Sample size calculation in clinical trials with two co-primary endpoints including overdispersed count and continuous outcomes.

Count outcomes are collected in clinical trials for new drug development in several therapeutic areas and the event rate is commonly used as a single primary endpoint. Count outcomes that are greater than the mean value are termed overdispersion; thus, count outcomes are assumed to have a negative binomial distribution. However, in clinical trials for treating asthma and chronic obstructive pulmonary disease (COPD), a regulatory agency has suggested that a continuous endpoint related to lung function must be evaluated as a primary endpoint in addition to the event rate. The two co-primary endpoints that need to be evaluated include overdispersed count and continuous outcomes. Some researchers have proposed sample size calculation methods in the context of co-primary endpoints for various outcome types. However, methodologies for sample size calculation in trials with two co-primary endpoints, including overdispersed count and continuous outcomes, required when planning clinical trials for treating asthma and COPD, remain to be proposed. In this study, we aimed to develop a hypothesis-testing method and a corresponding sample size calculation method with two co-primary endpoints including overdispersed count and continuous outcomes. In a simulation, we demonstrated that the proposed sample size calculation method has adequate power accuracy. In addition, we illustrated an application of the proposed sample size calculation method to a placebo-controlled Phase 3 trial for patients with COPD.

Cautionary note on regional consistency evaluation in multiregional clinical trials with binary outcomes.

Multiregional clinical trials (MRCTs) have become increasingly common during the development of new drugs to obtain simultaneous drug approvals worldwide. When planning MRCTs, a major statistical challenge is determination of the regional sample size. In general, the regional sample size must be determined as the sample size such that the regional consistency probability, defined as the probability of meeting the regional consistency criterion, is greater than a prespecified value. The Japanese Ministry of Health, Labour and Welfare proposed two criteria for regional consistency. Moreover, many researchers have proposed corresponding closed-form formulas for calculating regional consistency probabilities when the primary outcome is continuous. Although some researchers have argued that those formulas are also applicable to cases with binary outcomes, it remains questionable whether such an argument can be true. Based on simulation results, we demonstrate that the existing formulas are inappropriate for binary cases, even when the regional sample size is sufficiently large. To address this issue, we develop alternative formulas and use simulation to show that they provide accurate regional consistency probabilities. Furthermore, we present an application of our proposed formulas for an MRCT of advanced or metastatic clear-cell renal cell carcinoma.

Efficacy and safety of the sodium-glucose co-transporter-2 inhibitor empagliflozin in elderly Japanese adults (≥65 years) with type 2 diabetes: A randomized, double-blind, placebo-controlled, 52-week clinical trial (EMPA-ELDERLY).

AIM: Use of sodium-glucose co-transporter-2 inhibitors (SGLT2is) for glycaemic control is increasing in individuals with type 2 diabetes (T2D) for their additional benefits on heart failure and chronic kidney disease. However, SGLT2is generally reduce body weight, which might promote sarcopenia in older individuals. We evaluated the effects of the SGLT2i empagliflozin on muscle mass and strength in addition to glucose control in elderly adults with T2D. MATERIALS AND METHODS: Individuals with T2D aged ≥65 years with body mass index ≥22 kg/m2 and glycated haemoglobin (HbA1c) 7.0%-10.0% were randomized 1:1 to once-daily empagliflozin 10 mg or placebo for 52 weeks. The primary endpoint was change from baseline in HbA1c at week 52. Secondary endpoints included changes from baseline in muscle mass and strength. RESULTS: Of the 129 individuals randomized, 72.4% were men, mean age 74.1 years, body mass index 25.6 kg/m2 and HbA1c 7.6%. The placebo-adjusted mean change from baseline in HbA1c at week 52 with empagliflozin was -0.57% [95% confidence interval (CI) -0.78, -0.36]. Change in body weight was -3.26 kg and -0.90 kg with empagliflozin and placebo, respectively (placebo-adjusted difference: -2.37 kg; 95% CI -3.07, -1.68). Placebo-adjusted change in muscle mass was -0.61 kg (95% CI -1.61, 0.39), fat mass -1.84 kg (95% CI -2.65, -1.04) and grip strength -0.3 kg (95% CI -1.1, 0.5). CONCLUSIONS: Empagliflozin improved glucose control and reduced body weight without compromising muscle mass or strength in elderly adults with T2D in this trial.

