Three-Year Outcomes of 6-Month Paliperidone Palmitate in Adults With Schizophrenia: An Open-Label Extension Study of a Randomized Clinical Trial.

Importance: Long-acting injectable (LAI) antipsychotics have the potential to improve adherence and symptom control in patients with schizophrenia, promoting long-term recovery. Paliperidone palmitate (PP) once every 6 months is the first and currently only LAI antipsychotic with an extended dosing interval of 6 months.

Objective: To assess long-term outcomes of PP received once every 6 months in adults with schizophrenia.

Design, Setting, And Participants: In a 2-year open-label extension (OLE) study of a 1-year randomized clinical trial (RCT), eligible adults with schizophrenia could choose to continue PP every 6 months if they had not experienced relapse after receiving PP once every 3 or 6 months in the 1-year, international, multicenter, double-blind, randomized noninferiority trial. The present analysis focused on patients receiving PP every 6 months in the double-blind trial through the OLE study (November 20, 2017, to May 3, 2022).

Intervention: Patients received a dorsogluteal injection of PP on day 1 and once every 6 months up to month 30.

Main Outcomes And Measures: End points included assessment of relapse and change from the double-blind trial baseline to the OLE end point in Positive and Negative Syndrome Scale (PANSS) total and subscale, Clinical Global Impression-Severity (CGI-S) Scale, and Personal Social Performance (PSP) Scale scores. Treatment-emergent adverse events (TEAEs), injection site evaluations, and laboratory tests were also assessed.

Results: Among 121 patients (83 [68.6%] male), mean (SD) age at baseline was 38.6 (11.24) years and mean (SD) duration of illness was 11.0 (9.45) years. At screening of the double-blind study, 101 patients (83.5%) were taking an oral antipsychotic and 20 (16.5%) were taking an LAI antipsychotic. Altogether, 5 of 121 patients (4.1%) experienced relapse during the 3-year follow-up; reasons for relapse were psychiatric hospitalization (2 [1.7%]), suicidal or homicidal ideation (2 [1.7%]), and deliberate self-injury (1 [0.8%]). Patients treated with PP every 6 months were clinically and functionally stable, and outcomes were well maintained, evidenced by stable scores on the PANSS (mean [SD] change, -2.6 [9.96] points), CGI-S (mean [SD] change, -0.2 [0.57] points), and PSP (mean [SD] change, 3.1 [9.14] points) scales over the 3-year period. In total, 101 patients (83.5%) completed the 2-year OLE. At least 1 TEAE was reported in 97 of 121 patients (80.2%) overall; no new safety or tolerability concerns were identified.

Conclusions And Relevance: In a 2-year OLE study of a 1-year RCT, results supported favorable long-term outcomes of PP once every 6 months for up to 3 years in adults with schizophrenia.