Regulatory programs of B-cell activation and germinal center reaction allow for B-ALL escape from CD19 CAR T-cell therapy
Ontology highlight
ABSTRACT: CAR T-cell therapy has led to tremendous successes in the treatment of B-cell malignancies. However, 30%-50% of treated patients relapse – often with reduced target antigen expression. We report that anti-CD19 CAR T-cells cause a rapid reduction of CD19 expression within hours in CAR-T exposed CD19+ B-ALL cells. Initially, anti-CD19 CAR T-cells cause CD19 clusters at the T-cell – leukemia cell interface followed by CD19 internalization and decreased CD19 surface expression. Subsequently, CD19 expression is repressed by transcriptional rewiring. Using single-cell RNA-seq and single-cell ATAC-seq we demonstrate that a subset of CD19low cells that are refractory to CAR T-cell killing employ transcriptional programs of physiological B-cell activation and germinal center reaction in order to sustain decreased CD19 expression. Inhibiting B-cell activation programs with the BTK inhibitor ibrutinib increased the cytotoxic efficacy of anti-CD19 CAR T-cells without effecting CAR T-cell viability. These results demonstrate transcriptional plasticity as an underlying mechanism of CAR T-resistance and highlight the importance of combining CAR T-cell therapy with targeted therapies that aim to overcome this plasticity.
Project description:While therapies targeting CD19 by antibodies, CAR-T cells and T cell engagers have improved the response rates in B-cell malignancies; the emergence of resistant cell populations with low CD19 expression can lead to relapsed disease. We developed an in vitro model of adaptive resistance facilitated by chronic exposure of leukemia cells to a CD19-immunotoxin. Single-cell (sc) RNAseq showed increase in transcriptionally distinct CD19low populations in resistant cells. Mass cytometry demonstrated that CD22 was also decreased in these CD19low resistant cells. ATAC-seq showed decreased chromatin accessibility at promoters of both CD19 and CD22 in the resistant cell populations. Combined loss of both CD19 and CD22 antigens was validated in samples from pediatric and young adult patients with B-ALL that relapsed after CD19 CAR-T targeted therapy. Functionally, resistant cells were characterized by slower growth and lower basal levels of MEK activation. CD19low resistant cells exhibited preserved B cell receptor signaling and were more sensitive to both BTK and MEK inhibition. These data demonstrate that resistance to CD19 immunotherapies can result in decreased expression of both CD19 and CD22 and can result in dependency on BTK pathways.
Project description:While therapies targeting CD19 by antibodies, CAR-T cells and T cell engagers have improved the response rates in B-cell malignancies; the emergence of resistant cell populations with low CD19 expression can lead to relapsed disease. We developed an in vitro model of adaptive resistance facilitated by chronic exposure of leukemia cells to a CD19-immunotoxin. Single-cell (sc) RNAseq showed increase in transcriptionally distinct CD19low populations in resistant cells. Mass cytometry demonstrated that CD22 was also decreased in these CD19low resistant cells. ATAC-seq showed decreased chromatin accessibility at promoters of both CD19 and CD22 in the resistant cell populations. Combined loss of both CD19 and CD22 antigens was validated in samples from pediatric and young adult patients with B-ALL that relapsed after CD19 CAR-T targeted therapy. Functionally, resistant cells were characterized by slower growth and lower basal levels of MEK activation. CD19low resistant cells exhibited preserved B cell receptor signaling and were more sensitive to both BTK and MEK inhibition. These data demonstrate that resistance to CD19 immunotherapies can result in decreased expression of both CD19 and CD22 and can result in dependency on BTK pathways.
Project description:To characterize transfer of molecules from target cells into CAR T cells via trogocytosis we cultured NALM-6 leukemia cell line expressing a CD19-mCherry fusion protein with CAR T cells. NALM6-CD19-mCherry were loaded with heavy amino acid and cocultured with CAR T cells for 1 hour. CAR T cells were next sorted into two fractions, mCherry-positive (TrogPos), and -negative (TrogNeg). Proteomics analysis revealed the presence of targeted antigen (CD19) in the TrogPos only.
Project description:RNA-seqeuncing of mock-electroporated (wild-type) anti-CD19 CAR T cells or BTLA-knockout anti-CD19 CAR T cells following repeated stimulation with OCI-Ly18 (CD19+ DLBCL cell line) Analyzed data used in Fig 7j
Project description:Zebley et al. show that CD8+ CD19-CAR T cells undergo genome-wide DNA methylation changes during an anti-tumor response in patients with B-cell acute lymphoblastic leukemia (ALL). Post-infusion CAR T cell differentiation involves acquisition of DNA methylation programs associated with effector function, repression of memory potential, and transition toward exhaustion.
Project description:Adoptive transfer of chimeric antigen receptor (CAR)-T cells is expected to become the first line of treatment for multiple malignancies, following the enormous success of anti-CD19 therapies. However, their mechanism of action is not fully understood, and clear guidelines for the design of safe and efficient receptors are missing. We hereby describe a systematic analysis of the CAR “signalosome” in human primary T cells. Two CAR designs were compared: a second-generation (PSCA2) and a third-generation (PSCA3) anti-PSCA CAR. Phosphorylation events triggered by CAR-mediated recognition of target cells were quantified by mass spectrometry.
