Abstract 3729: Association between clinical characteristics and treatment outcome of immune checkpoint inhibitor with or without chemotherapy in elderly non-small cell lung cancer patients with high PD-L1 expression

Abstract Background and Aim: The proportion of elderly patients diagnosed with advanced stage lung cancer has been increasing owing to the aging of the population. Thus, formulating a treatment strategy for elderly non-small cell lung cancer (NSCLC) patients is essential. For NSCLC with programmed cell death ligand-1 (PD-L1) tumor proportion score (TPS) ≧ 50%, both immune checkpoint inhibitor monotherapy (ICI mono) and combination therapy of ICI and chemotherapy (ICI/Chemo) have been established as standard treatment options. However, evidence based on the clinical trials specifically for elderly patients is limited, and it is not clear whether ICI mono or ICI/Chemo should be used in elderly NSCLC patients with PD-L1 TPS ≧ 50%. This study aimed to clarify which clinical population will benefit from ICI/Chemo in elderly NSCLC patients with PD-L1 TPS ≧ 50%. Method: We retrospectively analyzed 199 NSCLC patients aged ≧ 70 years of Eastern Cooperative Oncology Group performance status (ECOG PS) 0-1 with PD-L1 TPS ≧ 50% who were treated with ICI mono or ICI/Chemo. We analyzed the association between treatment outcome and baseline patient characteristics in each group. Comparing the treatment outcome, propensity score matching was used to reduce bias. Results: Of the 199 patients, 131 received ICI mono, and 68 received ICI/Chemo. The median overall survival (OS; 25. 0 vs. 42. 2 months, P = 0. 116) and median progression-free survival (PFS; 10. 9 vs. 11. 8 months, P = 0. 231) did not significantly differ between the ICI mono and ICI/Chemo groups. Multivariate analysis revealed the factors independently associated with OS: smoking history in the ICI mono group (smoking history/non-smoking history, hazard ratio HR 0. 36, 95% confidence interval CI 0. 16-0. 78, P = 0. 048), and ECOG PS (ECOG PS 1/PS 0, HR 3. 84, 95% CI 1. 44-10. 20, P = 0. 007) and histology type in the ICI/Chemo group (Non-squamous cell carcinoma/squamous cell carcinoma, HR 0. 17, 95% CI 0. 06-0. 44, P 0. 001). For patients with ECOG PS 0 (OS: 26. 1 months vs. not reached, P = 0. 0031, PFS: 6. 5 vs. 21. 7 months, P = 0. 0436) or non-squamous cell carcinoma (OS: 23. 8 months vs. not reached, P = 0. 0038, PFS: 10. 9 vs. 17. 3 months, P = 0. 0383) in the ICI/Chemo group, PFS and OS were significantly longer than in the ICI mono group. Discussion and Conclusion: In elderly NSCLC patients with high PD-L1 expression, this study suggested that ECOG PS and histological type may be predictive clinical factor when choosing ICI mono or ICI/Chemo treatment. Citation Format: Hayato Kawachi, Shota Takei, Tadaaki Yamada, Motohiro Tamiya, Yoshiki Negi, Yasuhiro Goto, Akira Nakao, Shinsuke Shiotsu, Takayuki Takeda, Asuka Okada, Taishi Harada, Koji Date, Yusuke Chihara, Isao Hasegawa, Nobuyo Tamiya, Takashi Kijima, Koichi Takayama. Association between clinical characteristics and treatment outcome of immune checkpoint inhibitor with or without chemotherapy in elderly non-small cell lung cancer patients with high PD-L1 expression abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 3729.