Pharmacokinetics and Dialyzability of a Single Oral Dose of Amenamevir, an Anti-Herpes Drug, in Hemodialysis Patients

Real-world safety and efficacy of amenamevir in patients with herpes zoster in Japan: A postmarketing observational study (REWARD)

The helicase-primase inhibitor amenamevir (AMNV) was approved for herpes zoster in Japan in 2017. The authors conducted a 1-month postmarketing observational study to evaluate the real-world safety and efficacy (cutaneous improvement and pain resolution) of AMNV in patients with herpes zoster. Of the 3453 patients registered between March 2018 and December 2020, 3110 were included in the safety analyses. The mean age (±standard deviation) was 63.7 ± 17.5 years, with 57.9% of patients aged ≥65 years. Most patients had mild (53.3%) or moderate (41.0%) cutaneous lesions. Regarding pain, 43.9%, 25.6%, and 12.5% of patients had pain at the levels of 1-3, 4-6, and 7-10 on the numerical rating scale. In total, 30.0%, 27.2%, and 16.1% of patients were concomitantly treated with analgesics: acetaminophen, nonsteroidal anti-inflammatory drugs, and Ca2+ channel α 2δ ligands, respectively, and 10.6% were treated with topical antiherpetic drugs. Adverse drug reactions occurred in 0.77% of patients, including four serious adverse drug reactions in four patients (hyponatremia, thrombocytopenia, rash, and rhabdomyolysis). Regarding important potential risks, renal disorder, cardiovascular events, and decreased platelets were observed in one, one, and two patients, respectively. Concerning efficacy, the cutaneous improvement rate (significantly improved or improved) was 95.5%, with significantly higher improvement rates in patients treated with AMNV for 7 days and in patients with less severe cutaneous lesions or less pain. Factors affecting the time to pain resolution were the severity of cutaneous lesions and pain at the start of AMNV treatment and older age. This study demonstrated that the AMNV is safe and effective in patients with herpes zoster in a real-world clinical setting.

A phase 3, randomized, double-blind, placebo-controlled study evaluating a single, patient-initiated dose of amenamevir for recurrent herpes labialis

Amenamevir (ASP2151), a novel, non-nucleoside analog, antiviral drug, inhibits the enzyme activities of helicase and primase, which are essential for replication of herpes viral genomic DNA. In this phase 3, randomized, double-blind, placebo-controlled, multicenter study, the authors investigated the efficacy and safety of a single patient-initiated dose of amenamevir to treat recurrent herpes labialis. Adult immunocompetent patients with recurrent herpes labialis who had the experience and ability to recognize prodromal symptoms were randomly assigned to administer amenamevir 1200 mg or placebo as a patient-initiated therapy within 6 hours after onset of prodromal symptoms. The primary efficacy end point was time to healing of all herpes labialis lesions in the modified intention-to-treat population. Secondary efficacy end points were time to crusting of all herpes labialis lesions, time to resolution of pain accompanying herpes labialis, proportion of patients with aborted lesions, and time to resolution of subjective symptoms accompanying herpes labialis. The modified intention-to-treat population, which excluded patients with aborted lesions, comprised 298 patients who self-initiated amenamevir and 307 who took placebo. Amenamevir demonstrated superiority over placebo for the primary end point; the median time to all lesion healing was 5.1 days for amenamevir versus 5.5 days for placebo (hazard ratio, 1.24; 95% confidence interval, 1.06-1.46; p = 0.0085). Time to crusting of all lesions was significantly shorter with amenamevir versus placebo (p = 0.0065); there were no significant between-group differences in other secondary outcomes. Treatment-emergent adverse events in both groups were generally mild in severity; there were two moderate events that were judged unrelated to study treatment, and no severe or serious events. In summary, a single patient-initiated dose of amenamevir 1200 mg taken within 6 hours of prodromal symptom onset significantly shortened the time to all lesion healing of recurrent herpes labialis compared with placebo, with no clinically important safety concerns.

The Efficacy of Amenamevir for the Treatment of Disseminated Herpes Zoster Complicated with Probable Varicella-zoster Pneumonia in an Immunocompromised Patient

We herein report the case of a 78-year-old woman who was diagnosed as having disseminated herpes zoster (DHZ) complicated with probable varicella-zoster pneumonia during maintenance therapy for microscopic polyangiitis. Because the patient had severe renal dysfunction, amenamevir administration was started to avoid any neurotoxicity of acyclovir, which is suggested to be optimal for treatment. It ameliorated her symptoms without any adverse events. This is the first report suggesting the efficacy of amenamevir in the treatment of severe herpes zoster infection with coexisting DHZ and probable varicella-zoster pneumonia. Amenamevir could thus be a treatment option for severe varicella zoster virus infections.