PD-L1 P146R is prognostic and a negative predictor of response to immunotherapy in gastric cancer.

Cancer cells evade immune detection via programmed cell death 1/programmed cell death-ligand 1 (PD-1/PD-L1) interactions that inactivate T cells. PD-1/PD-L1 blockade has become an important therapy in the anti-cancer armamentarium. However, some patients do not benefit from PD-1/PD-L1 blockade despite expressing PD-L1. Here, we screened 101 gastric cancer (GC) patients at diagnosis and 141 healthy control subjects and reported one such subpopulation of GC patients with rs17718883 polymorphism in PD-L1, resulting in a nonsense P146R mutation. We detected rs17718883 in 44% of healthy control subjects, and rs17718883 was associated with a low susceptibility to GC and better prognosis in GC patients. Structural analysis suggests that the mutation weakens the PD-1:PD-L1 interaction. This was supported by co-culture experiments of T cells, with GC cells showing that the P146R substitution results in interferon (IFN)-γ secretion by T cells and enables T cells to suppress GC cell growth. Similar results with animal gastric tumor models were obtained in vivo. PD-1 monoclonal antibody treatment did not enhance the inhibitory effect of T cells on GC cells expressing PD-L1 ^P146R in vitro or in vivo. This study suggests that rs17718883 is common and may be used as a biomarker for exclusion from PD-1/PD-L1 blockade therapy.
Competing Interests: Declaration of interests K.D.W. has received consulting fees from Sanofi Oncology, is a member of the SAB for Vibliome Therapeutics, and has or had sponsored research agreements with Astellas Pharmaceuticals and Revolution Medicine. K.D.W. declares that none of these relationships is directly or indirectly related to the content of this manuscript. The other authors declare no competing interests.
(Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)