Similarly, tissue lineage-specific antigen-targeted approaches (e.g., Melan-A/MART-1-specific ACT or multi-melanocytic marker peptide vaccination for melanoma; and CD19-targeted chimeric antigen receptor T cell (CAR-T) or CD19-targeted bi-specific T-cell engager for B-cell acute lymphoblastic leukemia) have demonstrated the subsequent selection for and predominance of antigen-negative subclones during disease relapse [4]. The gene discussed is CD19; the disease is B-cell acute lymphoblastic leukemia.