HerpesDRG: a comprehensive resource for human herpesvirus antiviral drug resistance genotyping.

The prevention and treatment of many herpesvirus associated diseases is based on the utilization of antiviral therapies, however therapeutic success is limited by the development of drug resistance. Currently no single database cataloguing resistance mutations exists, which hampers the use of sequence data for patient management. We therefore developed HerpesDRG, a drug resistance mutation database that incorporates all the known resistance genes and current treatment options, built from a systematic review of available genotype to phenotype literature. The database is released along with an R package that provides a simple approach to resistance variant annotation and clinical implication analysis from common sanger and next generation sequencing data. This represents the first openly available and community maintainable database of drug resistance mutations for the human herpesviruses (HHV), developed for the community of researchers and clinicians tackling HHV drug resistance.

Disproportionality analysis of amenamevir-induced encephalopathy using the Japanese adverse drug event report database.

INTRODUCTION: Anti-herpesvirus drug-induced encephalopathy can complicate herpes zoster treatment; however, the association between the recently developed anti-herpesvirus drug amenamevir and encephalopathy development remains unknown. Determining the characteristics of amenamevir-induced encephalopathy is essential for potentially improving patient outcomes in the treatment of herpes zoster. The aim of this study is to identify the association between amenamevir treatment and encephalopathy and to determine the risk factors for amenamevir-induced encephalopathy via disproportionality analysis using the Japanese Adverse Drug Event Report (JADER) database. METHOD: We conducted a retrospective observational study using anonymized data from the JADER database. Encephalopathy was defined according to the Standardized Medical Dictionary for Regulatory Activities Queries specific to "Noninfectious encephalopathy/delirium." Disproportionality analysis was used to calculate the reporting odds ratios (RORs) and 95 % confidence intervals (CIs) to assess associations between amenamevir and encephalopathy. Multivariable logistic regression considered age, gender, chronic kidney disease, and cytochrome P450 3A inhibitor use as potential risk factors. RESULTS: Out of 713,316 patients, 246 were prescribed amenamevir. The median onset of encephalopathy in these patients was 3 days. Disproportionality of encephalopathy was observed in patients treated with amenamevir (ROR, 3.44; 95 % CI, 2.48-4.78). Furthermore, multivariable logistic regression analysis suggested that an age of ≥70 years was associated with amenamevir-induced encephalopathy (ROR, 7.63; 95 % CI, 2.25-25.9). CONCLUSION: These results suggest that amenamevir treatment may be associated with encephalopathy, particularly in patients aged ≥70 years. Healthcare providers should be aware of this potential risk, especially in elderly patients, to prevent severe central nervous system complications.

Aseptic meningitis after amenamevir treatment for herpes zoster ophthalmicus with oculomotor nerve palsy in a patient taking immunosuppressant.

A 79-year-old woman presented with vomiting after being prescribed amenamevir by her primary care physician. She had a medical history of rheumatoid arthritis and was administered prednisolone and methotrexate. She was finally diagnosed with herpes zoster ophthalmicus and aseptic meningitis, and intravenous antiviral therapy was initiated. However, the patient developed oculomotor nerve palsy on the 11th day of hospitalization. In this case, there was a time lag between the administration of antiviral drugs and clinical improvement. Our case suggests the necessity of selecting antivirals, especially in high-risk cases of CNS complications, to avoid the low intracerebral transferability of antiviral drugs, including amenamevir.

Characteristics of Helicase-Primase Inhibitor Amenamevir-Resistant Herpes Simplex Virus.

