Karuna Therapeutics scores phase 3 win for schizophrenia therapy KarXT

Karuna Therapeutics has unveiled positive topline results from its phase 3 EMERGENT-2 trial evaluating the efficacy, safety, and tolerability of its lead investigational therapy, KarXT (xanomeline-trospium), in adults with schizophrenia.

KarXT is an oral, investigational muscarinic agonist comprised of the muscarinic agonist xanomeline and muscarinic antagonist trospium, developed for treating psychiatric and neurological conditions, including schizophrenia and psychosis in Alzheimer’s disease.

The double-blind, placebo-controlled trial involved 182 adults with a confirmed diagnosis of schizophrenia who were randomised 1:1 to receive a twice-daily, flexible dose of KarXT or placebo for five weeks. Results from the study showed that KarXT demonstrated a statistically significant and clinically meaningful 9.6-point reduction in the Positive and Negative Syndrome Scale (PANSS) total score compared to placebo at week five – a primary endpoint of the study.

Furthermore, the trial achieved its secondary endpoint, demonstrating a statistically significant reduction in both positive and negative symptoms at week five, and showed an early and sustained reduction of symptoms starting at week two and maintained throughout the trial.

Schizophrenia is a chronic condition characterised by positive symptoms, for example, hallucinations and delusions, negative symptoms (such as difficulty enjoying life and withdrawal from others), and cognitive impairment.

Antipsychotic medications are commonly used to treat the condition; however, many patients continue to experience limited efficacy or problematic side effects while taking such treatments. Consequently, up to 74% of patients discontinue medication before 18 months, a decision that can seriously impact their general health.

Unlike traditional antipsychotics, which typically work by inhibiting dopamine and serotonin receptors, KarXT’s dual mechanism does not rely on the dopaminergic or serotonergic pathway to treat symptoms of serious mental illness.

According to Karuna, this novel mechanism has the potential to provide a differentiated therapy and, if approved, to beneficially impact the lives of millions of people with serious mental illness.

“Despite the number of available treatment options, there continues to be a tremendous unmet need in the treatment of schizophrenia, placing an immense burden on both patients and their caregivers,” said Rishi Kakar, MD, chief scientific officer, Segal Trials and lead investigator of the Phase 3 EMERGENT-2 trial.

“This data builds on the growing body of clinical evidence supporting the potential of KarXT as a new and differentiated approach for schizophrenia, demonstrating notable improvements across both positive and negative symptoms, while not being associated with common problematic side-effects of current therapies, such as weight gain, sedation, and movement disorders.”

Boosted by the positive results from Karuna Therapeutics plans to use data from its EMERGENT programme to support the submission of a New Drug Application with the US FDA for KarXT as a treatment for schizophrenia.

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