Core Insights - Kyowa Kirin Co., Ltd. and Amgen Inc. have terminated their collaboration on the development and commercialization of rocatinlimab, with Kyowa Kirin regaining control over the global program [1][2] Group 1: Collaboration Details - The collaboration was initiated in June 2021, focusing on KHK4083, a Phase 3-ready anti-OX40 monoclonal antibody for atopic dermatitis and other autoimmune diseases [2] - Amgen made an upfront payment of $400 million and Kyowa Kirin was eligible for milestone payments up to $850 million [3] Group 2: Clinical Trial Insights - Preliminary topline results from the ASCEND study, evaluating rocatinlimab in adults and adolescents with moderate to severe atopic dermatitis, were released in September 2025 [3] - The incidence of gastrointestinal ulceration events with rocatinlimab is reported to be less than 1 per 100 patient-years across the Phase 3 ROCKET program [4] Group 3: Analyst Commentary - The decision to terminate the agreement was unexpected, occurring after a broad Phase 3 program and just before a planned regulatory submission [5] - Recent updates in the OX40 development landscape have diminished enthusiasm for the target, with Phase 3 efficacy falling short of Phase II benchmarks [5] - Concerns regarding rocatinlimab's toxicity profile, including high rates of pyrexia and chills, may pose commercial challenges [6] Group 4: Investor Sentiment - The discontinuation of rocatinlimab is not expected to impact the investment thesis for Amgen, given low investor expectations for therapies targeting the OX40 pathway [7] - Amgen's CEO shared findings from part 2 of the Phase 2 study of MariTide, an investigational obesity treatment, at a J.P. Morgan Healthcare Conference [7] - Amgen acquired Dark Blue Therapeutics for up to $840 million, focusing on precision oncology medicines [7] Group 5: Stock Performance - As of the publication date, Amgen's stock was down 0.81% at $340.17 [8]