Leveraging CD26high Meso-CAR T cells in patients with advanced pancreatic cancer

PROJECT SUMMARY This project translates an innovative, chimeric antigen receptor (CAR) T cell therapy to patients with pancreatic ductal adenocarcinoma (PDAC). We posit efficacy of CAR T targeting mesothelin (relevant PDAC antigen) can be enhanced by use of 1) a new subset expressing CD26 (a costimulatory molecule with enzymatic properties) termed CD26+

T cells; and 2) an innovative expansion protocol that incorporates the phosphatidyl inositol kinase-3 inhibitor (PI3Ki), duvelisib to improve CART persistence and metabolism. Our team reported that CD26+CD4+ T cells redirected with a Meso-CAR were polyfunctional and elicit activity against PDAC tumors in mice. Our overall

hypothesis is that PI3Ki-expanded, CD26+CD4+ T cells are an ideal template for safely redirecting immunity to PDAC. While CD26+CD4+ T cells are polyfunctional, they fully differentiate after expansion, which reduces potency. However, our data shows CD26+T cell differentiation can be reduced using duvelisib during

manufacturing, thus sustaining self-renewal (i.e., “stemness”), while enhancing in vivo cytolytic activity against orthotopic KPC tumors. This Project pursues three specific aims. Aim 1 will test our hypothesis that CD26+CD4+ CAR T cells degrade chemokines that induce suppressive myeloid cells, favorably altering the cell composition

in the tumor microenvironment using relevant murine PDAC models (orthotopic and metastatic) in immune competent mice. Functional impact of Meso-CAR T on endogenous T cells will be tested in parallel studies in RAG2 KO to further define mechanism of efficacy. Aim 2 will investigate the interaction between Duvelisib-expanded

CD26+CD4+ CAR T cells and conventional CAR T cells in targeting PDAC. Also, the role of CD26 in efficacy will be evaluated by using CD26+CD4+ MesoCAR T cells expressing enzymatically active or inactive CD26 or treating mice with a selective CD26 inhibitor (sitagliptin). The effect of CD26 enzyme modulation on the recruitment of

myeloid cells in the PDAC TME will be tested in both human and murine in vivo systems. In Aim 3, we conduct a novel first-in-human trial in patients with advanced PDAC to evaluate safety, persistence, and fate of co-infused Duvelisib-expanded CD26+CD4+ and conventional CD3+ Meso CAR T cells. We will refine manufacturing and

generate foundational feasibility/reproducible CMC data for an IND application. A phase 0/1 clinical trial will use low dose numbers of Duvelisib-expanded CD26+CD4+ Meso-CAR T cells, followed by dose escalation of Duvelisib-expanded CD26+CD4+ Meso-CAR T cells in combination with differentially bar-coded conventional

CD3+ Meso-CAR T cells to define safety and clinically effective dose of this novel ACT therapy. Engraftment and persistence of CAR T products in blood and patient tumor biopsies will be tested with spatial molecular imaging and multi-parameter flow cytometry to study CART's metabolic/effector properties. Collectively, this work will

define properties of novel Duvelisib-expanded CD26+CD4+ CAR T cells in animal PDAC models and determine safety and persistence of CD26+CD4+ CAR T cells in patients. Our results will enable subsequent trials with CD26+CD4+ Meso-CAR T cells as an individual therapy or a component of combined cell therapy in PDAC.