[The use of psilocybin for treatment-resistant depression].

The hallucinogen psilocybin is a potential novel treatment for treatment-resistant depression (TRD). Our goal is to review current knowledge on psilocybin and its efficacy in TRD. Literature searches were done on PubMed, Web of Science and Google Scholar, references reviewed in identified articles and other articles found on the website of COMPASS Pathways. Psilocybin treatment consists usually of a single oral administration of 25 mg of psilocybin along with psychological support for 5-8 hours during the ensuing hallucinogenic trip. Common side-effects include headache, nausea, fatigue and insomnia. A systematic review has demonstrated significant antidepressant efficacy in certain groups and a double-blind randomized study found antidepressant efficacy of psilocybin comparable to the SSRI escitalopram. In the phase 2 study of COMPASS Pathways, the psilocybin-COMP360 treatment led to a rapid response and remission as early as three weeks following the treatment for around one third of participants. Recent studies have shown that psilocybin significantly decreases the severity of depressive symptoms and is generally well tolerated. Further research will reveal whether it will be granted a license to treat treatment-resistant depression in the near future. There remains an urgent need for novel treatments for those who do not respond to current antidepressant therapies.

Bacillus Calmette-Guérin vaccine induces a selective serotonin reuptake inhibitor (SSRI)-resistant depression like phenotype in mice.

Preclinical studies have shown that administration of Bacillus Calmette-Guérin (BCG) vaccine induces depression-like behaviors in mice; however, the effect of antidepressant drug treatment has not been reported earlier. In the present study, we induced depression-like behavior by administering BCG vaccine to BALB/c mice. BCG treatment produced robust serum sickness as shown by a decrease in body weight, reduced spontaneous locomotor activity and reduced voluntary wheel running activity. BCG treatment also elevated plasma IL6 and IFNγ levels and produced a marked activation of lung IDO activity. At a time point when serum sickness-related behaviors had fully recovered (i.e., day 14) BCG-treated mice showed a significant increase in immobility in the forced swim test (FST) and tail suspension test (TST) indicative of a pro-depressant phenotype. We observed significant increase in [(3)H]PK11195 binding in cortex and hippocampus regions of BGC-treated mice in comparison to saline-treated mice indicating prominent neuroinflammation. Pharmacological evaluation of FST behavior in BCG-treated mice demonstrated selective resistance to the selective serotonin reuptake inhibitors (SSRIs) fluoxetine and escitalopram. In contrast the tricyclic antidepressant imipramine, the dual serotonin/norepinephrine reuptake inhibitor (SNRI) duloxetine, and the dual dopamine/norepinephrine reuptake inhibitor (DNRI) nomifensine retained antidepressant efficacy in these mice. The lack of efficacy with acute treatment with SSRIs could not be explained either by differences in drug exposure or serotonin transporter (SERT) occupancy. Our results demonstrate that BCG-vaccine induced depression like behavior is selectively resistant to SSRIs and could potentially be employed to evaluate novel therapeutic agents being developed to treat SSRI-resistance in humans.

Safety concerns on the abuse potential of esketamine: Multidimensional analysis of a new anti-depressive drug on the market.

Prominent features of esketamine (e.g., similar mechanism of action as ketamine and target population) require to be vigilant regarding its benefits/risks balance and its risks of abuse in real-life settings. The aim of this study was to review all available pharmacological and clinical data to assess the abuse potential of esketamine shortly after its marketing. This multidimensional study is a quantitative and qualitative analysis of complementary data sources, ranging from preauthorization data (i.e., fundamental pharmacology and clinical trials) to real-life settings data (i.e., pharmacovigilance databases and web forums). According to esketamine pharmacology, its psychoactive effects play a role both in its therapeutic effect and its abuse potential. Only one out of the three short-term efficacy trials found a significant difference between esketamine and placebo in treatment-resistant depression. Beside adverse events that may be sought for abuse purpose (e.g., dissociation, sedation, euphoric mood, hallucination, feeling drunk, and derealization), clinical signs related to substance use disorder (e.g., tolerance, withdrawal syndrome, and drug dependence) and misuse (e.g., off-label use) were also identified in pharmacovigilance databases. Analysis of pharmacovigilance narratives and web forums showed that esketamine psychoactive effects are appreciated by some patients, while they are badly experienced by others. Strict compliance with the market authorization, close monitoring of patients by psychiatrists, and surveillance of any signs of misuse, abuse, or dependence must be part of any treatment course.

Efficacy and Safety of Subcutaneous Esketamine in the Treatment of Suicidality in Major Depressive Disorder and Bipolar Depression.

