[CART therapy followed by allo-HSCT for patients with B-cell acute lymphoblastic leukemia relapsing after the first hematopoietic stem cell transplantation].

Objective: To study the clinical efficacy of chimeric antigen receptor T-cell (CART) treatment followed by a second allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with B-cell acute lymphoblastic leukemia (ALL) who relapsed following the first HSCT. Methods: Retrospective analysis of the clinical characteristics and prognosis of 41 patients with B-cell ALL who received a second allo-HSCT from October 2015 to June 2020 in Hebei Yanda Lu Daopei Hospital. After the first HSCT, all patients received CD19-CART, or CD22-CART treatment following a relapse of bone marrow morphology or extramedullary leukemia. Results: A total of 41 patients (male, 21; female, 20) were included in this study. The median age at the second HSCT was 16 (3-46) years. There were 31 cases of bone marrow recurrence (75.6%) , 5 cases of extramedullary recurrence (12.2%) , and 5 cases of bone marrow and extramedullary recurrences (12.2%) . After relapse, 35 patients (85.4%) received CD19-CART treatment, 2 patients received CD22-CART treatment (4.9%) , and 4 patients received CD19-CART and CD22-CART treatments (9.8%) . The expected 3-year overall survival (OS) , leukemia-free survival, cumulative relapse incidence, and non-relapse mortality (NRM) of patients after the second HSCT were 48.9% (95%CI 23.0%-70.6%) , 41.8% (95%CI 17.3%-64.9%) , 8.8% (95%CI 2.9%-26.4%) , and 51.1% (95%CI 31.2%-83.6%) , respectively. The 1-year OS of patients who relapsed ≤6 months and >6 months after the first HSCT were 45.0% (95%CI 12.7%-73.5%) and 75.0% (95%CI 51.4% -88.8%) (P=0.017) , respectively. Conclusion: CART bridging in the second HSCT enables some B-cell ALL patients who relapsed after the first HSCT to achieve long-term survival. However, because of the high NRM, further modifications could help improve the outcome.