A systematic review and meta-analysis estimated the frequency of second primary malignant neoplasms after T-cell–engaging bispecific antibody therapy in adult NHL and multiple myeloma. The analysis pooled outcomes from 20 studies comprising 2,551 patients reporting total second primary malignancies and found a pooled estimate of 3.5% at a median follow-up of 17.4 months. The paper reported pooled estimates of 2.2% for second primary malignancies leading to treatment discontinuation and 1.4% for second primary malignancies leading to death. Exploratory meta-regression did not identify study-level drivers of total second primary malignancies estimates, but the authors emphasized limitations tied to short follow-up and heterogeneous reporting. As T-cell–engaging bispecifics move earlier in treatment and broaden in use, the review provides a measurable, clinically relevant long-term safety signal while underscoring the need for longer observation windows.