Abstract 3702: Dissecting circulating tumor cells phenotype in a cohort of locally advanced non-small cell lung cancer patients undergoing neoadjuvant chemotherapy

Abstract Background: Platinum-based neoadjuvant chemotherapy (pb-NACT) is the primary treatment approach for locally advanced non-small cell lung cancer (LA-NSCLC), despite offering only a limited overall survival (OS) gain. Cisplatin-induced cell damage has been shown to activate the SDF-1/CXCR4 axis in preclinical models of NSCLC, resulting in the recruitment of a cell subset co-expressing the stemness marker CD133 and CXCR4 (SDF-1 receptor) at distant sites. These cells, known as metastasis-initiating cells (MIC), exhibit prometastatic activity. By longitudinally monitoring circulating tumor cells (CTC) in the blood of LA-NSCLC patients (pts) undergoing pb-NACT, our objective is to assess the potential prognostic significance of CTC number and phenotype. Methods: Between February 2019 and August 2023, a total of 61 pts with LA-NSCLC undergoing pb-NACT, were included in the study. Blood samples were obtained at baseline (T1), post-pb-NACT (T2), and post-surgery (T3) for the characterization of CTC, including total CTC, CXCR4+CTCs, and CXCR4+CD133+ MIC. This characterization utilized a validated marker-independent strategy combining Parsortix and DEPArrayTM technologies. Logistic regression models were employed to examine the association between CTC subsets and the response to pb-NACT (Disease Control Rate [DCR], Overall Response Rate [ORR]), while Cox-regression models were used to assess their association with survival endpoints (event-free survival [EFS], OS, disease-free survival [DFS]). Results: Out of the 61 enrolled patients, 34 had available CTC data for analysis. In this population, DCR was 64.7%, and the ORR 29.4%. Surgery was performed in 14 pts (41.2%). At baseline (T1), elevated levels of CXCR4+CTCs were linked to a lower DCR (10 vs 3/mL, odds ratio [OR]=0.02, 95% confidence interval [CI]: 0-0.40, p=0.008), as well as shorter EFS (10 vs 3/mL, HR=4.20, 95% CI: 1.84-9.58, p=0.002) and OS (10 vs 3/mL, HR=3.14, 95% CI: 1.25-7.88, p=0.004). At the post- CT time point (T2), higher levels of MIC were associated with shorter EFS (3 vs 0/mL, HR=1.41, 95% CI: 1.00-1.99, p=0.047) and OS (3 vs 0/mL, HR=1.55, 95% CI: 1.03-2.34, p=0.035). Although the sample size was limited, a higher number of MIC at the post-surgery time point (T3) showed a trend toward reduced DFS. Discussion: CTC could serve as a novel biomarker for assessing the effectiveness of pb-NACT in LA-NSCLC. Elevated levels of CXCR4+CTC both at baseline and after pb-NACT, along with increased MIC post-pb-NACT and post-surgery, indicate unfavorable prognostic factors for survival. Specifically, a higher baseline of CXCR4+CTCs may be linked to a suboptimal response to treatment, suggesting the potential need for treatment intensification in patients exhibiting elevated CXCR4+CTC baseline levels. Citation Format: Rita Leporati, Teresa Beninato, Sara Iadecola, Chiara Andreon, Fabio Murianni, Melissa Balsamo, Antonia Martinetti, Benedetta Lombardi Stocchetti, Laura Mazzeo, Sara Manglaviti, Mario Occhipinti, Marta Brambilla, Arsela Prelaj, Claudia Proto, Rosalba Miceli, Luca Roz, Gabriella Sozzi, Filippo De Braud, Giuseppe Lo Russo, Giulia Bertolini. Dissecting circulating tumor cells phenotype in a cohort of locally advanced non-small cell lung cancer patients undergoing neoadjuvant chemotherapy [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(6_Suppl):Abstract nr 3702.