Characterization of ENTPD1/CD39-mediated myeloid-T-cell crosstalk and its role in immunotherapy response in triple-negative breast cancer.

Abstract

e14564 Background: Immunotherapy efficacy in triple-negative breast cancer (TNBC) is limited by mechanisms of immune suppression within the tumor microenvironment (TME) . Ectonucleoside triphosphate diphosphohydrolase 1 (ENTPD1, encoding CD39) has been implicated in immune evasion, yet its precise regulatory role in orchestrating intercellular crosstalk and driving resistance to PD-L1 blockade in TNBC remains unclear . Methods: We analyzed single-cell RNA sequencing (scRNA-seq) data from 167,166 immune cells from 27 tumor and metastatic samples across 14 TNBC patients treated with paclitaxel $\pm$ atezolizumab . Quantitative metrics—treatment contribution (TC), ENTPD1 dynamic index (EDI), and tumor response index (TRI)—were developed to capture dynamic immune responses . Findings were validated in an independent cohort of 112 TNBC patients via immunohistochemical (IHC) assessment of CD39 expression and survival analysis . Results: ENTPD1 was predominantly expressed in M2-like macrophages and a subset of regulatory T cells (CD4+CD39+ Tregs) . ENTPD1+ macrophages exhibited M2-like polarization and suppression of STING-type I interferon signaling . Cell-cell communication analysis identified a previously unrecognized lymphotoxin (LT)-centered axis (LTA-TNFRSF1B/14) linking CD4+CD39+ T cells with M2 macrophages, bridging adenosine metabolism with cytokine-driven immunoregulation . LT signaling was selectively enriched in non-responders and coincided with enhanced M2 macrophage interactions . In the validation cohort, high CD39 protein expression significantly correlated with reduced overall survival (OS) ($P < 0.001$) . Responders to PD-L1 blockade showed marked ENTPD1 downregulation post-treatment, whereas non-responders maintained high levels . Conclusions: ENTPD1/CD39 orchestrates an adenosine-rich immunosuppressive microenvironment that promotes M2 macrophage polarization and resistance to PD-L1 blockade via a novel LT-mediated crosstalk axis . CD39 serves as both a prognostic biomarker and a tractable immunotherapeutic target to overcome resistance in TNBC .