The US FDA has approved a drug to treat Herpes Simplex Virus (HSV-1 and HSV-2) lesions, which can cause painful blisters and mucocutaneous sores. The FDA has approved Hovilpri (pritelivir) tablets for adults with weakened immune systems (i.e., immunocompromised patients) who have mucocutaneous lesions caused by HSV infection and have not responded to other therapies (acyclovir, valacyclovir, or famciclovir). Mucocutaneous lesions occur on skin or mucosal surfaces, such as lips, nostrils, eyes and genitals. 

HSV-1 and HSV-2 are common viral infections that typically cause painful mucocutaneous lesions, or fluid-filled blisters that break open and crust over the infectious site. Once a person has HSV, the infection cannot be cured. The virus can be dormant or reactivate, leading people to have outbreaks or release contagious viral particles without being symptomatic.

There are several FDA-approved antiviral treatments that can help control or improve outbreaks. Patients with compromised immune systems can have more frequent and serious HSV outbreaks that might not respond well to available treatments because their virus is resistant to the medications or they cannot tolerate side effects.

The efficacy of Hovilpri was evaluated in a randomised, 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.

Participants received Hovilpri or the trial investigator’s choice of available treatments for up to 28 days until all mucocutaneous lesions healed, which was extended up to 42 days if lesions were improving but not completely healed after 28 days.

A total of 101 immunocompromised adults were randomly assigned and treated with Hovilpri or the investigator’s choice of available treatments. Participants had a wide range of immunosuppressive clinical conditions, including one or more of the following: hematologic malignancy/disorder, hematopoietic stem-cell transplantation, HIV infection, autoimmune/inflammatory diseases, non-hematologic malignancies, or solid-organ transplantation.

The primary efficacy endpoint was the proportion of participants with all lesions healed during the treatment period up to 28 days. By 28 days, all lesions were healed in 63 percent of patients receiving Hovilpri, compared with 34 percent of patients receiving one of the other medications. 

The most common adverse reaction was headache.