Project description:A significant challenge for chimeric antigen receptor (CAR) T cell therapy against glioblastoma (GBM) is its immunosuppressive tumor microenvironment (TME), which is densely populated and supported by protumoral glioma-associated microglia and macrophages (GAMs). Targeting CD47, a don't-eat-me signal overexpressed by tumor cells, disrupts the CD47-SIRPalpha axis and induces GAM phagocytic function. However, antibody-mediated CD47 blockade monotherapy is associated with toxicity and low bioavailability in solid tumors. To overcome these limitations, we combined local CAR T cell therapy with paracrine GAM modulation to effectively eliminate GBM. To this end, we engineered a new CAR T cell against epidermal growth factor receptor variant III (EGFRvIII) that constitutively secretes a signal regulatory protein gamma (SIRPgamma)-related protein (SGRP) with high affinity to CD47. Anti-EGFRvIII-SGRP CAR T cells eliminated EGFRvIII+ GBM in a dose-dependent manner in vitro and eradicated orthotopically xenografted EGFRvIII-mosaic GBM by locoregional application in vivo. This resulted in significant tumor-free long-term survival, followed by partial tumor control upon tumor re-challenge. Combining anti-CD47 antibodies with anti-EGFRvIII CAR T cells failed to achieve a similar therapeutic effect, underscoring the importance of sustained paracrine GAM modulation. Multidimensional brain immunofluorescence microscopy and in-depth spectral flow cytometry on GBM-xenografted brains showed that anti-EGFRvIII-SGRP CAR T cells accelerated GBM clearance, increased CD68+ cell trafficking to tumor scar sites and promoted GAM-mediated tumor cell uptake. In a peripheral lymphoma mouse xenograft model, anti-CD19-SGRP CAR T cells had superior efficacy to conventional anti-CD19 CAR T cells. Validation on human GBM explants revealed that anti-EGFRvIII-SGRP CAR T cells had a similar tumor-killing capacity to anti-EGFRvIII CAR monotherapy but showed a slight improvement in the maintenance of tumor-infiltrated CD14+ cells. Thus, local anti-EGFRvIII-SGRP CAR T cell therapy combines the potent antitumor effect of engineered T cells with the modulation of the surrounding innate immune TME. This results in the additive elimination of bystander EGFRvIII- tumor cells in a manner that overcomes the main mechanisms of CAR T cell therapy resistance, including tumor innate immune suppression and antigen escape.
Project description:<p>Anti-CD19 chimeric antigen receptor (CAR) T-cell therapy for relapsed or refractory (r/r) large B-cell lymphoma (LBCL) results in durable response in only a subset of patients. MYC overexpression in LBCL tumors is associated with poor response to treatment. We tested whether a MYC-driven polyamine signature, as a liquid biopsy, is predictive of response to anti-CD19 CAR-T therapy in patients with r/r LBCL. Elevated plasma acetylated polyamines were associated with non-durable response. Concordantly, increased expression of spermidine synthase, a key enzyme which regulates levels of acetylated spermidine, was prognostic for survival in r/r LBCL. A broad metabolite screen identified additional markers which resulted in a 6-marker panel (6MetP) consisting of acetylspermidine, diacetylspermidine and lysophospholipids which was validated in an independent set from another institution as predictive of non-durable response to CAR T therapy. A polyamine centric metabolomics liquid biopsy panel has predictive value for response to CAR-T therapy in r/r LBCL. </p>
Project description:Adoptive transfer of chimeric antigen receptor (CAR)-T cells is expected to become the first line of treatment for multiple malignancies, following the enormous success of anti-CD19 therapies. However, their mechanism of action is not fully understood, and clear guidelines for the design of safe and efficient receptors are missing. We hereby describe a systematic analysis of the CAR “interactome” in human primary T cells, which allowed us to identify molecular traits that influence CAR-T cell efficacy. Interactome analysis was based on immunoprecipitation of CARs followed by protein identification by mass spectrometry.
Project description:Adoptive cell therapy, a subset of cancer immunotherapy, is collection of therapeutic approaches which aim to redirect the immune system by reprogramming patient T-cells to target antigenic molecules differentially and specifically expressed in certain cancers. One promising immunotherapy technique is CAR T-cell therapy, where cancer cells are targeted through the expression a chimeric antigen receptor (CAR), a synthetic trans- membrane receptor that functionally compensates for the T-cell receptor (TCR) but targets a tumor associated antigen on the cancer cell surface. While CAR T-cell therapy is promising with two clinically approved second-generation CARs (Kymriah and Yescarta), few studies have investigated the mechanism of signal propagation in T-cells and no studies have investigated the potential signaling response in the target cells. To gain further insight to CAR-based signaling, we stimulated third generation CD19 CAR-expressing Jurkat T-cells by co-culture with SILAC labeled CD19HI Raji B-cells and used two phosphoenrichment strategies coupled with liquid chromatography-tandem mass spec- trometry (LC-MS/MS) to detect and analyze global phosphorylation changes in both cell populations. Analysis of the phosphopeptides originating from the CD19-CAR T cells revealed an increase in many phosphorylation events necessary for canonical TCR signaling. We also observed for the first time a significant decrease in B-cell receptor- related phosphopeptide abundance in CD19HI Raji B-cells after co-culture with CD19-targetted CAR T-cells.