Background before CAR T-cell therapy
A 12-year-old girl was diagnosed with B-ALL 14 months ago. Bone marrow (BM) morphology showed that lymphoblastic cells occupied 46%. Immunophenotype via flow cytometry (FCM) demonstrated 51% malignant cells expressing CD38+, CD10+, CD19+, CD20+, CD34+, HLA-DR+, CD71+, and cCD79a+. Genetic examination showed no specific fusion gene. According to CCLG 2008 protocol(12), she was classified as intermediate risk. She received five courses of intense chemotherapy, and minimal residual disease (MRD) was continuously positive. Three months ago, the BM test showed relapse. Then, she received continuous strengthened chemotherapy, including vincristine, doxorubicin, L-asparaginase, ifosfamide, and three doses of bortezomib. The BM morphology still showed no remission. She was diagnosed as R/R ALL and recruited to the CAR T-cell clinical trial. This trial was registered at the Chinese Clinical Trial Registry as study ChiCTR-OPN-17013507.