OSAKA, Japan and CAMBRIDGE, Massachusetts, June 15, 2026
Takeda has unveiled new pivotal Phase 3 data demonstrating that oveporexton (TAK-861) significantly improved daily functioning, cognitive performance, and nighttime sleep quality in patients with narcolepsy type 1 (NT1). Presented at SLEEP 2026, the findings further strengthen the clinical profile of the investigational orexin receptor 2 (OX2R) agonist, which is currently under regulatory review and has the potential to become the first and only orexin agonist therapy approved for NT1. The latest results build upon previously reported Phase 3 findings and reinforce the potential of oveporexton to address the underlying orexin deficiency responsible for the disease rather than simply managing individual symptoms.
Phase 3 Data Demonstrate Improvements Across Daily Function and Cognition
The newly presented analyses originated from the global FirstLight and RadiantLight Phase 3 studies, two randomized, placebo-controlled trials evaluating the efficacy and safety of oveporexton in adults with narcolepsy type 1. Results showed that patients receiving oveporexton achieved significant improvements in daily functioning across all major domains of disease burden, including fatigue, cognitive function, cataplexy, social participation, everyday activities, and personal responsibilities. Improvements were measured using the Functional Impacts of Narcolepsy Instrument (FINI), with patients across all active treatment groups reaching or exceeding published normative thresholds.
Importantly, the therapy also demonstrated meaningful benefits in cognitive performance. Objective neuropsychological assessments and patient-reported outcomes showed improvements in attention, executive function, and memory. Approximately 70% of treated patients reported no significant cognitive difficulties, compared with only about 15% of individuals receiving placebo. These findings highlight the broad impact of orexin restoration on symptoms that significantly affect quality of life and day-to-day productivity among people living with narcolepsy type 1.
Oveporexton Restores Orexin Signaling and Improves Sleep Quality
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Unlike currently available therapies that primarily target symptoms such as excessive daytime sleepiness, oveporexton is designed to address the root cause of narcolepsy type 1 by restoring deficient orexin signaling. Orexin deficiency is the primary biological driver of NT1 and contributes to both daytime and nighttime symptoms. Exploratory endpoints from the Phase 3 program demonstrated that oveporexton improved nighttime sleep quality and reduced hallmark sleep disturbances associated with the condition. Across both studies, most patients receiving active treatment reported elimination or substantial reductions in sleep paralysis and hypnagogic hallucinations, while many experienced meaningful reductions in fragmented nighttime sleep.
Researchers also observed a normalization of rapid eye movement (REM) sleep timing and patterns toward levels typically seen in healthy individuals. These findings suggest that restoring orexin activity may provide a comprehensive treatment approach capable of improving both daytime wakefulness and nighttime sleep architecture, an outcome that has remained difficult to achieve with current treatment options.
Regulatory Reviews Underway for Potential First-in-Class Therapy
The positive Phase 3 results arrive as regulatory submissions for oveporexton are currently under review in multiple regions. The U.S. Food and Drug Administration (FDA) has already accepted Takeda’s New Drug Application and granted Priority Review, with a PDUFA decision expected later this year. Regulatory reviews are also ongoing in Japan and China. Oveporexton represents a significant scientific milestone because it is designed as a selective orexin receptor 2 agonist, directly targeting the biological mechanism responsible for narcolepsy type 1. If approved, the therapy could establish an entirely new treatment paradigm and potentially redefine the standard of care for a disorder that affects patients around the clock.
With more than 95% of Phase 3 participants enrolling in the long-term extension study, ongoing data generation is expected to provide additional insights into the durability and long-term safety of orexin-based therapy for narcolepsy. The latest findings further position oveporexton as one of the most closely watched neuroscience drug candidates currently advancing through the global regulatory process.
Source: Takeda press release