BACKGROUND AND OBJECTIVE: Affective disorders account for most cases of suicide. The pharmacological arsenal to treat suicidality is limited and available agents take too long to take effect. A large body of evidence shows optimal results of ketamine for treating depression, but the evidence concerning suicidality has not been fully described. We report the first real-world study of severely depressed patients presenting with suicide ideation who were treated with repeated administration of subcutaneous esketamine. METHODS: We analyzed data from 70 acutely depressed subjects diagnosed with resistant major depressive disorder or bipolar depression. Subjects were administered subcutaneous esketamine once a week for 6 weeks. The primary efficacy endpoint, the change from baseline to 24-h post-administration 6 in the item 10 Montgomery-Åsberg Depression Rating Scale score, was analyzed using a mixed-effects repeated-measures model. RESULTS: There were significant effects for time on item 10 Montgomery-Åsberg Depression Rating Scale scores (p < 0.0001) but not for a time × diagnosis interaction (p = 0.164) from baseline to the end of the study. Efficacy of esketamine did not differ between groups (major depressive disorder vs bipolar depression) at any timepoint. Statistical significance on suicidality scores was observed from 24 h after the first administration (p < 0.001), and a further reduction was observed with repeated administrations. Esketamine was safe and well tolerated. Mean heart rate remained stable during the administrations and the blood pressure increase was self-limited. CONCLUSIONS: Repeated subcutaneous esketamine administration had significant anti-suicidality effects in both major depressive disorder and bipolar groups, with a rapid onset of action and a good tolerability profile. Large randomized controlled trials are warranted to confirm these preliminary findings.

Characterization of the adrenocorticotrophic hormone - induced mouse model of resistance to antidepressant drug treatment.

Approximately 30-60% of patients treated with existing antidepressants fail to achieve remission of depressive symptoms leading to Treatment Resistant Depression (TRD). There is an urgent need to develop novel medications, which is highly limited by the non-availability of relevant animal models with good predictive validity. ACTH administration has been shown to result in the resistance to acute and chronic effects of imipramine. However, the pharmacology of the model and the mechanisms contributing to the resistance are not completely understood. Furthermore, it is not known whether the ACTH administered animals show signs of depression-like behavior. Accordingly, we characterized the behavioral profile and sensitivity to antidepressants in BALB/c mice treated with ACTH and to evaluate some of the mechanisms responsible for the behavioral effects. Daily treatment with ACTH for 14, 21 or 28days failed to produce a depression-like phenotype in the sucrose preference test, voluntary wheel running or FST. In contrast, the acute antidepressant response in the FST was no longer observed in ACTH mice treated with fluoxetine, imipramine, duloxetine or bupropion. Interestingly, the combination of fluoxetine and a low dose of olanzapine, or the combination of fluoxetine and bupropion was efficacious in ACTH treated mice. Further, the sensitivity to a GluN2B receptor antagonist, radiprodil was retained in the ACTH model. To understand the mechanism responsible for the diminished response in these mice, we evaluated p11 (S100A10) mRNA expression and 5-HT2A protein expression. p11 expression was decreased and 5-HT2A protein content increased in ACTH treated mice. In summary, this model may have utility for the identification of novel treatments for TRD.

Heading off depressive illness evolution and progression to treatment resistance.

Viewing recurrent depression as a potentially progressive illness may help transform treatment toward earlier, more consistent intervention and prevention. Evidence indicates that recurrent stressors, episodes of depression, and bouts of substance abuse can each show sensitization (increased reactivity upon repetition) and cross-sensitization to the others, and drive illness progression and treatment resistance. These long-lasting increases in pathological responsivity appear to be mediated by epigenetic mechanisms involving alterations in chemical marks placed on DNA and histories. These types of sensitization effects are amenable to clinical attempts at amelioration and prevention, and provide treatment targets and strategies to minimize the likelihood of illness progression to treatment resistance.

Rodent models of treatment-resistant depression.

Major depression is a prevalent and debilitating disorder and a substantial proportion of patients fail to reach remission following standard antidepressant pharmacological treatment. Limited efficacy with currently available antidepressant drugs highlights the need to develop more effective medications for treatment- resistant patients and emphasizes the importance of developing better preclinical models that focus on treatment- resistant populations. This review discusses methods to adapt and refine rodent behavioral models that are predictive of antidepressant efficacy to identify populations that show reduced responsiveness or are resistant to traditional antidepressants. Methods include separating antidepressant responders from non-responders, administering treatments that render animals resistant to traditional pharmacological treatments, and identifying genetic models that show antidepressant resistance. This review also examines pharmacological and non-pharmacological treatments regimes that have been effective in refractory patients and how some of these approaches have been used to validate animal models of treatment-resistant depression. The goals in developing rodent models of treatment-resistant depression are to understand the neurobiological mechanisms involved in antidepressant resistance and to develop valid models to test novel therapies that would be effective in patients that do not respond to traditional monoaminergic antidepressants.

Glucagon-like peptide-2 but not imipramine exhibits antidepressant-like effects in ACTH-treated mice.

We investigated the effectiveness of glucagon-like peptide-2 (GLP-2) against refractory depression in adrenocorticotropic hormone (ACTH)-treated mice as a model of tricyclic antidepressant (TCA)-resistant depression. Chronic ACTH treatment (0.45 mg/kg, s.c., 14 days) weakened the antidepressant-like effects of imipramine (20 mg/kg, i.p., 6 days) in the forced-swim test (FST). Conversely, GLP-2 (3 µg/mice, i.c.v., 6 days) induced antidepressant-like effects in the ACTH-treated mice in the FST. ACTH-treatment increased basal serum corticosterone levels, with an additional increase induced by the FST. Imipramine or GLP-2 had no effect on the basal corticosterone level, but GLP-2 attenuated the additional increase caused by the FST. Moreover, GLP-2 increased 5-HT levels, but not 5-HIAA. These results suggest that GLP-2 induced antidepressant-like effects under imipramine-resistant conditions through increase in 5-HT levels.