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.

Phase 1/2 study of the WT1 peptide cancer vaccine WT4869 in patients with myelodysplastic syndrome.

WT4869 is a synthetic peptide vaccine derived from the Wilms' tumor gene 1 (WT1) protein. This phase 1/2 open-label study evaluated the safety and efficacy of WT4869, and biomarkers for response, in patients with myelodysplastic syndrome. WT4869 (5-1200 µg/dose) was administered intradermally every 2 weeks, according to a 3 + 3 dose-escalation method in higher-risk (International Prognostic Scoring System score ≥1.5) or lower-risk (score <1.5) red blood cell transfusion-dependent patients with myelodysplastic syndrome. Twenty-six patients were enrolled and treated (median age, 75 years; range, 32 to 89). The most common adverse event was injection site reaction (61.5%). Main grade 3 or 4 adverse events were neutropenia (30.8%), febrile neutropenia, pneumonia, elevated blood creatine phosphokinase levels and hypoalbuminemia (all 7.7%). Dose-limiting toxicities occurred in 1 patient in the 50 µg/dose cohort (pyrexia, muscle hemorrhage and hypoalbuminemia) and 1 patient in the 400 µg/dose cohort (pneumonitis); however, the maximum tolerated dose could not be determined from this trial. The overall response rate was 18.2%, the disease control rate was 59.1% and median overall survival was 64.71 weeks (95% confidence interval: 50.29, 142.86) as assessed by the Kaplan-Meier method. Subgroup analysis of azacitidine-refractory patients with higher-risk myelodysplastic syndrome (11 patients) showed median overall survival of 55.71 weeks (approximately 13 months). WT1-specific cytotoxic T lymphocyte induction was observed in 11 of 25 evaluable patients. WT4869 was well tolerated in patients with myelodysplastic syndrome and preliminary data suggest that WT4869 is efficacious. This trial was registered at www.clinicaltrials.jp as JapicCTI-101374.

Challenges on Multiple Endpoints in Clinical Trials: An Industry Survey in Japan.

BACKGROUND: Two issues on clinical trials with multiple endpoints were surveyed: (1) the terminology of multiple endpoints, relationship between rare events and endpoints, and differences in multiplicity adjustment between regions; and (2) the current practice on multiplicity adjustment and sample size calculation. This article provides a summary of the results of a survey on the first issue. METHODS: The survey was conducted among 63 members of the Japan Pharmaceutical Manufacturers Association from October to November 2017. RESULTS: Thirty-five companies based in Japan and 12 companies based in other countries, 47 companies in total, responded to the survey. The terms co-primary endpoints, secondary endpoint, and composite endpoint were used in a variety of ways. An endpoint for a clinically most important event that is expected to occur rarely differed between regions. Although the Pharmaceuticals and Medical Devices Agency did not demand multiplicity adjustment, it was considered in clinical trials with multiple endpoints for approval in Japan. CONCLUSIONS: The use of terminology differed from the definition in the Food and Drug Administration guidance and the European Medicines Agency guideline. There remain challenges on a clinically most important event that is expected to occur rarely and multiplicity adjustment in clinical trials with multiple endpoints.

Multiplicity Adjustment and Sample Size Calculation in Clinical Trials with Multiple Endpoints: An Industry Survey of Current Practices in Japan.

BACKGROUND: Two issues in clinical trials with multiple endpoints were surveyed: (1) the terminology of multiple endpoints, the relationship between rare events and endpoints, and the differences in multiplicity adjustment between regions, and (2) the current practice on multiplicity adjustment and sample size calculation. This article summarizes the results of the survey on the second issue. METHODS: Eligible trials for this survey fulfilled the following conditions: (1) confirmatory phase 3 trial; (2) use of multiple primary endpoints, co-primary endpoints, key secondary endpoint(s) or composite endpoint(s); (3) inclusion of Japanese participants; and (4) protocols created in 2010 or later. The survey was conducted at member companies of the Japan Pharmaceutical Manufacturers Association from October 2017 to November 2017. RESULTS: Useable responses were obtained from 78 trials in 13 companies based in Japan and 9 companies based in other countries. The Bonferroni procedure was mostly used in clinical trials with multiple primary endpoints, while multiple testing procedures that consider a hierarchy of endpoints or a structure of hypotheses were used in clinical trials with key secondary endpoint(s). In sample size calculation, we can consider the probability of study success, such as the probability of statistical significance in at least one comparison of primary endpoints; however, other probabilities were also considered. This survey reveals that multiplicity adjustment and the correlation of endpoints were not always considered in sample size calculation. CONCLUSIONS: In clinical trials with multiple endpoints, clinical importance was considered when determining multiple testing procedures. Challenges remain with the definition of power, the consideration of multiple testing procedures and the correlation between endpoints in sample size calculation.

