Recent Trends and Patient Outcomes of Phase I Trials: A Single-Institution Experience in the Era of New Therapeutic Agents

PURPOSE Phase I trials of anticancer agents have evolved after advances in tumor molecular biology and immunology. However, information on phase I trials targeting multiple solid tumors remains limited. We analyzed recent trends of phase I trials for solid tumors at a single center in Japan. MATERIALS AND METHODS This retrospective study included 806 patients with advanced solid tumors who participated in phase I trials at the National Cancer Center Hospital East, Japan, from January 2019 to December 2023. We evaluated the trends in treatments and outcomes over the study period. RESULTS A total of 40.0% of patients received molecular targeted therapy (MTA), including kinase inhibitors and antibody-drug conjugates (ADCs), while 44.8% of patients received immune-oncology (IO) agents such as anti–PD-1/PD-L1 ligand therapies and T-cell engagers (TCEs). The remaining 15.3% received other agents. The proportions of patients receiving ADCs, TCEs, and treatments on the basis of their genetic profile increased during the study period, while treatment on the basis of protein expression remained constant. No treatment-related death was observed. The overall response rate was significantly higher in patients treated with MTA (23.0%) compared with those treated with IO and other agents (10.5%), in patients in a dose-expansion (23.7%) compared with a dose-escalation cohort (11.0%), and in patients treated with biomarker selection (22.8%) compared with those without (12.4%). CONCLUSION Phase I trials increasingly used ADCs, TCEs, and biomarker-based enrollment, showing improved response rates over time. These findings might reflect recent advances in trial design and outcomes.