Shares of Sage Therapeutics (SAGE -0.78%) tumbled Thursday morning after the company reported slower-than-expected revenue growth for its drug for post-partum depression (PPD), and didn't have anything new to say about its stalled effort to bring its drug for major depressive disorder (MDD) to market.

Revenue from sales of PPD drug Zulresso, which launched last summer, came in at $1.96 million, when analysts were expecting $3.68 million. The company said that it now expects that most sites that will administer the drug will take over nine months to become treatment-ready, and some large hospitals and healthcare systems will take a year or more. Previously, the company had said it expected that it would take six to nine months for sites to become treatment-ready.

Investors are focused on the prospects for Sage's MDD candidate, Zuranolone (SAGE-217), but the company couldn't provide any new reasons for them to be optimistic about its chances of approval. The company's share price was cut in half in December after the potential blockbuster drug failed to hit its primary endpoint in a pivotal trial.

Silhouette of a depressed man.

Image source: Getty Images.

Sage's strategy is to amend three other phase 3 studies to test Zuranolone in higher doses in hopes of getting better results, but when questioned on the conference call, company officials had to admit that they had no real data to prove this would work. Sage expects to meet with the U.S. Food and Drug Administration this quarter to review the drug's path forward.

With a slower sales ramp up for Zulresso ahead, as well as an uncertain future for Zuranolone in the face of potential competition from Axsome Therapeutics (AXSM -1.36%) -- 2019's top-performing biotech stock due to successful clinical results from its own MDD drug -- investors were hoping for better news from Sage Thursday.