Challenges on Multiple Endpoints in Clinical Trials: An Industry Survey in Japan.

BACKGROUND: Two issues on clinical trials with multiple endpoints were surveyed: (1) the terminology of multiple endpoints, relationship between rare events and endpoints, and differences in multiplicity adjustment between regions; and (2) the current practice on multiplicity adjustment and sample size calculation. This article provides a summary of the results of a survey on the first issue. METHODS: The survey was conducted among 63 members of the Japan Pharmaceutical Manufacturers Association from October to November 2017. RESULTS: Thirty-five companies based in Japan and 12 companies based in other countries, 47 companies in total, responded to the survey. The terms co-primary endpoints, secondary endpoint, and composite endpoint were used in a variety of ways. An endpoint for a clinically most important event that is expected to occur rarely differed between regions. Although the Pharmaceuticals and Medical Devices Agency did not demand multiplicity adjustment, it was considered in clinical trials with multiple endpoints for approval in Japan. CONCLUSIONS: The use of terminology differed from the definition in the Food and Drug Administration guidance and the European Medicines Agency guideline. There remain challenges on a clinically most important event that is expected to occur rarely and multiplicity adjustment in clinical trials with multiple endpoints.

Current Practice on Multiplicity Adjustment and Sample Size Calculation in Multi-arm Clinical Trials: An Industry Survey in Japan.

BACKGROUND: This study provides the results of a survey on the current practice of multiplicity adjustment and sample size calculation in multi-arm clinical trials. METHODS: The survey was aimed at members of the Japan Pharmaceutical Manufacturers Association (JPMA) and was conducted in 2015. RESULTS: Of the 66 JPMA member companies, effective responses were obtained on 151 trials from 33 companies based in Japan and 11 companies based in other countries. The results from this survey indicate that multiplicity adjustment in confirmatory multi-arm trials is adequate in terms of controlling the familywise error rate. Multiplicity was adjusted in 38.3% of exploratory multi-arm trials. Various multiple comparison procedures (MCPs) were applied, with the fixed sequence procedure being the one applied most frequently. This survey also reveals that there are issues that need to be addressed within sample size calculation. CONCLUSIONS: To adequately design a multi-arm clinical trial, it is important within sample size calculation to consider whether to perform multiplicity adjustment, select MCPs, and define their power.

Current Practice in Japan for the Prevention and Treatment of Missing Data in Confirmatory Clinical Trials: A Survey of Japanese and Foreign Pharmaceutical Manufacturers.

This study aims to survey the current practice in Japan for the prevention and treatment of missing data in clinical trials since the publication of regulatory guidelines on missing data issues. A web-based questionnaire was conducted among 65 member companies of the Japan Pharmaceutical Manufacturers Association in 2013. Responses were obtained on 187 clinical trials from 55 companies, including 42 based in Japan and 13 based in other countries. Missing data were most frequent in trials involving the central nervous system (65.2% had ≥10% missing data). Overall, last observation carried forward (LOCF) was the most popular method for handling missing data (45.0%), followed by mixed-effect models for repeated measures (15.5%), although this was used as frequently as LOCF imputation in central nervous system trials. Even after the publication of regulatory guidelines discouraging use of LOCF, LOCF imputation remains the most popular method for treating missing data among pharmaceutical manufacturers in Japan.

Long-term safety and tolerability of lurasidone in schizophrenia: a 12-month, double-blind, active-controlled study.

The aim of this study is to evaluate the long-term safety and tolerability of lurasidone in the treatment of schizophrenia. Clinically stable adult outpatients with schizophrenia were randomized in a 2 : 1 ratio to 12 months of double-blind treatment with once-daily, flexibly-dosed lurasidone (40-120 mg) or risperidone (2-6 mg). Outcome measures included adverse events (AEs), vital signs, ECG, and laboratory tests. Secondary assessments included measures of psychopathology. A total of 427 patients were randomized to treatment with lurasidone and 202 with risperidone. The three most frequent AEs in the lurasidone group (vs. risperidone) were nausea (16.7 vs. 10.9%), insomnia (15.8 vs. 13.4%), and sedation (14.6 vs. 13.9%); the three most frequent AEs in the risperidone group (vs. lurasidone) were increased weight (19.8 vs. 9.3%), somnolence (17.8 vs. 13.6%), and headache (14.9 vs. 10.0%). A higher proportion of patients receiving risperidone had at least a 7% endpoint increase in weight (14 vs. 7%). The median endpoint change in prolactin was significantly higher for risperidone (P<0.001). A comparable improvement in efficacy measures was observed with both agents and the rates of relapse were similar. All-cause discontinuation rates were higher for lurasidone versus risperidone. Long-term treatment with lurasidone was generally well tolerated in this study, with minimal effects on weight and metabolic outcomes.