Phase III Success Signals Early Payoff for BMS's $14B Karuna Acquisition

Bristol Myers Squibb recently revealed interim findings from the Phase III EMERGENT-4 study, highlighting the efficacy of the experimental antipsychotic KarXT in treating schizophrenia. The study, which was open-label, showed that KarXT, a combination of xanomeline and trospium, led to significant symptom improvement that was sustained over time.

The data, unveiled at the Schizophrenia International Research Society's annual gathering, indicated that over three-quarters of the patients treated with KarXT experienced at least a 30% reduction in their symptoms after a year, as measured by the Positive and Negative Syndrome Scale (PANSS). The average PANSS score dropped by 33.3 points from the start of the study.

In addition to the PANSS score improvements, KarXT recipients also saw a 1.7-point increase in the Clinical Global Impression-Severity score, reflecting a shift from severe illness at the outset to a milder state after one year. Roland Chen, Bristol Myers Squibb's senior vice president, emphasized in a statement that the EMERGENT-4 results further confirm KarXT's consistent symptom reduction over a 52-week period in an outpatient environment.

Chen also announced that more data from the EMERGENT program would be shared later in the year and that discussions with the FDA regarding KarXT's ongoing review would continue.

KarXT, initially developed by Karuna Therapeutics, is a novel muscarinic antipsychotic that differs from traditional schizophrenia treatments by not blocking dopamine receptors. Instead, it activates M1 and M4 Muscarinic acetylcholine receptors, which is believed to lead to improvements in both the positive and negative symptoms of schizophrenia.

Bristol Myers Squibb's acquisition of Karuna for $14 billion in December 2023 brought KarXT into its portfolio. The drug is currently under FDA review, with a Prescription Drug User Fee Act (PDUFA) date set for September 2024.

At the SIRS annual meeting, Bristol Myers Squibb also presented long-term safety data for KarXT from the EMERGENT clinical development program. The data from EMERGENT-4 and EMERGENT-5 studies showed that KarXT was generally well-tolerated and had a safety profile in line with previous trials.

Furthermore, KarXT had a positive impact on patients' weight and metabolic health, with most experiencing weight loss after 52 weeks of treatment. However, it did not significantly alter total cholesterol, triglyceride, or HbA1c levels.

Chen described the long-term data as "extremely encouraging," suggesting that KarXT does not come with "burdensome side effects" even after extended use. He noted that the drug's safety and tolerability profile could make it a valuable new option for individuals living with schizophrenia.