With a US FDA decision expected in Q3 2026, Takeda (TSE:4502/NYSE:TAK) presented secondary and exploratory endpoint data from its two pivotal Phase III studies of oveporexton (TAK-861) at SLEEP 2026, showing that the oral orexin receptor 2 (OX2R)-selective agonist produced statistically significant improvements in daily functioning, cognition, and nighttime sleep in patients with narcolepsy type 1 (NT1). The data extend the previously disclosed topline results from September 2025 and arrive at a moment when the NT1 treatment landscape is on the verge of its first mechanistic shift in decades — making the breadth of the clinical effect central to how clinicians and payers will evaluate oveporexton against entrenched competitors.
The results came from two global, placebo-controlled studies: FirstLight (NCT06470828), which enrolled 168 patients across three dosing arms (twice-daily 2mg, 1mg, and placebo), and RadiantLight (NCT06505031), which enrolled 105 patients in two arms (twice-daily 2mg and placebo), both conducted across 19 countries over 12 weeks.
Across all doses, oveporexton produced statistically significant improvements at week 12 versus placebo (p<0.001) across all six domains of the Functional Impacts of Narcolepsy Instrument (FINI), which captures tiredness, cognitive functioning, cataplexy, social activities, everyday activities, and everyday responsibilities. Most patients reached or exceeded published normative domain thresholds — a clinically meaningful benchmark suggesting functional normalization rather than mere symptom reduction.
On cognition, approximately 70% of patients across all dose groups reported no significant cognitive difficulties on the FINI Cognitive Function domain, compared with approximately 15% in the placebo arm. Objective neuropsychological testing of attention, executive function, and memory corroborated the patient-reported findings. On nighttime sleep, exploratory endpoints indicated that most patients reported no hallucinations or sleep paralysis, most patients on the 2mg twice-daily dose reported meaningful reductions in disturbed nighttime sleep from baseline, and REM sleep timing and pattern shifted toward those seen in healthy controls.
Safety data were not reported in this release; the primary endpoint results and full safety data were disclosed at the time of the topline readout in September 2025.
Competitive context
The significance of these data lies partly in what existing approved therapies do not provide. Jazz Pharmaceuticals' Xyrem (sodium oxybate) and Xywav (low-sodium oxybate) remain the standard of care for cataplexy and excessive daytime sleepiness in NT1, but both require REMS programs, carry Schedule III controlled substance designations, and in the case of Xyrem, require a second dose taken in the middle of the night. Harmony Biosciences' Wakix (pitolisant), a histamine H3 receptor inverse agonist, is non-scheduled and covers both EDS and cataplexy, but it acts downstream of the orexin deficit rather than addressing it directly. Oveporexton is designed to restore orexin signaling at OX2R, directly targeting the pathophysiology of NT1 — a mechanistic distinction that no currently approved therapy offers.