Point mutation inCD19facilitates immune escape of B cell lymphoma from CAR-T cell therapy

Abstract

BackgroundTumor relapse due to mutation in CD19 can hinder the efficacy of chimeric antigen receptor (CAR)-T cell therapy. Herein, we focused on lymphoma patients whose B cells exhibited a point mutation in CD19 of B cells after CAR-T cell infusion.MethodsThe CAR-T and CD19+ B cells from peripheral blood or bone marrow were assessed using flow cytometry. Genome sequencing was conducted to identify the molecular characteristics of CAR-T and CD19+ B cells from pre-relapse and postrelapse samples. CD19 in CARs comprising single chain fragments variable (scFV) antibody with FMC63 or 21D4 was constructed. The cytotoxic efficacy of CAR-T cells was also evaluated via in vitro and in vivo experiments.ResultsA patient with high-grade B cell lymphoma exhibited complete response, but the lymphoma relapsed in her left breast at 6 months after CD19 CAR (FMC63)-T cell infusion. A mutation was found in exon 3 of CD19 (p.163. R-L) in malignant B cells of the patient. In two lymphoma patients who exhibited resistance to CAR-T cell therapy, a mutation was detected in exon 3 of CD19 (p.174. L-V). Functional analysis revealed that FMC63 CAR-T cells exhibited antitumor ability against wild-type CD19+ cells but were unable to eradicate these two types of mutated CD19+ cells. Interestingly, 21D4 CAR-T cells were potentially capable of eradicating these mutated CD19+ cells and exhibiting high antitumor capacity against CD19+ cells with loss of exon 1, 2, or 3.ConclusionsThese findings suggest that point mutation can facilitate immune escape from CAR-T cell therapy and that alternative CAR-T cells can effectively eradicate the mutated B cells, providing an individualized therapeutic approach for lymphoma patients showing relapse.

Genomic drivers of large B-cell lymphoma resistance to CD19 CAR-T therapy

“…The last case with CD19 L174V is an emblematic example reflecting the complexity of the anti-tumor activity promoted by CAR-19. An identical mutation was found as clonal at baseline in a patient that was completely refractory to CAR-19 treatment (Figure 5A, top) 50 . In line with this prior evidence, in our patient we would have expected a CAR CD19 mediated eradication of all CD19 wild type (wt) cells, but not of the one harboring CD19 L174V mutation (Figure 5a, middle).…”

“…Past studies have assessed loss of CD19 as a mechanism of resistance to CAR-19 therapy 49 . Although individual examples of such cases demonstrate lack of response 50 , this mechanism of escape seems to explain only a small proportion of resistance in DLBCL 51 . In our cohort, pre-treatment CD19 expression was tested in 20 cases by flow cytometry, with 3 (15%) having reduced expression.…”

The landscape of bispecific T cell engager in cancer treatment

“…One patient with CD19-negative relapse presented both antigen mutations and increased alternatively spliced RNA isoforms, suggesting they are likely to occur in parallel and responsible for antigen loss [94]. Alternative splicing and CD19 mutations were also demonstrated in other CD19-targeted immunotherapies such as CAR T cell therapy [122,123]. Interestingly, the lineage switch of B lymphocytes from the lymphoid lineage to the myeloid lineage can be seen in patients with B-ALL who experienced CD19-directed immunotherapy in which CD19 expression was lost while myeloid marker levels such as CD33 were upregulated [124,125].…”

CAR T-Cells for CNS Lymphoma: Driving into New Terrain?

“…The frequency of antigen loss in lymphoma is less clear given that biopsies are rarely obtained during relapse. However, several of such cases have been described after CAR T-cell therapy for systemic lymphoma [37], and antigen loss might therefore be also relevant for PCNSL [38]. In the future, (re-)biopsies of cerebral manifestations should be encouraged for antigenic profiling of the new lesion in order to substantiate the presence of druggable targets.…”