Disappointing outcome of bitopertin treatment for negative symptoms in schizophrenia

Reports new study in Biological Psychiatry

Philadelphia, PA, June 14, 2017

Two new phase III clinical trials investigating the efficacy and safety of bitopertin, a glycine uptake inhibitor considered to be a promising new add-on therapy for treating negative symptoms in schizophrenia, failed to show a benefit of the drug over placebo. The findings throw a wrench in the hopeful efforts to find a treatment for negative symptoms of schizophrenia, which account for some of the most debilitating aspects of the disorder and are associated with poorer outcomes in patients.

The outcomes of the trials were published in a paper in Biological Psychiatry by Dr. Dragana Bugarski-Kirola of Roche Pharmaceuticals in Basal, Switzerland. The randomized, double-blind, parallel-group, placebo-controlled studies were a collaboration between Roche and several research institutions around the world.

“We are back to the drawing board,” said Dr. John Krystal, Editor of Biological Psychiatry.

Previous attempts to treat negative symptoms have employed drugs, hormones, and brain stimulation, but none have provided the desired clinical benefit. Research fingering glutamate signaling in negative symptoms has spurred the idea of targeting glutamate receptors, but this approach has failed in large trials. Glycine reuptake inhibitors have been considered a promising alterative to enhance glutamatergic signaling, and a small proof-of-concept study showed that bitopertin, which selectively inhibits glycine transporter type 1 (GlyT-1), reduced negative symptoms in stable patients with schizophrenia.

“GlyT-1 inhibition was one of the most promising approaches to the treatment of schizophrenia,” said Krystal. “While it still may be possible to optimize GlyT-1 inhibition as a treatment, these negative results suggest GlyT-1 inhibition is not a broadly effective or optimal therapeutic strategy to enhance NMDA glutamate receptor function in schizophrenia.”

The trials were carried out over 201 sites, with each trial including about 600 patients with persistent, predominant negative symptoms of schizophrenia. Patients treated with antipsychotics were administered placebo or bitopertin (5, 10, or 20 mg) for 24 weeks. The doses were chosen to test the minimal effective dose (5 mg) and the dose with a predicted maximal effect (20 mg).

All participants showed some improvement in the negative symptom factor score, but there were no differences between placebo or bitopertin treatment at 24 weeks. No differences were observed in other symptom domains of schizophrenia either. All three doses of bitopertin were well-tolerated and generally safe over the course of the study.

According to Bugarski-Kirola, tackling complex clinical, regulatory and commercial development processes, reliability and quality control was a daunting task when dealing with over 200 study sites across different cultures. “We demonstrated that quality can be accomplished across the sites, but consider a different approach to the design,” she said, explaining that rather than treating negative symptom patients as one homogenous target, priority should be given to exploring the usefulness of novel mechanisms in separate negative symptom domains to better define the target population and maximize the chance of success before launching large phase III trials.

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Notes for editors
The article is "Bitopertin in Negative Symptoms of Schizophrenia—Results From the Phase III FlashLyte and DayLyte Studies," by Dragana Bugarski-Kirola, Thomas Blaettler, Celso Arango, Wolfgang W. Fleischhacker, George Garibaldi, Alice Wang, Mark Dixon, Rodrigo A. Bressan, Henry Nasrallah, Stephen Lawrie, Julie Napieralski, Tania Ochi-Lohmann, Carol Reid, and Stephen R. Marder (http://dx.doi.org/10.1016/j.biopsych.2016.11.014). It appears in Biological Psychiatry, volume 82, issue 1 (July 2017), published by Elsevier.

Copies of this paper are available to credentialed journalists upon request; please contact Rhiannon Bugno at Biol.Psych@UTSouthwestern.edu or +1 214 648 0880. Journalists wishing to interview the authors may contact Dragana Bugarski-Kirola, M.D., at dragana.bugarski.kirola@gmail.com.

The authors’ affiliations and disclosures of financial and conflicts of interests are available in the article.

John H. Krystal, M.D., is Chairman of the Department of Psychiatry at the Yale University School of Medicine, Chief of Psychiatry at Yale-New Haven Hospital, and a research psychiatrist at the VA Connecticut Healthcare System. His disclosures of financial and conflicts of interests are available here.

About Biological Psychiatry
Biological Psychiatry is the official journal of the Society of Biological Psychiatry, whose purpose is to promote excellence in scientific research and education in fields that investigate the nature, causes, mechanisms and treatments of disorders of thought, emotion, or behavior. In accord with this mission, this peer-reviewed, rapid-publication, international journal publishes both basic and clinical contributions from all disciplines and research areas relevant to the pathophysiology and treatment of major psychiatric disorders.

The journal publishes novel results of original research which represent an important new lead or significant impact on the field, particularly those addressing genetic and environmental risk factors, neural circuitry and neurochemistry, and important new therapeutic approaches. Reviews and commentaries that focus on topics of current research and interest are also encouraged.

Biological Psychiatry is one of the most selective and highly cited journals in the field of psychiatric neuroscience. It is ranked 5th out of 140 Psychiatry titles and 11th out of 256 Neurosciences titles in the Journal Citations Reports® published by Thomson Reuters. The 2015 Impact Factor score for Biological Psychiatry is 11.212.

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Media contact
Rhiannon Bugno
Editorial Office, Biological Psychiatry
+1 214 648 0880
Biol.Psych@UTSouthwestern.edu