Background: “Rare cases of Burkitt leukemia/lymphoma (BL) exhibiting a precursor B-cell phenotype (termed herein pre-BLL) were admitted by WHO Classification of Hematopoetic and Lymphoid Tissue, recent evidence suggests that these neoplasms genetically and epigenetically resemble precursor B-cell leukemia/lymphoma (pB-acute lymphoblastic leukemia/lymphoblastic lymphoma (ALL)/LBL) rather than BL. The clinical features and treatment of childhood pre-BLL with C-myC rearrangement are poorly understood. Methods：The clinical features, treatment strategies and follow-up information of 9 cases with pre-BLL diagnosed by Shanghai Children’s Medical Center affiliated to Shanghai Jiao Tong University School of Medicine from 2011 to 2020 were retrospectively analyzed. Results: All the 9 cases were confirmed to be pre-BLL by flow cytometry and fluorescence in situ hybridization, morphological classification were L2/L3, immunophenotype was CD10, CD19 positive, CD20, TDT, CD34 selective expression, sIgM negative, Kappa and Lambda light chain negative. Most of the pre-BLL cases were accompanied by elevated lactate dehydrogenase (LDH), uric acid levels. 5 cases received intensive chemotherapy with overlapping regimen, and all achieved sustained remission except for 1 case relapse and death. Among the 4 cases who received low-intensity chemotherapy for acute lymphoblastic leukemia, 2 cases died due to early relapse of the disease. Conclusions: Pre-BLL cases are rare. and intensive chemotherapy treatment according to protocols for mature B-cell NHL. Currently, the treatment strategies are still controversial. Considering the small number of cases, multi-center clinical studies should be actively carried out to find a standard treatment plan.

Background: Anti-CD19 Chimeric Antigen Receptor T-Cell Immunotherapy (19CAR-T) has achieved impressive clinical achievements in both adult and pediatric relapsed/refractory (r/r) B-lineage acute lymphoblastic leukemia (B-ALL). However, the application and effect of CAR-T therapy in B-ALL patients with extramedullary relapse are rarely issued even disqualified in some clinical trials. Here, we examined the efficacy of 19CAR-T in patients with both bone marrow and extramedullary involvement. Methods: CAR-T cells were generated by a lentiviral vector transfection into primary human T lymphocytes to express anti-CD19 and anti-CD22 single chain antibody fragments (scFvs) with the cytoplasmic domains of 4-1BB and CD3ζ. Patients diagnosed as r/r B-ALL with extramedullary origination were infused with anti-CD19 CAR-T cells. The clinical responses were evaluated by bone marrow aspiration, imaging, and flow cytometry examination. Results: A total of 8 patients received 19CAR-T infusion and all of them acquired complete remission (CR), in which only 1 patient was bridged to hematopoietic stem cell transplantation (HSCT). Even though there were 3 patients relapsed after infusion, they received 19/22CAR-T infusion sequentially and acquired the second remission. To date, 5 patients are continuous CR, and all patients are still alive. The mean follow-up time was 21.9 months while the 24-month estimated event-free survival (EFS) is 51.4%. Conclusions: Anti-CD19 CAR-T therapy can lead to clinical remission for extramedullary relapsed pediatric B-ALL patients. However, the problem of CD19+ relapses after CAR-T remained to be solved. For patients relapsing after CAR-T, the second CAR-T therapy suggests creating another opportunity of remission for subsequent HSCT.