Brexanolone in Postpartum Depression: Post Hoc Analyses to Help Inform Clinical Decision-Making

Nonsedating anxiolytics

Anxiety disorders are the most prevalent psychiatric pathology with substantial cost to society, but the existing treatments are often inadequate. This has rekindled the interest in the GABAA-receptor (GABAAR) positive allosteric modulator (PAM) compounds, which have a long history in treatment of anxiety beginning with diazepam, chlordiazepoxide, and alprazolam. While the GABAAR PAMs possess remarkable anxiolytic efficacy, they have fallen out of favor due to a host of adverse effects including sedation, motor impairment, addictive potential and tolerance development. A substantial effort was thus devoted to the design of GABAAR PAMs as anxiolytics with reduced sedative liabilities. Several non-benzodiazepine (BZD) GABAAPAMs progressed to clinical trials (bretazenil, abecarnil, alpidem, and ocinaplon) with alpidem obtaining regulatory approval as anxiolytic, but later withdrawn from market due to hepatotoxicity. Advances in molecular biology gave birth to a host of subtype selective GABAAR-PAMs which suffered from signs of sedation and motor impairment and only three compounds progressed to proof-of-concept studies (TPA-023, AZD7325 and PF-06372865). TPA-023 was terminated due to toxicity in preclinical species while AZD7325 and PF-06372865 did not achieve efficacy endpoints in patients. We highlight a new compound, KRM-II-81, that is an imidazodiazepine selective for GABAAR containing α2/3 and β3 proteins. In preclinical studies KRM-II-81 produced anxiolytic-like effects but with minimal sedation, respiratory depression, and abuse liability. Thus, KRM-II-81 is a newly discovered, non- BZD anxiolytic compound, which targets a selective population of GABAAR for improved therapeutic gain and reduced side effects.

The role of stress in perinatal depression and anxiety - A systematic review

Perinatal depression (PND) and anxiety affect around 20% of women, but available pharmacotherapy is not sufficiently effective in 20-60% of them, indicating a need for better understanding of these diseases. Since stress is a significant risk factor for PND, the aim was to examine the role of biological, environmental and psychological stress in PND and anxiety through a systematic literature search. Overall 210 studies were included, among which numerous rodent studies showed that perinatal stress induced depressive-like and anxious behavior, which was associated with HPA-axis alterations and morphological brain changes. Human studies indicated that the relationship between cortisol and perinatal depression/anxiety was not as clear and with many contradictions, although social and psychological stress were clearly positively associated with PND. Finally, oxytocin, synthetic neuroactive steroid and n-3 PUFA diet have been identified as potentially beneficial in the therapy of PND and anxiety, worth to be investigated in the future.

Indirect comparisons of relative efficacy estimates of zuranolone and selective serotonin reuptake inhibitors for postpartum depression

AIMS

Estimate relative efficacy of zuranolone, a novel oral, Food and Drug Administration-approved treatment for postpartum depression (PPD) in adults vs. selective serotonin reuptake inhibitors (SSRIs) and combination therapies used for PPD in the United States.

MATERIALS AND METHODS

Randomized controlled trials (RCTs) for zuranolone and SSRIs, identified from systematic review, were used to construct evidence networks, linking via common comparator arms. Due to heterogeneity in placebo responses, matching-adjusted indirect comparison (MAIC) was applied, statistically weighting the zuranolone treatment arm of Phase 3 SKYLARK Study (NCT04442503) to the placebo arm of RCTs investigating SSRIs for PPD. MAIC outputs were applied in Bucher indirect treatment comparisons (ITCs) and network meta-analysis (NMA), using Edinburgh Postnatal Depression Scale (EPDS) and 17-item Hamilton Rating Scale for Depression (HAMD-17) change from baseline (CFB) on Days 3, 15, 28 (Month 1), 45, and last observation (Day 45, Week 12/18).

RESULTS

Larger EPDS CFB was observed among zuranolone-treated vs. SSRI-treated patients from Day 15 onward. Zuranolone-treated (vs. SSRI-treated) patients exhibited 4.22-point larger reduction in EPDS by Day 15 (95% confidence interval: -6.16, -2.28) and 7.43-point larger reduction at Day 45 (-9.84, -5.02) with Bucher ITC. NMA showed EPDS reduction for zuranolone was 4.52 (-6.40, -2.65) points larger than SSRIs by Day 15 and 7.16 (-9.47, -4.85) larger at Day 45. Lack of overlap between study populations substantially reduced effective sample size post-matching, making HAMD-17 CFB analysis infeasible.

LIMITATIONS

Limited population overlap between SKYLARK Study and RCTs reduced feasibility of undertaking HAMD-17 CFB ITCs and may introduce uncertainty to EPDS CFB ITC results.

