Improvement of Negative Symptoms in Schizophrenia with Paliperidone Palmitate 1-Month and 3-Month Long-Acting Injectables: Results from a Phase 3 Non-Inferiority Study

BACKGROUND: Negative symptoms in schizophrenia are associated with impairments in social and cognitive functioning leading to substantial long-term disability. Available antipsychotic treatments have demonstrated only modest benefit in the improvement of negative symptoms. OBJECTIVE: To compare improvements in negative symptoms among patients treated with paliperidone palmitate 3-month (PP3M) or paliperidone palmitate 1-month (PP1M) long-acting injectable (LAI) formulations. METHODS: Data from a randomized double-blind (DB), phase-3, non-inferiority study in patients with schizophrenia were analyzed. Following screening, patients entered a 17-week open-label (OL) phase to receive flexibly dosed PP1M followed by a 48-week DB phase where patients were randomized (1:1) to receive either PP1M or PP3M. Positive and Negative Syndrome Scale (PANSS) total scores with emphasis on 7-item negative subscale scores for PP1M vs PP3M were assessed. RESULTS: Of 1429 patients enrolled, 1016 were randomized to receive PP3M (n=504) or PP1M (n=512). At baseline, mean (SD) PANSS negative subscale was 23.2 (4.60) and negative symptom factor score was 22.3 (4.87), indicating moderate-to-severe negative symptoms. Negative subscale and symptoms factor scores showed continuous improvements throughout OL (15.9 [4.99]) and DB (14.9 [4.81]) phases. Mean (SD) changes from DB baseline in the PANSS negative subscale score were comparable between PP1M (–1.4 [3.67]) and PP3M (–1.4 [3.63]) treatment groups. CONCLUSION: Treatment with PP3M or PP1M demonstrated comparable improvement in negative symptoms in patients with moderate-to-severe negative symptoms and in patients with prominent negative symptoms. Long-term treatment with PP3M demonstrated benefit, suggesting that continuous antipsychotic medication treatment for >1 year is needed to achieve greater benefit for negative symptoms. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01515423.