Mechanisms of failure of chimeric antigen receptor T-cell therapy

Although chimeric antigen receptor T (CART)-cell therapy is best recognized for its antitumor effect in relapsed/refractory B-cell hematological cancers, it is still associated with a high relapse rate. RECENT FINDINGS: We firstly analyzed internal immunological and genetic reasons of CD19+ relapse after treatment for R/R B-cell hematological cancers with CART19 cells. The reasons: murine-derived scFv may limit expansion of CART cells. Repeated antigen exposure leads to T-cell exhaustion. Activation of T cells can cause T-cell senescence and high expression of inhibitive receptors, PD-1, CTLA4, TIGIT, LAG-3, CD244, CD160, TIM3, which might be solved by some external pharmacological intervention methods [for instance, the use of FC (Fludarabine, Cyclophosphamide) lymphodepletion regimen, lenalidomide, PD-1 inhibitor, ibrutinib and humanized CD19-CART cells. Secondly, mechanism of CD19 relapse can be attributed to the preexisting of CD19(-) subclone, the loss or alternative RNA splicing on exon 2 of chromosome 16 on which CD19 gene is located, B-cell transcript factors – paired-box 5 (PAX5) and early B-cell factor 1 (EBF1) are down-regulated to cause lineage-switch from lymphoid to myeloid. SUMMARY: Although different preparation techniques generates various entities of CART 19 cells, these problems could be conquered by novel agents and novel CAR system. VIDEO ABSTRACT: Although Chimeric Antigen Receptor T (CART) cell therapy is best recognized for its antitumor effect in Relapsed/Refractory B-cell hematological cancers, it still shows a high relapse rate. We review mechanisms of failure of CART therapy.