Erschienen in:
22.05.2020 | Original Article
Expression of programmed death-ligand 1 (PD-L1) in human pituitary neuroendocrine tumor
verfasst von:
Valentine Suteau, Alexandre Collin, Philippe Menei, Patrice Rodien, Marie-Christine Rousselet, Claire Briet
Erschienen in:
Cancer Immunology, Immunotherapy
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Ausgabe 10/2020
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Abstract
Objective
To explore the programmed death-ligand 1 (PD-L1) expression in varied subtypes of pituitary neuroendocrine tumors with assessment of their clinical behavior at diagnosis and follow-up.
Methods
We conducted a retrospective monocentric study, including all patients operated in the Academic Hospital of Angers (France) for a pituitary neuroendocrine tumor between 2012 and 2018. PDL-1 immunostaining was performed using a European Conformity—In Vitro Diagnostic-labeled anti-PDL1 antibody (clone 22C3). PD-L1 immunostaining was evaluated as the percentage of tumor cells showing positive membrane staining, into four grades: grade 0 = < 1%, grade 1 = 1 to 5%, grade 2 = 6 to 49% and grade 3 = ≥ 50%. PD-L1 expression was compared with tumor features (secretion, proliferation, invasion) and outcome.
Results
The study included 139 pituitary neuroendocrine tumors, including 84 (60%) nonfunctioning adenomas. Twenty-five pituitary neuroendocrine tumors were PD-L1 positive (18%), including 3 grade 3, 8 grade 2 and 14 grade 1. PD-L1 expression was not different between functioning and nonfunctioning adenomas (p = 0.26). Among 16 tumors with proliferative markers (Ki-67 ≥ 3% and p53 positive), only one was PD-L1 positive.
Conclusion
In our series, PD-L1 was expressed in a rather small proportion of PitNET (18%), and this immune marker was not associated with any biological characteristic or behavior of the pituitary tumors. Thus, PD-L1 staining may be necessary before considering PD-L1 blockage in pituitary neuroendocrine tumors, in case of therapeutic impasse.