Project 2 - Modulation of Tumor-Induced Tolerance by Inhibitory Receptors

University Of Pittsburgh At Pittsburgh, Pittsburgh PA

Investigators

Linked publications, trials & patents

Abstract

PROJECT SUMMARY The cell surface inhibitory receptors (IRs) PD1 and LAG3 regulate T cell function, maintain immune homeostasis, and guide CD8+ exhausted T cells (Tex) in chronic disease settings. Targeting IRs in cancer immunotherapy can lead to tumor remission and clinical benefits, but the mechanisms are unclear. IR expression on Tex and CAR-T cells limits their anti-tumor efficacy. Mouse tumor models facilitate the analysis of IR mechanisms. PD1 and LAG3 show synergistic effects in various disease models. However, we still lack a clear understanding of the drivers of PD1/LAG3 function in CD8+ T cell exhaustion and their role in CD4+ T cell development and function. This project will test the central hypothesis that “PD1 and LAG3 synergize to enforce tumor-induced tolerance through a combination of overlapping and unique cell-intrinsic functions in CD4+ and CD8+ T cells that impact effector function and differentiation”. Due to potency of tolerance in the tumor microenvironment (TME), mouse models represent an outstanding system to study IR mechanisms to compare with processes in autoimmune (Project 1) and chronic viral settings (Project 3). We will pursue two Aims: AIM 1: What molecules and mechanisms downstream of PD1 and/or LAG3 modulate CD8+ T cell fate and function? We hypothesize that “PD1/LAG3 drive core pathways that control cell fate, differentiation, and function of effector-like and exhausted CD8+ T cells that are impacted by temporal and autocrine modulators”. We will address 3 questions: (A) What are the causal genes and mechanisms driven by PD1, LAG3, or the combination in CD8+ Tex? (B) What is the autocrine impact of IFNγ produced by PD1+LAG3+ Tex? (C) Does CD8+ T cell signaling architecture (TCR vs CAR) affect the impact of PD1/LAG3? We will use a combination of PD1/LAG3 recombinant antibodies, transcriptomic analysis, targeted CRISPR screens and in vivo functional analysis using tumor-specific T cell adoptive transfer systems and CD8+ T cell restricted PD1/LAG3-deficient model systems. AIM 2: What are the relative and synergistic contributions of PD1 and/or LAG3 in limiting CD4+ Tconv anti- tumor effector function and fate? We hypothesize that “PD1/LAG3 have synergistic effects on anti-tumor activity of CD4+ Tconv cells”. We will address 2 questions: (A) What is the impact of PD1 and/or LAG3 loss or blockade on CD4+ Tconv cells? (B) What are the causal pathways that mediate the downstream impact of PD1/LAG3 on CD4+ Tconv cells? We will use a combination of CD4+ T cell restricted PD1/LAG3-deficient model systems, tumor-specific T cell adoptive transfer systems, PD1/LAG3 recombinant antibodies, transcriptomic analysis and targeted CRISPR screens to deduce PD1/LAG3 mechanisms in intratumoral CD4+ Tconv cells. IR-PPG Interactions: P2 will collaborate with: [i] P1 and P3 in Aim 1 to determine if the PD1/LAG3 downstream pathways in CD8+ T cells are the same or different in distinct disease settings; [ii] P1 in Aim 2 to compare the impact of PD1/LAG3 loss on CD4+ T cell function in autoimmune versus tumoral settings; and [iii] Core A to exchange data, Core B to obtain mice, Core C for CRISPR libraries, and Core D for rAbs and ADCs.