BARCELONA – Brexanolone injection provided rapid and durable improvement in postpartum depression in an integrated analysis of three pivotal randomized trials collectively known as the Hummingbird trials, Christine Clemson, PhD, reported at the annual congress of the European College of Neuropsychopharmacology.
This was accomplished with a favorable safety experience. The most common treatment-emergent adverse events – dizziness and sleepiness – were roughly twice as common as with placebo in the 247-patient Hummingbird safety analysis.
On Dec. 19, 2018, the agency is expected to respond to SAGE Therapeutics’s application for marketing approval of intravenous brexanolone given as a continuous 60-hour infusion at 90 mcg/kg per hour, according to Dr. Clemson, senior medical director at Cambridge, Mass.–based SAGE Therapeutics, which is developing the therapy.
Brexanolone is a proprietary IV formulation of allopregnanolone, a metabolite of progesterone. The drug’s mechanism of action involves modulation of the neurotransmitter gamma-aminobutyric acid (GABA). The drug binds to both synaptic and extra-synaptic GABA A receptors, thereby increasing receptor functionality.
The decision to target GABA as a novel therapeutic strategy in PPD was based upon translational studies demonstrating that GABA is the chief neuroinhibitory mechanism in the brain, and its actions are mediated mainly by GABA A receptors. Brexanolone’s efficacy is consistent with a theory that the pathogenesis of PPD involves triggers such as inflammation, hormonal fluctuations, or chronic stress, which in some women cause GABA hypofunction, both at the receptors and in terms of tissue GABA levels. This, in turn, leads to an overactive HPA axis and dysregulated neural networks, with resultant PPD, Dr. Clemson explained.
The three Hummingbird clinical trials were double blind, randomized, and placebo controlled. Two were restricted to women with severe PPD. The third and largest focused on moderately affected patients as defined by a baseline Hamilton Depression Scale for Depression () score of 20-25.
The efficacy analysis included 207 patients who received brexanolone at 90 mcg/kg per hour or placebo for 60 hours in an inpatient setting and were followed for 30 days. The primary endpoint was the change in HAM-D total score from baseline to 60 hours. The mean 17-point reduction in the active treatment arm was significantly better than the 12.8-point decrease with placebo. The between-group difference was significant within the first 24 hours and remained so at all time points out to the study’s end at day 30. There was no individual item on the HAM-D in which the drug performed worse than placebo, and there were many in which brexanolone performed significantly better, including depressed mood, anxiety, insomnia, and feelings of guilt.
In terms of the rigorous secondary endpoint of HAM-D remission as defined by a total score of 7 or less, the brexanolone injection significantly outperformed placebo at every time point except for day 30.
There was a 2% rate of serious adverse events in both study arms. These included suicidal ideation, an intentional overdose attempt post discharge, altered state of consciousness, and syncope.
A vastly more convenient once-daily oral formulation of brexanolone is now in phase 3 clinical trials for PPD and major depressive disorder, and in phase 2 for insomnia and bipolar depression.
Elsewhere at the ECNP congress, other investigators from Sage Therapeutics presented for the first time the outcomes of an 89-patient, randomized, double-blind, multicenter, placebo-controlled, phase 2 clinical trial offor treatment of major depressive disorder.
Participants received a nightly 30-mg dose of the drug or placebo for 2 weeks, with a primary study endpoint being the change in HAM-D total score from baseline to day 15. Patients on the oral GABA A receptor positive modulator averaged a 17.4-point improvement, significantly better than the 10.3-point spread in placebo-treated controls. A statistically significant between-group difference was noted on days 2 through 28. HAM-D remission at day 15 was documented in 64% of the oral brexanolone group, compared with 26% of controls.
Those improvements in depression were accompanied by significant gains in numerous domains of health-related quality of life as assessed via the. Indeed, day 15 health-related quality of life scores in the oral brexanolone group approached normative values for the general population.
The studies were funded by SAGE Therapeutics.