Karuna's KarXT reaches FDA with hopes for first new schizophrenia drug mechanism in decades

The fate of Karuna’s schizophrenia drug, KarXT, now rests with U.S. regulators after the company formally submitted its new drug application Thursday. 

The company had been projecting a third-quarter submission and, if approved, a launch in the second half of 2024. The filing is based on data from three placebo-controlled studies—two phase 3s and one phase 2. The company also has two long-term extension trials ongoing.

Karuna passed the primary endpoints in all three completed trials, with the first of the two phase 3 readouts in August 2022 showing that treated patients had a nearly 10-point drop on the Positive and Negative Syndrome Scale for Schizophrenia, a measure of severity for the condition. The readout of the second phase 3 trial earlier this year found that the drug-induced an 8.4-point reduction on the scale compared to placebo at week 5. 

One of Karuna’s top selling points has been the clinical performance paired with the lack of side effects that have plagued existing schizophrenia treatments, including drowsiness and weight gain. 

“KarXT, if approved, will represent the first novel pharmacological approach to treating schizophrenia in several decades and provide a new treatment option for patients and their physicians,” President and CEO Bill Meury said in a release. 

The market potential recently attracted Royalty Pharma, which coughed up $100 million to PureTech, owner of a Karuna, for a slice of future sales. Royalty stands to make 3% on the first $2 billion in sales and then a third of what’s made after that. PureTech also stands to earn an additional $400 million in milestone payments. 

The looming commercial effort will be aided by the $1.4 billion Karuna has in the bank, as of the end of June. The company is also looking to enlarge KarXT’s use, with ongoing trials testing it as a treatment for psychosis in Alzheimer’s patients and as an adjunctive treatment with another psychosis med, among other uses.