Is this phase 2 trial the end of the road for a potential new treatment?
A phase 2 trial of an adjunctive treatment for schizophrenia has stopped after failing to meet its primary and secondary endpoints. The treatment, CTP-692, developed by Concert Pharmaceuticals Inc, was a deuterated form of D-serine.
“The body of evidence in the field supporting D-serine as an adjunctive treatment for schizophrenia was compelling and led us to advance CTP-692 into a Phase 2 proof of concept study,” Roger Tung, PhD, president and chief executive officer of Concert Pharmaceuticals told the press. “Unfortunately, we didn’t see the results we hoped for to support continuation of this program.”1
CTP-692 was designed to improve on the efficacy and safety profile of existing schizophrenia treatments. Current research suggests that D-serine can improve outcomes for patients with schizophrenia, but it is accompanied by significant renal safety issues.2 Patients with schizophrenia also experience from cognitive impairments, and it was hoped that D-serine, which has shown positive effects on cognition in other contexts, would improve patient cognition without the renal risks.
The phase 2 trial was a double-blind, placebo-controlled study. It included 325 patients on antipsychotic medication. These participants were randomly selected to receive 1, 2, or 4-gram doses of CTP-692 once-daily, or a placebo. The trial took place over a 12-week period.1
At the end of the 12-week period, the patients showed no improvement on the Positive and Negative Syndrome Scale (PANSS) compared to baseline scores, and the trial was discontinued. The company has also decided to discontinue study of this compound.2
1. Concert Pharmaceuticals announces results from CTP-692 phase 2 trail in patients with schizophrenia. News release. Concert Pharmaceuticals Inc. February 1, 2021. Accessed February 17, 2021. https://ir.concertpharma.com/news-releases/news-release-details/concert-pharmaceuticals-announces-results-ctp-692-phase-2-trial
2. Concert Pharmaceuticals discontinues schizophrenia drug after trial failure. GlobalData Healthcare. February 3, 2021. February 17, 2021. https://www.clinicaltrialsarena.com/comment/concert-pharmaceuticals-schizophrenia-failure/