RESUMO
BACKGROUND: The efficacy of different letermovir (AIC246, MK8228) doses (60, 120, and 240 mg/day) against human cytomegalovirus (HCMV) was evaluated in a recent phase 2b dose-range-finding prophylaxis study in stem-cell transplant recipients. Here we report the genotypic and phenotypic characterization of 15 viral breakthroughs considered to be virological failures. METHODS: Direct sequencing of an HCMV open reading frame UL56 region that included amino acids 230-370 and thus encompassed all known letermovir resistance mutations was followed by marker-transfer experiments to assess the impact of the identified sequence polymorphisms on viral fitness and susceptibility to letermovir. RESULTS: UL56 genotyping was successful for 12 of 15 patients. Six amino acid substitutions were detected in 5 patients. In 1 subject from the 60-mg-dose group, the known letermovir resistance mutation V236M was identified subsequent to a wild-type viremic episode. The remaining 5 sequence variants (L134V, S227I, Q228H, R410G, and D414N) were shown to be inert with regard to letermovir susceptibility, thus representing natural polymorphisms. CONCLUSIONS: Our findings represent the first case of a letermovir resistance mutation emerging in the clinic, apparently because of a suboptimal prophylactic dose (60 mg/day). This is in agreement with the trial's efficacy analyses, findings of which suggest that letermovir doses of 60 mg/day and 120 mg/day are suboptimal for prophylaxis whereas a dose of 240 mg/day appears to achieve complete suppression of viremia.
Assuntos
Infecções por Citomegalovirus/tratamento farmacológico , Infecções por Citomegalovirus/virologia , Citomegalovirus/efeitos dos fármacos , Citomegalovirus/genética , Acetatos/farmacologia , Acetatos/uso terapêutico , Antivirais/farmacologia , Antivirais/uso terapêutico , Infecções por Citomegalovirus/epidemiologia , DNA Viral/sangue , DNA Viral/genética , Farmacorresistência Viral/efeitos dos fármacos , Farmacorresistência Viral/genética , Humanos , Fases de Leitura Aberta/genética , Quinazolinas/farmacologia , Quinazolinas/uso terapêutico , Carga Viral , ViremiaRESUMO
Cytomegalovirus (CMV) infection remains a significant cause of morbidity and mortality in transplant recipients. Letermovir (AIC246), is a novel anti-HCMV drug in development, acting via a novel mechanism of action. In this proof-of-concept trial with first administration of letermovir to patients, 27 transplant recipients with active CMV replication were randomly assigned to a 14-day oral treatment regimen of either letermovir 40 mg twice a day, letermovir 80 mg once a day, or local standard of care (SOC) in a multicenter, open-label trial. Efficacy, safety, and limited pharmacokinetic parameters were assessed. All groups had a statistically significant decrease in CMV-DNA copy number from baseline (40 mg BID: P = 0.031; 80 mg QD: P = 0.018; SOC: P = 0.001), and comparison of viral load reduction between treatment groups showed no statistically significant differences. Viral clearance was achieved for 6 of 12 patients (50%) in the letermovir groups versus two of seven SOC patients (28.6%). Letermovir treatment was generally well tolerated, no patient developed CMV disease during the trial. Both letermovir treatment regimens resulted in equally high trough level plasma concentrations. The efficacy, safety, and pharmacokinetics observed in these viremic transplant recipients indicate that letermovir is a promising new anti-CMV drug.
Assuntos
Acetatos/administração & dosagem , Infecções por Citomegalovirus/tratamento farmacológico , Transplante de Rim , Quinazolinas/administração & dosagem , Acetatos/farmacocinética , Adulto , Idoso , Antivirais/administração & dosagem , Antivirais/farmacocinética , Citomegalovirus/genética , Infecções por Citomegalovirus/virologia , DNA Viral/sangue , Feminino , Humanos , Transplante de Rim/efeitos adversos , Masculino , Pessoa de Meia-Idade , Infecções Oportunistas/tratamento farmacológico , Infecções Oportunistas/virologia , Quinazolinas/farmacocinética , Carga Viral , Viremia/virologiaRESUMO
Prominent in the current stage of antiviral drug development are: (i) for human immunodeficiency virus (HIV), the use of fixed-dose combinations (FDCs), the most recent example being Stribild(TM); (ii) for hepatitis C virus (HCV), the pleiade of direct-acting antivirals (DAAs) that should be formulated in the most appropriate combinations so as to obtain a cure of the infection; (iii)-(v) new strategies (i.e., AIC316, AIC246, and FV-100) for the treatment of herpesvirus infections: herpes simplex virus (HSV), cytomegalovirus (CMV), and varicella-zoster virus (VZV), respectively; (vi) the role of a new tenofovir prodrug, tenofovir alafenamide (TAF) (GS-7340) for the treatment of HIV infections; (vii) the potential use of poxvirus inhibitors (CMX001 and ST-246); (viii) the usefulness of new influenza virus inhibitors (peramivir and laninamivir octanoate); (ix) the position of the hepatitis B virus (HBV) inhibitors [lamivudine, adefovir dipivoxil, entecavir, telbivudine, and tenofovir disoproxil fumarate (TDF)]; and (x) the potential of new compounds such as FGI-103, FGI-104, FGI-106, dUY11, and LJ-001 for the treatment of filoviruses (i.e., Ebola). Whereas for HIV and HCV therapy is aimed at multiple-drug combinations, for all other viruses, HSV, CMV, VZV, pox, influenza, HBV, and filoviruses, current strategies are based on the use of single compounds.
Assuntos
Antivirais/farmacologia , Descoberta de Drogas/tendências , Animais , Antivirais/química , Antivirais/uso terapêutico , Humanos , Viroses/tratamento farmacológico , Vírus/efeitos dos fármacosRESUMO
Infection with cytomegalovirus is prevalent in immunosuppressed patients. In solid organ transplant and hematopoietic stem cell transplant recipients, cytomegalovirus infection is associated with high morbidity and preventable mortality. Prevention and treatment of cytomegalovirus with currently approved antiviral drugs is often associated with side effects that sometimes preclude their use. Moreover, cytomegalovirus has developed mutations that confer resistance to standard antiviral drugs. During the last decade, there have been calls to develop novel antiviral drugs that could provide better options for prevention and treatment of cytomegalovirus. Letermovir (AIC246) is a highly specific antiviral drug that is currently undergoing clinical development for the management of cytomegalovirus infection. It acts by inhibiting the viral terminase complex. Letermovir is highly potent in vitro and in vivo against cytomegalovirus. Because of a distinct mechanism of action, it does not exhibit cross-resistance with other antiviral drugs. It is predicted to be active against strains that are resistant to ganciclovir, foscarnet, and cidofovir. To date, early-phase clinical trials suggest a very low incidence of adverse effects. Herein, we present a comprehensive review on letermovir, from its postulated novel mechanism of action to the results of most recent clinical studies.
RESUMO
Letermovir is a new drug in Phase 3 clinical development for the prevention of human Cytomegalovirus (HCMV) infections in hematopoietic-stem-cell transplant recipients (HSCT). In contrast to marketed anti-HCMV drugs which all target the viral DNA polymerase, letermovir's novel mode of action targets the UL56 subunit of the viral terminase complex. Consistently letermovir resistance has mapped in vitro to a distinct region within ORF UL56 (amino acid 230-370). Here we used marker transfer to demonstrate that two naturally occurring UL56 sequence variants within this region, located directly adjacent to sites known to mediate letermovir resistance in vitro (D242G and A327V) represent normal interstrain polymorphisms unrelated to drug-resistance.