Author ORCID Identifier

https://orcid.org/0009-0009-8309-2572

Date of Award

10-8-2026

Document Type

Thesis (Ph.D.)

Department or Program

Microbiology and Immunology

First Advisor

Edward Usherwood, PhD

Abstract

T cell exhaustion remains a significant barrier to effective adoptive cell therapy in solid tumors. Here, we demonstrate that in vitro treatment with the PI3Kδ inhibitor CAL-101 generates T cells with enhanced stemness and metabolic fitness, though the stemness of these cells is not dependent on HIF-1α -dependent mechanisms. These cells show increased mitochondrial dependence and spare respiratory capacity while maintaining normal basal metabolism. Under chronic antigen stimulation, CAL-101-treated T cells, including human T cells, resist terminal exhaustion and maintain stem-like properties. Using single-cell RNA sequencing and spatial transcriptomics of B16 melanoma tumors, we found that CAL-101-treated T cells preferentially acquire a progenitor exhausted-like state (Tpex2) within the tumor microenvironment (TME). These cells demonstrate enhanced tumor infiltration and upregulate the Cxcl10/Cxcr3 signaling axis. The TME of tumors containing CAL-101-treated T cells have reduced glycolysis, oxidative phosphorylation, and proliferation signatures, while exhibiting increased pro-inflammatory signaling via Cxcl9/Cxcl10 and decreased presence of immunosuppressive tumor-associated macrophages (TAMs). Single-cell analysis revealed that the CAL-101-treated T cells concurrently increase oxidative phosphorylation, proliferation, and immune signaling pathways. Mechanistically, CAL-101-treated T cells maintain high expression of stemness-associated genes (Tcf7, Slamf6) while resisting expression of genes associated with terminal exhaustion (Tim3, Mt1/2). These findings uncovered mechanisms behind how PI3Kδ inhibition generates T cells capable of establishing and maintaining an anti-tumor immune response, suggesting a promising strategy for improving adoptive cell therapy outcomes in solid tumors.

Original Citation

Turnquist, A. et al. PI3Kδ inhibition alters CD8 T cell differentiation and reprograms the tumor microenvironment following adoptive immunotherapy. The Journal of Immunology 215, vkag108 (2026).

Download

Share

COinS