The antiherpetic drug amenamevir (AMNV) inhibits the helicase-primase complex of herpes simplex virus 1 (HSV-1), HSV-2, and varicella-zoster virus directly as well as inhibiting the replication of these viruses. Although several mutated HSV viruses resistant to helicase-primase inhibitors have been reported, the mutations contributing to the resistance remain unclear, as recombinant viruses containing a single mutation have not been analyzed. We obtained AMNV-resistant viruses with amino acid substitutions by several passages under AMNV treatment. Twenty HSV-1 and 19 HSV-2 mutants with mutation(s) in UL5 helicase and/or UL52 primase, but not in cofactor UL8, were isolated. The mutations in UL5 were located downstream of motif IV, with UL5 K356N in HSV-1 and K355N in HSV-2, in particular, identified as having the highest frequency, which was 9/20 and 9/19, respectively. We generated recombinant AMNV-resistant HSV-1 with a single amino acid substitution using bacterial artificial chromosome (BAC) mutagenesis. As a result, G352C in UL5 helicase and F360C/V and N902T in UL52 primase were identified as novel mutations. The virus with K356N in UL5 showed 10-fold higher AMNV resistance than did other mutants and showed equivalent viral growth in vitro and virulence in vivo as the parent HSV-1, although other mutants showed attenuated virulence. All recombinant viruses were susceptible to the other antiherpetic drugs, acyclovir and foscarnet. In conclusion, based on BAC mutagenesis, this study identified, for the first time, mutations in UL5 and UL52 that contributed to AMNV resistance and found that a mutant with the most frequent K356N mutation in HSV-1 maintained viral growth and virulence equivalent to the parent virus.

Gummi Formulations Comprising Amenamevir Solid Dispersions with Polyvinyl Alcohol.

The aim of the present study was to determine whether solid dispersions (SDs) are applicable to gummi formulations. Amenamevir was selected as a model of a poorly water-soluble drug, and polyvinyl alcohols (PVAs) with various degrees of hydrolysis (PVA 66, PVA 80, PVA 88, and PVA 66/88) were used as SD carriers. Design of experiments (DOE) was used to develop a gummi formulation that was suitable for an amenamevir SD using SD with PVA 66. Dissolution studies and clinical sensory tests on 11 formulations calculated by DOE revealed that a gummi formulation comprising 10.5% gelatin and 22.8% water was suitable for SD of the drug. Gummi formulations comprising amenamevir SDs with various PVAs were prepared using the determined gummi formulation, and their ability to dissolve amenamevir, their stability, and their oral absorption in dogs were evaluated. The results suggested that PVA 66, PVA 66/88, and PVA 80 were appropriate in terms of dissolution, stability, and in vivo absorption, respectively. Considering these results comprehensively, it was concluded that PVA 80, which enabled the highest degree of absorption, was the most suitable SD carrier for gummi formulations. Thus, it was possible to apply a PVA SD of amenamevir to gummi formulations.

Advances and Perspectives in the Management of Varicella-Zoster Virus Infections.

Varicella-zoster virus (VZV), a common and ubiquitous human-restricted pathogen, causes a primary infection (varicella or chickenpox) followed by establishment of latency in sensory ganglia. The virus can reactivate, causing herpes zoster (HZ, shingles) and leading to significant morbidity but rarely mortality, although in immunocompromised hosts, VZV can cause severe disseminated and occasionally fatal disease. We discuss VZV diseases and the decrease in their incidence due to the introduction of live-attenuated vaccines to prevent varicella or HZ. We also focus on acyclovir, valacyclovir, and famciclovir (FDA approved drugs to treat VZV infections), brivudine (used in some European countries) and amenamevir (a helicase-primase inhibitor, approved in Japan) that augur the beginning of a new era of anti-VZV therapy. Valnivudine hydrochloride (FV-100) and valomaciclovir stearate (in advanced stage of development) and several new molecules potentially good as anti-VZV candidates described during the last year are examined. We reflect on the role of antiviral agents in the treatment of VZV-associated diseases, as a large percentage of the at-risk population is not immunized, and on the limitations of currently FDA-approved anti-VZV drugs. Their low efficacy in controlling HZ pain and post-herpetic neuralgia development, and the need of multiple dosing regimens requiring daily dose adaptation for patients with renal failure urges the development of novel anti-VZV drugs.

Antiviral Drugs Against Alphaherpesvirus.

The discovery of acyclovir and penciclovir has led to the development of a successful systemic therapy for treating herpes simplex virus infection and varicella-zoster virus infection, and the orally available prodrugs, valacyclovir and famciclovir, have improved antiviral treatment compliance. Acyclovir and penciclovir are phosphorylated by viral thymidine kinase and are incorporated into the DNA chain by viral DNA polymerase, resulting in chain termination. Helicase-primase plays an initial step in DNA synthesis to separate the double strand into two single strands (replication fork) and is a new target of antiviral therapy. The helicase-primase inhibitors (HPIs) pritelivir and amenamevir have novel mechanisms of action, drug resistance properties, pharmacokinetic characteristics, and clinical efficacy for treating genital herpes. The clinical study of amenamevir in herpes zoster has been completed, and amenamevir has been submitted for approval for treating herpes zoster in Japan. The clinical use of HPIs will be the beginning of a new era of anti-herpes therapy.

