Supplementary Material for: Prognostic role of PD-L1 and IDO-1 expression in sinonasal carcinoma

Introduction: Sinonasal carcinomas (SNC) are rare, aggressive tumours with complex immunological aspects. Still, prognostic markers are missing. The study aimed to investigate the relationship between immune checkpoints - specifically programmed death-ligand 1 (PD-L1) and Indolamin-2,3-dioxygenase 1 (IDO-1) - and clinical parameters in SNC. Methods: In this monocentric study immunohistochemical analysis of the checkpoints PD-L1 and IDO-1 was carried out in 85 SNC patients from 2004 to 2020. Tumour proportion score (TPS), combined positive score (CPS) and combined IDO-1 score classified the PD-L1 and IDO-1 expression. The study was conducted in a specialized tertiary care center, indicating comprehensive multidisciplinary care with surgical, radiotherapeutic and systemic treatment intervention. Results: Over a median observation period of 41 months, 52 squamous cell carcinomas (SCC, 61%) and 33 adenocarcinomas (AC, 39%) were included. 31 patients (37%) were classified in UICC IV stage, 90.6 % (n=77) received a primary resection. 3-year progression-free survival (PFS)/-overall survival (OS) rates were 63.6% / 81.4% in SCC and 73.1% / 82.5% in AC, respectively. Sinonasal AC showed significantly more frequently negative PD-L1 expression and CPS 50%, combined low IDO-1 Score and high UICC stage showed significantly worse 3-year-PFS and – OS values (p50% and combined low IDO-1 score correlate with shortened 3-year-PFS and -OS in sinonasal SCC. Immune checkpoints could therefore represent important target molecules for the prognosis assessment of sinonasal SCC.