Pharmacokinetics, Safety, and Tolerability of Letermovir Following Single- and Multiple-Dose Administration in Healthy Japanese Subjects.

Letermovir is a human cytomegalovirus terminase inhibitor for the prophylaxis of cytomegalovirus infection and disease in allogeneic hematopoietic stem cell transplant recipients. The pharmacokinetics, safety, and tolerability of letermovir were assessed in healthy Japanese subjects in 2 phase 1 trials: trial 1-single ascending oral doses (240, 480, and 720 mg) and intravenous (IV) doses (240, 480, and 960 mg), and trial 2-multiple oral doses (240 and 480 mg once daily for 7 days). Following administration of oral single and multiple doses, letermovir was absorbed with a median time to maximum plasma concentration of 2 to 4 hours, and concentrations declined in a biphasic manner with a terminal half-life of ≈10 to 13 hours. The post absorption plasma concentration-time profile of letermovir following oral administration was similar to the profile observed with IV dosing. There was minimal accumulation with multiple-dose administration. Letermovir exposure in healthy Japanese subjects was ≈1.5- to 2.5-fold higher than that observed in non-Japanese subjects. Based on the population pharmacokinetic analysis, weight differences primarily accounted for the higher exposures observed in Asians. Letermovir was generally well tolerated following oral and IV administration to healthy Japanese subjects.

Restricted mean survival time as a summary measure of time-to-event outcome.

Many clinical research studies evaluate a time-to-event outcome, illustrate survival functions, and conventionally report estimated hazard ratios to express the magnitude of the treatment effect when comparing between groups. However, it may not be straightforward to interpret the hazard ratio clinically and statistically when the proportional hazards assumption is invalid. In some recent papers published in clinical journals, the use of restricted mean survival time (RMST) or τ-year mean survival time is discussed as one of the alternative summary measures for the time-to-event outcome. The RMST is defined as the expected value of time to event limited to a specific time point corresponding to the area under the survival curve up to the specific time point. This article summarizes the necessary information to conduct statistical analysis using the RMST, including the definition and statistical properties of the RMST, adjusted analysis methods, sample size calculation, information fraction for the RMST difference, and clinical and statistical meaning and interpretation. Additionally, we discuss how to set the specific time point to define the RMST from two main points of view. We also provide developed SAS codes to determine the sample size required to detect an expected RMST difference with appropriate power and reconstruct individual survival data to estimate an RMST reference value from a reported survival curve.

Safety and Immunogenicity of the Quadrivalent HPV Vaccine in Japanese Boys: a Phase 3, Open-Label Study.

Human papillomavirus (HPV)-associated disease is common among men with HPV infection. A quadrivalent HPV (qHPV) vaccine has demonstrated 85.9% efficacy against HPV6/11/16/18-related, persistent (≥ 6 month) infection in a study of Japanese men aged 16-26 years old. Here, we report the results of an open-label study of the immunogenicity and tolerability of the qHPV vaccine (NCT02576054), conducted to bridge findings from Japanese men to Japanese boys aged 9-15 years old. A total of 100 boys completed a three-vaccination regimen (Day 1, and Months 2 and 6), and 99 boys were included in the primary analysis population. The rate of seroconversion at one month after vaccine Dose 3 (Month 7) was high for each type of HPV (anti-HPV6/11/16/18 seroconversion rates [95% CI]: 94.9% [85.5%, 98.3%], 99.0% [94.4%, 100.0%], 99.0% [94.5%, 100.0%], and 99.0% [94.4%, 100.0%], respectively). Moreover, anti-HPV6/11/16/18 geometric mean titers were 482.9 mMU/mL, 1052.8 mMU/mL, 3878.3 mMU/mL, and 1114.5 mMU/mL, respectively. Immune responses to the qHPV vaccine were non-inferior among Japanese boys included in the current study and compared with young Japanese men from a separate study. Injection-site reactions were the most common adverse events, and administration of the vaccine was well tolerated in Japanese boys.

Effectiveness on high-grade cervical abnormalities and long-term safety of the quadrivalent human papillomavirus vaccine in Japanese women.

