CD19 antigen loss after treatment of Bispecific T-cell Engager and effective response to salvage bispecific CAR-T therapy in B cell acute lymphoblastic leukemia: a case report and literature review
10.3760/cma.j.issn.0253-2727.2020.04.004
- VernacularTitle:双靶点嵌合抗原受体T细胞治疗CD19抗原表位缺失急性B淋巴细胞白血病一例报告并文献复习
- Author:
Xuehang FU
1
;
Ying WANG
;
Huijun WANG
;
Shuning WEI
;
Yingxi XU
;
Haiyan XING
;
Kejing TANG
;
Zheng TIAN
;
Qing RAO
;
Jianxiang WANG
;
Min WANG
Author Information
1. 中国医学科学院血液病医院（中国医学科学院血液学研究所），实验血液学国家重点实验室，国家血液系统疾病临床医学研究中心，天津 300020
- Keywords:
Leukemia, lymphoblastic, acute;
Bispecific T-cell engagers;
Epitope-loss;
Isoform;
CD19
- From:
Chinese Journal of Hematology
2020;41(4):282-286
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To analyze the influence of CD19 isoforms to the efficacy of CD19/CD3 Bispecific T-cell Engager (BiTE) antibody, and explore the resistance mechanism of BiTE immunotherapy.Methods:Semi-quantitative RT-PCR (qRT-PCR) was used to detect the expression of CD19 mRNA isoforms before and after BiTE treatment in a patient with CD19 + B cell acute lymphoblastic leukemia (ALL) . CD19 isoforms were analyzed by Sanger sequencing. Flow cytometry and transcriptome sequencing were performed to analyze the expression of cell lineage specific molecules before and after BiTE treatment. Results:The expression of CD19 isoform with exon 2 deletion was identified at diagnosis. After relapsed and treatment of BiTE antibody, the patient did not achieve remission and CD19 antigen on leukemic cells turned negative detected by flow cytometry after BiTE treatment. However the expression ratio of CD19 isoform with exon 2 deletion was not increased. Flow cytometry phenotype and transcriptome sequencing confirmed that no linage switching developed, which suggested the expression of CD19 isoform caused by exon alternative splicing and lineage switching was not related to CD19 epitope loss in this patient. This patient achieved complete remission by sequential administration of self-developed CD22 CAR-T and CD19 CAR-T after disease progression.Conclusion:Targeting or combining an alternative antigen specific CAR-T may be a promising treatment option after losing CD19 expression in relapsed ALL.