Usefulness of the placebo lead-in design for clinical trials with binary outcomes.

BACKGROUND: In placebo-controlled clinical trials to develop new drugs for the treatment of psychiatric or neurological disorders, a high and sometimes greater-than-expected placebo response makes it difficult to show the superiority of an investigational drug over a corresponding placebo. To avoid such difficulty, a placebo lead-in design has been presented, but its usefulness has been open to discussion. Although the statistical properties of the placebo lead-in design are investigated in the context of continuous outcomes, whether these properties can be generalized for binary or ordinal cases remains unclear. METHODS: We investigate whether the placebo lead-in design is useful in clinical trials with binary outcomes through mathematical formulae and a numerical investigation. Specifically, we compare the proportion of placebo responders, the drug-placebo difference, and the effect size between two populations: one enriched for placebo nonresponders and the other comprising the all-comers. RESULTS: Under positive correlation of the data between the lead-in stage and the randomized stage for both treatment groups, we mathematically show that the proportion of responders in the population enriched for placebo nonresponders is less than that in the all-comers population, and whether the placebo lead-in design increases the drug-placebo difference depends on the variances of outcomes in both treatment groups as well as the correlations of the outcomes between two stages. Further, through a numerical investigation, we show that whether the placebo lead-in design increases the effect size strongly depends on the magnitude of the correlations and their difference. CONCLUSION: If the correlation of the placebo-placebo group is much higher than that of the placebo-drug group, the placebo lead-in design is advantageous in most cases but has an impact on an estimand in placebo nonresponders. Therefore, we do not recommend using the placebo lead-in design for clinical trials with binary outcomes.

Ramucirumab Plus Erlotinib Versus Placebo Plus Erlotinib in Patients With Untreated Metastatic EGFR-Mutated NSCLC: RELAY Japanese Subset.

INTRODUCTION: The phase 3 RELAY global study (NCT02411448) revealed significant improvement in progression-free survival (PFS) with ramucirumab plus erlotinib (RAM + ERL) compared with placebo plus ERL (PL + ERL) in untreated EGFR-mutated metastatic NSCLC (hazard ratio [HR] = 0.59 [95% confidence interval (CI): 0.46-0.76, p < 0.0001]). This prespecified analysis evaluates efficacy, safety, and postprogression EGFR T790M rates of RELAY patients enrolled in Japan. METHODS: Patients were randomized (1:1) to oral ERL (150 mg/d) plus intravenous RAM (10 mg/kg) or PL every 2 weeks. End points included PFS (primary), safety (secondary), and biomarker analyses (exploratory). Plasma samples collected at baseline and poststudy treatment discontinuation were evaluated for EGFR T790M mutations by next-generation sequencing. RESULTS: The Japanese subset included 211 of 449 (47.0%) RELAY patients (RAM + ERL, n = 106; PL + ERL, n = 105). Median PFS was 19.4 versus 11.2 months for RAM + ERL versus PL + ERL treatment (HR = 0.610 [0.431-0.864]) in the Japanese intent-to-treat population, 16.6 versus 12.5 months (HR = 0.701 [0.424-1.159]) in the EGFR exon 19 deletion subgroup, and 19.4 versus 10.9 months (HR = 0.514 [0.317-0.835]) in the EGFR exon 21 L858R subgroup, respectively. Adverse events of grade 3 or above with RAM + ERL included hypertension (24.8%, all grade 3) and dermatitis acneiform (23.8%). Postprogression treatment-emergent T790M rates were similar between arms (RAM + ERL: 47%, 9 of 19 patients; PL + ERL: 50%, 20 of 40 patients). CONCLUSIONS: Clinically meaningful efficacy was observed with RAM + ERL versus PL + ERL in the RELAY Japanese subset, with no new safety concerns. Postprogression T790M rates were similar across treatment arms, indicating the addition of RAM did not affect the ERL-associated EGFR T790M rates at disease progression.

