Karuna keeps $6B sales forecast alive with blood pressure data on schizophrenia drug

Karuna Therapeutics has ticked another task off the to-do list for its blockbuster-in-waiting KarXT, posting phase 1b data that counter concerns about the effect of the schizophrenia therapy on blood pressure.

Questions about the effect of xanomeline, the active ingredient in KarXT, on blood pressure date back to the years before Eli Lilly shelved the candidate in the late 1990s. Karuna worked around the tolerability issues that halted Lilly’s project, specifically by formulating xanomeline with another molecule to prevent unwanted stimulation of peripheral receptors, but questions about blood pressure remained. 

Karuna shared data that could put the topic to bed after the market closed Thursday. The biotech looked at the effect of KarXT on 24-hour ambulatory blood pressure in adults with schizophrenia in a phase 1b trial. 

The eight-week, open-label trial tracked a 0.59-mmHg drop in 24-hour ambulatory systolic blood pressure, a result that fell short of the FDA’s definition of a clinically meaningful change. Analysts at Mizuho hailed the result as confirmation of their confidence in the cardiovascular (CV) safety profile of KarXT.

“KarXT appears to pose little, if any, worrisome CV risk. We’re pleased to see the positive phase 1 … data for KarXT, but as we had already assumed there to be no CV issue in the first place, it does little to change our already bullish view on the prospects of KarXT, for which, as a reminder, we model >$6bn in peak sales,” the analysts wrote in a note to investors. 

The data drop comes 11 months after Cerevel Therapeutics shared blood pressure data on its rival drug candidate, emraclidine. Cerevel ran the study in response to safety signals in an earlier trial that the FDA wanted clearing up and emerged with evidence that its molecule doesn’t increase blood pressure. With Karuna following suit, the Mizuho analysts said there is a “level playing field” for the rival treatments.

Karuna is leading the race to market. The biotech plans to add the blood pressure data to its filing for FDA approval. Management told the analysts that the update won’t delay the regulatory process, and, as such, Karuna is continuing to prepare to launch the product in the second half of next year. Cerevel aims to report data from its phase 2 program around the time KarXT comes to market.