PD-L1 expression comparison between primary and relapsed non-small cell lung carcinoma using whole sections and clone SP263

// Enrico Munari 1, 2, Giuseppe Zamboni 1, 2, Gianluigi Lunardi 3, Marcella Marconi 1, Marco Sommaggio 1, Matteo Brunelli 2, Guido Martignoni 2, 4, George J. Netto 5, Mohammad O. Hoque 6, Francesca Moretta 7, Maria Cristina Mingari 8, Maria Cristina Pegoraro 9, Francesca Romana Mariotti 10, Paola Vacca 10, Lorenzo Moretta 10 and Giuseppe Bogina 1 1 Department of Pathology, Sacro Cuore Don Calabria Hospital, 37024 Negrar VR, Italy 2 Department of Diagnostics and Public Health, University of Verona, 37134 Verona VR, Italy 3 Department of Oncology, Sacro Cuore Don Calabria Hospital, 37024 Negrar VR, Italy 4 Department of Pathology, Pederzoli Hospital, 37019 Peschiera del Garda VR, Italy 5 Department of Pathology, The University of Alabama at Birmingham, Birmingham, AL 35233, USA 6 Department of Otolaringology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA 7 Department of Laboratory Medicine, Sacro Cuore Don Calabria Hospital, 37024 Negrar VR, Italy 8 Department of Experimental Medicine (DIMES), University of Genova, 16132 Genova GE, Italy 9 Department of Oncology, Pederzoli Hospital, 37019 Peschiera del Garda VR, Italy 10 Immunology Research Area, IRCCS Bambino Gesù Pediatric Hospital, 00146 Rome RM, Italy Correspondence to: Enrico Munari, email: enricoₘunari@yahoo. it Keywords: PD-L1; lung; cancer; heterogeneity; metastases Received: March 01, 2018 Accepted: June 23, 2018 Published: July 13, 2018 ABSTRACT We assessed the concordance, in terms of PD-L1 expression, between primary and metastatic non-small cell lung carcinoma (NSCLC) of different histotypes using validated SP263 clone. A few samples of local recurrences have also been analyzed. Whole sections of consecutive cases of primary NSCLC and paired relapses undergone surgical resection have been stained with PD-L1 clone SP263; for scoring purposes, a three-tiered system was applied using the following thresholds: <1%, 1–49% and ≥50%. Eighty-four cases of paired primary and relapsed tumors from 83 patients were analyzed, including 75 metastases and 9 local recurrences. Regarding metastases, when considering a cutoff of 1%, discrepancy in PD-L1 expression occurred in 9/75 (12%) paired samples (kappa value = 0. 75) ; at 50% cutoff, discrepancy in PD-L1 expression was detected in 7/75 (9. 3%) of paired samples (kappa value = 0. 61). Regarding recurrences, at 1% cutoff, the discrepancy in PD-L1 expression was seen in 3/9 (33%) paired samples and in all cases there was a gained PD-L1 expression; at 50% cutoff, 1/9 (11%) paired samples showed gained PD-L1 expression. Our data provide important information regarding the concordance between primary and relapsed NSCLC and the degree of reliability of metastatic sites in terms of PD-L1 expression evaluation.