Abstract 3172: Prognostic and therapeutic implication of programmed death ligand 1 (PD-L1), microsatellite instability, and PIK3CA gene in lipoarcoma

Abstract

Abstract Background: With the promising efficacies with personalized approach, we tested clinically relevant molecular target programmed death ligand 1 (PD-L1), microsatellite Instability (MSI), and PIK3CA molecules in liposarcoma to provide practical guide. Methods: A consecutive series of 74 liposarcoma patients who underwent curative resection between 2005 and 2016 were assessed using immuno-molecular panels: PD-L1 (22C3 pharmDx assay) and mismatch repair proteins (MLH1, PMS2, MSH2, and MSH6) by immunohistochemistry (IHC), MSI using PCR, and PIK3CA mutation/amplification using pyrosequencing and fluorescence in situ hybridization. Results: For all the cases, PD-L1 was positive only in tumor infiltrating lymphocytes (TILs), while no PD-L1 expression was found on tumor cell and 23% were tumors with PD-L1+ TILs. PD-L1+ TILs was significantly predominant in abdominal site (P=0.004) and had significantly longer overall survival than PD-L1- TILs (5 year OS 84.4% vs 60.8%, P=0.007). Regarding the MSI status, 2 well differentiated liposarcoma showed MSI [MSI-H (n=1) and MSI-L (n=1)]. For concordance with mismatch repair protein using IHC, only 1 out of 8 with concurrent loss of MLH1, MSH6, and PMS2 showed MSI-H (D2S123, D17S250). Activating PIK3CA mutation was detected in 7 patients [9.5%, exon 9 (n=4) and exon 20 (n=3) mutation] and 6 cases were PD-L1-TIL group. PIK3CA copy number gain were detected in 18 (24.3%) cases and significantly associated with PD-L1+TIL tumors (P=0.045). Conclusions: With our comprehensive immuno-moleuclar panel, liposarcoma need to be categorized based on the molecular genomic subtype and this may facilitate the development of successful future clinical trials using molecular agents. Citation Format: Hyo Song Kim, Hyae Min Jeon, Jae Seok Lee, Soo Hee Kim, Young Han Lee, Hyuk Hur, Sung Hoon Kim, Seung Hyun Kim, Hei-Cheul Jeung. Prognostic and therapeutic implication of programmed death ligand 1 (PD-L1), microsatellite instability, and PIK3CA gene in lipoarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3172.