Therapy Areas: Central Nervous System
Karuna Therapeutics Reports Positive Outcome of End-of-Phase 2 Meeting with the FDA for KarXT for the Treatment of Acute Psychosis in Patients with Schizophrenia
24 June 2020 - - One additional Phase 3 trial, along with previously completed Phase 2 trial, would be acceptable to support an efficacy claim for a New Drug Application filing
company on track to initiate Phase 3 program, including efficacy and open-label long-term safety trials, by the end of 2020

US-based clinical-stage biopharmaceutical company Karuna Therapeutics, Inc. (NASDAQ: KRTX) has planned next steps in the clinical programme evaluating KarXT for the treatment of acute psychosis in patients with schizophrenia following the completion of a successful End-of-Phase 2 meeting with the US Food and Drug Administration, the company said.

The outcome of the meeting supports the progression of KarXT into Phase 3 development. The company remains on track to initiate the Phase 3 program by the end of 2020.

The End-of-Phase 2 discussion was supported by pre-clinical and clinical efficacy data, including results from the previously completed positive Phase 2 trial evaluating KarXT in patients with schizophrenia.

In the Phase 2 trial, KarXT demonstrated robust efficacy on primary and key secondary outcome measures and was generally safe and well tolerated.

The company and FDA aligned on key elements of the Phase 3 program to support a New Drug Application filing, including the initiation of additional trials evaluating the efficacy and long-term safety of KarXT.

The formal minutes from the meeting confirmed that the completed Phase 2 trial, along with one successful Phase 3 efficacy and safety trial, and additional safety data to meet regulatory requirements, would be acceptable to support an NDA filing.

The company plans to initiate two five-week inpatient trials evaluating the efficacy and safety of KarXT for the treatment of acute psychosis in adults with schizophrenia. Both trials will share key characteristics of the completed Phase 2 trial, such as duration of treatment, patient population and primary outcome measure, among other aspects.

The first Phase 3 trial is expected to commence by the end of 2020. This five-week, 1: 1 randomised, flexible-dose, double-blind, placebo-controlled, inpatient trial will enroll approximately 250 adults in the US and evaluate the change in Positive and Negative Syndrome Scale total score at Week 5 of KarXT versus placebo as the primary outcome measure.

Details of the second efficacy trial will be finalised by the end of 2020, with initiation expected in the first half of 2021.

In conjunction with the short-term efficacy and safety trials, the company will collect long-term, open-label data to assess the safety and tolerability of KarXT in patients for up to one year in an outpatient setting.

Following the five-week, double-blind, inpatient phase in both efficacy trials, patients may enter a 52-week open-label safety and tolerability extension in which all patients will receive active treatment.

The company currently plans to also conduct a separate 52-week open-label trial evaluating the long-term safety of KarXT in adults with schizophrenia who have not been enrolled in the inpatient trials. This trial is expected to begin the first half of 2021.

Data from these trials will be used to support regulatory safety requirements for an NDA filing.

As previously shared, the company is well capitalized, with sufficient funding to support development activities for the NDA filing.

Additional details regarding the development plan, including anticipated completion timelines, will be shared in the second half of 2020.

KarXT, a proprietary oral modulator of muscarinic cholinergic receptors, is Karuna's lead product candidate that combines xanomeline, a novel muscarinic agonist, with trospium, an FDA-approved muscarinic antagonist that does not appreciably cross the blood-brain-barrier, to preferentially stimulate muscarinic receptors in the central nervous system.

This novel product candidate, if approved, has the potential to usher in a new treatment paradigm and dramatically impact patients with schizophrenia and other psychotic disorders by providing a differentiated mechanism of action relative to current D2 dopamine and serotonin receptor-targeting antipsychotic drugs.

Schizophrenia is a chronic, disabling disorder typically diagnosed in late teenage years or early adulthood.

Characterised by recurring episodes of psychosis requiring long-term treatment with antipsychotic drugs in most patients, it affects more than 21m people worldwide and 2.7m Americans (0.5% - 1.0% of US population).

At least one-third of patients with schizophrenia fail to respond to current treatments, with 74% of patients discontinuing within 18 months of initiation. People with schizophrenia have a 10- to 15-year reduction in life expectancy and struggle to maintain meaningful interpersonal relationships.

The World Health Organization ranks psychosis as the third-most disabling medical condition in the world.

Karuna is a clinical-stage biopharmaceutical company committed to developing and delivering first-in-class therapies with the potential to transform the lives of people with CNS disorders which remain among the most disabling and potentially fatal disorders worldwide.