Peripheral immunological response to treatment with a novel bifunctional anti-PD-L1/TGFβRII agent in recurrent/metastatic nasopharyngeal carcinoma.

Abstract

e14622 Background: Anti-programmed cell death protein-ligand 1 (PD-L1) monotherapy has not shown promising anti-tumor effects in recurrent/metastatic nasopharyngeal carcinoma (R/M NPC) in first-line settings. Consequently, second-generation checkpoint inhibitors via targeting multiple pathways are urgently needed. Bintrafusp alfa (also known as M7824) is one of such agents that targets both the transforming-growth factor beta (TGF-β) and PD-L1 pathways. As T cells are the major immune cell subset responsible for tumor destruction, we focus on the peripheral memory T-cell subsets. Through the evaluation of peripheral biomarker analysis and their correlation with clinical outcomes, we have characterized blood-based dynamic phenotypes that predict responses to M7824 in NPC. Methods: Biomarker analysis was performed as part of a phase II clinical trial (NCT04396886) in patients with treatment-refractory histologically confirmed recurrent NPC (n=32) who received M7824. Peripheral blood samples were obtained at baseline before treatment (D0) and every 2 weeks during treatment. Samples collected at D0 and at time of best response assessment (DR) were analysed using multicolor flow cytometry. Patients with complete/partial response or stable disease for at least 6 months were considered responders (R), those with stable disease less than 6 months or progressive disease were considered non-responders (NR). Results: Peripheral T cells between R (n=10) and NR (n=22) patients were compared. While the overall percentage of memory T-cell subsets was similar in both groups after treatment, R patients displayed a significantly lower amount of prototype cell death receptor, CD95, among terminally differentiated effector memory (TEMRA; CD45RA+CD62L+) T cells (CD45+CD3+and CD45+ CD3+CD4+: p<0.0001; CD45+CD3+CD8+: p=0.0047) (CD95DR/RvsNR) as compared to patient in NR group. Besides, reduced expression of CD95DR on TEMRA CD4 T cells was significantly associated with longer overall survival (OS), regardless of response status (median OS: 16.26 months for patients with lower CD95 levels; median OS: 5.29 months for patients with higher CD95 levels [p < 0.0001]). Notably, we noticed that R patients displayed a lower frequency of CD95-expressing TEMRA at the baseline (CD95D0/Rvs NR) as compared to NR group. Conclusions: The apoptotic response of peripheral blood TEMRA CD4 T cells (CD95DR/R vsNR) may be a useful surrogate biomarker for predicting prognosis to M7824 therapy in NPC. The finding of a lower frequency of CD95D0TEMRA in R patients suggesting that CD95 may potentially act as a biomarker for predicting treatment response as well as reveal a possible target for guiding therapeutic strategy for R/M NPC.[Table: see text]