Clinical Pharmacology Characterization of Bispecific T-Cell Engagers: A Summary Based on FDA Approvals

Bispecific T-cell engagers (Bi-TCEs) have demonstrated clinical efficacy and safety, with 7 approved for hematological cancers and 2 approved for solid tumors by the US Food and Drug Administration (FDA) as of May 2025. Its intricate mechanism of action through the formation of a trimer involving Bi-TCE, T cell, and tumor cell presents challenges to clinical development requiring special strategies for multiple disciplines. This review summarizes key clinical pharmacology characterizations of these 9 FDA-approved Bi-TCEs to understand the current practice and to identify potential knowledge gaps. The topics covered include dosing strategies, general clinical pharmacology evaluations, and cytokine-related drug-drug interaction (DDI) assessment. The dosing strategy part discusses the criteria for step-up dose and full treatment dose selection, the potential for further optimization of dose regimen in later cycles, and the analyses supporting the restarting strategy after dosage delay. The section on general clinical pharmacology evaluations summarizes pharmacokinetic (PK) property and its impact on dosing strategy, PK in specific populations (e.g., organ impairment, pediatrics), pharmacodynamics property, and immunogenicity information. The cytokine-related DDI part discusses cytokine profiles, risk mitigation strategy, and physiologically based PK (PBPK) models and their limitations. Finally, future perspectives are provided regarding efficient dose selection, PBPK modeling application, and Bi-TCEs for solid tumors and non-oncology indications.