Response Pharmaceuticals has met the primary endpoint of a Phase Ib clinical trial of a first-in-class inhibitor, RDX-002, for the treatment of antipsychotic-induced weight gain.

Full results from the two-week, open-label study (NCT05857566) continue to be analysed however interim data shows RDX-002 was generally well tolerated, and the study met its primary objective. Trial results and Phase II development plans should be completed in September 2023.

How the Phase Ib trial was conducted

The Phase Ib trial involved antipsychotic-naïve, healthy patients who were initially treated with olanzapine, a widely used antipsychotic with a well-documented side effect of weight gain, for one week. One cohort then continued to receive olanzapine alone while the second cohort received RDX-002 and olanzapine.

The primary endpoint was to measure the effect of RDX-002 on postprandial triglyceride levels. The results will be used to direct the design of a Phase II study where RDX-002 will be co-administered with olanzapine in patients with schizophrenia.

Response Pharmaceuticals' chief medical officer Bill Sasiela said: "This serious side effect is commonly observed with multiple antipsychotic drugs that treat debilitating mental diseases and often results in non-compliance with treatment.

"Intestinal MTP is an exciting therapeutic target with the potential to address unmet needs in a wide range of metabolic indications. We are extremely pleased that we have met our primary objective in this first trial and are working to complete analysis of the complete data package."

What is RDX-002?

RDX-002 is under development for the treatment of drug-induced weight gain. The drug candidate is administered orally. It is a novel small molecule that acts by targeting intestinal microsomal triglyceride transfer protein (iMTP).

iMTP is a protein believed to be a key driver of weight gain and metabolic dysregulation in patients treated with antipsychotic drugs for schizophrenia, bipolar disorder, and major depressive disorder.