title: Expression of PD-1 and PD-L1 in thymic epithelial neoplasms.
abstract: Thymic epithelial neoplasms are rare tumors that are difficult to diagnose and treat. Programmed death 1 (PD-1) receptor and its ligand (PD-L1) are expressed by various malignancies and are considered a prognostic factor and immunotherapeutic target. We examined the expression of both antibodies in 100 thymic epithelial neoplasms to assess their use as a biomarker and to correlate their expression with clinicopathological parameters. Whole-tissue sections of 74 thymomas and 26 thymic carcinomas were examined. Expression of PD-1 and PD-L1 was evaluated by immunohistochemistry and scored by the percentage of positive T-cells or tumor cells, respectively. Cases with strong membranous reactivity of the antibody in ≥5% of T-cells (PD-1) or tumor cells (PD-L1), respectively, were considered positive. Expression of PD-1 was detected in 52/100 cases (52%) including 6/26 thymic carcinomas (23%) and 46/74 thymomas (62%). PD-L1 was positive in 61/100 cases (61%) including 14/26 thymic carcinomas (54%) and 47/74 thymomas (64%). A total of 82 cases (82%) showed expression of PD-1 or PD-L1. PD-1+cases were associated with higher stage in thymic carcinoma (P=0.01) and PD-1-cases with thymic carcinoma histology (P=0.0014), whereas PD-L1+cases were associated with neoadjuvant therapy in thymoma (P=0.0065). There was no statistical difference between PD-1 or PD-L1 expression status and other clinicopathological parameters including overall survival. PD-1 and/or PD-L1 are expressed in up to 82% of thymic epithelial neoplasms. These results confirm that these tumors should be considered for PD-1/PD-L1-targeted therapy, however their predictive value in terms of prognosis remains uncertain.
authors.affiliation: Department of Pathology, MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Annikka
authors.initials: A
authors.lastname: Weissferdt
authors.affiliation: Department of Translational Molecular Pathology, MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Junya
authors.initials: J
authors.lastname: Fujimoto
authors.affiliation: Department of Pathology, MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Neda
authors.initials: N
authors.lastname: Kalhor
authors.affiliation: Department of Translational Molecular Pathology, MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Jaime
authors.initials: J
authors.lastname: Rodriguez
authors.affiliation: Department of Biostatistics, MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Roland
authors.initials: R
authors.lastname: Bassett
authors.affiliation: Department of Translational Molecular Pathology, MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Ignacio I
authors.initials: II
authors.lastname: Wistuba
authors.affiliation: Department of Pathology, MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Cesar A
authors.initials: CA
authors.lastname: Moran
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D060890:B7-H1 Antigen / Q000032:analysis*; D014408:Biomarkers, Tumor / Q000032:analysis*; D017024:Chemotherapy, Adjuvant; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009367:Neoplasm Staging; D009375:Neoplasms, Glandular and Epithelial / Q000737:chemistry* / Q000401:mortality / Q000473:pathology / Q000628:therapy; D061026:Programmed Cell Death 1 Receptor / Q000032:analysis*; D013934:Thymectomy; D013945:Thymoma / Q000737:chemistry* / Q000401:mortality / Q000473:pathology / Q000628:therapy; D013953:Thymus Neoplasms / Q000737:chemistry* / Q000401:mortality / Q000473:pathology / Q000628:therapy; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D060890:B7-H1 Antigen; D014408:Biomarkers, Tumor; C423236:CD274 protein, human; C105992:PDCD1 protein, human; D061026:Programmed Cell Death 1 Receptor