An exploratory study of the efficacy and safety of amenamevir for the treatment of herpes zoster in patients receiving immunosuppressive drugs.

Amenamevir is an oral once-daily antiherpesvirus drug that can be administered without dose adjustment in patients with impaired renal function. There are currently no clinical data on immunocompromised patients with herpes zoster treated with amenamevir. Therefore, an exploratory study of the efficacy and safety of amenamevir against herpes zoster in patients with immunosuppression was conducted. Inclusion criteria included patients with acute herpes zoster receiving immunosuppressive drugs or those with malignant tumors or autoimmune diseases. Twenty-four patients were included and received amenamevir (400 mg once daily after meals) for up to 14 days. The primary end point of overall improvement in skin symptoms 7 days after treatment initiation (day 7) was 58.3% for "markedly improved" and 20.8% for "improved." The combined improvement rate was 79.2% (95% confidence interval, 57.8-92.9), and 20.8% of patients experienced "worsened" symptoms. The secondary end points of overall improvement in skin symptoms on day 14 and day 28 were 95.7% and 100%, respectively. The skin symptoms progressed during treatment, peaking on day 7, and then began to heal. By Kaplan-Meier estimation, the median periods to complete crusting and healing were both day 14. There were five adverse events with a possible causal relationship to amenamevir (bacterial skin infection, anemia, hyponatremia, headache, and abnormal liver function) in one of the 24 patients. Although the bacterial skin infection was severe, all events in this patient were reported to be either recovered or recovering. These findings indicate that amenamevir can be effective and safe in immunocompromised patients with herpes zoster. However, as worsening can happen around day 7, it is necessary to carefully monitor such patients and switch to other therapies such as intravenous acyclovir if necessary. Clinical trial identifier: Japan Registry of Clinical Trials jRCTs031190208.

Varicella-Zoster Meningitis and Myelitis After Herpes Zoster Dermatitis Treatment With Amenamevir: A Case Series and Literature Review.

Varicella-zoster virus (VZV), known for causing chickenpox, establishes latent infections in neural tissues. Reactivation of VZV can lead to herpes zoster (HZ) and various neurological complications. In this report, we present four cases of VZV meningitis and myelitis following amenamevir treatment for HZ dermatitis with positive VZV DNA in cerebrospinal fluid (CSF) revealed by polymerase chain reaction (PCR). Three of them were considered immunocompromised hosts given the fact that two of these patients were taking immunosuppressive drugs for rheumatoid arthritis, and one patient had a history of sigmoid colon cancer (four months after resection). After HZ onset, amenamevir, which has poor CSF transfer, was prescribed for all the patients, and all of them developed central nervous complications by VZV (meningitis in three cases and myelitis in one case) confirmed by PCR. All the patients were treated with acyclovir, which has a higher CSF transfer, and fully recovered. We speculate that amenamevir might have failed to prevent VZV infection in the central nervous system (CNS) and think that consideration should be given to administering acyclovir in preference to amenamevir for ΗΖ patients at high risk of CNS VZV infection, such as immunocompromised hosts.

Helicase-primase inhibitors for the treatment of herpes simplex virus infections - patent evaluation of WO2023/225162 from Gilead Sciences Inc.

Helicase-primase is an interesting target for small-molecule therapy of herpes simplex virus (HSV) infections. With amenamevir already approved for varicella-zoster virus and herpes simplex in Japan and with pritelivir's granted breakthrough therapy designation for the treatment of acyclovir-resistant HSV infections in immunocompromised patients, the target has sparked interest in helicase-primase inhibitors (HPIs). Here, we analyze the first patent application from Gilead in this field, which pursued a me-too approach combining elements from an old Bayer together with a recent Medshine HPI application (which covers the Phaeno Therapeutics drug candidate HN0037). The asset was contributed to Assembly Biosciences, where it is under development as ABI-1179 at the investigational new drug (IND) enabling stage for high-recurrence genital herpes. A structure proposal for indolinoyl derivative ABI-1179 is presented, showing its potential opportunities and limitations compared to other HPIs.

