Daiichi Sankyo has dosed the first patient in a Phase I clinical trial assessing DS1025 in adults with advanced or metastatic solid tumours who have experienced disease progression after at least one previous standard therapy.
DS1025 is an investigational antibody drug conjugate (ADC) specifically engineered to target cluster of differentiation 25 (CD25).
CD25 is a cell surface protein commonly found on regulatory T cells (Treg cells) involved in suppressing the immune system’s anti-cancer response.
The open-label, dose escalation, multi-centre trial will evaluate the safety, pharmacokinetics, tolerability, and preliminary efficacy of DS1025.
The main objectives of the trial are to assess the tolerability and safety, including dose-limiting toxicities and adverse events.
Secondary measures will look at pharmacokinetics and immunogenicity, while exploratory endpoints include overall response rate, duration of response, and time to response.
Enrolment is expected to reach up to 45 patients at multiple clinical sites in Asia and Europe.
DS1025 has been discovered by Daiichi Sankyo and builds on the company’s DXd ADC technology.
Daiichi Sankyo research and development (R&D) global head John Tsai said: “While immunotherapies have transformed cancer treatment, continued innovation in leveraging pathways that can activate the immune system is needed.
“The initiation of this trial evaluating DS1025 reflects continued progress in advancing our pipeline through the development of novel antibody drug conjugates in order to deliver medicines that improve outcomes for patients with cancer.”
DS1025 forms part of Daiichi Sankyo’s wider ADC portfolio, which includes nine compounds in clinical development, with several being co-developed and commercialised with AstraZeneca and Merck & Co (MSD).
In December 2025, Daiichi Sankyo dosed the first patient in the DESTINY-Ovarian01 Phase III trial’s randomisation phase, assessing Enhertu (trastuzumab deruxtecan) with bevacizumab versus bevacizumab alone as first-line maintenance therapy for ovarian cancer.
