Abstract
Early-phase clinical trials (EPCTs) have been increasingly adopted as the pivotal trial to support US Food and Drug Administration (FDA) approval of novel anticancer drugs. Among EPCT designs, dose-escalation and -expansion cohort (DEEC) substantially reduces the time and resources that are required in the traditional three-phase paradigm. DEEC facilitates expedited approvals of investigational drugs, particularly those targeting novel mechanisms, helping to address the pressing needs of patients with cancer. From 2012 to 2023, DEECs provided pivotal trial evidence that supported the FDA approval for 46 indications across 36 targeted anticancer drugs. Dose escalation uses 3 + 3, Bayesian optimal interval design, or continual reassessment method to explore the optimal dose level, whereas expansion cohorts directly incorporate dose-escalation cohort at the recommended phase II dose level. Expansion cohorts adopt flexible designs such as basket, umbrella, and platform trials. In addition, each expansion cohort in DEEC often uses adaptive approaches, such as Simon's two-stage design. To avoid the bias of end point assessment, conducting DEEC trials requires end point adjudication, often by an independent review committee. The design, conduct, and analysis of DEEC trials each have distinct characteristics. However, these characteristics were often overlooked in DEEC reporting. We reviewed the structural domains and items in trial design and conduct and discussed the strengths and limitations of DEEC studies, aiming to enhance the utilization of this trial design to generate higher-quality clinical evidence and ultimately contribute to better outcomes for patients with cancer.