Sage and Biogen’s depression drug quickly relieved symptoms of depression in a phase 3 trial, but the readout did little to quell concerns about the med’s durability of effect, an issue that investors and analysts have been concerned about, according to a blog published today on Fierce Biotech.

In the phase 3 trial called Coral, zuranolone met the primary endpoint, which was depression symptom improvement at day 3, and the drug was administered along with standard-of-care medications. Sage is positioning the drug as a fast-acting option for patients who begin depression treatment, as the usual medications can take up to a month to become active.

Sage tweaked the endpoint for the Coral study in November 2021 to look at day 3 rather than day 15. RBC Capital Markets analysts at the time said the change could help the company avoid a miss on the original goal and therefore prevent confusion once the FDA gets hold of an application for the therapy in major depressive disorder (MDD). But the change would not reveal anything about zuranolone’s durability

Now, with the results in hand, RBC said the change was “indeed prudent.” But overall, the firm called the data mixed. On the one hand, the topline results showed zuranolone’s rapid-acting effect and that it could play a role in higher-risk patients, particularly those at risk of suicide.

But the durability question is still unanswered after Coral.