Gittins, B. | bioRxiv Science

bioRxiv2025

Intratumoral Treg ablation is sufficient to mediate tumor control systemically without autoimmunity

Regulatory T cells (Tregs) infiltrate most tumors, yet whether they suppress immune responses directly within tumor tissues is not clear. We used intratumoral (IT) delivery of diphtheria toxin (DT) in Foxp3DTR mice to deplete IT Tregs while leaving peripheral Tregs intact. IT delivery of DT reduced Treg frequencies in the tumor, which promoted potent tumor control without autoimmunity. Interestingly, this control was principally mediated by CD4+ T cells, whereas CD8+ T cells only contributed when CD4+ T cells were absent. While conventional dendritic cells (cDCs) were required to clear tumors, Batf3+ cDC1s were dispensable. Distant secondary tumors, mimicking metastases, were also controlled by IT Treg ablation. Mechanistically, IT Tregs suppressed antitumor T cell responses by blocking the acquisition of tumor antigen by cDC2s. Importantly, similar mechanisms of control were observed using a clinically translatable IT Treg-depleting anti-CCR8 antibody and reveal a distinct therapeutic strategy that leverages cDC2s and CD4+ T cells.

cancer biology↗

bioRxiv2023

Antigen-dependent IL-12 signaling in CAR T cells promotes regional to systemic disease targeting

Chimeric antigen receptor (CAR) T cell therapeutic responses are hampered by limited T cell trafficking, persistence, and durable anti-tumor activity in solid tumor microenvironments. However, these challenges can be largely overcome by relatively unconstrained synthetic engineering strategies, which are being harnessed to improve solid tumor CAR T cell therapies. Here, we describe fully optimized CAR T cells targeting tumor-associated glycoprotein-72 (TAG72) for the treatment of solid tumors, identifying the CD28 transmembrane domain upstream of the 4-1BB co-stimulatory domain as a driver of potent anti-tumor activity and IFN{gamma} secretion. These findings have culminated into a phase 1 trial evaluating safety, feasibility, and bioactivity of TAG72-CAR T cells for the treatment of patients with advanced ovarian cancer (NCT05225363). Preclinically, we found that CAR T cell-mediated IFN{gamma} production facilitated by IL-12 signaling was required for tumor cell killing, which was recapitulated by expressing an optimized membrane-bound IL-12 (mbIL12) molecule on CAR T cells. Critically, mbIL12 cell surface expression and downstream signaling was induced and sustained only following CAR T cell activation. CAR T cells with mbIL12 demonstrated improved antigen-dependent T cell proliferation and potent cytotoxicity in recursive tumor cell killing assays in vitro and showed robust in vivo anti-tumor efficacy in human xenograft models of ovarian cancer peritoneal metastasis. Further, locoregional administration of TAG72-CAR T cells with antigen-dependent IL-12 signaling promoted durable anti-tumor responses against both regional and systemic disease in mice and was associated with improved systemic T cell persistence. Our study features a clinically-applicable strategy to improve the overall efficacy of locoregionally-delivered CAR T cells engineered with antigen-dependent immune-modulating cytokines in targeting both regional and systemic disease.

cancer biology↗