Enhancing CAR-T cell therapy for DLBCL - Project Summary/Abstract The long-term goal of this proposal is to improve anti-CD19 chimeric antigen receptor T cell (CART19) therapy for patients with relapsed or refractory large B cell lymphoma (r/r LBCL). Unfortunately, 50%-60% of patients with r/r LBCL receiving FDA-approved autologous CART19 therapy (tisa-, axi- or liso-cel) will relapse, often due to poor in vivo expansion and persistence of the CART19. IL-7, IL-15, and IL-21 are critical homeostatic regulators of T cells and promote stem cell memory phenotypes. NT-I7 is a long-acting version of human IL-7, while HCW11-006 is a long-acting multimeric protein containing IL-7, IL-15, and IL-21. While our recent Phase 1b trial (NCT05075603) confirmed that NT-I7 is safe 21 days post-CART19, this timing coincided with the CART19 contraction phase, resulting in minimal expansion. In Aim 1a, we will conduct a new Phase 1b trial evaluating early (Day 10) and repeated (Day 31) dosing of NT-I7 following axi- or liso-cell infusion in r/r LBCL patients. Aim 1b will involve extensive correlative studies to analyze the impact of NT-I7 on (1) serum cytokines, (2) CART19 and endogenous T cells, (3) other non-T cell subsets, and (4) the tumor microenvironment (TME) using flow cytometry, single cell RNA-sequencing, and multiplexed TME profiling. We hypothesize that initiating a repeated NT-I7 dosing schedule during CART19 expansion (Day 10) is safe, promotes superior in vivo CART19 persistence/expansion and improves clinical outcomes for r/r LBCL patients. However, because NT-I7 may not provide durable remissions, we will perform an unbiased CRISPR screen to identify genes enhancing NT-I7-treated CART19 function (Aim 1c). In Aim 2, we will evaluate the impact of NT-I7 or HCW11-006 (IL-7/IL-15/IL-21) on CART19-mediated toxicities (CRS/ICANS) and efficacy using autologous (Aim 2a) and allogeneic (Aim 2b) preclinical mouse models. We hypothesize that early, repeated cytokine administration sustains CART19 proliferation, persistence, and tumor killing without exacerbating toxicity. Using immunocompetent and “humanized” NSGS mice, we will compare an early regimen (days 1 and 21) against the clinical schedule (days 10 and 31). Since new approaches are needed to overcome host-mediated allogeneic CART rejection by CD2-expressing T cells and NK, we will test if CD2 epitope editing of allogeneic CART19 confers resistance to CD2 antibody-mediated lymphodepletion and enhances their persistence and efficacy in murine allogeneic or xenogeneic hosts with LBCL. Preclinical mouse models are essential to capture the complex dynamics of autologous and allogeneic CART19, including trafficking, TME remodeling, and CRS/ICANS, which in silico and in vitro methods cannot replicate. By preserving an intact vascular system and host immunity, these models provide a robust foundation for clinical trials designed to improve LBCL survival while minimizing toxicities.
