Indivior PLC has announced top-line results from its phase 3 clinical trial of RBP-7000, an investigational drug in development for the treatment of schizophrenia. In this pivotal study, both doses of RBP-7000 tested, 90 mg and 120 mg administered once-monthly, met the primary endpoint with statistically and clinically significant reductions in the symptoms of acute schizophrenia over an 8-week treatment period. Symptom reduction was measured using the change from baseline to end of treatment in the total Positive and Negative Syndrome Scale (PANSS) scores. RBP-7000 also met the key secondary endpoint with statistically significant improvements in the Clinical Global Impression-Severity of Illness (CGI-S) scale compared with placebo over the 8-week treatment period using change from baseline to end of treatment.

"With these positive phase 3 data in hand, we are moving forward expeditiously to complete the open-label long-term assessment of the safety and tolerability of RBP-7000," said Christian Heidbreder, Ph.D., Chief Scientific Officer of Indivior. "We understand there is a great unmet need among patients living with this chronic disease, and we hope to bring a new, long-acting treatment option to those individuals and the physicians who treat them."

Based on the success of the open-label phase of the trial, Indivior expects to submit a New Drug Application (NDA) to the U.S. Food and Drug Administration for potential approval in 2017.

During the 8-week, double-blind treatment period, patients treated once-monthly with either 90 mg or 120 mg of RBP-7000 demonstrated statistically and clinically significant mean reductions from baseline in PANSS total scores (-9.2 points for placebo; -15.4 points for RBP-7000, 90 mg, p=0.0004 vs. placebo; and -16.4 points for RBP-7000, 120 mg, p<0.0001 vs. placebo). In addition to meeting the pre-specified primary efficacy endpoint of PANSS total score reduction, the study also met the pre-specified key secondary endpoint of improvement on the CGI-S scale for each RBP-7000 group vs. placebo at Week 8 (p=0.0002 vs. placebo for RBP-7000, 90 mg; and p<0.0001 vs. placebo for RBP-7000, 120 mg). RBP-7000 was generally well tolerated in the study, and the observed safety profile of RBP-7000 was similar to that reported with oral risperidone.

Schizophrenia is a chronic, severe and disabling brain disorderi that affects an estimated 26 million people worldwide.ii Treatment is aimed at reducing or eliminating the symptoms of the disease and often includes antipsychotic medications and various psychosocial treatments.i

About the Study Design

The phase 3, randomized, multicenter, double-blind, placebo-controlled study was designed to assess the efficacy, safety and tolerability of RBP-7000 (90 mg and 120 mg) in patients experiencing acute exacerbation of schizophrenia. The trial included adult male and female patients between the ages of 18 to 55 years who met the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR®) criteria for schizophrenia and had a PANSS total score between 80 and 120 at the initial screening visit, and a score of 4 or greater on at least two of the following four items of the PANSS positive subscale: hallucinatory behavior, delusions, conceptual disorganization or suspiciousness.

A total of 354 patients were randomized to receive once-monthly subcutaneous injections of RBP-7000, 90 mg; RBP-7000, 120 mg; or a matching placebo injection for 8 weeks. Following randomization, patients received their first injection of RBP-7000.

The primary efficacy endpoint of the study was the mean change from baseline at Week 8 in PANSS total score. Statistical analyses of the effect of study treatment vs. placebo on the primary efficacy endpoint were conducted using a mixed effects model for repeated measures taking into account all available observations of the primary efficacy endpoint at various visits, and including terms for treatment (RBP-7000 [90 mg], RBP-7000 [120 mg], placebo), baseline total PANSS score, visit (5, 6, 8, 9) and treatment-by-visit interaction as fixed effects. The unstructured covariance type was used to model the variance-covariance matrix. Dunnett's procedure was used to adjust for the comparison between two levels of study treatment (RBP-7000 [90 mg and 120 mg]) with a single placebo.

All participants who completed the double-blind portion of the study and met some additional inclusionary/exclusionary criteria were eligible to continue in an open-label phase and receive RBP-7000 for a total of 13 injections (2 in the double-blind phase and 11 in the open-label phase). The objective of the extension phase of the study is to assess the safety and long-term tolerability of once-monthly RBP-7000.

About RBP-7000

RBP-7000 is a novel sustained-release product using the Atrigel® delivery system for the subcutaneous administration of risperidone once every month.iii RBP-7000 consists of a two-syringe system, whose contents are mixed immediately prior to administration. One syringe contains the Atrigel® delivery system, and the other contains the powder-filled drug substance risperidone. These phase 3 clinical trial results further emphasize the compatibility of our Atrigel® drug delivery platform with a range of pharmaceutical compounds for their safe, sustained release over targeted time period through an easy biodegradable and biocompatible process.