Experimental Kv7 Channel Opener Azetukalner Fails Brain Imaging Endpoint but Shows Hints of Benefit in Depression

A novel experimental antidepressant that works by tuning the electrical activity of brain cells has delivered a mixed but intriguing verdict in one of the first rigorous tests of its kind. Azetukalner, a positive allosteric modulator of Kv7 potassium channels, did not significantly change reward-related brain activity in people with major depressive disorder and anhedonia, the crippling inability to feel pleasure. Yet the drug produced numerical improvements across a broad range of secondary and exploratory clinical measures, and it was well tolerated, leaving researchers cautiously optimistic that the Kv7 channel family may still represent a promising new direction for treating depression. The findings come from a phase II, randomized, double-blind, placebo-controlled trial conducted by a team at the Icahn School of Medicine at Mount Sinai in collaboration with Baylor College of Medicine and other institutions, published in the journal Translational Psychiatry.

The trial enrolled 60 participants who were experiencing a current major depressive episode accompanied by clinically significant anhedonia, a symptom domain that has long frustrated psychiatrists. Anhedonia, which involves diminished interest, motivation, and capacity for pleasure, is common in depression, often persists even when other symptoms improve, and is strongly linked to dysfunction in the brain’s reward circuitry. Standard antidepressants such as selective serotonin reuptake inhibitors frequently leave this dimension untouched, which is why the field has been searching for treatments that target reward processing directly rather than mood in general. The researchers designed the study as an experimental medicine trial, a design that uses a neurobiological measure as the primary endpoint to test whether a drug engages its intended brain circuit before committing to larger efficacy trials.

Participants were randomized one to one to receive either azetukalner at a dose of 20 milligrams taken orally once daily with food, or a matching placebo, for eight weeks. The primary endpoint was the change in activity of the bilateral ventral striatum, a key hub of the brain’s reward system, measured with functional magnetic resonance imaging while participants performed a reward task, comparing scans taken at baseline with those taken at week eight. The ventral striatum, which includes the nucleus accumbens, responds robustly to the anticipation and receipt of rewards, and blunted activation in this region has been repeatedly observed in depressed patients, particularly those with prominent anhedonia. The logic of the trial was straightforward: if azetukalner truly modulates reward circuitry, eight weeks of treatment should measurably strengthen the ventral striatum’s response to anticipated rewards.

That primary hypothesis was not borne out. The researchers found no significant difference in the ventral striatum response to reward anticipation between the azetukalner group, which comprised 29 participants, and the placebo group, which comprised 31. In the world of clinical neuroscience, this kind of negative primary endpoint is not unusual, and the authors were careful to report it plainly. Functional MRI measures are noisy, sample sizes in experimental medicine studies are typically modest, and the link between a drug’s molecular mechanism and a hemodynamic imaging signal involves many layers of biology that can dilute an effect. Still, the result means that the most direct test of the drug’s proposed mechanism of action in this study did not find the expected neural signature.

The secondary outcomes told a more encouraging story. Compared with placebo, azetukalner was associated with numerical benefit on the Montgomery-Åsberg Depression Rating Scale, a clinician-administered measure of depression severity, and on the Snaith-Hamilton Pleasure Scale, a widely used self-report instrument for anhedonia. Neither difference reached statistical significance, a critical caveat, but the direction of the effects was consistent with a genuine signal. Perhaps more telling, most of the exploratory endpoints in the trial also numerically favored azetukalner over placebo. When a drug shows a consistent directional trend across many independent measures, even without statistical significance, it can suggest that a real effect exists but that the study was underpowered to detect it, though it can also reflect chance, and the authors acknowledged this ambiguity.

Safety results were a clear positive. Discontinuation rates due to adverse events were low and did not differ between the azetukalner and placebo groups, an important finding for a medication that would need to be taken chronically if it ever reaches the clinic. Kv7 channel openers, which include the anticonvulsant ezogabine that preceded azetukalner in experimental psychiatry research, have generally shown tolerable side effect profiles at the doses used in neuropsychiatric studies. The favorable tolerability observed here matters because depression is a chronic, relapsing condition, and any future treatment must be something patients can sustain over months or years without burdensome side effects driving them off the drug.

