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Can Target Engagement Studies Miss Their Targets and Mislead Drug Development?
... Despite its high incidence and prevalence, clinical symptoms are the primary basis for a diagnosis of MDD, and there is little evidence at the molecular level [2]. In addition, current drug therapy for MDD is not effective, with only 27% of patients in remission after the first treatment and 67% in remission after four complete treatments [3]. These considerations imply that the currently available antidepressants that target the monoaminergic system are insufficient for therapeutic use. ...
Background:
Major depressive disorder (MDD) is the most frequent reason of disabled people in the world, as reported by the World Health Organization. However, the diagnosis of MDD is mainly based on clinical symptoms.
Case summary:
The clinical, genetic, and molecular characteristics of two Chinese families with MDD are described in this study. There were variable ages of onset and severity in depression among the families. Both Chinese families had a very low pre-valence of MDD. The mitochondrial genomes of these pedigrees were sequenced and indicated a homoplasmic T3394C (Y30H) mutation, with the polymorphism located at a highly conserved tyrosine at position 30 of ND1. The analysis also revealed unique sets of mitochondrial DNA (mtDNA) polymorphisms orig-inating from haplogroups M9a3 and M9a.
Conclusion:
This finding of the T3394C mutation in two unrelated depressed patients provides strong evidence that this mutation may have a part in the etiology of MDD. However, In these two Chinese families having the T3394C mutation, no functional mtDNA mutation was observed. Therefore, T3394C mutations are related with MDD, and the phenotypic manifestation of these mutations may be affected by changes in nuclear genes or environmental factors.
... Further, current first-line pharmacological treatments for MDD are inadequate, as only 27% of patients remit after an initial trial and only 67% after four full trials [3]. Evaluation of new therapeutic approaches should include specific biomarkers that objectively identify the involvement of pathogenic mechanisms underlying MDD and may reveal relevant molecular targets [4,5]. ...
To characterize neuronal mitochondrial abnormalities in major depressive disorder (MDD), functional mitochondrial proteins (MPs) extracted from enriched plasma neuron-derived extracellular vesicles (NDEVs) of MDD participants (n = 20) were quantified before and after eight weeks of treatment with a selective serotonin reuptake inhibitor (SSRI). Pretreatment baseline NDEV levels of the transcriptional type 2 nuclear respiratory factor (NRF2) which controls mitochondrial biogenesis and many anti-oxidant gene responses, regulators of diverse neuronal mitochondrial functions cyclophilin D (CYPD) and mitofusin-2 (MFN2), leucine zipper EF-hand containing transmembrane 1 protein (LETM1) component of a calcium channel/calcium channel enhancer, mitochondrial tethering proteins syntaphilin (SNPH) and myosin VI (MY06), inner membrane electron transport complexes I (subunit 6) and III (subunit 10), the penultimate enzyme of nicotinamide adenine dinucleotide (NAD) generation nicotinamide mononucleotide adenylytransferase 2 (NMNAT2), and neuronal mitochondrial metabolic regulatory and protective factors humanin and mitochondrial open-reading frame of the 12S rRNA-c (MOTS-c) all were significantly lower than those of NDEVs from matched controls (n = 10), whereas those of pro-neurodegenerative NADase Sterile Alpha and TIR motif-containing protein 1 (SARM1) were higher. The baseline NDEV levels of transcription factor A mitochondrial (TFAM) and the transcriptional master-regulator of mitochondrial biogenesis PPAR γ coactivator-1α (PGC-1α) showed no differences between MDD participants and controls. Several of these potential biomarker proteins showed substantially different changes in untreated MDD than those we reported in untreated first-episode psychosis. NDEV levels of MPs of all functional classes, except complex I-6, NRF2 and PGC-1α were normalized in MDD participants who responded to SSRI therapy (n = 10) but not in those who failed to respond (n = 10) by psychiatric evaluation. If larger studies validate NDEV MP abnormalities, they may become useful biomarkers and identify new drug targets.
