Tumor Infiltrating Lymphocytes and PD-L1 Expression Differ in Low and High Grade Neuroendocrine Tumors

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Introduction: Although much progress has been made in the past 2-3 years in terms of understanding signaling pathways in gastroenteropancreatic neuroendocrine tumors (GEP-NENs), approved treatment options are still limited. Cancer Immunotherapy has been announced as the breakthrough of the year in 2013 and might become an integral part of the clinical management strategy for solid tumors including GEP-NENs. Therefore, to develop immunotherapeutic strategies against NENs we need to know which immune escape mechanisms are relevant in high and low grade NEC/NENs.

Aim(s): We aim to characterize the tumor microenvironment (TME) of NEN/NECs on the cellular level in order to define relevant immunophenotypes.

Materials and methods: TMAs of 70 poorly differentiated neuroendocrine carcinomas (PDECs) of all localizations and 20 well differentiated ilial neuroendocrine carcinomas (WDNET) of two different institutions (Charite - Universitätsmedizin Berlin and Zentralklinik Bad Berka) were stained for CD3 expression; 50 PDECs and 20 WDNETs were stained for PD-L1 expression.

Conference: 12th Annual ENETSConcerence (2015)

Presenting Author: Grabowski P

Authors: Grabowski P, Joehrens K, Arsenic R, Kaemmerer D, Hummel M,

Keywords: Immunophenotype, PD-L1, poorly differentiated NECs, immunotherapy,