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Objective:To explore the efficacy and safety of blinatumomab in treatment of relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL).Methods:The data of 8 patients with relapsed/refractory B-ALL treated with blinatumomab in Shanghai Zhaxin Traditional Chinese and Western Medicine Hospital from September 2020 to December 2021 were retrospectively analyzed, and their clinical characteristics, overall survival, lymphocyte subsets, cytokines, tandem transplantation and adverse reactions were analyzed.Results:The median follow-up time of 8 patients was 143 d (range: 41-534 d). Five of the 8 patients were alive; among them, 4 of 6 patients assessed to be in minimal residual disease (MRD)-negative complete remission (CR) and 1 of 2 patients assessed to be in non-remission at the time of belintuzumab discontinuation were alive. The median duration of treatment with belintuzumab was 28 d (10-56 d), and it was 23 d (10-56 d) for patients with MRD-positive at baseline and 28 d (25-31 d) for the 4 non-remission patients. Six patients achieved MRD-negative CR after treatment, of which 4 were assessed as MRD-positive at baseline and 2 were assessed as non-remission at baseline. All 4 patients with MRD-positive CR achieved MRD-negative CR after treatment with belintuzumab, including 1 patient with Philadelphia chromosome-positive (Ph +) ALL bridged to autologous hematopoietic stem cell transplantation, and 1 patient with Ph + ALL and 1 patient with Ph - ALL received sequential allogeneic hematopoietic stem cell transplantation and had persistent MRD-negative CR. Two of the 4 non-remission patients achieved MRD-negative CR after treatment with belintuzumab, including 1 patient with Ph + ALL bridged to autologous hematopoietic stem cell transplantation, and 1 patient with Ph - ALL received sequential allogeneic hematopoietic stem cell transplantation, and the 2 patients had persistent MRD-negative CR. Leukocyte counts and neutrophils decreased in both MRD-positive CR and non-remission patients after receiving belintumomab. The proportion and absolute number of CD3 + T and CD3 + CD8 + T lymphocytes in patients with MRD-positive CR were higher than those in patients without remission, and both decreased after drug administration. Median interleukin-6 (46.23, 1.42 pg/ml), interleukin-8 (17.85, 2.10 pg/ml), interleukin-10 (7.43, 1.49 pg/ml) and interferon-γ (11.82, 0.39 pg/ml) levels were elevated in MRD-positive CR and non-remission patients at week 3 of treatment. Grade 1 cytokine release syndrome occurred in 1 case with clinical manifestations of fever, which improved after drug suspension. Three cases developed infections, 2 of which were pulmonary and 1 of which was upper respiratory tract infection. No immune effector cell-associated neurotoxic syndrome was observed. Conclusions:Belintumomab is effective for MRD clearance in relapsed/refractory B-ALL with manageable adverse reactions, providing an effective therapeutic option for bridging hematopoietic stem cell transplantation to prolong the survival of patients.
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OBJECTIVE@#To explore the genetic basis for a rare case of acute B-lymphocytic leukemia (B-ALL) with double Philadelphia chromosomes (Ph) and double derivative chromosome 9s [der(9)].@*METHODS@#A patient with double Ph and double der(9) B-ALL who presented at Shanghai Zhaxin Intergrated Traditional Chinese and Western Medicine Hospital in June 2020 was selected as the subject. Bone marrow morphology, flow cytometry, G-banding karyotyping, fluorescence in situ hybridization (FISH), genetic testing and chromosomal microarray analysis (CMA) were used to analyze bone marrow samples from the patient at various stages.@*RESULTS@#At initial diagnosis, the patient's bone marrow morphology and flow immunotyping have both supported the diagnosis of B-ALL. G-banded karyotyping of the patient indicated double Ph, in addition with hyperdiploid chromosomes involving translocations between chromosomes 9 and 22. BCR-ABL1 fusion gene was positive. Genetic testing at the time of recurrence revealed presence of a heterozyous c.944C>T variant in the kinase region of the ABL1 gene. FISH showed a signal for ABL1-BCR fusion on both chromosome 9s. CMA showed that the mosaicism homozygosity ratio of chromosome 9 was about 40%, and the mosaicism duplication ratio of chromosome 22 was about 43%.@*CONCLUSION@#Since both der(9) homologs were seen in 40% of cells, the possible mechanism for the double der(9) in this patient may be similar to that of double Ph, which might have resulted from non-disjunction during mitosis in the Ph chromosome-positive cell clone.