Detailed characterization of immune cell infiltrate and expression of immune checkpoint molecules PD-L1/CTLA-4 and MMR proteins in testicular germ cell tumors disclose novel disease biomarkers

Authors and Affiliations:

João Lobo ^1,2,3, Ângelo Rodrigues ^1,2,3, Rita Guimarães ^1,2, Mariana Cantante ^1,2, Paula Lopes ^1,2, Joaquina Maurício ⁴, Jorge Oliveira ⁵, Carmen Jerónimo ^2,3,*,# and Rui Henrique ^1,2,3,*,#

¹ Department of Pathology, Portuguese Oncology Institute of Porto (IPOP), R. Dr. António Bernardino de Almeida, 4200-072, Porto, Portugal

² Cancer Biology and Epigenetics Group, Research Center of Portuguese Oncology Institute of Porto (GEBC CI-IPOP) and Porto Comprehensive Cancer Center (P.CCC), R. Dr. António Bernardino de Almeida, 4200-072, Porto, Portugal

³ Department of Pathology and Molecular Immunology, Institute of Biomedical Sciences Abel Salazar, University of Porto (ICBAS-UP), Rua Jorge Viterbo Ferreira 228, 4050-513, Porto, Portugal

⁴ Department of Medical Oncology & Urology Clinic, Portuguese Oncology Institute of Porto (IPOP), R. Dr. António Bernardino de Almeida, 4200-072, Porto, Portugal

⁵ Department of Urology & Urology Clinic, Portuguese Oncology Institute of Porto (IPOP), R. Dr. António Bernardino de Almeida, 4200-072, Porto, Portugal

# Joint senior authors

Abstract:

Introduction: The immune infiltrate plays an important part in testicular germ cell tumors, but it remains scarcely studied. We aimed at thoroughly characterizing the immune infiltrate and expression of immune checkpoints PD-L1/CTLA-4 and mismatch repair (MMR) proteins in these neoplasms, seeking for associations with patient outcome. Methods: A total of 162 consecutively diagnosed patients (2005-2018) were included. Immunostaining for PD-L1, CTLA-4 and MMR proteins was independently assessed both in immune cells (ICs) and tumor cells (TCs) of primary tumors and metastases, and characterization of IC populations was pursued. Results: PD-L1 and CTLA-4 positivity in ICs was frequent (85.5% and 96.3%). Patients with absent PD-L1 positive ICs exhibited significantly worse relapse-free survival (hazard ratio=4.481, 95%CI 1.366-14.697, p=0.013), both in univariable and multivariable analysis. Lower CD20 and CD3 IC infiltration in seminomas associated with higher disease stage (p=0.0216, p=0.0291). CTLA-4 TC intensity was significantly higher in yolk sac tumor, choriocarcinoma and teratoma, while PD-L1 TC positivity was significantly more frequent in choriocarcinoma. Both PD-L1 and CTLA-4 immunoexpression in ICs of metastatic samples was frequent (100% and 88.2%). MMR proteins were differentially expressed among the different tumor subtypes. Conclusions: Immune infiltrate/checkpoints associate with patients’ outcome, constituting novel (potentially targetable) disease biomarkers.

Journal: Cancers

Link: https://doi.org/10.3390/cancers11101535