Project description:Cellular immunotherapy using T cells engineered to express chimeric antigen receptors targeting CD19 (CART19) leads to long-term remission in patients with B-cell malignancies1-5. Unfortunately, a significant fraction of patients demonstrate primary resistance to CART19 or experience relapse after achieving remission. Beyond loss of target antigen, the molecular pathways governing CART19 failure are unknown. Here we demonstrate that death receptors, cell surface signaling molecules that induce target cell apoptosis, are key mediators of leukemic resistance and CART19 failure. Using a functional CRISPR/Cas9-based genome-wide knockout screen6 in B-cell acute lymphoblastic leukemia (ALL), we identified the death receptor signaling pathway as a central regulator of sensitivity to CART19-induced cell death. In the absence of the pro-apoptotic death receptor signaling molecules BID or FADD, ALL cells were resistant to CART19 cytotoxicity, resulting in rapid disease progression in mice. We found that this initial resistance to cytotoxicity led to persistence of tumor cells, which drove the development of T cell dysfunction that further compromised anti-tumor immunity and permitted tumor outgrowth. We validated these findings using clinical samples collected from patients with ALL treated with CD19-targeted CAR T cells and found that expression of pro-apoptotic death receptor pathway genes in pre-treatment tumor samples correlated with CAR T cell expansion and persistence, as well as patient response and overall survival. Our findings indicate that tumor-intrinsic death receptor signaling directly contributes to CAR T cell failure.
Project description:Cellular immunotherapy using T cells engineered to express chimeric antigen receptors targeting CD19 (CART19) leads to long-term remission in patients with B-cell malignancies1-5. Unfortunately, a significant fraction of patients demonstrate primary resistance to CART19 or experience relapse after achieving remission. Beyond loss of target antigen, the molecular pathways governing CART19 failure are unknown. Here we demonstrate that death receptors, cell surface signaling molecules that induce target cell apoptosis, are key mediators of leukemic resistance and CART19 failure. Using a functional CRISPR/Cas9-based genome-wide knockout screen6 in B-cell acute lymphoblastic leukemia (ALL), we identified the death receptor signaling pathway as a central regulator of sensitivity to CART19-induced cell death. In the absence of the pro-apoptotic death receptor signaling molecules BID or FADD, ALL cells were resistant to CART19 cytotoxicity, resulting in rapid disease progression in mice. We found that this initial resistance to cytotoxicity led to persistence of tumor cells, which drove the development of T cell dysfunction that further compromised anti-tumor immunity and permitted tumor outgrowth. We validated these findings using clinical samples collected from patients with ALL treated with CD19-targeted CAR T cells and found that expression of pro-apoptotic death receptor pathway genes in pre-treatment tumor samples correlated with CAR T cell expansion and persistence, as well as patient response and overall survival. Our findings indicate that tumor-intrinsic death receptor signaling directly contributes to CAR T cell failure.
Project description:Cellular immunotherapy using T cells engineered to express chimeric antigen receptors targeting CD19 (CART19) leads to long-term remission in patients with B-cell malignancies1-5. Unfortunately, a significant fraction of patients demonstrate primary resistance to CART19 or experience relapse after achieving remission. Beyond loss of target antigen, the molecular pathways governing CART19 failure are unknown. Here we demonstrate that death receptors, cell surface signaling molecules that induce target cell apoptosis, are key mediators of leukemic resistance and CART19 failure. Using a functional CRISPR/Cas9-based genome-wide knockout screen6 in B-cell acute lymphoblastic leukemia (ALL), we identified the death receptor signaling pathway as a central regulator of sensitivity to CART19-induced cell death. In the absence of the pro-apoptotic death receptor signaling molecules BID or FADD, ALL cells were resistant to CART19 cytotoxicity, resulting in rapid disease progression in mice. We found that this initial resistance to cytotoxicity led to persistence of tumor cells, which drove the development of T cell dysfunction that further compromised anti-tumor immunity and permitted tumor outgrowth. We validated these findings using clinical samples collected from patients with ALL treated with CD19-targeted CAR T cells and found that expression of pro-apoptotic death receptor pathway genes in pre-treatment tumor samples correlated with CAR T cell expansion and persistence, as well as patient response and overall survival. Our findings indicate that tumor-intrinsic death receptor signaling directly contributes to CAR T cell failure.
Project description:RNA sequencing was performed on three biological replicates of CART19 (GM-CSF wildtype), GM-CSF knockout CART19, and Ctrl gRNA CART19 produced from normal donors.
Project description:RNA sequencing was performed on three biological replicates of DMSO treated CART19 (control) and TP0903 treated CART19 produced from normal donors.
Project description:We performed single-cell RNA sequencing of a lymphoma (OCI-Ly18) subcutaneous tumor harvested from NSG mice two weeks after infusion with CART19 plus DMSO or CART19 plus Venetoclax (Suppl. Fig. 3A). Lymphoma cells with shared gene expression profiles were clustered using uniform manifold and approximation (UMAP) analysis. We identified six clusters characterized by different cell-cycle phases (Suppl. Fig. 3B), including one G1-dominant cluster, two S clusters, one G1/G2 cluster, one G2/M cluster, and an M cluster with high Ki67 expression. First, we observed a substantially lower proportion of cells assigned to G1-dom in the CART19/venetoclax-treated condition (8.4%) than in the CART19-treated condition (24%). These indicated a prevalent depletion of the G1-dom cluster by the addition of venetoclax (Suppl. Fig. 4C). In accordance with recent reports that venetoclax can induce cell cycle arrest and death in tumor cells in G1 39, these results suggest that venetoclax treatment also enhances CART’s anti-tumor efficacy by hindering the progression of cell cycle. Interestingly, the “G1-dominant (G1-dom)” and the additional “MKI67hi” cluster (high proliferative cells) showed significant enrichment of genes corresponding to interferon-gamma responsiveness, suggesting that the cells of these two clusters might have been interacting with CART cells (Suppl. Fig. 4D). Of note, by performing GO enrichment analysis with differentially expressed genes (DEGs) between CART19 and CART19/venetoclax combination in the MKI67hi cluster that represent a rapidly proliferating tumor subpopulation, we identified several pathways, including enrichment of the negative regulation of the G2/M phase transition in the CART19/venetoclax-treatment condition in the MKI67hi cluster (Suppl. Fig. 4E and 4F). Taken together, these data implicate that venetoclax treatment enhances CART-mediated tumor killing by promoting tumor apoptosis and inhibiting the cell cycle in cancer cells while also enhancing the interferon responses in neoplastic B-cells when engaging CART cells.
Project description:Identify the expression intensity for all genes in Nalm6 cells and all the genes are divided into 4 equal groups with group 1 containing the 25% of genes that were expressed at the highest levels, and group 4 containing the 25% of genes that were expressed at the lowest levels. Total RNA are isolated from 3 lots of Nalm6 cells and gene expression are determined by microarray gene expression analysis with Nimblegen Human 385K array.
Project description:TP-0903 was obtained from Tolero Pharmaceuticals. CART19 cells from five biological replicates were thawed and stimulated with irradiated Jeko-1 cells (120 Gy) for 5 days. Jeko-1 is a human mantle cell lymphoma cell line that expresses the CD19 antigen (ATCC). Each sample was treated with either 30 nM TP0903 (treated condition) or DMSO (untreated control). CART19 were isolated to a purity of 100% using CD19 microbeads (Miltenyi). RNA was isolated from the CART19 using QIAGEN RNeasy Plus Mini Kit (Cat. No. 74134). RNA was further treated with DNase I and purified using Zymo Research RNA Clean & Concentrator (Cat. No. R1015).