CONCLUSIONS

Analysis showed zuranolone-treated patients with PPD experienced greater symptom improvement than SSRI-treated patients from Day 15 onward, with largest mean difference at Day 45. Adjusting for differences between placebo arms, zuranolone may be associated with greater PPD symptom improvement (measured by EPDS) vs. SSRIs.

Meta-Analyses of Genome-Wide Association Studies for Postpartum Depression

OBJECTIVE

Postpartum depression (PPD) is a common subtype of major depressive disorder (MDD) that is more heritable, yet is understudied in psychiatric genetics. The authors conducted meta-analyses of genome-wide association studies (GWASs) to investigate the genetic architecture of PPD.

METHOD

Meta-analyses were conducted on 18 cohorts of European ancestry (17,339 PPD cases and 53,426 controls), one cohort of East Asian ancestry (975 cases and 3,780 controls), and one cohort of African ancestry (456 cases and 1,255 controls), totaling 18,770 PPD cases and 58,461 controls. Post-GWAS analyses included 1) single-nucleotide polymorphism (SNP)-based heritability ([Formula: see text]), 2) genetic correlations between PPD and other phenotypes, and 3) enrichment of the PPD GWAS findings in 27 human tissues and 265 cell types from the mouse central and peripheral nervous system.

RESULTS

No SNP achieved genome-wide significance in the European or the trans-ancestry meta-analyses. The [Formula: see text] of PPD was 0.14 (SE=0.02). Significant genetic correlations were estimated for PPD with MDD, bipolar disorder, anxiety disorders, posttraumatic stress disorder, insomnia, age at menarche, and polycystic ovary syndrome. Cell-type enrichment analyses implicate inhibitory neurons in the thalamus and cholinergic neurons within septal nuclei of the hypothalamus, a pattern that differs from MDD.

CONCLUSIONS

While more samples are needed to reach genome-wide levels of significance, the results presented confirm PPD as a polygenic and heritable phenotype. There is also evidence that despite a high correlation with MDD, PPD may have unique genetic components. Cell enrichment results suggest GABAergic neurons, which converge on a common mechanism with the only medication approved by the U.S. Food and Drug Administration for PPD (brexanolone).

Understanding the mechanism of action and clinical effects of neuroactive steroids and GABAergic compounds in major depressive disorder

The pathophysiology of major depressive disorder (MDD) is thought to result from impaired connectivity between key brain networks. Gamma-aminobutyric acid (GABA) is the key inhibitory neurotransmitter in the brain, working primarily via GABAA receptors, with an important role in virtually all physiologic functions in the brain. Some neuroactive steroids (NASs) are positive allosteric modulators (PAMs) of GABAA receptors and potentiate phasic and tonic inhibitory responses via activation of synaptic and extrasynaptic GABAA receptors, respectively. This review first discusses preclinical and clinical data that support the association of depression with diverse defects in the GABAergic system of neurotransmission. Decreased levels of GABA and NASs have been observed in adults with depression compared with healthy controls, while treatment with antidepressants normalized the altered levels of GABA and NASs. Second, as there has been intense interest in treatment approaches for depression that target dysregulated GABAergic neurotransmission, we discuss NASs approved or currently in clinical development for the treatment of depression. Brexanolone, an intravenous NAS and a GABAA receptor PAM, is approved by the U.S. Food and Drug Administration for the treatment of postpartum depression (PPD) in patients 15 years and older. Other NASs include zuranolone, an investigational oral GABAA receptor PAM, and PH10, which acts on nasal chemosensory receptors; clinical data to date have shown improvement in depressive symptoms with these investigational NASs in adults with MDD or PPD. Finally, the review discusses how NAS GABAA receptor PAMs may potentially address the unmet need for novel and effective treatments with rapid and sustained antidepressant effects in patients with MDD.

Serum oxytocin and corticotropin-releasing hormone levels in the third trimester of pregnancy for predicting postpartum depression in Thai women

PURPOSE

This prospective observational study aimed to determine whether serum oxytocin (OT) or corticotrophin-releasing hormone (CRH) levels in the third trimester of pregnancy (or late pregnancy) could prospectively predict postpartum depression (PPD) at six weeks after childbirth.

METHODS

We measured late pregnancy OT and CRH levels in Thai women, assessed depression using the Edinburgh Postnatal Depression Scale (EPDS) and Patient Health Questionnaire-9 (PHQ-9), and collected mothers, labor, and newborn data. At six weeks postpartum, an EPDS score ≥ 11 or PHQ-9 score ≥ 10 was defined as the presence of PPD. Multivariable binary logistic regression analysis was performed to determine the predictors of PPD.

