BI 425809
BI 425809 is a once-daily oral inhibitor of glycine transporter 1 (Gly-T1) specifically designed to alleviate cognitive impairment in people with schizophrenia. Underactivity by the NMDA (N-methyl-D-aspartic acid) receptor has been implicated in this cognitive dysfunction. Glycine is an NMDA cotransmitter. By blocking glutamatergic presynaptic and astrocyte reuptake of glycine, BI 425809 results in increased glycine levels in the synaptic cleft, facilitating neurotransmission, explained W. Wolfgang Fleischhacker, MD, president of the Medical University of Innsbruck (Austria), where he is also professor of psychiatry.
He presented the results of a phase 2, randomized, double-blind, 11-country study in which 509 adults with stable schizophrenia on no more than two antipsychotics were placed on add-on BI 425809 at 2, 5, 10, or 25 mg once daily or placebo for 12 weeks.
The primary endpoint was change from baseline to 12 weeks in the MATRICS (Measurement and Treatment Research to Improve Cognition in Schizophrenia) Consensus Cognitive Battery (MCCB) score. The results were strongly positive, with patients on the two top doses of BI 425809 – 10 and 25 mg/day – showing roughly a 2-point greater improvement in MCCB overall composite T-score compared with controls. Dr. Fleischhacker drew attention to the high study completion rates in the various study arms, ranging from a low of 91% to 97.6% in the 25 mg/day group.
“That’s a very nice but also an unusual finding for a trial of this length,” he observed.
The high study completion rate was a reflection of the drug’s high-level tolerability. Indeed, the rate of adverse events leading to treatment discontinuation was 0% with BI 425809 at 10 mg/day, 2.4% at 25 mg/day, and identical at 2.4% with placebo. No increase was found in psychiatric adverse events such as suicidal ideation or behavior.
“This is a first very promising result,” Dr. Fleischhacker concluded. “Basically, this is the first study that has really shown in a convincing fashion an effect of any novel compound on cognitive impairment in people suffering from schizophrenia.”
A separate ongoing phase 2 study is evaluating BI 425809 in combination with adjunctive computerized cognitive training in an effort to increase cognitive stimulation. The company is awaiting those study results before designing its phase 3 program.
Pimavanserin
It has been a busy year for pimavanserin, with both successes and disappointments in clinical trials addressing a range of psychotic disorders, according to Dragana Bugarski-Kirola, MD, MBA, MSc, vice president for clinical development at Acadia Pharmaceuticals in San Diego.
Dr. Dragana Bugarski-Kirola
At present, pimavanserin is Food and Drug Administration–approved as Nuplazid only for treatment of hallucinations and delusions associated with Parkinson’s disease psychosis. But in July 2020, on the strength of the positive results of the pivotal phase 3 HARMONY trial, Acadia filed an application with the FDA for marketing approval of the drug for treatment of dementia-related psychosis. In HARMONY, patients on placebo proved to be 2.8-fold more likely to experience a relapse of delusions or hallucinations than with pimavanserin.
A big recent disappointment was that pimavanserin failed to meet its primary endpoint in the phase 3 CLARITY I and CLARITY II trials as adjunctive therapy for major depressive disorder inadequately responsive to a selective serotonin reuptake inhibitor or serotonin norepinephrine reuptake inhibitor. The change in Hamilton Depression Rating Scale–17 scores in patients on the atypical antipsychotic wasn’t significantly better than with placebo. However, pimavanserin did outperform placebo on the secondary endpoint of Clinical Global Impression–Severity. Additional clinical trials of the drug for treatment of major depression are planned, Dr. Bugarski-Kirola said.