ENPP3 CAR T cells combined with CD206 modulation suppress adrenocortical carcinoma growth in PDX models
Background
Adrenocortical carcinoma (ACC) is a rare, aggressive malignancy with poor prognosis and limited curative treatments. While chimeric antigen receptor (CAR) T cells show promise in solid tumors, their application in ACC remains largely unexplored. A key challenge for CAR T-cell efficacy in solid tumors is the immunosuppressive tumor microenvironment (TME). This study aimed to identify novel immunotherapeutic targets and develop effective CAR T-cell strategies for ACC, specifically addressing TME-mediated resistance.
Study Design
Researchers identified targets using public bulk/single-cell RNA sequencing and validated candidates via surface proteomic analysis and flow cytometry on ACC PDX models (n=7 for target identification). They engineered ENPP3-targeted CAR T cells and assessed their cytotoxicity in vitro and in vivo. The study also profiled CAR T cells using flow cytometry and cytokine analysis. For attenuated in vivo efficacy, they introduced co-treatment with an agent modulating CD206+ tumor-associated macrophages (TAMs) to restore CAR T-cell function and improve antitumor responses in both ENPP3high and ENPP3low PDX models.
Results
Researchers identified ectonucleotide pyrophosphatase/phosphodiesterase family member 3 (ENPP3) as a shared immunotherapy target in 4/7 (57%) of the ACC PDXs analyzed. In vitro, ENPP3-targeted CAR T cells demonstrated potent cytotoxicity, eradicating >85% of ENPP3+ ACC cells. However, these CAR T cells showed attenuated efficacy in PDX mouse models. This restrained activity correlated with immunosuppressive features within the tumor microenvironment, particularly the presence of CD206+ tumor-associated macrophages (TAMs). > Co-treatment with an agent specifically modulating CD206+ TAMs successfully restored CAR T-cell function and significantly improved antitumor responses in both ENPP3high and ENPP3low PDX models, with a difference between mean tumor weights of -270.1 mg±117.4 and a p<0.05. This combinatorial approach mediated robust tumor growth suppression.
Key Findings
ENPP3identified as an immunotherapy target in 4/7 (57%) of ACC PDXs.ENPP3CAR T cells eradicated >85% ofENPP3+ ACC cells in vitro.- Attenuated CAR T-cell efficacy in vivo correlated with
CD206+ tumor-associated macrophages (TAMs). CD206modulation restored CAR T-cell function and improved antitumor responses.- Combination therapy resulted in a tumor weight difference of -270.1 mg±117.4 (p<0.05).
Why It Matters
This study offers a novel, dual-pronged strategy for treating aggressive adrenocortical carcinoma (ACC), a cancer with few effective options. By identifying ENPP3 as a CAR T-cell target and demonstrating that CD206+ TAM modulation can overcome TME-mediated immune suppression, this research paves the way for more effective immunotherapies in solid tumors. For clinicians and researchers, it underscores that CAR T-cell efficacy in solid cancers often requires addressing the immunosuppressive microenvironment, suggesting that combination therapies targeting both tumor cells and the TME are crucial. This approach could extend beyond ACC, potentially improving outcomes for other solid tumors where CAR T cells currently face similar limitations.