strategy.” (opens the source at this quote in a new tab)

Priority review voucher: company statement, February 2026

“At this time, we do not anticipate receiving a priority review voucher.” (opens the source at this quote in a new tab)

Drugs@FDA record, NDA number, and approval letter

No evidence found.

Orange Book patent and exclusivity listings

No evidence found.

Regulatory status outside the United States: company statements on plans

“Regarding sales regions, our policy is to prioritize the U.S. market.” (opens the source at this quote in a new tab)
“Approval and sales outside the U.S. are under consideration, but we are not yet at a stage where we can disclose specific plans.” (opens the source at this quote in a new tab)
“If drug prices were set significantly lower outside the U.S., this could lead to substantial reductions in U.S. drug prices as well. Given the current uncertainty surrounding the regulatory environment, we intend to proceed cautiously.” (opens the source at this quote in a new tab)

“Full results will be presented at an upcoming medical conference and will form the basis for regulatory filings with the FDA and globally” (opens the source at this quote in a new tab)

Regulatory status outside the United States: European Union paediatric investigation plan

Field	Quoted record
Active substance	“pritelivir (mesylate monohydrate)”
Therapeutic area	“Infectious diseases”
Decision number	“P/0458/2021”
PIP number	“EMEA-002180-PIP02-19”
Pharmaceutical form(s)	“Film-coated tablet”
Condition(s) / indication(s)	“Treatment and prevention of Herpes simplex virus disease”
Decision type	“P: decision agreeing on a investigation plan, with or without partial waiver(s) and or deferral(s)”
Decision date	“29/10/2021”
Compliance check done	“No”

“on the agreement of a paediatric investigation plan and on the granting of a deferral and on the granting of a waiver for pritelivir (mesylate monohydrate), (EMEA-002180-PIP02-19) in accordance with Regulation (EC) No 1901/2006 of the European Parliament and of the Council” (opens the source at this quote in a new tab)
“Having regard to the application submitted by AiCuris Anti-infective Cures AG on 28 October 2019 under Article 16(1) of Regulation (EC) No 1901/2006 also requesting a deferral under Article 20 of said regulation and a waiver under Article 13 of said Regulation,” (opens the source at this quote in a new tab)
“This decision does not constitute entitlement to the rewards and incentives referred to in Title V of Regulation (EC) No 1901/2006.” (opens the source at this quote in a new tab)

Regulatory status outside the United States: compassionate use in Germany and early access in other countries

“In December 2020, the "Bundesinstitut für Arzneimittel und Medizinprodukte (BfArM)" acknowledged to initiate a Compassionate Use Program for pritelivir in Germany.” (opens the source at this quote in a new tab)
“This is part of an Early Access Program (EAP) in various countries throughout the world.” (opens the source at this quote in a new tab)

“An Early Access Program (EAP) has been launched in various countries globally.” (opens the source at this quote in a new tab)

Regulatory status outside the United States: compassionate use programme in Belgium

“In this Compassionate Use Program (CUP) Pritelivir is indicated for the treatment of acyclovir-resistant and/or foscarnet-resistant/intolerant mucocutaneous HSV (Herpes Simplex Virus) infections in immunocompromised patients” (opens the source at this quote in a new tab)
“Pritelivir will be provided free of charge by AiCuris / myTomorrows on an individual patient basis following the criteria stated in this program and from the approval of the Compassionate Use Program by FAMHP until:” (opens the source at this quote in a new tab)
“the product will be commercially available in Belgium in the envisaged indication, or” (opens the source at this quote in a new tab)

Regulatory status outside the United States: compassionate access authorisation in France

Field	Quoted record (French)
Product	“Pritelivir 100 mg, comprimé”
Company	“AiCuris”
Access framework and status	“Autorisation d'accès compassionnel (AAC) – En cours”
Granting criteria	“Infection à HSV en situation d’échec, de résistance, d’intolérance ou de contre-indication au (val)aciclovir et foscarnet chez des patients adultes immunodéprimés”
Record dates	“PUBLIÉ LE 30/05/2022”