Phase 2 randomized placebo-controlled study of lasmiditan for the acute treatment of migraine in Japanese patients.

OBJECTIVE: To evaluate the efficacy and safety of lasmiditan in Japanese adults with migraine. BACKGROUND: Global clinical studies have demonstrated the efficacy and safety of lasmiditan in the acute treatment of migraine. METHODS: This was a multicenter, randomized, double-blind, placebo-controlled, phase 2 study in Japan (NCT03962738), which enrolled adults with migraine with or without aura. Participants were randomized 7:3:7:6 to placebo, lasmiditan 50 mg, 100 mg, or 200 mg to be self-administered orally within 4 h of onset of a single moderate-to-severe migraine attack. Participants recorded their response to treatment prior to dosing and for 48 h postdose. The primary endpoint was headache pain freedom at 2 h postdose. RESULTS: Participants (N = 846) were randomized and treated (N = 691, safety; N = 682, modified intent-to-treat). At 2 h postdose, a significantly higher proportion of participants were headache pain-free in the lasmiditan 200 mg (40.8%, 73/179; odds ratio 3.46 [95% confidence interval 2.17 to 5.54]; p < 0.001; primary objective) and 100 mg groups (32.4%, 67/207; odds ratio 2.41 [1.51 to 3.83]; p < 0.001) compared with the placebo group (16.6%, 35/211), whereas the lasmiditan 50 mg group had a numerically higher proportion of participants headache pain-free (23.5%, 20/85; odds ratio 1.55 [0.83 to 2.87]; p = 0.167) compared with placebo. A statistically significant linear dose-response relationship for pain freedom was achieved at 2 h by a Cochran-Armitage trend test (p < 0.001). Lasmiditan treatment was also associated with headache pain relief, most bothersome symptom freedom, and improvement on disability and Patient Global Impression of Change outcomes. The majority of treatment-emergent adverse events were mild and of short duration, the most common of which were dizziness (39.4%; 188/477), somnolence (19.3%; 92/477), and malaise (10.5%; 50/477) in all lasmiditan groups, with no serious adverse events reported. CONCLUSIONS: Lasmiditan was well tolerated and effective for the acute treatment of Japanese patients with migraine, consistent with global phase 3 studies.

Quality of Life Associated with Ramucirumab Treatment in Patients with Advanced Gastric Cancer in Japan: Exploratory Analysis from the Phase III RAINBOW Trial.

BACKGROUND AND OBJECTIVE: Gastric cancer has been associated with notable geographic heterogeneity in previous multi-regional studies. In particular, patients from Japan have better outcomes compared with patients from other regions. Here, we assess patient-focused outcomes for the subgroup of Japanese patients in the global RAINBOW study. METHODS: Quality of life (QoL) was assessed using the European Organization for Research and Treatment of Cancer Quality-of-Life Questionnaire-Core 30 (QLQ-C30) at baseline and 6-week intervals. Investigators assessed performance status before each 4-week cycle. Time-to-deterioration in each QLQ-C30 scale was defined as randomization to first worsening of ≥ 10 points (on a 100-point scale). Time-to-deterioration in performance status was defined as first worsening to ≥ 2. Hazard ratios were estimated using Cox proportional hazards models. RESULTS: The Japan subgroup contained 140 patients (ramucirumab plus paclitaxel, n = 68; placebo plus paclitaxel, n = 72); baseline QoL data were available for all patients. At baseline, QLQ-C30 scores were similar between study arms. Of the 15 QLQ-C30 scales, nine had a hazard ratio < 1, indicating similar or numerically longer time-to-deterioration in QoL for ramucirumab plus paclitaxel; all 95% confidence intervals included 1. Best mean change from baseline numerically favored ramucirumab plus paclitaxel in most QoL scales. The hazard ratios for time-to-deterioration of performance status to ≥ 2 were 0.64 in the Japan subgroup and 0.88 in the non-Asian subgroup. The Japan subgroup had better QoL at baseline compared with the non-Asian subgroup. CONCLUSIONS: Treatment with ramucirumab plus paclitaxel maintained QoL and performance status over time compared with placebo plus paclitaxel in the Japan subgroup of the RAINBOW trial. These data suggest that the heterogeneity in gastric cancer between geographic regions includes multiple measures of QoL. TRIAL REGISTRATION NUMBER: NCT01170663 (first submitted 21 July, 2010).

