Marinus’ IV ganaxolone holds efficacy promise for PPD Phase II based on Sage's success but suicide watch recommended; molecular structure-led differentiation debated, experts say

12 Jul 2018

Marinus Pharmaceuticals’ (NASDAQ:MRNS) IV ganaxolone has experts generally optimistic for efficacy success in its Phase II trial for severe postpartum depression (PPD). Having competitor Sage Therapeutics’ (NASDAQ:SAGE) brexanolone, a similar IV-administered positive allosteric GABA-A receptor modulator, show positive Phase III efficacy as well as strong preclinical work in the drug class accounts for their optimism, they added.

However, some experts pointed out that the molecular structural difference between the two compounds could spell a different blood-brain barrier (BBB) penetrance. Ganaxolone might not be able to fully ride on the coattails of brexanolone’s success, they said.

Safety of IV ganaxolone is expected to be sound, similar to brexanolone’s Phase III trials, experts said. However, as the IV trial is enrolling severe PPD patients, they drew caution to suicide risks linked to GABA-A neurosteroids.

The 60-patient IV ganaxolone (NCT03228394) MAGNOLIA trial has top-line data expected in 3Q18, according to the company's 1Q18 earnings.

Analysts expect similar response rates between ganaxolone and brexanolone trials due to similar mechanism of action, noting Marinus’ decision to use the same study design as brexanolone’s, derisked the program and a similar adverse event profile is expected.

Analysts predict ganaxolone could reach sales of USD 609m by 2025, and Marinus has a market cap of USD 326.6m.

Marinus did not respond to a request for company comment.

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