Marinus Pharmaceuticals says its treatment for postpartum depression (PPD) is showing encouraging results in a mid-stage study—enough to continue clinical development. But it’s unclear whether the results are statistically significant or enough to make the drug competitive against a Sage Therapeutics drug now awaiting an FDA decision for the same condition.
Marinus (NASDAQ: MRNS) said Monday that 75 percent of patients taking its intravenous drug, ganaxolone, showed a reduction in scores on the Hamilton Depression Scale after 34 days of treatment. The company added that 50 percent of patients showed remission from depression.
Radnor, PA-based Marinus is trying to catch up to Sage Therapeutics (NASDAQ: SAGE) in the race to bring the first postpartum depression (PPD) drug to the market. A little more than a year ago, Cambridge, MA-based Sage reported that its IV drug, brexanolone, succeeded in reducing depression compared to a placebo in two Phase 3 studies. The drug, which requires a 60-hour infusion, has, however, led to an abrupt loss of consciousness in some patients. Despite that unexplained side effect, an FDA advisory panel voted last month to recommend approval of brexanolone. The FDA recently extended its deadline for a decision on the Sage drug by three months, to March 19.
The Marinus drug was developed to modulate a receptor for GABA, a neurotransmitter in the brain. The company has been testing an IV version of this drug in a 60-patient dose-escalation Phase 2 study. Of the three doses, Marinus said that the strongest results were observed with the highest dose, which was given to 10 patients. At that dose, patients had an average 16.9 point reduction in depression scores after 60 hours of treatment, compared to a 4.2 point reduction in the placebo group. Measured after 34 days of treatment, the treated patients showed an average 15.7 point reduction in the depression scale compared to a 4.1 point change for the placebo.
The most common side effects were sedation and dizziness. That’s consistent with earlier tests of the drug, and also matches the side effect profile of the Sage drug.
But Stifel analyst Paul Matteis contends that it’s hard to view the Marinus IV drug as a competitor to Sage’s. In a research note, he wrote that Marinus did not provide enough information to show that its results were statistically significant, and also the data were only from a Phase 2 trial. “Generally speaking in depression, effect sizes shrink when one goes from phase II to phase III,” he wrote.
Still, Marinus could offer a competitive challenge to Sage with an oral drug that would be more convenient for patients. The company said a Phase 2 study testing a capsule version of its PPD drug is continuing. In the most recently treated group of patients from this trial, consisting of 18 patients, the company said the reduction in depression scores averaged 13.2 points after 28 days, and 15.7 points at day 36. But Marinus also noted that enrollment is ongoing and not all patients in the study have reached day 28.
Matteis wrote that the Marinus data for its capsule so far offer “plausible but not at all unequivocal evidence of drug activity.”