Data collection in expanded access: real-world examples 23 PRITELIVIR FOR TREATMENT-RESISTANT HERPES SIMPLEX INFECTIONS Background Pritelivir is being investigated as a treatment of herpes simplex virus 1 (HSV1) and 2 (HSV2) infections.51 While nucleoside analogs like acyclovir, (or valacyclovir, famciclovir, and ganciclovir) or phosphonic acid derivatives like foscarnet are the primary treatments for HSV infections, patients may develop resistance to these drugs or experience intolerable side effects, making trials or expanded access programs to drugs in development (like pritelivir) necessary. Patients with HSV suffer from painful lesions (blisters, sores) that usually appear around the mouth or genital area.52 Typically, these lesions present in episodes when the immune system is weakened. Immunocompromised patients, such as those living with HIV/AIDS, undergoing stem cell or solid organ transplant, or patients that depend on the use of immunosuppressants, may suffer from HSV infections that last longer, occur more frequently, and are less responsive to conventional therapies. Additionally, patients with persistent HSV infections often present with multiple underlying conditions that weaken their immune system, leading to severe complications from the infections. For example, patients could develop bedsores being unable to sleep due to pain caused by blisters or become morphine-dependent due to the severe pain associated with their HSV infection. For these severely ill patients, physicians sought access to pritelivir when conventional therapies were inadequately effective or safe. Pritelivir is an anti-HSV helicase-primase inhibitor that is currently in phase III clinical development for the treatment of acyclovir-resistant HSV infections in immunocompromised patients.53,54 Pritelivir is administered orally through tablets. In the ongoing PRIOH-1 trial (NCT03073967), pritelivir is compared with foscarnet, the only available treatment option for acyclovir-resistant HSV infections. Patients are initially treated with a 28-day course and if clinically necessary, this course may be extended up to 42 days. Setup and methodology of the expanded access program In addition to the trial, a global expanded access program was initiated by AiCuris (the sponsor) and myTomorrows (the service provider) for ineligible trial patients in 2019. Apart from the aforementioned medical reasons for ineligibility, there were also several practical reasons patients could not partake in the trial, either sites being fully enrolled, or sites not activated within traveling distance. Additionally, and different from the clinical trial, patients in the expanded access program were allowed to be previously treated with multiple cycles of pritelivir (nonnaïve) if lesions re-occurred. Hence, the patient population differed by design from the patients in the trial.
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