Anti-CD19 immunotherapy based on antibody conjugated drugs or CD19-CAR-T cells has demonstrated unprecedented positive response in relapsing/refractory B-cell acute lymphoblastic leukemia (r/r B-ALL). However, many patients still relapse and up to 30-50% of those relapses are characterized by the loss of CD19 surface antigen. Patients with CD19-negative relapse usually have a poor prognosis. The mechanisms underlying CD19-negative relapses are not fully understood and it is important to develop solutions to supplement post-CD19 immunotherapies.

Potential markers for recurrent leukemic blasts in an emerging CD19-negative blast population include many known B-cell lineage antigens. To prevent further target escape and improve the therapeutic effects, the 4th generation CAR gene-modified T cells targeting CD22, CD10, CD20, CD38, or CD123 have been considered in post anti-CD19 treatment. This study aims to evaluate safety and efficacy of administrating one or multiple non-CD19 targeting CAR-T cells to patients with CD19-escaped B cell malignancies.