Differences in PD-L1–Expressing Macrophages and Immune Microenvironment in Testicular Germ Cell Tumors

• DOI: 10.1093/ajcp/aqz184
• Publication Date: 2019-10-10T19:34:04Z
• Authors: Sam Sadigh; Sahar J Farahani; Abhishek Shah; David Vaughn; Priti Lal
• Keywords: Adult; Adolescent; Macrophages; Programmed Cell Death 1 Receptor; Antigens, Differentiation, Myelomonocytic; Forkhead Transcription Factors; Receptors, Cell Surface; Middle Aged; Neoplasms, Germ Cell and Embryonal; DNA Mismatch Repair; Immunohistochemistry; B7-H1 Antigen; Young Adult; 03 medical and health sciences; 0302 clinical medicine; Testicular Neoplasms; Antigens, CD; Biomarkers, Tumor; Tumor Microenvironment; Humans; Orchiectomy; Aged

AbstractObjectivesTo characterize the tumor microenvironment of testicular germ cell tumors (GCTs) using immunohistochemical markers.MethodsSeventy-seven orchiectomies, including 36 nonmetastatic (NM) seminomas, 15 metastatic (M) seminomas, 13 nonmetastatic nonseminomatous germ cell tumors (NSGCTs), and 13 metastatic NSGCTs, were studied with PD-1, PD-L1, FOXP3, CD68, CD163, and mismatch repair (MMR) immunohistochemistry. FOXP3+ and PD-1+ tumor-infiltrating lymphocytes (TILs) and tumor-associated macrophages (TAMs) expressing CD68 and CD163 were enumerated. PDL-1 expression was evaluated on tumor cells and macrophages.ResultsGCTs primarily express PD-L1 on TAMs, except choriocarcinoma, where true tumor cell positivity was noted. Seminomas reveal increased intratumoral PD-L1+ TAMs compared with NSGCTs (P < .05). Activated TILs are increased in NM-seminomas compared with M-seminomas (P < .05). All GCTs retained MMR expression.ConclusionsRobust PD-L1+ TAMs are significantly expanded in seminomas compared with NSGCTs. Among all GCTs, only choriocarcinoma cells reveal true positivity for PD-L1. These findings expand the realm of potentially targeted treatments for GCTs.