... However, the secondary endpoints were reached, demonstrating significant reductions in depression and anhedonia ratings. These findings present an interesting conundrum that Dr. Alan Schatzberg from Stanford University addresses in his editorial (20). In his piece, Schatzberg questions the wisdom of the NIMH "fast-fail trial" strategy with the goal of first demonstrating target engagement before moving forward with further psychopharmacological drug development. ...
Glutamate neurotransmission is a prioritized target for antipsychotic drug development. Two metabotropic glutamate receptor 2/3 (mGluR2/3) agonists (pomaglumetad [POMA] and TS-134) were assessed in two Phase Ib proof of mechanism studies of comparable designs and using identical clinical assessments and pharmacoBOLD methodology. POMA was examined in a randomized controlled trial under double-blind conditions for 10-days at doses of 80 or 320 mg/d POMA versus placebo (1:1:1 ratio). The TS-134 trial was a randomized, single-blind, 6-day study of 20 or 60 mg/d TS-134 versus placebo (5:5:2 ratio). Primary outcomes were ketamine-induced changes in pharmacoBOLD in the dorsal anterior cingulate cortex (dACC) and symptoms reflected on the Brief Psychiatric Rating Scale (BPRS). Both trials were conducted contemporaneously. 95 healthy volunteers were randomized to POMA and 63 to TS-134. High-dose POMA significantly reduced ketamine-induced BPRS total symptoms within and between-groups (p < 0.01, d = −0.41; p = 0.04, d = −0.44, respectively), but neither POMA dose significantly suppressed ketamine-induced dACC pharmacoBOLD. In contrast, low-dose TS-134 led to moderate to large within and between group reductions in both BPRS positive symptoms (p = 0.02, d = −0.36; p = 0.008, d = −0.82, respectively) and dACC pharmacoBOLD (p = 0.004, d = −0.56; p = 0.079, d = −0.50, respectively) using pooled across-study placebo data. High-dose POMA exerted significant effects on clinical symptoms, but not on target engagement, suggesting a higher dose may yet be needed, while the low dose of TS-134 showed evidence of symptom reduction and target engagement. These results support further investigation of mGluR2/3 and other glutamate-targeted treatments for schizophrenia.
The National Institute of Mental Health (NIMH) ‘fast-fail’ approach seeks to improve too-often-misleading early-phase drug development methods by incorporating biomarker-based proof-of-mechanism (POM) testing in phase 2a. This first comprehensive application of the fast-fail approach evaluated the potential of κ-opioid receptor (KOR) antagonism for treating anhedonia with a POM study determining whether robust target engagement favorably impacts the brain circuitry hypothesized to mediate clinical effects. Here we report the results from a multicenter, 8-week, double-blind, placebo-controlled, randomized trial in patients with anhedonia and a mood or anxiety disorder (selective KOR antagonist (JNJ-67953964, 10 mg; n = 45) and placebo (n = 44)). JNJ-67953964 significantly increased functional magnetic resonance imaging (fMRI) ventral striatum activation during reward anticipation (primary outcome) as compared to placebo (baseline-adjusted mean: JNJ-67953964, 0.72 (s.d. = 0.67); placebo, 0.33 (s.d. = 0.68); F(1,86) = 5.58, P < 0.01; effect size = 0.58 (95% confidence interval, 0.13–0.99)). JNJ-67953964, generally well tolerated, was not associated with any serious adverse events. This study supports proceeding with assessment of the clinical impact of target engagement and serves as a model for implementing the ‘fast-fail’ approach.
Current versions of the DSM and ICD have facilitated reliable clinical diagnosis and research. However, problems have increasingly been documented over the past several years, both in clinical and research arenas (e.g., 1, 2). Diagnostic categories based on clinical consensus fail to align with findings emerging from clinical neuroscience and genetics. The boundaries of these categories have not been predictive of treatment response. And, perhaps most important, these categories, based upon presenting signs and symptoms, may not capture fundamental underlying mechanisms of dysfunction. One consequence has been to slow the development of new treatments targeted to underlying pathophysiological mechanisms.
