Amgen has ended its partnership with Kyowa Kirin regarding the development of rocatinlimab, an anti-OX40 antibody for autoimmune diseases. According to a statement from Kyowa Kirin, the termination is due to "a strategic portfolio prioritization by Amgen." Both companies have committed to ensuring that patients currently enrolled in clinical trials will continue receiving treatment, and Amgen will keep manufacturing the drug for these studies.
The decision has led to mixed reactions among analysts. William Blair described Amgen's move as "somewhat of a surprise," especially given that a broad late-stage program was recently completed and regulatory submission was expected soon. However, Leerink Partners indicated they were not surprised because of "long-standing questions about [rocatinlimab’s] efficacy and tolerability profile." The firm noted that Amgen did not announce plans to seek approval even after finishing late-stage testing.
In September 2024, Phase III trial results showed that 32.8% of patients treated with rocatinlimab achieved a 75% improvement in eczema severity, compared to 13.7% for those on placebo. Despite this, Jefferies called the results “modest” and said they were at “the lower end of efficacy and expectations.”
Further safety data released in September 2025 included findings from an extension study with up to 56 weeks of patient follow-up. The companies reported low dropout rates across all groups and no new safety concerns during this period.
However, earlier data from March revealed higher rates of chills and fever among those taking rocatinlimab compared to placebo recipients. William Blair commented that these side effects would present commercial challenges for chronic conditions such as atopic dermatitis and could limit both dose intensity and effectiveness: “Ultimately, rocatinlimab’s unique side effects were always going to be a headwind to commercialization,” analysts stated.
Despite Amgen’s exit from the collaboration, Kyowa Kirin remains optimistic about rocatinlimab's future potential. The company intends to submit an application for FDA approval within the first half of this year.