Ramucirumab or placebo plus erlotinib in EGFR-mutated, metastatic non-small-cell lung cancer: East Asian subset of RELAY.

In the global phase III RELAY study, ramucirumab plus erlotinib (RAM + ERL) demonstrated superior progression-free survival (PFS) to placebo plus erlotinib (PL + ERL) in untreated patients with epidermal growth factor receptor (EGFR) mutation-positive metastatic non-small-cell lung cancer (NSCLC) (hazard ratio (HR) [95% CI]: 0.59 [0.46-0.76]). This prespecified analysis assessed RAM + ERL efficacy and safety in the RELAY subset enrolled in East Asia (Japan, Taiwan, South Korea, Hong Kong). Randomized (1:1) patients received oral ERL (150 mg/d) plus intravenous RAM (10 mg/kg) or PL Q2W. Primary endpoint was PFS (investigator-assessed). Key secondary endpoints included objective response rate (ORR), disease control rate (DCR), duration of response (DoR), overall survival (OS), and safety. Exploratory endpoints included biomarker analyses and time to second progression (PFS2). Median PFS was 19.4 vs 12.5 mo for RAM + ERL (n = 166) vs PL + ERL (n = 170) (HR: 0.636 [0.485-0.833]; P = .0009). The 1-y PFS rate was 72.4% vs 52.2%, respectively. PFS benefit was consistent in most subgroups, including by EGFR mutation (Ex19del, Ex21.L858R). ORR and DCR were similar in both arms, but median DoR was longer with RAM + ERL. OS and PFS2 were immature at data cut-off (censoring rates, 81.2%-84.3% and 64.1%-70.5%, respectively). Grade ≥ 3 treatment-emergent adverse events were more frequent with RAM + ERL (70.7%) than PL + ERL (49.4%). Adverse events leading to treatment discontinuation were similar in both arms (RAM + ERL, 13.3%; PL + ERL, 12.9%), as were post-progression EGFR T790M mutation rates (43%; 50%). With superior PFS over PL + ERL and safety consistent with the overall RELAY population, RAM + ERL is a viable treatment option for EGFR-mutated metastatic NSCLC in East Asia.

Ramucirumab after prior sorafenib in patients with advanced hepatocellular carcinoma and elevated alpha-fetoprotein: Japanese subgroup analysis of the REACH-2 trial.