Objective:
Preclinical studies point to the KCNQ2/3 potassium channel as a novel target for the treatment of depression and anhedonia, a reduced ability to experience pleasure. The authors conducted the first randomized placebo-controlled trial testing the effect of the KCNQ2/3 positive modulator ezogabine on reward circuit activity and clinical outcomes in patients with depression.
Methods:
Depressed individuals (N=45) with elevated levels of anhedonia were assigned to a 5-week treatment period with ezogabine (900 mg/day; N=21) or placebo (N=24). Participants underwent functional MRI during a reward flanker task at baseline and following treatment. Clinical measures of depression and anhedonia were collected at weekly visits. The primary endpoint was the change from baseline to week 5 in ventral striatum activation during reward anticipation. Secondary endpoints included depression and anhedonia severity as measured using the Montgomery-Åsberg Depression Rating Scale (MADRS) and the Snaith-Hamilton Pleasure Scale (SHAPS), respectively.
Results:
The study did not meet its primary neuroimaging endpoint. Participants in the ezogabine group showed a numerical increase in ventral striatum response to reward anticipation following treatment compared with participants in the placebo group from baseline to week 5. Compared with placebo, ezogabine was associated with a significantly larger improvement in MADRS and SHAPS scores and other clinical endpoints. Ezogabine was well tolerated, and no serious adverse events occurred.
Conclusions:
The study did not meet its primary neuroimaging endpoint, although the effect of treatment was significant on several secondary clinical endpoints. In aggregate, the findings may suggest that future studies of the KCNQ2/3 channel as a novel treatment target for depression and anhedonia are warranted.
In 2012, the US National Institute of Mental Health launched three clinical trial contracts under a new FAST initiative. The overall goal for these contracts (Fast-Fail Trials) was to focus early-stage trials, testing novel pharmacologic agents that target the central nervous system, on pharmacologic-based designs to objectively identify doses that produce central nervous system effects. The three contracts targeted different psychiatric populations: psychotic (FAST-PS), mood and anxiety (FAST-MAS), and autism spectrum disorders (FAST-AS). The FAST initiative was a first attempt for the National Institute of Mental Health to adapt an experimental medicine approach to its clinical trial portfolio. As the Fast-Fail trials implemented this new approach for the field, we present the rationale for each trial, design considerations, results, and how each one contributed new knowledge to the field of psychopharmacology; important lessons for pharma and biotech. Under the FAST initiative, the National Institute of Mental Health assembled research teams with a broad range of expertise, who developed and validated the outcome measures and study protocol, and conducted multi-site clinical trials, testing candidate compounds. In the FAST-PS contract, the team validated an imaging-based pharmacodynamic biomarker of the effect of ketamine in the brain that could be utilized in subsequent clinical trials. The initial FAST-AS study was an important first step in the design of early-stage target-engagement trials in autism spectrum disorder, suggesting that a resting electroencephalogram can be used as a pharmacodynamic measure in future studies. The FAST-MAS study showed that blocking the kappa-opioid receptor significantly affects functional magnetic resonance imaging ventral striatal activation in the monetary incentive delay task in anticipation of gain. Together, the outcomes of the FAST-FAIL trials demonstrated the importance of rigorously designed and informative central nervous system trials, including the value of pharmacodynamic measures in early-stage trials. Use of these measures furthered our knowledge about the relationship between specific molecular mechanisms, brain effects, and therapeutic effects in patients with mental illnesses.
For more than 20 years, there have been rumbles about banning the P value,¹⁻³ because it is so often misused, miscomputed, and, even when used and computed correctly, misinterpreted. Consequently, findings that affect medical decision-making, policy, and research are often misled by the very research that is supposed to provide their evidence base.⁴ Recently, such rumbles have increased.⁵⁻⁷ Is now the time to ban the P value in all medical research?