Successful treatment of acyclovir-resistant herpes simplex virus infection with amenamevir in a patient who received umbilical cord blood transplantation for T-cell prolymphocytic leukemia.

A 34-year-old woman received umbilical cord blood transplantation for refractory T-cell prolymphocytic leukemia after salvage therapy with alemtuzumab. She developed right angular cheilitis on the 46th day after transplantation, which worsened after receiving systemic steroid therapy for extensive chronic graft versus host disease. The treatment dosage of acyclovir (ACV), ganciclovir, and vidarabine ointment was not effective due to ACV-resistant mutations of the herpes simplex virus type 1 (HSV-1) in the thymidine kinase domain. Foscarnet is expected to be effective against ACV-resistant HSV-1 infection. However, it could not be used because the patient developed renal dysfunction. Several viral thymidine kinase mutations related to ACV resistance were found in the patient's sample. Nevertheless, amenamevir, a helicase-primase complex inhibitor, was effective in our patient who was significantly immunocompromised after allogeneic hematopoietic stem cell transplantation (allo-HSCT). ACV-resistant HSV infection after allo-HSCT is an rare but important complication in the era of low-dose long-term ACV prophylaxis. To date, there is no established treatment against ACV-resistant HSV infection. This case report showed that amenamevir could be a promising treatment option for ACV-resistant HSV infection in patients with renal failure after allo-HSCT.

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.

Segmental cutaneous leukocytoclastic vasculitis associated with herpes zoster: a case report and literature review.

Varicella zoster virus (VZV) infection may cause large or medium vessel vasculitis, including granulomatous arteritis of the nervous system and central nervous system vasculitis. However, small vessel vasculitis, such as cutaneous leukocytoclastic vasculitis (LCV) associated with localized cutaneous VZV infection, herpes zoster, is uncommon. Herein, we present the case of a 75- year-old man with segmental leukocytoclastic vasculitis associated with herpes zoster on the leg. To the best of our knowledge, there are four cases of segmental leukocytoclastic vasculitis in herpes zoster reported in the English literature; we compared our case with these previous reports. Our review of five patients suggests that most patients were immunosuppressed. We also found that the leg is susceptible to LCV associated with herpes zoster. Anti-viral treatment was effective for LCV as well as herpes zoster. Prior reports have proposed etiologies inducing LCV; for example, immune complexes are mediated by vessel wall damage. In support of this, histopathology in our case showed a C3-positive reaction with the small vessel walls in the dermis in direct immunofluorescence. Although the mechanism of LCV associated with herpes zoster remains unclear, we should consider LCV while diagnosing and treating patients with herpes zoster, especially immunosuppressed patients.

Recent topics in the management of herpes zoster.

Herpes zoster is a disease caused by reactivation of the varicella-zoster virus that has been latently infecting the body and is more common among the elderly. In Japan, the incidence of herpes zoster has been increasing steadily and is expected to increase further in the future. In 2016, the varicella vaccine was expanded to include prevention of herpes zoster, and a new subunit vaccine was also launched in 2020. In recent years, anti-herpesvirus drugs with novel pharmacological effects have also been introduced, and the environment surrounding the treatment of herpes zoster is entering a new era.

Current scenario and future applicability of antivirals against herpes zoster.

Herpes zoster (HZ) is a common disease in the aging population and immunocompromised individuals, with a lifetime risk of 20%-30% that increases with age. HZ is caused by reactivation of the varicella-zoster virus (VZV), which remains latent in the spinal dorsal root ganglia and cranial sensory ganglia after resolution of the primary VZV infection. The main focus of HZ management is rapid recovery from VZV infection as well as the reduction and prevention of zoster-associated pain (ZAP) and postherpetic neuralgia (PHN). The use of antivirals against VZV is essential in the treatment of HZ. However, limited antivirals are only licensed clinically for the treatment of HZ, including acyclovir, valacyclovir, famciclovir, brivudine, and amenamevir. Fortunately, some new antivirals against different types of Herpesviridae have been investigated and suggested as novel drugs against VZV. Therefore, this review focuses on discussing the difference in efficacy and safety in the currently licensed antivirals for the treatment of HZ, the applicability of future novel antivirals against VZV, and the preventive or therapeutic effects of these antivirals on ZAP or PHN.

