Abstract 2173: A multi-institutional prospective biomarker study of durvalumab after concurrent chemoradiation therapy in patients with unresectable stage III non-small cell lung cancer (WJOG11518L/SUBMARINE)

Abstract

Abstract Background: Programmed cell death-ligand 1 (PD-L1) inhibitor durvalumab has been found to improve disease control in patients with unresectable stage III non-small cell lung cancer (NSCLC) treated with definitive concurrent chemoradiation therapy (dCCRT), but approximately a half of patients eventually experience disease progression within one year after the start of durvalumab. The mechanism of this resistance at such an early timing is poorly identified. Therefore, we conducted a prospective biomarker study to explore the resistance mechanisms to durvalumab after CCRT (Trial Identifier: UMIN000035916). Methods: A total of 139 patients with unresectable stage III NSCLC enrolled into this study after dCCRT were treated with durvalumab for up to 1 year. 135 patients who fulfilled the predetermined selection criteria were included for this primary biomarker analysis. Archival tumor tissues collected before the treatment were analyzed by immunohistochemistry for several key biomarkers such as PD-L1, CD8, and CD73, DNA sequencing for tumor-mutation burden (TMB) and genomic profile, as well as gene expression profiling (GEP). Peripheral blood mononuclear cells (PBMC) were also collected before and after durvalumab for flow-cytometry (FCM) analysis where available. Progression-free survival (PFS) was compared based on these biomarkers. Results: Median follow-up time was 14.4 months. Median PFS was 14.9 months (95% confidence interval [CI], 11.3-not reached), and 1-year PFS rate was 56.3% (95% CI, 47.3-64.3). CD8+ tumor-infiltrating lymphocytes (TILs), PD-L1 tumor proportion score (TPS), TMB, and CD73 on tumor cells were associated with PFS (hazard ratios [HRs], 0.40 [95% CI, 0.22-0.73] for CD8+TILs; 0.67 [95% CI, 0.40-1.11] for PD-L1-TPS ≥1%; 0.59 [95% CI, 0.34-1.02] for high TMB; 1.45 [95% CI, 0.86-2.43] for high CD73). Common pathogenic gene alterations such as EGFR, KRAS, and TP53 were not associated with PFS. Multivariable analysis including key clinical factors as covariables indicated that CD8+TILs and the CD73-expressing tumor cells were independently associated with durvalumab outcome (HRs, 0.26 [95% CI, 0.08-0.89] for CD8+TILs; 5.83 [95% CI, 1.33-25.62] for CD73). The significance of CD73-expressing tumor cells as a resistance factor was more obvious in patients with high CD8+TILs (HR, 2.35 [95% CI, 1.14-4.86]). GEP of tumor tissue and FCM of PBMC suggested that CD73-expressing tumor cells prevented effective reinvigoration of antigen-reactive CD8+ T cells by durvalumab due to the immunosuppressive activity. Conclusions: Low preexisting CD8+TILs or high CD73-expressing tumor cells were suggested to be primary resistance mechanism to durvalumab after CCRT in stage III NSCLC. Further development of next treatment approach will be prompted based on these findings. Citation Format: Koji Haratani, Atsushi Nakamura, Nobuaki Mamesaya, Kenji Sawa, Yasuto Yoneshima, Ryota Saito, Tomohiro Ozaki, Kenjiro Tsuruoka, Akito Hata, Kosuke Tsuruno, Tomohiro Sakamoto, Shunsuke Teraoka, Masahide Oki, Hiroshi Watanabe, Tomoyuki Otani, Kazuko Sakai, Shuta Tomida, Yasutaka Chiba, Akihiko Ito, Kazuto Nishio, Nobuyuki Yamamoto, Kazuhiko Nakagawa, Hidetoshi Hayashi. A multi-institutional prospective biomarker study of durvalumab after concurrent chemoradiation therapy in patients with unresectable stage III non-small cell lung cancer (WJOG11518L/SUBMARINE) [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 2173.