Abstract: The mortality rate of the acute lymphocyte disease is extremely high, and CAR-T cell immunotherapy
provides a new choice. This paper introduced a refractory acute B-lymphoblastic leukemia (B-ALL) patient with TP53
positive mutation and short-term recurrence after remission from CD19 CAR-T therapy. The case was successfully treated
by CD22 CAR-T combined with allogeneic hematopoietic stem cell transplantation. The proportions of peripheral blood
CD19 CAR-T and CD22 CAR-T cells were analyzed by flow cytometry. The expression of CAR gene in peripheral blood was
detected by PCR method. The efficacy and the side effects of CD19 CAR-T and CD22 CAR-T therapy were observed in this
patient. The CD19 CAR-T and CD22 CAR-T cell treatments both achieved complete remission on the day 14, and the side
effects were minor. But bone marrow recurrence 2 weeks after remission from CD19 CAR-T cell therapy with abnormal 19  CAR gene expression in peripheral blood and increased TP53 mutation level. The patient was successfully treated with CD22
CAR-T cells bridged with haploid hematopoietic stem cell transplantation therapy. In a word, the purity of CD3+ cells should
be further improved in the process of CAR-T cell manufacture. CD22 CAR-T therapy could be used as a salvage measures
for the patient with relapse of CD19 CAR-T therapy.

Key words: acute lymphoblastic leukemia, CD19 chimeric antigen receptor engineered T cell, CD22 chimeric antigen
receptor engineered T cell, mutation of TP53 gene, hematopoietic stem cell transplantation