Effects of immune checkpoint blockade on antigen‐specific CD8⁺ T cells for use in adoptive cellular therapy

Abstract

Adoptive T-cell therapies have been successfully used as prophylaxis or treatment for immunocompromised patients at risk of viral infections or advanced cancers. Unfortunately, for some refractory cancers, they have failed. To overcome this, checkpoint inhibitors are used to rescue immune antitumor responses. We hypothesized that in vitro checkpoint blockade during T-cell stimulation and expansion with messenger RNA (mRNA)-pulsed DCs may enhance the activity of antigen-specific T cells and improve the efficacy of adoptive cellular therapy platforms. Human peripheral blood mononuclear cells were isolated from cytomegalovirus (CMV)-seropositive donors to generate DCs. These were pulsed with CMV matrix phosphoprotein 65 (CMVpp65)-mRNA to educate T cells in coculture for 15 days. Three checkpoint blockade conditions were evaluated (anti-PD1, anti-Tim3, and anti-PD1 + Tim3). IL-2 and antibodies blockades were added every 3 days. Immunophenotyping was performed on Day 0 and Day 15. Polyfunctional antigenspecific responses were evaluated upon rechallenge with CMVpp65 peptides. CMVpp65-activated CD8 + T cells upregulate Lag3 and Tim3 (P ≤ 0.0001). Tim3 antibody blockade alone or in combination led to a significant upregulation of Lag3 expression on CD8 + pp65Tetramer + central memory, effector memory, and terminal effector memory cells re-expressing RA (TEMRA) T cells. This latter T-cell subset uniquely maintains double-positive Tim3/Lag3 expression after checkpoint blockade. By contrast, PD1 blockade had minimal effects on Tim3 or Lag3 expression. In addition, IFN-γ secretion was reduced in T cells treated with Tim3 blockade in a dosedependent manner (P = 0.004). In this study, we have identified a potential activating component of Tim3 and linkage between Tim3 and Lag3 signaling upon blocking the Tim3 axis during T-cell-antigen-presenting cell interactions that should be considered when targeting immune checkpoints for clinical use.

Expanded specific T cells to hypomutated regions of the SARS-CoV-2 using mRNA electroporated antigen-presenting cells

“…Our group has extensive experience developing RNA-based cellular therapies to expand T cells specific against virus-derived tumor antigens. 28 , 29 , 30 , 31 , 32 , 33 , 34 In this study, we use a novel approach that takes advantage of circulating APCs transfected with full-length SARS-CoV-2 structural protein encoding mRNAs to activate and expand low frequency T cells specific against hypomutated and non-hypomutated regions of SARS-CoV-2 ( Figure S6 ). Since the beginning of the pandemic, SARS-CoV-2 has genomically evolved with new variants acquiring mutations that confer increasing infectivity and virulence.…”

CAR T Cell Locomotion in Solid Tumor Microenvironment

“…Our group has taken advantage of IL-8 tumor secretion and genetically engineered CD70-directed CAR T cells to constitutively expressed IL-8 receptor to be tested in a first-in-human trial (NCT05353530) [ 138 ]. Furthermore, novel approaches are under investigation to positively reprogram the TME to enhance CAR T cell migration into tumor niche ( Table 2 ) [ 227 ].…”

Three-Dimensional Bioconjugated Liquid-Like Solid (LLS) Enhance Characterization of Solid Tumor - Chimeric Antigen Receptor T cell interactions

“…Despite a better understanding of cancer biology and the discovery of new targeted cellular therapies, many patients still succumb to refractory solid cancers [1][2][3][4]. Chimeric antigen receptor (CAR) T therapy has shown great promise against hematological malignancies with complete remission rates as high as 90% during the first-month post CAR T cell infusion, leading to US FDA approval of now six CAR T-cells for B-cell malignancies [5][6][7][8][9][10].…”