Positive trial results for schizophrenia drug, KarTX, from PureTech’s founded entity, Karuna Therapeutics

August 8, 2022 - 4 minutes
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Positive topline results from a phase 3 trial looking at the effect of a drug to treat schizophrenia were announced today (August 8).

Karuna Therapeutics Inc, the founded entity of PureTech Health plc, said results from the EMERGENT-2 trial evaluating the efficacy, safety and tolerability of KarXT (xanomeline-trospium) in adults met its primary endpoint and demonstrated statistically significant results.

The findings showed a clinically meaningful 9.6 reduction Positive and Negative Syndrome Scale (PANSS) – a scale for measuring schizophrenia – and KarXT also demonstrated an early and sustained statistically significant reduction of symptoms, as assessed by the total score, starting at week two and maintained such reduction throughout all timepoints on the trial.

Schizophrenia

The Phase 3 EMERGENT-2 trial is a double-blind, placebo-controlled, five-week, inpatient trial evaluating the efficacy, safety, and tolerability of lead investigational therapy, KarXT, as compared to placebo in adults with schizophrenia in the U.S.

The primary endpoint was change from baseline in PANSS total score symptom severity, of KarXT compared to placebo at week five.

A total of 252 adults (between the ages of 18-65 years) with a confirmed diagnosis of schizophrenia who were experiencing symptoms of psychosis enrolled in the trial.

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Steve Paul, chief executive officer at Karuna Therapeutics, said: “We are thrilled that these topline results from the phase 3 EMERGENT-2 trial confirm what was seen in our Phase 2 EMERGENT-1 trial and underscore the potential for KarXT, with its novel and unique mechanism of action, to redefine what successful treatment looks like for the 21 million people living with schizophrenia worldwide, and potentially usher in the first new class of medicine for these patients in more than 50 years.

“These results represent our second positive registrational trial. We look forward to continuing to gather long-term safety data to support our submission of a New Drug Application with the U.S. Food and Drug Administration (FDA) for KarXT as a treatment for schizophrenia, which we expect to occur in mid-2023.”

Mild symptoms

KarXT also met key secondary endpoints in the Phase 3 EMERGENT-2 trial, demonstrating a statistically significant reduction in both positive symptoms including a reduction in hallucinations or delusions and negative symptoms including difficulty enjoying life or withdrawal from others as measured by the PANSS negative and PANSS negative Marder factor subscales. Physically, the drug was fairly well tolerated with only mild symptoms including constipation, acid reflux, dizziness and diarrhea.

When schizophrenia treatment is discontinued, it can lead to impacts on health including relapse, hospitalization, and longer time to remission.

Rishi Kakar, chief scientific officer at Segal Trials who was also the lead investigator of the phase 3 EMERGENT-2 said: “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.

“These data build 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. This unique profile of KarXT has the potential to provide a new meaningful treatment option for our patients and their families beyond the current standard of care.”

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Royalty payments

As of August 3 this year (2022), PureTech owned approximately 5.5% of Karuna’s outstanding stock. A founder of Karuna and co-inventor of the KarXT program, PureTech has a right to royalty payments of 3% of net sales of any commercialized product covered by the license agreement, as well as 20% sublicense income covered by the license agreement. The license agreement covers key territories including the U.S., European Union, and Japan. PureTech is also eligible to receive certain milestone payments upon the achievement of regulatory approvals.

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