Abstract 5373: Circulating tumor cell as a predictive marker for immunotherapy in advnaced non-small cell lung cancer

Abstract

Abstract Background: Circulating tumor cells (CTCs) have potential to provide minimally invasive way for the response monitoring of various cancer. This study aimed to investigate the feasibility of CTCs as a predictive marker for anti-PD-L1 immunotherapy in patients with advanced non-small cell lung cancer (NSCLC). Methods: This study included 37 patients with advanced NSCLC receiving atezolizumab monotherapy as second-line or more from July to November 2019. Blood was collected in a K2-EDTA tube and CTCs were isolated and enriched by using CD-PRIMETM system which is antibody-independent size-based isolation method. By Bioview CCBS system, total CTCs (tCTCs) were identified by a sum of single EpCAM/CK-positive (sCTCs) and double EpCAM/CK-CD45-positive cells (dCTCs). Results: Among 26 response-evaluable patients, objective response rate (ORR) and disease control rate (DCR) were 11.5% (3/26) and 57.7% (15/26), respectively. At cycle 1 (C1), patients with progression (PD) showed higher sCTC count (median, 8.6 vs. 4.3, p=0.065) and sCTC-to-tCTC ratio (median %, 35.9 vs. 9.8, p=0.024) than those without PD. During treatment, tCTC and sCTC count showed significant increase from C1 to C2 (p=0.019 and p=0.022). The subgroup with high sCTC increase from C1 to C2 (more than 2-folds) showed higher DCR than subgroup with low sCTC increase (less than 2-folds) (88.9% vs. 44.4%, p=0.066). Patients with high sCTC-to-tCTC ratio at C1 showed worse progression-free survival (median, 2.1 months) than those with low sCTC-to-tCTC ratio (not reached, hazard ratio 2.87, 95% confidence interval: 1.06-7.75, p=0.082). Conclusion: The baseline sCTC count and sCTC increase (more than 2-folds) at the first 3-week after atezolizumab could be potential biomarkers to predict the disease progression and poor survival in advanced NSCLC. Citation Format: Cheol-Kyu Park, Joon-Young Yoon, Min-Suk Kim, Bo-Gun Koh, Hyun-Ju Cho, In-Jae Oh, Young-Chul Kim. Circulating tumor cell as a predictive marker for immunotherapy in advnaced non-small cell lung cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5373.