GSK Licenses Linerixibat to Alfasigma for $690M; Eisai's E2086 Receives Orphan Designation

GSK agreed to license linerixibat, its investigational treatment for cholestatic pruritus in primary biliary cholangitis (PBC), to Italian pharmaceutical company Alfasigma in a deal valued at upwards of $690 million. Under the terms of the agreement, Alfasigma is expected to acquire worldwide exclusive rights to develop, manufacture and commercialize linerixibat.

GSK will receive an upfront payment of $300 million, with a further $100 million due upon FDA approval, which is expected ahead of a PDUFA target date of March 24. Additional milestones will be tied to regulatory approvals in the EU and UK, and up to $270 million in sales-based payments, round out the deal, alongside tiered double-digit royalties on global net sales.

PBC is a cholestatic liver disease in which disrupted bile flow leads to a buildup of bile acids thought to drive cholestatic pruritus, a debilitating internal itch that cannot be relieved by scratching. The condition can cause sleep disturbance, fatigue, and significantly impaired quality of life. US data suggest that up to one-third of patients with clinically significant itch receive no treatment at all.

Linerixibat is currently under regulatory review in the U.S., E.U., U.K., China and Canada, based on data from the Phase III Glisten trial, which met its primary and key secondary endpoints. The drug carries Orphan Drug Designation in the U.S., E.U. and Japan.

For GSK, the deal represents a deliberate narrowing of focus. The company said the agreement allows it to concentrate on its next wave of liver disease innovation, including potential treatments for chronic hepatitis B, MASH and alcoholic liver disease. The chief scientific officer stated that the agreement sharpens GSK's focus to deliver its next wave of liver disease innovation.

In separate news, Eisai announced that it has received an orphan drug designation for its in-house discovered and developed novel selective orexin 2 receptor agonist E2086, with prospective indication for narcolepsy, from the Ministry of Health, Labour and Welfare (MHLW) in Japan.

Narcolepsy is a chronic sleep disorder that is characterized by excessive daytime sleepiness (EDS). Due to problems with fatigue, cognition, and persistence of residual symptoms despite treatment, disease burden for narcolepsy is high, and narcolepsy remains a disease with high unmet medical needs. While estimates vary depending on the study data, a 2025 report estimates the narcolepsy patient population in Japan to be approximately 46,000.

Narcolepsy is classified into two subtypes, type 1 (narcolepsy with cataplexy) and type 2 (narcolepsy without cataplexy). The pathogenesis of narcolepsy type 1 is thought to involve a deficiency of orexin due to autoimmune destruction of orexin-producing neurons located in the hypothalamus. Although the pathogenesis of narcolepsy type 2 remains unknown, it has been suggested that a reduction in orexin neurotransmission may also be involved.

Orexin is a neurotransmitter that plays a central role in regulating sleep and wakefulness. Activating orexinergic neurons is believed to help maintain a more stable state of wakefulness. Eisai has created E2086, a selective orexin 2 receptor agonist that activates orexinergic neurons. E2086 has the potential to improve patients' symptoms by enhancing orexin receptor activity and acting on the pathophysiology of narcolepsy. Eisai presented data from a Phase Ib clinical study in patients with narcolepsy type 1, which suggests that E2086 has the potential to improve daytime wakefulness, at the World Sleep 2025 congress.

Eisai considers neurology, including sleep-wake disorders such as insomnia and narcolepsy, as a therapeutic area of focus.