Updates on Antibody Drug Conjugates and Bispecific T-Cell Engagers in SCLC

Background/Objectives: Small-cell lung cancer (SCLC) is an aggressive neuroendocrine malignancy characterized by rapid proliferation, early metastasis, and near-universal relapse after initial therapy. While chemo-immunotherapy modestly improves first-line outcomes, survival after progression remains poor and highlights the urgent need for biomarker-directed strategies. Methods: A comprehensive literature search was conducted using major medical databases looking at key relevant studies on SCLC antibody studies. All authors reviewed the literature, assessed study quality, and interpreted the results from each study. Results: Recent advances in antibody–drug conjugates (ADCs) and T-cell engagers (TCEs) have transformed therapeutic development by targeting antigens selectively expressed on SCLC cells, enabling more precise and potentially durable tumor control. DLL3 has emerged as the most clinically relevant target to date, with the bispecific TCE tarlatamab demonstrating meaningful and durable response, manageable cytokine-release toxicity, and ultimately achieving accelerated FDA approval for previously treated extensive-stage SCLC. Concurrently, DLL3-directed ADCs have shown variable efficacy, underscoring the importance of payload selection, linker chemistry, and antigen density. Beyond DLL3, next-generation ADCs targeting TROP2, B7-H3, and SEZ6 have reported encouraging early-phase activity, including response rates exceeding those of existing second-line cytotoxic options, though myelosuppression, interstitial lung disease, and hepatic toxicity remain key considerations. Conclusions: Collectively, these emerging immunotherapies illustrate a shift toward antigen-specific targeting in a disease historically defined by limited therapeutic innovation. Continued optimization of antigen selection, payload and linker engineering, and biomarker-driven trial design will be critical for translating early promise into durable clinical benefit and reshaping the treatment landscape for SCLC.