Effects of CD4⁺ T-cell responses to 2 pools of mCAR19 peptides on tisagenlecleucel transgene expansion and patient outcomes in pediatric and young adult patients with r/r B-ALL. Tisagenlecleucel transgene expansion (A-B) and patient outcomes (C-D). Patients from the ELIANA trial are indicated by blue circles, and patients from the ENSIGN trial are indicated by red triangles. Maximum T-cell responses are grouped by response category. Negative response data represent patients whose posttreatment T-cell responses were lower than their baseline responses. CRi, CR with incomplete blood count recovery; NR, no response.