The biology behind the approach is worth understanding. Kv7 channels, encoded by the KCNQ gene family, are voltage-gated potassium channels that act as molecular brakes on neuronal firing. By regulating the flow of potassium ions out of neurons, they help stabilize the membrane potential and control how easily a cell fires an action potential. A positive allosteric modulator like azetukalner does not block or activate the channel directly at its main gate; instead, it binds to a site away from the pore and makes the channel easier to open, thereby dampening neuronal excitability. In reward circuits, this dampening is thought to reduce the excessive phasic activity of neurons that project to the ventral striatum, which some theories link to the blunted, dysregulated reward processing seen in depression and anhedonia. Preclinical work and earlier small human studies of ezogabine suggested that enhancing Kv7 activity could normalize reward circuit function, motivating the development of azetukalner as a more refined candidate.

The experimental medicine framework itself is a notable feature of the study. Rather than measuring only symptom scores, the trial put a mechanistic biomarker, reward-related ventral striatum activation, at the center of the design, funded in part by the National Institute of Mental Health under an award supporting this translational strategy. The idea is that demonstrating target engagement in the brain early in development can guide decisions about whether to advance a compound to larger and far more expensive efficacy trials. In this case, the biomarker result argues for caution, while the clinical signal argues for continued interest. The study was registered at ClinicalTrials.gov under identifier NCT04827901, and the investigational product and matching placebo were provided by Xenon Pharmaceuticals under a research agreement with the Icahn School of Medicine at Mount Sinai.

For patients and clinicians, the practical takeaway is that azetukalner remains an unproven but scientifically interesting candidate. The trial was small, with 60 participants, and its primary purpose was to test mechanism rather than to win regulatory approval, so neither a positive nor a negative primary endpoint would have been definitive about clinical efficacy. The consistent numerical trends on depression severity and anhedonia measures, combined with good tolerability, give the researchers grounds to argue that larger trials with adequate statistical power are warranted. At the same time, the failure to shift the ventral striatum imaging signal raises real questions about whether the drug, at this dose and duration, engages the reward circuitry in the way the hypothesis predicted, or whether fMRI measures of reward anticipation are simply too insensitive to capture the effect.

The broader significance of the study lies in what it says about the future of antidepressant development. Depression remains one of the most common and debilitating diseases worldwide, and a substantial fraction of patients do not respond adequately to existing medications, which mostly act on monoamine neurotransmitter systems discovered decades ago. Novel targets such as the Kv7 potassium channels, glutamatergic agents, and psychedelic compounds are all being tested in parallel, reflecting a field-wide effort to find treatments that work through fundamentally different biology. This trial, led by senior author James W. Murrough and first author Rachel Fremont, exemplifies the careful, mechanistically grounded path that new candidates must travel: a clear molecular hypothesis, a measurable brain endpoint, honest reporting of a negative primary result, and a transparent account of the suggestive but unproven clinical signals that remain. Whether azetukalner ultimately helps people with depression and anhedonia will depend on the larger studies that this work now makes easier to design.

Subject of Research: A randomized controlled trial of the Kv7 channel opener azetukalner in major depressive disorder with anhedonia

Article Title: A randomized, controlled experimental medicine study of the novel Kv7 channel opener azetukalner in individuals with major depressive disorder and anhedonia

Article References: Fremont, R., Neukam, P. T., Govindarajulu, U. S., Ables, J. L., Hameed, S., Corwin, M., Hargrove, M. B., Chang, H. L., Boukezzi, S., Kelly, C. A., Swann, A., Salas, R., Amarneh, D., Engelhardt, J., Weyland, A., Bagiella, E., Morris, L., Mathew, S. J., & Murrough, J. W. (2026). A randomized, controlled experimental medicine study of the novel Kv7 channel opener azetukalner in individuals with major depressive disorder and anhedonia. Translational Psychiatry. https://doi.org/10.1038/s41398-026-04431-6

Image Credits: AI Generated

DOI: 10.1038/s41398-026-04431-6

Keywords: azetukalner, Kv7 channels, major depressive disorder, anhedonia, ventral striatum, functional MRI, reward processing, clinical trial, translational psychiatry, potassium channels, antidepressant development, Xenon Pharmaceuticals