Daiichi Sankyo has dosed the first patient in a first-in-human Phase 1 trial evaluating DS1025, an investigational CD25-directed antibody-drug conjugate (ADC), in patients with advanced or metastatic solid tumors.
The company announced the milestone in an August 27 press release, marking the entry of DS1025 into clinical development.
DS1025 is a potential first-in-class CD25-directed ADC designed to target regulatory T cells (Tregs) within the tumor microenvironment. CD25 is highly expressed on Tregs, which can suppress antitumor immune responses and contribute to tumor immune evasion.
According to Daiichi Sankyo, DS1025 combines a CD25-directed antibody with an immuno-oncology-optimized cytotoxic payload designed to deplete immunosuppressive Tregs in the tumor microenvironment and promote activation of the immune system against cancer.
Currently, no CD25-directed ADCs are approved for the treatment of cancer.
John Tsai, MD, Global Head of R&D at Daiichi Sankyo, said:
“While immunotherapies have transformed cancer treatment, continued innovation in leveraging pathways that can activate the immune system is needed.”
Phase 1 Trial of DS1025
The multicenter, open-label, dose-escalation Phase 1 trial (DS1025-103; NCT07681882) is evaluating DS1025 in adults with advanced, metastatic, or unresectable solid tumors whose disease has progressed on or after at least one prior line of standard therapy. The study is expected to enroll up to 45 patients.
Its primary objectives include evaluating the safety and tolerability of DS1025 and determining a recommended dose for further development. Primary assessments include dose-limiting toxicities and adverse events.
Secondary endpoints include pharmacokinetics and immunogenicity, while exploratory efficacy measures include overall response rate, duration of response, and time to response.
The study is currently recruiting, with clinical development planned across sites in Asia and Europe.
DS1025 joins Daiichi Sankyo’s expanding ADC pipeline, which currently includes nine ADCs in clinical development. The investigational agent has not been approved for any indication, and its safety and efficacy have not yet been established.
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