Phase 2 study of RG1678 for the treatment of schizophrenia

Genentech announced eight-week results from a Phase 2 study of RG1678 for the treatment of schizophrenia. The data showed a clinically meaningful reduction in the negative symptoms of schizophrenia, accompanied by beneficial changes in patients’ personal and social functioning. This study was a multicenter, randomized, double-blind, parallel group, 323-patient study investigating RG1678 compared to placebo in patients with predominantly negative symptoms of schizophrenia. In the study, the efficacy and safety profile of three dose regimens of RG1678 (10mg, 30mg and 60mg) were assessed. The primary efficacy endpoint was the change from baseline at week eight in the negative symptom factor score as assessed by the Positive and Negative Syndrome Scale (PANSS). Secondary endpoints were measured using the Clinical Global Impression (CGI)-Improvement in negative symptoms and Personal and Social Performance (PSP) scale.  The study yielded the following results.

  • Changes in PANSS negative symptom factor score demonstrated a statistically significant improvement in negative symptoms in patients taking RG1678 10mg and 30mg compared to placebo (per-protocol (PP) population).
  • Differences in CGI improvement in negative symptoms were statistically significant between RG1678 10mg and placebo (PP population).
  • There was also a trend towards functional improvement as assessed by the PSP scale in the RG1678 10mg group compared to placebo (PP population).
  • In line with pre-clinical data, the 60mg dose did not show statistically significant improvements in any endpoints.

RG1678 is an investigational first-in-class glycine reuptake inhibitor (GRI). RG1678 normalizes glutamate neurotransmission by increasing synaptic levels of glycine, thereby targeting an important pathway in the treatment of psychiatric disorders.

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