Shionogi has struck a deal to take full control of its sleep disorder joint venture, agreeing to pay Apnimed $100 million upfront for its partner’s half of the business.
Japan-based Shionogi set up the joint venture with Apnimed in 2023. Forming the Massachusetts-based company enabled Shionogi to pair its drug discovery capabilities with Apnimed’s obstructive sleep apnea (OSA) know-how. Last year, the joint venture, Shionogi-Apnimed Sleep Science (SASS), started a phase 2a trial of one candidate and added a second asset to its pipeline.
Shionogi called the joint venture’s progress “steady” in a statement. Seeking to accelerate progress, the drugmaker agreed to buy Apnimed’s 50% stake in SASS. The deal includes the $100 million upfront fee and a $50 million milestone tied to SASS-002.
SASS-001 is the most advanced candidate owned by SASS. The drug candidate combines sivopixant, a P2X3 receptor antagonist discovered by Shionogi, with a molecule that has an undisclosed mechanism of action. SASS is testing the combination in adults with sleep apnea with a central component in the phase 2a trial that began last year. Apnimed said one year ago to expect top-line data in the first half of 2026.
Related
The joint venture’s other named candidate is SASS-002, a formulation of the anti-seizure drug sulthiame. Apnimed acquired the rights to develop sulthiame in sleep apnea from Desitin Arzneimittel last year and cut Shionogi in on the deal to make the program part of SASS’ pipeline. Desitin completed a phase 2 trial of sulthiame in OSA in 2023.
Adding the sulthiame program to SASS’ pipeline allowed Apnimed to keep its internal teams focused on AD109, a drug combination that targets a cause of upper airway collapse in people with OSA. Apnimed reported two phase 3 wins for AD109 last year and plans to seek FDA approval in the second quarter.
In a statement, Apnimed CEO Larry Miller, M.D., said selling the SASS stake is “a strategic monetization” that will strengthen the biotech’s balance sheet. Apnimed disclosed a $35 million financing in December.