A 1-Year Survey of Zoster-Associated Pain after Amenamevir Treatment.

INTRODUCTION: Amenamevir is a new anti-varicella-zoster virus drug that inhibits the helicase-primase complex involved in viral replication. Amenamevir has the same effect as valaciclovir on acute pain and skin eruption, but no studies have examined the presence of long-term zoster-associated pain (ZAP) or postherpetic neuralgia (PHN) after amenamevir treatment. METHODS: A total of 785 herpes zoster patients treated with amenamevir were followed up for 12 months. Patients recorded their pain status on a questionnaire once a month. RESULTS: The proportion of patients with pain was 20.8% at 90 days, 8.0% at 180 days, 3.8% at 270 days, and 2.7% at 360 days after treatment. The median residual pain duration was 48 days. ZAP resolution rate slowed between 90 and 120 days, suggesting that the main feature of ZAP is a shift from nociceptive pain to neuropathic pain. Older age and more severe skin symptoms at the first visit were associated with a higher risk of developing PHN. Median ZAP duration was high for the head, face, and upper back and chest. Regarding the nature of pain, sudden pain attacks that felt like electric shocks, sensation of numbness, burning sensation, and cold/heat pain tended to remain as PHN. CONCLUSIONS: Although conclusions must remain tentative without further comparative studies, amenamevir seems to have a similar effect on PHN as conventional nucleoside analogs, despite having a different action mechanism. CLINICAL TRIAL REGISTRATION: UMIN000035938.

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.

A Comparison Between Effects of Amenamevir and Famciclovir on Intensities of Acute Pain and the Incidence of Postherpetic Neuralgia in Adult Patients with Herpes Zoster.

Objective: Herpes zoster (HZ) is a common disease, whose most common complication is postherpetic neuralgia (PHN). We conducted this study to compare effects of amenamevir (AMNV) and famciclovir (FCV) on intensities of acute HZ pain and the incidence of PHN, which have not been compared yet. Methods: After approval by the Ethics Committee, we retrospectively investigated adult patients with HZ treated with AMNV or FCV at Juntendo University Hospital between October, 2018 and February, 2020. We compared, between 143 AMNV-treated and 131 FCV-treated patients, pain scores of acute HZ pain evaluated on an 11-point numerical rating scale (NRS) and the incidence of PHN with the Mann-Whitney U test and Pearson's chi-square test, respectively. The univariate logistic regression analysis was used to identify predictors of PHN. Results: Pain scores during the acute HZ period remained significantly lower in AMNV-treated patients than FCV-treated patients (p = 0.049, 0.011, and 0.016 for Day 3-4, Day 7, and Week 2-3, respectively), although the pain score at Day 0 before treatment didn't differ between them (p > 0.05). The incidence of PHN didn't differ between them (9.8% vs. 11.5%, p > 0.05). In the total cohort, the pain score at Week 2-3 was significantly associated with the development of PHN (r 2 = 0.180, p < 0.00001). Conclusions: Compared with FCV, AMNV was more effective in reducing acute HZ pain, possibly reflecting its unique mechanism of action. However, AMNV didn't reduce the incidence of PHN possibly due to the multifactorial etiology of PHN.

Aseptic Meningitis after Amenamevir Treatment for Herpes Zoster in the First Branch of the Trigeminal Nerve.

Amenamevir has been approved for the treatment of herpes zoster (HZ); however, its therapeutic efficacy against central nervous system (CNS) infection may be insufficient due to its low spinal fluid permeability. We herein report a case of aseptic meningitis in a 91-year-old Japanese man treated with amenamevir for HZ in the trigeminal nerve region. Several cases of CNS infection have been reported in patients receiving amenamevir treatment for HZ. Patients with CNS complications often have skin rashes near the trigeminal region. Thus, we should be alert for signs of CNS infection when administering amenamevir to patients with such rashes.