BACKGROUND: The global, randomized, phase 3 REACH-2 study (ClinicalTrials.gov identifier: NCT02435433) found significantly longer overall survival (OS) for second-line ramucirumab versus placebo (hazard ratio [HR]: 0.710, 95% confidence interval [CI] 0.531-0.949, P = 0.0199) in patients with advanced hepatocellular carcinoma (HCC) and alpha-fetoprotein (AFP) ≥ 400 ng/mL. This prespecified subgroup analysis evaluated the efficacy and safety of ramucirumab in the Japanese patients enrolled in the study. METHODS: Patients with advanced HCC and AFP ≥ 400 ng/mL after first-line sorafenib were randomized 2:1 to ramucirumab (8 mg/kg intravenously) or placebo every 2 weeks. Hazard ratios for progression-free survival (PFS) and OS (primary endpoint of the overall study) were estimated using the stratified Cox regression model. We also pooled individual patient data from REACH-2 with data from REACH (NCT01140347) for patients with AFP ≥ 400 ng/mL. RESULTS: In the Japanese REACH-2 subpopulation, there were improvements for ramucirumab (n = 41) versus placebo (n = 18) in PFS (HR 0.282, 95% CI 0.144-0.553) and OS was numerically prolonged (HR 0.599, 95% CI 0.303-1.187), consistent with the significant benefit seen in the overall REACH-2 study population. In the ramucirumab and placebo arms, respectively, the objective response rate was 7.3% and 0%, and the disease control rate was 70.7% and 33.3%. The most frequently reported grade ≥ 3 treatment-emergent adverse event was hypertension (ramucirumab: 15%; placebo: 11%). CONCLUSIONS: Ramucirumab after prior sorafenib improved PFS and OS compared with placebo, with a manageable safety profile, in the Japanese REACH-2 subpopulation, consistent with the overall REACH-2 study results. Ramucirumab is the first agent to demonstrate clinical benefit for Japanese patients with HCC in the second-line setting.

Sequential parallel comparison design with two coprimary endpoints.

A placebo-controlled randomized clinical trial is required to demonstrate that an experimental treatment is superior to its corresponding placebo on multiple coprimary endpoints. This is particularly true in the field of neurology. In fact, clinical trials for neurological disorders need to show the superiority of an experimental treatment over a placebo in two coprimary endpoints. Unfortunately, these trials often fail to detect a true treatment effect for the experimental treatment versus the placebo owing to an unexpectedly high placebo response rate. Sequential parallel comparison design (SPCD) can be used to address this problem. However, the SPCD has not yet been discussed in relation to clinical trials with coprimary endpoints. In this article, our aim was to develop a hypothesis-testing method and a method for calculating the corresponding sample size for the SPCD with two coprimary endpoints. In a simulation, we show that the proposed hypothesis-testing method achieves the nominal type I error rate and power and that the proposed sample size calculation method has adequate power accuracy. In addition, the usefulness of our methods is confirmed by returning to an SPCD trial with a single primary endpoint of Alzheimer disease-related agitation.

Sequential parallel comparison design for "gold standard" noninferiority trials with a prespecified margin.

Three-arm noninferiority trials (involving an experimental treatment, a reference treatment, and a placebo)-called the "gold standard" noninferiority trials-are conducted in patients with mental disorders whenever feasible, but often fail to show superiority of the experimental treatment and/or the reference treatment over the placebo. One possible reason is that some of the patients receiving the placebo show apparent improvement in the clinical condition. An approach to addressing this problem is the use of the sequential parallel comparison design (SPCD). Nonetheless, the SPCD has not yet been discussed in relation to gold standard noninferiority trials. In this article, our aim was to develop a hypothesis-testing method and its corresponding sample size calculation method for gold standard noninferiority trials with the SPCD. In a simulation, we show that the proposed hypothesis-testing method achieves the nominal type I error rate and power and that the proposed sample size calculation method has adequate power accuracy.

A simple test for the treatment effect in clinical trials with a sequential parallel comparison design and negative binomial outcomes.

In placebo-controlled, double-blinded, randomized clinical trials, the presence of placebo responders reduces the effect size for comparison of the active drug group with the placebo group. An attempt to resolve this problem is to use the sequential parallel comparison design (SPCD). Although there are SPCDs with dichotomous or continuous outcomes, an SPCD with negative binomial outcomes-with which investigators deal eg, in clinical trials involving multiple sclerosis, where the investigators are still concerned about the presence of placebo responders-has not yet been discussed. In this article, we propose a simple test for the treatment effect in clinical trials with an SPCD and negative binomial outcomes. Through simulations, we show that the analysis method achieves the nominal type I error rate and power, whereas the sample size calculation provides the sample size with adequate power accuracy.