BSI-706

In recent years, antibody-drug conjugate (ADC) technology, which uses monoclonal antibodies (mAbs) to specifically deliver effective cytotoxic payloads to tumor cells, has become a promising method of tumor targeted therapy. ADCs are a powerful class of biopharmaceuticals that link antibodies targeting specific antigens and small molecule drugs with potent cytotoxicity via a linker, thus enabling selective destruction of cancer cells while minimizing systemic toxicity. DXd is a topoisomerase I inhibitor that induces DNA damage leading to cell cycle arrest, making it an option for ADC payloads. The DXd-ADC technology, developed by Daiichi Sankyo, is a cutting-edge platform that produces a new generation of ADCs with improved therapeutic metrics and has shown significant therapeutic potential in various types of cancer. This review provides a comprehensive assessment of drugs developed with DXd-ADC technology, with a focus on mechanisms of action, pharmacokinetics studies, preclinical data, and clinical outcomes for DS-8201a, U3-1402, DS-1062a, DS-7300a, DS-6157a, and DS-6000a. By integrating existing data, we aim to provide valuable insights into the current therapeutic status and future prospects of these novel agents.

Delta-like ligand 3 (DLL3) is overexpressed in small cell lung cancer (SCLC) and has been considered an attractive target for SCLC therapy. Rovalpituzumab tesirine was the first DLL3-targeted antibody–drug conjugate (ADC) to enter clinical studies. However, serious adverse events limited progress in the treatment of SCLC with rovalpituzumab tesirine. In this study, we developed a novel DLL3-targeted ADC, FZ-AD005, by using DXd with potent cytotoxicity and a relatively better safety profile to maximize the therapeutic index. FZ-AD005 was generated by a novel anti-DLL3 antibody, FZ-A038, and a valine–alanine (Val–Ala) dipeptide linker to conjugate DXd. Moreover, Fc-silencing technology was introduced in FZ-AD005 to avoid off-target toxicity mediated by FcγRs and showed negligible Fc-mediated effector functions in vitro. In preclinical evaluation, FZ-AD005 exhibited DLL3-specific binding and demonstrated efficient internalization, bystander killing, and excellent in vivo antitumor activities in cell line–derived xenograft and patient-derived xenograft models. FZ-AD005 was stable in circulation with acceptable pharmacokinetic profiles in cynomolgus monkeys. FZ-AD005 was well tolerated in rats and monkeys. The safety profile of FZ-AD005 was favorable, and the highest nonseverely toxic dose was 30 mg/kg in cynomolgus monkeys. In conclusion, FZ-AD005 has the potential to be a superior DLL3-targeted ADC with a wide therapeutic window and is expected to provide clinical benefits for the treatment of patients with SCLC.