PD-L1+ aneuploid circulating tumor endothelial cells (CTECs) exhibit resistance to the checkpoint blockade immunotherapy in advanced NSCLC patients

Abstract

Sustained angiogenesis and increased PD-L1 expression on endothelial and carcinoma cells contribute toward fostering an immunosuppressive microenvironment suitable for tumor growth. PD-L1⁺ CTCs were reported to associate with poor prognosis in NSCLC patients. However, whether or not aneuploid circulating tumor endothelial cells (CTECs) express PD-L1, then serve as a surrogate biomarker to evaluate immunotherapy efficacy remains unknown. In this study, a novel SE-iFISH strategy was established to comprehensively quantify and characterize a full spectrum of aneuploid CTCs and CTECs in advanced NSCLC patients subjected to second-line anti-PD-1 (nivolumab) immunotherapy. In situ co-detection of diverse subtypes of aneuploid CTCs and CTECs expressing PD-L1 and Vimentin was performed. The present clinical study demonstrated that significant amounts of PD-L1⁺ aneuploid CTCs and CTECs could be detected in histopathologic hPD-L1^- patients. In contrast to decreased PD-L1⁺ CTCs, the number of multiploid PD-L1⁺ CTECs (≥tetrasomy 8) undergoing post-therapeutic karyotype shifting increased in patients along with tumor progression following anti-PD-1 treatment. Progressive disease (PD) lung cancer patients possessing multiploid PD-L1⁺ CTECs had a significantly shorter PFS compared to those without PD-L1⁺ CTECs. In carcinoma patients, aneuploid CTCs and CTECs may exhibit a functional interplay with respect to tumor angiogenesis, progression, metastasis, and response to immunotherapy.