RESULTS

Of 200 participants, 136 (68.0%) were reassessed at six weeks postpartum, and 19 of them (14.0%) had PPD. Of the 19 participants with PPD, 9 met the EPDS criterion only, 3 met the PHQ-9 criterion only, and 7 met both criteria. OT levels were not significantly different between those with and without PPD (p = 0.35). CRH levels (aOR = 1.011, 95% CI = 1.001-1.023, p = 0.041), DASS-21 stress (aOR = 1.259, 95% CI = 1.132-1.400, p < 0.001), and APGAR at 1 min (aOR = 0.425, 95% CI = 0.240-0.752, p = 0.003) were significant predictors of PPD.

CONCLUSIONS

Only high CRH but not OT levels in late pregnancy may predict 6-week PPD. However, combining these CRH levels, late pregnancy stress, and newborn well-being immediately after birth seems to increase the accuracy of PPD prediction.

Effect of brexanolone on depressive symptoms, anxiety, and insomnia in women with postpartum depression: Pooled analyses from 3 double-blind, randomized, placebo-controlled clinical trials in the HUMMINGBIRD clinical program

BACKGROUND

Brexanolone is currently the only treatment specifically approved for postpartum depression (PPD) in the United States, based on the results from one Phase 2 and two Phase 3 double-blind, randomized, controlled trials in the HUMMINGBIRD program.

METHODS

Adults with PPD randomized to a 60-h infusion of brexanolone 90 μg/kg/h (BRX90) or placebo from the 3 trials were included in these post hoc analyses. Data on change from baseline (CFB) in the 17-item Hamilton Rating Scale for Depression (HAMD-17) total score, HAMD-17 Anxiety/Somatization and Insomnia subscales, and Clinical Global Impression of Improvement (CGI-I) scale were pooled. Response rates for HAMD-17 (≥50 % reduction from baseline) and CGI-I (score of 1 or 2) scales and time to response were analyzed.

RESULTS

Patients receiving BRX90 (n = 102) versus placebo (n = 107) achieved a more rapid HAMD-17 response (median, 24 vs 36 h; p = 0.0265), with an Hour-60 cumulative response rate of 81.4 % versus 67.3 %; results were similar for time to CGI-I response (median, 24 vs 36 h; p = 0.0058), with an Hour-60 cumulative response rate of 81.4 % versus 61.7 %. CFB in HAMD-17 Anxiety/Somatization and Insomnia subscales also favored BRX90 versus placebo, starting at Hour 24 through Day 30 (all p < 0.05), and response rates for both subscales were higher with BRX90.

LIMITATIONS

The study was not powered to assess exploratory outcomes.

CONCLUSIONS

Brexanolone was associated with rapid improvement in depressive symptoms and symptoms of anxiety and insomnia compared with placebo in women with PPD. These data continue to support the use of brexanolone to treat adults with PPD.

Investigational Drugs for the Treatment of Depression (Part 1): Monoaminergic, Orexinergic, GABA-Ergic, and Anti-Inflammatory Agents

Therapeutic management of depression has currently important limitations, and its low efficacy is reflected in high rates of non-response even after multiple trials of antidepressants. Almost two-thirds of the patients diagnosed with major depression who received a 4–6 weeks trial of antidepressant could not reach remission, and more than 30% of these patients are considered treatment-resistant. In bipolar depression, the situation is also discouraging if we analyze the high suicide rate, the risk for the treatment-emergent affective switch when antidepressants are added, the high rate of treatment resistance (up to 25%), and the severe functional impairments associated with these episodes. Therefore, new therapeutic agents are needed, as well as new pathogenetic models for depression. The vast majority of the currently approved antidepressants are based on the monoamine hypothesis, although new drugs exploiting different neurotransmitter pathways have been recently approved by FDA. Brexanolone, an allopregnanolone analog, is an example of such new antidepressants, and its approval for post-partum depression inspired the search for a new generation of neurosteroids and GABA-ergic modulators, with an easier way of administration and superior tolerability profile. Orexin receptors antagonists are also extensively studied for different psychiatric disorders, depression included, in phase II trials. Antiinflammatory drugs, both cyclo-oxygenase 2 inhibitors and biological therapy, are investigated in patients with depressive disorders based on the proven correlation between inflammation and mood disorders in preclinical and clinical studies. Also, a new generation of monoamine-based investigational drugs is explored, ranging from triple reuptake inhibitors to atypical antipsychotics, in patients with major depression. In conclusion, there is hope for new treatments in uni- and bipolar depression, as it became clear, after almost seven decades, that new pathogenetic pathways should be targeted to increase these patients’ response rate.

