A systematic review and meta-analysis estimated second primary malignant neoplasms (SPMs) following treatment with T-cell–engaging bispecific antibodies used in B-cell non-Hodgkin lymphoma and multiple myeloma. The analysis, published via PubMed and based on searches through October 1, 2025, pooled data from 20 studies and 2,551 patients across included cohorts. The review reported a pooled estimated proportion of total SPMs of 3.5% (95% CI, 1.8–6.9) at a median follow-up of 17.4 months, with additional pooled estimates for SPMs leading to treatment discontinuation (2.2%) and SPMs leading to death (1.4%). Exploratory meta-regression did not identify study-level covariates that explained total SPM variation. For developers and clinicians, the report provides a clearer long-term safety baseline as bispecific antibodies expand earlier in treatment lines—highlighting that longer follow-up will still be required to refine risk estimates.