This study for the first time assessed quadrivalent human papillomavirus (qHPV) vaccine effectiveness against HPV6/11/16/18-related high-grade cervical disease in Japanese women (16-26 years old), as previously demonstrated in overseas trials, and vaccine safety in a longer term (48-month) open-label study (NCT01544478). Participants received three doses of qHPV vaccine (Day 1, Month 2, Month 6). Effectiveness endpoints, assessed in the per-protocol population, included incidence of HPV6/11/16/18-related cervical intraepithelial neoplasia (CIN) Grade 2 or worse (CIN Grade 2 and 3, adenocarcinoma in situ, and/or cervical cancer) as primary endpoint and incidence of external genital lesions (EGLs). Disease related to other high-risk HPV types was also assessed. Adverse events (AEs) and serious AEs (SAEs) were collected from Days 1-15 after any vaccination; vaccine-related SAEs, deaths, and new medical conditions were collected throughout the study. A total of 1030 women received at least one vaccination. No cases of CIN2 or worse or EGLs were reported in the per-protocol population. Injection site-related AEs were reported in 14.5% of participants; most were mild and resolved within 15 days. Vaccine-related systemic AEs occurred in 8.6% of participants, most commonly headache (2.3%), malaise (1.7%), and pyrexia (1.3%). There were no vaccine-related SAEs; one participant discontinued due to a vaccine-related AE of mild uticaria. Overall, qHPV vaccine effectiveness against HPV6/11/16/18-related high-grade cervical disease and EGLs was indicated in Japanese women. The vaccine was well-tolerated, without new safety signals throughout the 48-month study period. Findings are consistent with overseas qHPV vaccine pivotal trials. CLINICAL TRIAL REGISTRY: clinicaltrials.gov; NCT01544478.

Efficacy, safety, and immunogenicity of a quadrivalent HPV vaccine in Japanese men: A randomized, Phase 3, placebo-controlled study.

BACKGROUND: The quadrivalent (q) human papillomavirus (HPV) vaccine protects against infection and disease related to HPV types 6, 11, 16, and 18. We report efficacy, immunogenicity, and safety of qHPV vaccine in a Phase 3 study in Japanese men. METHODS: In this randomized, double-blind trial (NCT01862874), Japanese men (aged 16-26 years) were randomized in a 1:1 ratio to receive three doses of qHPV vaccine or placebo (Day 1, Month 2, Month 6). The primary efficacy endpoint was the combined incidence of HPV6/11/16/18-related persistent anogenital infection (detected at ≥2 consecutive visits ≥6 months apart), assessed in the per-protocol population of men who received all three vaccinations, and were seronegative at Day 1 and PCR negative from Day 1 to Month 7 to the relevant HPV type. Results are from the interim and final analyses. RESULTS: In total, 1124 participants were randomized. The vaccine demonstrated 83.3% (95% confidence interval: 24.9, 98.2; p = 0.007) and 85.9% (95% confidence interval: 52.7, 97.3; p < 0.001) efficacy against HPV6/11/16/18-related persistent infection in the interim and final analyses, respectively. Two cases of HPV6/11/16/18-related external genital lesions (condyloma and PIN 1) were observed in the placebo group and none in the qHPV vaccine group at study end. At Month 7, >97% of participants who received qHPV vaccine seroconverted to each of the vaccine HPV types. Most participants remained seropositive at Month 36, although the seropositivity rate declined between Months 7 and 36. Vaccination-related adverse events were reported in 60.8% and 56.5% of participants in the qHPV vaccine and placebo groups, respectively; most commonly mild to moderate injection-site pain, erythema, and swelling. Injection-site pain and swelling were more common with qHPV vaccine than placebo (each p < 0.05). CONCLUSIONS: Results suggest qHPV vaccine is efficacious against HPV6/11/16/18-related persistent infections, immunogenic, and well-tolerated in Japanese men. Clinical trial registration identifier: NCT01862874.

Safety and Immunogenicity of a 9-Valent Human Papillomavirus Vaccine Administered to 9- to 15-Year-Old Japanese Girls.

A 9-valent human papillomavirus (HPV 6/11/16/18/31/33/45/52/58) virus-like particle vaccine (9vHPV) has been proven highly efficacious in preventing anogenital diseases related to HPV, in a pivotal phase III study for women aged 16-26 years. Here, we report the results of an open-label phase III study conducted to bridge the gap between the findings in women aged 16-26 years and Japanese girls aged 9-15 years. All subjects (n = 100) received a 3-dose regimen of 9vHPV vaccine on day 1 and at months 2 and 6. Anti-HPV serological assays were performed on day 1 and at months 7, 12, 24, and 30. At month 7 (4 weeks after the third dose), 100% of the subjects exhibited seroconversion for each type of HPV. Increases in geometric mean of the titers for anti-HPV 6/11/16/18/31/33/45/52/58 in the subjects were similar to those in Japanese women aged 16-26 years in a previous phase III study. Persistence of the anti-HPV response was observed for 2 years after administration of the third dose. In addition, administration of the 9vHPV vaccine was generally well-tolerated in Japanese girls.