Abstract 6404: Clinical scenario of immune checkpoint inhibitor treatment in metastatic nasopharyngeal carcinoma

Abstract Advanced in local treatment technology and early detection methodology, distant metastasis became a critical issue in Nasopharyngeal carcinoma (NPC). Recently, cancer immunotherapy especially immune checkpoint inhibitors (ICIs) including anti-programmed death-1 (PD-1) and PD-1 ligand (PD-L1) monoclonal antibodies (Mabs) had a rapid progress in cancer patient management. We try to clarify the clinical scenario of immune-related parameters in metastatic NPC. We had check 81 metastatic tissue PD-L1 expression without ICI treatment from the tissue bank of CGMH, Linkou, during 2005~2019. Using anti-PD-L1 antibody, 22C3 Dako, tumor proportional score (TPS) was positive in 43.2% (35/81) checked tissue and combine positive score (CPS) was positive in 58.0% (47/81) tissue respectively. For overall survival (OS) combined with PD-L1 expression in metastatic tissue analysis, positive CPS but not TPS correlated with longer survival with statistical significance (TPS: >0% vs =0%, median survival, 24m vs 22.5m, p=0.615186; CPS: >0% vs =0%, median survival, 28m vs 16m, p=0.003709). Retrospectively analysis of metastatic NPC treatment of combination of chemotherapy, ICIs, and local treatment in our institute in the past 6 years, total 40 patients was enrolled with median overall survival of 34.1 months. Objective response rate by RECIST criteria for immunotherapy-based regimen was 75% (CR:40%; PR:35%) and disease control rate was 85%. According to response by RECIST criteria, median overall survival were 34.1 months vs. 16.7 months respectively for responders and non-responders. With pre-treated NLR as cutoff value of 1.6, difference of median overall survival between two groups (responder vs nonresponder) was statistically significant (p=0.021). We also found that lower median post-treatment NLR in responders than in non-responders (1.4 vs. 3.2, p=0.013). Using rapid lymphocyte amplification protocol via IL-2 stimulation, the PBMC from most of the patient received ICIs treatment can be amplified 1~10 folds and positively correlated with total lymphocyte count. Through flowcytometry analysis, we found these amplified PBMC was lymphocyte dominant and rich in CD8+. We also found these amplified PBMC can kill the NPC EBV-positive cell line and xenograft in vitro and in vivo. These results demonstrated that combination of chemotherapy, ICIs, and local treatment will benefit metastatic NPC patients. Citation Format: Cheng-Lung Hsu, Yung-Chia Kuo. Clinical scenario of immune checkpoint inhibitor treatment in metastatic nasopharyngeal carcinoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6404.