Population-level forecasting of CAR-T–related toxicities using meta-analytic data.

e18602 Background: Chimeric antigen receptor T-cell (CAR-T) therapy has transformed the treatment of hematologic malignancies but is frequently complicated by cytokine release syndrome (CRS) and immune-mediated neurotoxicity (NS). As CAR-T programs expand, population-level projections of treatment-related toxicities are essential for program planning and risk mitigation, yet remain poorly characterized. Methods: We performed a cohort-based forecasting analysis using pooled incidence rates of CRS and NS derived from published meta-analyses of CAR-T clinical trials. Expected numbers of toxicity events were projected for hypothetical cohorts of 100, 500, and 1,000 CAR-T–treated patients. Uncertainty was quantified using binomial 95% confidence intervals. Disease-specific projections were generated by applying stratified pooled toxicity rates for hematologic malignancies and solid tumors. Results: For a projected cohort of 1,000 CAR-T–treated patients, forecasts estimated approximately 770 patients would experience CRS of any grade, 290 would develop grade ≥3 CRS, 400 would experience NS of any grade, and 280 would develop grade ≥3 NS. Toxicity counts increased proportionally with cohort size and demonstrated predictable uncertainty bounds. When stratified by disease type, hematologic malignancies exhibited substantially higher toxicity burdens than solid tumors across all endpoints. At a cohort size of 1,000 patients, hematologic malignancies were associated with markedly higher rates of both CRS and severe neurotoxicity, whereas solid tumors demonstrated consistently lower toxicity burdens. Conclusions: Using pooled clinical trial data, this forecasting model provides quantitative estimates of CAR-T–associated toxicity burdens at the population level. Severe CRS and neurotoxicity remain common and scale predictably with program size, particularly in hematologic malignancies. These findings offer a pragmatic framework for anticipating resource utilization, toxicity management needs, and safety planning as CAR-T therapy continues to expand.