Background:
Post-partum depression is associated with substantial morbidity, and improved pharmacological treatment options are urgently needed. We assessed brexanolone injection (formerly SAGE-547 injection), a positive allosteric modulator of γ-aminobutyric-acid type A (GABAA) receptors, for the treatment of moderate to severe post-partum depression.
Methods:
We did two double-blind, randomised, placebo-controlled, phase 3 trials, at 30 clinical research centres and specialised psychiatric units in the USA. Eligible women were aged 18-45 years, 6 months post partum or less at screening, with post-partum depression and a qualifying 17-item Hamilton Rating Scale for Depression (HAM-D) score (≥26 for study 1; 20-25 for study 2). Women with renal failure requiring dialysis, anaemia, known allergy to allopregnanolone or to progesterone, or medical history of schizophrenia, bipolar disorder, or schizoaffective disorder were excluded. Patients were randomly assigned (1:1:1) to receive a single intravenous injection of either brexanolone 90 μg/kg per h (BRX90), brexanolone 60 μg/kg per h (BRX60), or matching placebo for 60 h in study 1, or (1:1) BRX90 or matching placebo for 60 h in study 2. Patients, the study team, site staff, and the principal investigator were masked to treatment allocation. The primary efficacy endpoint was the change from baseline in the 17-item HAM-D total score at 60 h, assessed in all patients who started infusion of study drug or placebo, had a valid HAM-D baseline assessment, and had at least one post-baseline HAM-D assessment. The safety population included all randomised patients who started infusion of study drug or placebo. Patients were followed up until day 30. The trials have been completed and are registered with ClinicalTrials.gov, numbers NCT02942004 (study 1) and NCT02942017 (study 2).
Findings:
Participants were enrolled between Aug 1, 2016, and Oct 19, 2017, in study 1, and between July 25, 2016, and Oct 11, 2017, in study 2. We screened 375 women simultaneously across both studies, of whom 138 were randomly assigned to receive either BRX90 (n=45), BRX60 (n=47), or placebo (n=46) in study 1, and 108 were randomly assigned to receive BRX90 (n=54) or placebo (n=54) in study 2. In study 1, at 60 h, the least-squares (LS) mean reduction in HAM-D total score from baseline was 19·5 points (SE 1·2) in the BRX60 group and 17·7 points (1·2) in the BRX90 group compared with 14·0 points (1·1) in the placebo group (difference -5·5 [95% CI -8·8 to -2·2], p=0·0013 for the BRX60 group; -3·7 [95% CI -6·9 to -0·5], p=0·0252 for the BRX90 group). In study 2, at 60 h, the LS mean reduction in HAM-D total score from baseline was 14·6 points (SE 0·8) in the BRX90 group compared with 12·1 points (SE 0·8) for the placebo group (difference -2·5 [95% CI -4·5 to -0·5], p=0·0160). In study 1, 19 patients in the BRX60 group and 22 patients in the BRX90 group had adverse events compared with 22 patients in the placebo group. In study 2, 25 patients in the BRX90 group had adverse events compared with 24 patients in the placebo group. The most common treatment-emergent adverse events in the brexanolone groups were headache (n=7 BRX60 group and n=6 BRX90 group vs n=7 placebo group for study 1; n=9 BRX90 group vs n=6 placebo group for study 2), dizziness (n=6 BRX60 group and n=6 BRX90 group vs n=1 placebo group for study 1; n=5 BRX90 group vs n=4 placebo group for study 2), and somnolence (n=7 BRX60 group and n=2 BRX90 group vs n=3 placebo group for study 1; n=4 BRX90 group vs n=2 placebo group for study 2). In study 1, one patient in the BRX60 group had two serious adverse events (suicidal ideation and intentional overdose attempt during follow-up). In study 2, one patient in the BRX90 group had two serious adverse events (altered state of consciousness and syncope), which were considered to be treatment related.
