PD-L1 expression and presence of TILs in small intestinal neuroendocrine tumours

// Angela Lamarca 1 , Daisuke Nonaka 2, 3 , Wolfgang Breitwieser 4 , Garry Ashton 5 , Jorge Barriuso 1, 3 , Mairéad G. McNamara 1, 3 , Sharzad Moghadam 5 , Jane Rogan 5 , Wasat Mansoor 1 , Richard A. Hubner 1 , Christopher Clark 4 , Bipasha Chakrabarty 2 and Juan W. Valle 1, 3 1 Department of Medical Oncology, The Christie NHS Foundation Trust, Manchester, UK 2 Department of Histopathology, The Christie NHS Foundation Trust, Manchester, UK 3 Division of Molecular and Clinical Cancer Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK 4 Molecular Biology Core Facility, Cancer Research UK Manchester Institute, Manchester, UK 5 Manchester Cancer Research Centre (MCRC) BioBank, University of Manchester, Manchester, UK Correspondence to: Juan W. Valle, email: juan.valle@manchester.ac.uk , juan.valle@christie.nhs.uk Keywords: PD-L1; tumour infiltrating lymphocytes; neuroendocrine; immunotherapy; treatment Received: November 22, 2017 Accepted: February 03, 2018 Epub: February 12, 2018 Published: March 13, 2018 ABSTRACT Background: The extent of resistance to immune surveillance in patients with well-differentiated (Wd) (grade 1/2) small-intestinal neuroendocrine tumours (Si-NETs) is unknown. Methods: Patients diagnosed with Wd Si-NETs (excluding appendix, which are considered to have a different biology to other midgut NETs) were eligible. Tumoural programmed death (PD)-ligand(L) 1 (PD-L1)/PD-L2/PD-1 and tumour infiltrating lymphocytes (TILs) [presence and phenotype] were analysed in archival tissue by immunohistochemistry (IHC); reverse transcription quantitative polymerase chain reaction (RT-qPCR) was used for confirmation of IHC results. Results: Of 109 patients screened, 62 were eligible: 54.8% were male; median age was 63.7 years (95%-CI 59.7-67.2); disease stage II: 4.8%, III: 40.3% and IV: 54.8%; 41.9% were functional. Analysed samples (67.1% from primary tumours, 32.9% from metastases) were of grade 1 (67.1%) or 2 (32.86%) with a median Ki-67 of 2%. From the total of 62 eligible patients, 70 and 63 samples were suitable for IHC and RT-qPCR analysis, respectively. PD-L1 expression within tumour cells and TILs were identified in 12.8% and 24.3% of samples respectively; 30% of samples showed PD-L1 expression within tumour cells and/or TILs. PD-1 was present in TILs in 22.8% of samples. Majority of samples showed significant presence of CD4 + (focal 42.86%; moderate 2.86%) and CD8 + (focal 92.86%; moderate 4.29%) TILs. IHC findings were confirmed with RT-qPCR; which showed higher expression levels of PD-L1 (p-value 0.007) and PD-1 (p-value 0.001) in samples positive for IHC compared to negative-IHC. Conclusions: Thirty-percent of patients express PD-L1 within tumour cells and/or TILs. Identification of presence of TILs was also significant and warrant the investigation of immunotherapy in this setting.