Kyowa Kirin Co., Ltd. has regained sole global rights to the rocatinlimab program, an anti-OX40 human monoclonal antibody targeting atopic dermatitis, following the termination of its collaboration with Amgen Inc. The agreement between the two companies, which had been established in June 2021, officially ended on a Friday, marking a significant shift in the drug’s development and commercialization pathway.
The partnership initially aimed to combine resources to advance KHK4083 (rocatinlimab) through late-stage clinical development and prepare for market introduction. Amgen contributed a substantial upfront payment of $400 million to Kyowa Kirin as part of this collaboration, with potential milestone payments amounting to up to $850 million contingent on regulatory and commercial achievements.
Upon termination, Kyowa Kirin assumed full control over all aspects of the rocatinlimab program globally, including regulatory submissions and future commercialization activities. Amgen’s decision to disengage from the project was driven by a strategic portfolio prioritization, signaling a realignment of their therapeutic focus away from the OX40 target.
Rocatinlimab had progressed through an extensive Phase 3 clinical trial program investigating its efficacy and safety in patients with moderate to severe atopic dermatitis (AD). The most recent data emanated from the ASCEND trial, which evaluated adult and adolescent populations continuing therapy over a total of 56 weeks following initial participation in the ROCKET trial.
Analysis from these Phase 3 programs indicated that gastrointestinal ulceration events associated with rocatinlimab were rare, occurring in less than one per 100 patient-years. However, other adverse effects such as pyrexia and chills presented notable toxicity concerns that could complicate the drug’s chronic use in AD and potentially limit dosing intensity and thus therapeutic efficacy.
Industry analysis from William Blair highlighted the unexpected timing of the collaboration termination, which came shortly before a planned regulatory submission after the completion of a broad Phase 3 program. William Blair analyst Matt Phipps noted a decline in enthusiasm for the OX40 pathway as a therapeutic target, reinforced by Phase 3 efficacy results that failed to replicate Phase 2 benchmarks for both rocatinlimab and amlitelimab in atopic dermatitis.
Despite these concerns, William Blair maintained an Outperform rating on the stock, but underscored the commercial challenges posed by the adverse event profile of rocatinlimab.
From an investor perspective, the discontinuation of the Amgen-Kyowa Kirin collaboration for rocatinlimab appears to have a limited impact on Amgen’s overall investment outlook. The decision reflects broader strategic priorities rather than significant financial setbacks.
Amgen remains active in other areas of therapeutic development and commercialization. For instance, the company recently presented phase 2 data on MariTide, an investigational treatment for obesity, at the J.P. Morgan Healthcare Conference, signaling ongoing pipeline progression.
Additionally, in January, Amgen completed the acquisition of Dark Blue Therapeutics, focusing on precision oncology, for up to $840 million, thereby reinforcing its commitment to oncology innovation.
Furthermore, in December 2025, Amgen secured FDA approval for Uplinza (inebilizumab-cdon), an immunotherapy indicated for generalized myasthenia gravis (gMG), showcasing successful product launches outside of the dermatology space.
On the financial markets, Amgen shares experienced a slight decline, trading down by approximately 0.81% at around $340.17 per share on the day of the collaboration termination announcement, according to Benzinga Pro data.
This development underscores the complexities pharmaceutical companies face in navigating late-stage clinical development and portfolio management. The decision to end the collaboration on rocatinlimab, despite substantial investment and progress, reflects a pragmatic reassessment of therapeutic potential and commercial viability in a competitive market landscape.
The partnership initially aimed to combine resources to advance KHK4083 (rocatinlimab) through late-stage clinical development and prepare for market introduction. Amgen contributed a substantial upfront payment of $400 million to Kyowa Kirin as part of this collaboration, with potential milestone payments amounting to up to $850 million contingent on regulatory and commercial achievements.
Upon termination, Kyowa Kirin assumed full control over all aspects of the rocatinlimab program globally, including regulatory submissions and future commercialization activities. Amgen’s decision to disengage from the project was driven by a strategic portfolio prioritization, signaling a realignment of their therapeutic focus away from the OX40 target.
Rocatinlimab had progressed through an extensive Phase 3 clinical trial program investigating its efficacy and safety in patients with moderate to severe atopic dermatitis (AD). The most recent data emanated from the ASCEND trial, which evaluated adult and adolescent populations continuing therapy over a total of 56 weeks following initial participation in the ROCKET trial.
Analysis from these Phase 3 programs indicated that gastrointestinal ulceration events associated with rocatinlimab were rare, occurring in less than one per 100 patient-years. However, other adverse effects such as pyrexia and chills presented notable toxicity concerns that could complicate the drug’s chronic use in AD and potentially limit dosing intensity and thus therapeutic efficacy.
Industry analysis from William Blair highlighted the unexpected timing of the collaboration termination, which came shortly before a planned regulatory submission after the completion of a broad Phase 3 program. William Blair analyst Matt Phipps noted a decline in enthusiasm for the OX40 pathway as a therapeutic target, reinforced by Phase 3 efficacy results that failed to replicate Phase 2 benchmarks for both rocatinlimab and amlitelimab in atopic dermatitis.
Despite these concerns, William Blair maintained an Outperform rating on the stock, but underscored the commercial challenges posed by the adverse event profile of rocatinlimab.
From an investor perspective, the discontinuation of the Amgen-Kyowa Kirin collaboration for rocatinlimab appears to have a limited impact on Amgen’s overall investment outlook. The decision reflects broader strategic priorities rather than significant financial setbacks.
Amgen remains active in other areas of therapeutic development and commercialization. For instance, the company recently presented phase 2 data on MariTide, an investigational treatment for obesity, at the J.P. Morgan Healthcare Conference, signaling ongoing pipeline progression.
Additionally, in January, Amgen completed the acquisition of Dark Blue Therapeutics, focusing on precision oncology, for up to $840 million, thereby reinforcing its commitment to oncology innovation.
Furthermore, in December 2025, Amgen secured FDA approval for Uplinza (inebilizumab-cdon), an immunotherapy indicated for generalized myasthenia gravis (gMG), showcasing successful product launches outside of the dermatology space.
On the financial markets, Amgen shares experienced a slight decline, trading down by approximately 0.81% at around $340.17 per share on the day of the collaboration termination announcement, according to Benzinga Pro data.
This development underscores the complexities pharmaceutical companies face in navigating late-stage clinical development and portfolio management. The decision to end the collaboration on rocatinlimab, despite substantial investment and progress, reflects a pragmatic reassessment of therapeutic potential and commercial viability in a competitive market landscape.