Interpretation:
Administration of brexanolone injection for post-partum depression resulted in significant and clinically meaningful reductions in HAM-D total score at 60 h compared with placebo, with rapid onset of action and durable treatment response during the study period. Our results suggest that brexanolone injection is a novel therapeutic drug for post-partum depression that has the potential to improve treatment options for women with this disorder.
Funding:
Sage Therapeutics, Inc.
Background
Post-partum depression is a serious mood disorder in women that might be triggered by peripartum fluctuations in reproductive hormones. This phase 2 study investigated brexanolone (USAN; formerly SAGE-547 injection), an intravenous formulation of allopregnanolone, a positive allosteric modulator of γ-aminobutyric acid (GABAA) receptors, for the treatment of post-partum depression.
Methods
For this double-blind, randomised, placebo-controlled trial, we enrolled self-referred or physician-referred female inpatients (≤6 months post partum) with severe post-partum depression (Hamilton Rating Scale for Depression [HAM-D] total score ≥26) in four hospitals in the USA. Eligible women were randomly assigned (1:1), via a computer-generated randomisation program, to receive either a single, continuous intravenous dose of brexanolone or placebo for 60 h. Patients and investigators were masked to treatment assignments. The primary efficacy endpoint was the change from baseline in the 17-item HAM-D total score at 60 h, assessed in all randomised patients who started infusion of study drug or placebo and who had a completed baseline HAM-D assessment and at least one post-baseline HAM-D assessment. Patients were followed up until day 30. This trial is registered with ClinicalTrials.gov, number NCT02614547.
Findings
This trial was done between Dec 15, 2015 (first enrolment), and May 19, 2016 (final visit of the last enrolled patient). 21 women were randomly assigned to the brexanolone (n=10) and placebo (n=11) groups. At 60 h, mean reduction in HAM-D total score from baseline was 21·0 points (SE 2·9) in the brexanolone group compared with 8·8 points (SE 2·8) in the placebo group (difference −12·2, 95% CI −20·77 to −3·67; p=0·0075; effect size 1·2). No deaths, serious adverse events, or discontinuations because of adverse events were reported in either group. Four of ten patients in the brexanolone group had adverse events compared with eight of 11 in the placebo group. The most frequently reported adverse events in the brexanolone group were dizziness (two patients in the brexanolone group vs three patients in the placebo group) and somnolence (two vs none). Moderate treatment-emergent adverse events were reported in two patients in the brexanolone group (sinus tachycardia, n=1; somnolence, n=1) and in two patients in the placebo group (infusion site pain, n=1; tension headache, n=1); one patient in the placebo group had a severe treatment-emergent adverse event (insomnia).
Interpretation
In women with severe post-partum depression, infusion of brexanolone resulted in a significant and clinically meaningful reduction in HAM-D total score, compared with placebo. Our results support the rationale for targeting synaptic and extrasynaptic GABAA receptors in the development of therapies for patients with post-partum depression. A pivotal clinical programme for the investigation of brexanolone in patients with post-partum depression is in progress.
Funding
Sage Therapeutics, Inc.
Despite enormous progress in defining, diagnosing and treating mental disorders, EU health systems face a mounting challenge in responding to ‘unmet need’. Mental illnesses produce a societal burden that exceeds that for either cancers or cardiovascular conditions. Leveraging advances in science and medicine to make available new innovative medicines is a key component in responding to this challenge. The dominant paradigm has been, is and will continue to be, one of incremental progress. Better medicines for depression, anxiety and psychoses in the working age population would add great value to patients and improve labour productivity. But psychotropic medicines face exceptional challenges in demonstrating their added value, due to uncertainty in patient diagnosis, selecting treatments and ensuring adherence. Also, there are major difficulties in estimating costs.
Kraemer HC: Is it time to ban the p value?
Kraemer HC: Is it time to ban the p value? JAMA Psychiatry
2019; 76:1219-1220