GABAkines - Advances in the discovery, development, and commercialization of positive allosteric modulators of GABAA receptors

Positive allosteric modulators of γ-aminobutyric acid-A (GABA_A) receptors or GABAkines have been widely used medicines for over 70 years for anxiety, epilepsy, sleep, and other disorders. Traditional GABAkines like diazepam have safety and tolerability concerns that include sedation, motor-impairment, respiratory depression, tolerance and dependence. Multiple GABAkines have entered clinical development but the issue of side-effects has not been fully solved. The compounds that are presently being developed and commercialized include several neuroactive steroids (an allopregnanolone formulation (brexanolone), an allopregnanolone prodrug (LYT-300), Sage-324, zuranolone, and ganaxolone), the α2/3-preferring GABAkine, KRM-II-81, and the α2/3/5-preferring GABAkine PF-06372865 (darigabat). The neuroactive steroids are in clinical development for post-partum depression, intractable epilepsy, tremor, status epilepticus, and genetic epilepsy disorders. Darigabat is in development for epilepsy and anxiety. The imidazodiazepine, KRM-II-81 is efficacious in animal models for the treatment of epilepsy and post-traumatic epilepsy, acute and chronic pain, as well as anxiety and depression. The efficacy of KRM-II-81 in models of pharmacoresistant epilepsy, preventing the development of seizure sensitization, and in brain tissue of intractable epileptic patients bodes well for improved therapeutics. Medicinal chemistry efforts are also ongoing to identify novel and improved GABAkines. The data document gaps in our understanding of the molecular pharmacology of GABAkines that drive differential pharmacological profiles, but emphasize advancements in the ability to successfully utilize GABA_A receptor potentiation for therapeutic gain in neurology and psychiatry.

Development of neuroactive steroids for the treatment of postpartum depression

Postpartum depression (PPD) is a common major depressive episode surrounding childbirth, with estimated rates ranging from 5.5% to 23.5% of all live births across Europe and the USA based on the presence of key symptoms. PPD has been associated with significant impairments in both maternal functioning and mother-infant attachment, and these impairments can have lasting effects on the emotional and cognitive development of children. Although the precise pathophysiology of PPD is unknown, preclinical findings suggest that large fluctuations in neurosteroid hormone levels can induce physiological plasticity in the expression of functional GABA_A receptors during pregnancy and the postpartum period, and that deficits in this plasticity may underpin a biological mechanism that contributes to the manifestation of depressive symptoms. Here, we review the controlled clinical trials to date that have assessed the efficacy of pharmacological treatments for PPD, including oestradiol, selective serotonin reuptake inhibitors, brexanolone (an iv formulation of allopregnanolone) and an investigational neuroactive steroid and GABA_A positive allosteric modulator, zuranolone. Coupled with the GABAergic deficits implicated in major depressive disorder, these findings highlight not only the potential role of GABA_A receptor plasticity in the pathophysiology of PPD, but also the novel therapeutic approach of using positive allosteric modulators targeting GABAergic transmission to treat women affected by PPD.

The imidazodiazepine, KRM-II-81: An example of a newly emerging generation of GABAkines for neurological and psychiatric disorders

GABAkines, or positive allosteric modulators of γ-aminobutyric acid-A (GABA_A) receptors, are used for the treatment of anxiety, epilepsy, sleep, and other disorders. The search for improved GABAkines, with reduced safety liabilities (e.g., dependence) or side-effect profiles (e.g., sedation) constituted multiple discovery and development campaigns that involved a multitude of strategies over the past century. Due to the general lack of success in the development of new GABAkines, there had been a decades-long draught in bringing new GABAkines to market. Recently, however, there has been a resurgence of efforts to bring GABAkines to patients, the FDA approval of the neuroactive steroid brexanolone for post-partum depression in 2019 being the first. Other neuroactive steroids are in various stages of clinical development (ganaxolone, zuranolone, LYT-300, Sage-324, PRAX 114, and ETX-155). These GABAkines and non-steroid compounds (GRX-917, a TSPO binding site ligand), darigabat (CVL-865), an α2/3/5-preferring GABAkine, SAN711, an α3-preferring GABAkine, and the α2/3-preferring GABAkine, KRM-II-81, bring new therapeutic promise to this highly utilized medicinal target in neurology and psychiatry. Herein, we also discuss possible conditions that have enabled the transition to a new age of GABAkines. We highlight the pharmacology of KRM-II-81 that has the most preclinical data reported. KRM-II-81 is the lead compound in a new series of orally bioavailable imidazodiazepines entering IND-enabling safety studies. KRM-II-81 has a preclinical profile predicting efficacy against pharmacoresistant epilepsies, traumatic brain injury, and neuropathic pain. KRM-II-81 also produces anxiolytic- and antidepressant-like effects in rodent models. Other key features of the pharmacology of this compound are its low sedation rate, lack of tolerance development, and the ability to prevent the development of seizure sensitization.