Project description:Cytokine release syndrome (CRS) is a strong immune system response that can occur as a result of the reaction of a cellular immunotherapy with malignant cells. While the frequency and management of CRS in CAR T-cell therapy has been well documented, there is emerging interest in pre-emptive treatment to reduce CRS severity and improve overall outcomes. Accordingly, identification of genomic determinants that contribute to cytokine release may lead to the development of targeted therapies to prevent or abrogate the severity of CRS. We examined CD22 CAR T-cells using the Nanostring nCounter platform and found that the expression of the PFKFB4 gene and glycolytic pathway activity were upregulated in CAR T-cells in those who developed CRS compared to those who did not have CRS.
Project description:Chimeric antigen receptor (CAR) T cells are effective against B-cell malignancies but are associated with cytokine-driven inflammatory toxicities such as cytokine release syndrome (CRS). Historically, T cell receptor (TCR) engineered T cell therapies are rarely associated with CRS. However, it is challenging to compare diverse cell products utilized in different clinical contexts and against different antigens. In this study, TCR and CAR were made to target the same source of antigen, CD22, expressed by B-cell malignancies: the TCR recognizes CD22-derived peptide processed and presented in the context of HLA-A*02:01, and the CAR recognizes CD22 protein expressed on the cell surface. In vivo studies comparing the CD22 TCR-T cells to CD22 CAR-T cells demonstrated that the TCR-T cells could clear leukemia without inducing systemic proinflammatory cytokine elevation, whereas CD22 CAR-T cells induced high levels of circulating proinflammatory cytokine reminiscent of CRS. T cells activated through either the TCR or CAR by an identical leukemia cell line demonstrated differential transcriptional responses. T cells activated via the CAR had disproportionate and significant upregulation of inflammatory gene sets compared to T-cells activated via the TCR.
Project description:Chimeric antigen receptor (CAR) T cell therapy have demonstrated remarkable success in treating B-cell malignancies that are refractory to standard therapies; however, preclinical and clinical studies have demonstrated that CAR T cell efficacy is greatly reduced against antigen-low tumors. This was exemplified in a clinical trial of CD22-directed CAR T cells where post-CAR relapses were driven by a decrease in the surface expression of the CD22 antigen. To address the poor response of CAR T cells to antigen-low tumor cells, we performed global phosphoproteomics using a SILAC/mass spectrometry approach to examine signal transduction events within CAR T cells in response to high- and low-levels of CD22 antigen. Stimulation with low levels of CD22 antigen resulted in decreased activation of several canonical T cell signaling pathways in CAR T cells, suggesting poor utilization of LAT. To overcome this inefficiency of LAT activation, we designed a bicistronic construct consisting of a clinically active 2nd generation CD22-BBz CAR along with a novel Adjunctive LAT Activating CAR incorporating the intracellular signaling domain of LAT (ALA-CART). ALA-CART cells demonstrated enhanced phosphorylation of LAT and restored downstream signaling in response to low levels of CD22. In xenograft models, ALA-CART cells completely eradicated CD22-low leukemia, significantly extending survival of mice in comparison to the clinically-active, standard CD22-BBz CAR T cells. Compared to the standard CD22-BBz CAR T cells, ALA-CART cells exhibited transcriptional differences in the resting state reflecting a less differentiated state, which corresponded to an enrichment of T stem cell memory cells and enhanced in vivo persistence. Thus, through the identification of CAR signaling deficits, we rationally designed the ALA-CART platform which improves the sensitivity and persistence of CAR T cells to target antigen-low cells, overcoming a mechanism of resistance to standard CAR therapies.
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:CD22 (Siglec-2) is a member of the Siglec family. It is an inhibitory co-receptor of the B-cell-receptor (BCR) and inhibits B–cell activation. Upon BCR stimulation ITIMs in the cytoplasmic tail of CD22 are phosphorylated. This triggers CD22 signalling pathways, which lead to a decreased calcium mobilization in the B cell and thus an inhibition of BCR signalling. Although some CD22 binding partners, such as the phosphatase SHP-1, have already been identified, we deciphered the CD22 interactome in more detail, to gain a deeper understanding of CD22 molecular mechanisms and signalling events after BCR activation. Stable isotope labelling of amino acids in cell culture (SILAC) in combination with mass spectrometry analysis enabled the identification of specific CD22 interaction partners in a quantitative proteomics approach. Hereby, several new CD22 associated proteins were identified that have not been linked to CD22 yet. One of those interacting proteins is cullin 3, an E3 ubiquitin ligase. It was revealed that cullin 3 is important for clathrin-dependent CD22 internalization after BCR stimulation and CD22 surface expression. Further analysis of B-cell specific cullin 3 deficient mice showed an important role of cullin 3 in B cell development. These mice have strongly reduced numbers of mature B cells in the periphery, which are characterized by increased CD22 expression and additionally by pre-activated and apoptotic phenotypes.
Project description:The purpose of this experiment was two-fold. The first was to examine how the gene expression profile changes over time in C7R-CAR NK cells. C7R is a constitutively active IL-7 receptor that provides persistent activation of STAT5. The second was to examine the differential gene expression in C7R CAR NK cells or CAR NK treated with exogenous IL-15 (exIL15) after 2 weeks of stimulation.
Project description:Background: Autologous CD19 CAR T cell therapy leads to durable responses and improved survival in patients with relapsed or refractory large B cell lymphoma (R/R LBCL). Among approved CAR T cell products, axicabtagene ciloleucel (axi-cel; CD19/CD28) has greater real-world efficacy and cytokine-associated toxicity than tisagenlecleucel (tisa-cel; CD19/4-1BB), for reasons that are poorly understood. Methods: Here we report single cell RNA sequencing (scRNA-seq) of 57 pre-infusion CAR T cell products from axi-cel (n=39) and tisa-cel (n=18) patients treated as standard-of-care for R/R LBCL, and their biological associations with clinical outcomes. In vitro CAR manufacturing conditions mimicking those known for axi-cel and tisa-cel were performed using CD19/CD28z or CD19/4-1BBz constructs. Results: ScRNA-seq revealed that axi-cel and tisa-cel are markedly different products. Axi-cel is comprised of more CD4 central memory, CD8 central memory, and CD8 effectors, whereas tisa-cel is comprised of more proliferative CD4 and CD8 cells. Across multiple T cell subsets, axi-cel had greater expression of immune response pathways and protein synthesis and trafficking pathways vs. tisa-cel. On comparison of infusion product CAR transgene-positive (CAR+) cells to CAR transgene-negative (CAR-) T cells, axi-cel CAR+ cells had vastly different gene expression than axi-cel CAR- cells. Unexpectedly, tisa-cel CAR+ cells were highly similar to tisa-cel CAR- cells. Under recapitulated CAR-T manufacturing conditions known to be utilized for axi-cel and tisa-cel, we found that CAR+ cells differed from CAR- cells early after manufacturing yet became more similar to CAR- cells after prolonged expansion. Prolonged time in expansion culture, as utilized during tisa-cel manufacturing, greatly decreased naïve and central memory T cell subsets. Conclusions: Following manufacture, axi-cel is less differentiated and has greater immune activation compared to tisa-cel, potentially accounting for its greater efficacy and toxicity in patients. Our data support the conclusion that tisa-cel is adversely affected by its manufacturing rather than by the CAR construct.