Kyowa Kirin Co., Ltd. and Amgen Inc. (NASDAQ:AMGN) terminated on Friday the current rocatinlimab development and commercialization collaboration.
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Kyowa Kirin will regain control of the global rocatinlimab program, including regulatory filings and future commercialization.
The business decision is the result of a strategic portfolio prioritization by Amgen.
In June 2021, Amgen and Kyowa Kirin agreed to jointly develop and commercialize KHK4083, a Phase 3-ready anti-OX40 fully human monoclonal antibody for atopic dermatitis, with potential in other autoimmune diseases.
Amgen paid $400 million upfront payment, and Kyowa Kirin was eligible to receive milestone payments worth up to an additional $850 million.
In September 2025, the companies released preliminary topline results from the ASCEND study evaluating rocatinlimab in adults and adolescents with moderate to severe atopic dermatitis (AD).
The analysis focused on adults who completed the first 24 weeks of therapy in a previous ROCKET trial and continued in ASCEND for an additional 32 weeks.
Across the Phase 3 ROCKET program, including ASCEND, the incidence of gastrointestinal ulceration events with rocatinlimab to date is less than 1 per 100 patient-years.
Analyst Take
William Blair on Friday wrote that the timing of the decision to terminate the agreement (following completion of a broad Phase 3 program and just before a planned regulatory submission) comes as somewhat of a surprise.
Analyst Matt Phipps also notes that the recent updates in the OX40 development landscape have reduced enthusiasm for the target.
In recent updates with both rocatinlimab and amlitelimab in atopic dermatitis, efficacy in Phase 3 studies has fallen short of Phase II benchmarks.
William Blair maintains the Outperform rating.
In addition, the William Blair analyst says that rocatinlimab's toxicity profile, with relatively high rates of pyrexia and chills, was going to be a commercial challenge in treating chronic conditions like atopic dermatitis, and also potentially limiting dosing intensity and therefore efficacy.
Investor Focus
Given investors' low expectations for therapies targeting the OX40 pathway at this point, the rocatinlimab discontinuation decision will not impact the investment thesis for Amgen.
At a J.P. Morgan Healthcare Conference, Amgen’s CEO shared findings from part 2 of the phase 2 Study of MariTide, its investigational obesity treatment.
In January, Amgen acquired Dark Blue Therapeutics, a company focused on precision oncology medicines, for up to $840 million.
In December 2025, the U.S. Food and Drug Administration (FDA) approved Amgen’s Uplinza (inebilizumab-cdon) for generalized myasthenia gravis (gMG).
AMGN Price Action: Amgen stock is down 0.81% at $340.17 at publication on Friday, according to Benzinga Pro data.
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