Treatment of cancer patients by adoptive T cell therapy has yielded promising results. In solid tumors, however, T cells encounter a hostile environment, in particular with increased inflammatory activity as a hallmark of the tumor milieu that goes along with abundant reactive oxygen species (ROS) that substantially impair antitumor activity. We present a strategy to render antitumor T cells more resilient toward ROS by coexpressing catalase along with a tumor specific chimeric Ag receptor (CAR) to increase their antioxidative capacity by metabolizing H2O2. In fact, T cells engineered with a bicistronic vector that concurrently expresses catalase, along with the CAR coexpressing catalase (CAR-CAT), performed superior over CAR T cells as they showed increased levels of intracellular catalase and had a reduced oxidative state with less ROS accumulation in both the basal state and upon activation while maintaining their antitumor activity despite high H2O2 levels. Moreover, CAR-CAT T cells exerted a substantial bystander protection of nontransfected immune effector cells as measured by CD3ζ chain expression in bystander T cells even in the presence of high H2O2 concentrations. Bystander NK cells, otherwise ROS sensitive, efficiently eliminate their K562 target cells under H2O2-induced oxidative stress when admixed with CAR-CAT T cells. This approach represents a novel means for protecting tumor-infiltrating cells from tumor-associated oxidative stress–mediated repression.

Adoptive T-cell transfer showed promising efficacy in recent trials raising interest in T cells with redirected specificity against tumors. T cells were engineered with a chimeric antigen receptor (CAR) with predefined binding and CD3ζ signaling to initiate T-cell activation. CD28 costimulation provided by a CD28-CD3ζ signaling CAR moreover improved T cell activation and persistence; however, it failed to meet the expectations with respect to mounting attacks against solid tumors infiltrated with regulatory T (Treg) cells. We revealed that a CD28 CAR-redirected T-cell attack is accompanied by higher numbers of Treg cells infiltrating the tumor and is less efficient against cancer cells in presence of Treg cells than a CD3ζ CAR T-cell attack. Deletion of the lck binding moiety in the CD28 CAR endodomain, however, improved redirected anti-tumor activity in presence of Treg cells without impairing interferon-γ (IFN-γ) secretion, proliferation, and cytolysis. CD28 modification abrogated interleukin-2 (IL-2) induction upon CAR engagement which in turn is no longer available to sustain Treg cell persistence. CARs with the modified CD28 endodomain thereby expedite the implementation of adoptive T-cell therapy in patients with a variety of cancer types that are heavily infiltrated by Treg cells.

Redirecting T cells with a chimeric antigen receptor (CAR) of predefined specificity showed remarkable efficacy in the adoptive therapy trials of malignant diseases. The CAR consists of a single chain fragment of variable region (scFv) antibody targeting domain covalently linked to the CD3ζ signalling domain of the T cell receptor complex to mediate T cell activation upon antigen engagement. By using an antibody-derived targeting domain a CAR can potentially redirect T cells towards any target expressed on the cell surface as long as a binding domain is available. Antibody-mediated targeting moreover circumvents MHC restriction of the targeted antigen, thereby broadening the potential of applicability of adoptive T cell therapy. While T cells were so far genetically modified by viral transduction, transient modification with a CAR by RNA transfection gained increasing interest during the last years. This chapter focuses on methods to modify human T cells from peripheral blood with a CAR by electroporation of in vitro transcribed RNA and to test modified T cells for function for use in adoptive immunotherapy.

Genomic profiling revealed the identity of at least 5 subtypes of DLBCL, including the MCD/C5 cluster characterized by aberrations in MYD88, BCL2, PRDM1 and/or SPIB. We generated mouse models harboring B cell-specific Prdm1 or Spib aberrations on the background of oncogenic Myd88 and Bcl2 lesions. We deployed whole exome sequencing, transcriptome, flow- and mass cytometry analyses to demonstrate that Prdm1- or Spib-altered lymphomas display molecular features consistent with pre-memory B cells and light zone B cells, whereas lymphomas lacking these alterations were enriched for late light-zone and plasmablast-associated gene sets. Consistent with the phenotypic evidence for increased B cell receptor signaling activity in Prdm1-altered lymphomas, we demonstrate that combined BTK/BCL2 inhibition displays therapeutic activity in mice and in five out of six relapsed/refractory DLBCL patients. Moreover, Prdm1-altered lymphomas were immunogenic upon transplantation into immuno-competent hosts, displayed an actionable PD-L1 surface expression and were sensitive to anti-murine-CD19-CAR-T cell therapy, in vivo.