Efficacy and safety of paliperidone palmitate three-monthly formulation in East Asian patients with schizophrenia: subgroup analysis of a global, randomized, double-blind, Phase III, noninferiority study

OBJECTIVE: To demonstrate the efficacy and safety of paliperidone palmitate three-monthly (PP3M) formulation in an East Asian population with schizophrenia by subgroup analysis of a double-blind (DB), multicenter, noninferiority study. PATIENTS AND METHODS: Of 1,429 patients who entered the open-label (OL) phase, 510 were East Asian (China: 296 [58%], Japan: 175 [34%], South Korea: 19 [4%] and Taiwan: 20 [4%]). In the 17-week OL phase, patients received paliperidone palmitate once-monthly (PP1M) formulation on day 1 (150 mg eq.), day 8 (100 mg eq.) and once-monthly thereafter (50–150 mg eq., flexible). Following the OL phase, patients (n=344 East Asian) entered DB phase and were randomized (1:1) to PP1M (n=174) or PP3M (n=170). Primary efficacy endpoint was the percentage of patients who remained relapse free at the end of the 48-week DB phase, using Kaplan–Meier cumulative survival estimate. Secondary efficacy endpoints included change from DB baseline to endpoint in Positive and Negative Syndrome Scale, Clinical Global Impression Severity, Personal and Social Performance scores and symptomatic remission. Additional assessments included caregiver burden and safety. RESULTS: A total of 285/344 (83%) randomized East Asian patients completed the DB phase. The percentage of patients who had a relapse event was similar on comparing PP3M (17 [10.2%]) to PP1M (20 [11.8%]), and also for Japan (PP3M: 9 [17.6%], PP1M: 13 [23.2%]) and China (PP3M: 6 [5.9%], PP1M: 7 [6.9%]). Mean change from baseline in secondary efficacy parameters was similar to the global population, regardless of treatment. Symptomatic remission was attained by 50% of the treated patients. Caregiver burden was significantly reduced (P<0.001) following treatment with PP3M/PP1M. Frequency of treatment-emergent adverse events in PP3M group during DB phase was greater in the East Asian subgroup (81%) than the global population (68%) and was higher in Japan (92%) than China (75%). CONCLUSION: Results suggest that PP3M is efficacious in the East Asian subgroup. Although treatment-emergent adverse events were slightly higher in the East Asian subgroup versus the global population, no new safety signals were identified.