Espie, D. | Search bioRxiv

bioRxiv2026

Monocytes promote intraepithelial infiltration of effector memory CD8+ T cells in regressing tumors

Despite the clinical success of cancer immunotherapies, the cellular interactions driving tumor regression remain incompletely understood. Here, we investigated the dynamic remodeling of the tumor immune microenvironment during regression of transplanted PyMT mammary tumors following STING agonist treatment. Using scRNA-seq of sorted CD8+ T cells and myeloid cells, combined with imaging approaches, we identified major changes in both lymphoid and myeloid compartments during tumor regression. Regressing tumors showed a transient accumulation of Ly6Chi monocyte populations associated with a decline in macrophage subsets, while effector and memory CD8+ T-cell populations increased at the expense of exhausted T cells. Interaction analyses predicted enhanced chemotactic and adhesion interactions between CXCL9+ Ly6Chi monocytes and effector CD8+ T cells. Consistently, dynamic imaging revealed increased CD8+ T-cell motility and infiltration into tumor cores following treatment. In particular, CXCR6+ effector CD8+ T cells transiently accumulated within tumor islets during regression before relocalizing to stromal regions. Together, these findings reveal a coordinated spatiotemporal remodeling of myeloid and CD8+ T-cell populations during immunotherapy-induced tumor regression and highlight cooperative interactions that may promote durable anti-tumor immunity.

immunology↗

bioRxiv2025

Harnessing the CD2 axis to broaden and enhance the efficacy of CAR T cell therapies

Patients with T-cell lymphomas and leukemias have overall poor outcomes due to the lack of targeted and effective treatments, particularly in the relapsed and refractory settings. Development of chimeric antigen receptor (CAR) T-cells against T-cell neoplasms is limited by a lack of discriminating T-cell antigens that allow for effective anti-tumor responses while preventing CAR T-cell fratricide. We hypothesized that targeting CD2, a pan-T-cell antigen, using anti-CD2 CAR T-cells engineered without CD2 expression (CART2), would support CAR T-cell manufacturability and preclinical efficacy. Optimized CD2-knockout CART2, generated using CRISPR-Cas9, eradicated primary patient-derived CD2+ hematological neoplasms in vitro and in vivo, secreted effector cytokines, and exhibited adequate proliferative capacity. Nevertheless, CD2 has a key costimulatory function, and its deletion could lead to CAR T-cell dysfunction. Therefore, we tested the role of the CD2:CD58 axis in CAR T-cells, using the anti-CD19 CART models. We demonstrate that CD2 loss attenuates CART19 efficacy by reducing avidity for tumor antigen, co-stimulation, and ultimately in vivo activity. Analogously, we show that tumor CD58 loss reduces CART19 efficacy. To overcome this issue, we developed a novel PD-1:CD2 switch receptor that rescues intracellular CD2 signaling, particularly when PD-L1 is engaged, resulting in improved in vivo outcomes. Collectively, we studied the role of CD2 both as a target for CAR T cell therapy and as a critical costimulatory protein, whose signaling can be rescued using the PD-1:CD2 switch receptor. This receptor can be incorporated into CAR T-cells and provides an effective strategy to overcome CD2-signaling deficiencies.

cancer biology↗