Abstract P3-01-01: Circulating tumor cells (CTCs) after neoadjuvant chemotherapy for triple negative breast cancer (TNBC)

Abstract

Abstract Background: ARTEMIS (A Randomized, TNBC Enrolling trial to confirm Molecular profiling Improves Survival) is a randomized trial to determine if precision guided neoadjuvant chemotherapy (NAC) impacts rates of pathologic complete response in the breast and axillary nodes (pCR). We hypothesized that CTCs in peripheral blood after completion of NAC would provide prognostic information beyond pCR alone in TNBC patients. Methods: Blood was assessed for CTCs after NAC as part of two IRB approved studies, ARTEMIS (2014 – 0185/PA15-1050), and LAB04-0698. CTCs were identified using the Cell Search® System (Menarini Silicon Biosystems). Samples with one or more cells, also having morphologic criteria for malignancy, were deemed CTC positive. Log-rank test and Cox regression analysis were applied to evaluate associations between CTC positive, pCR, and overall survival. Results: pCR was achieved in 24/68 (35%) patients with TNBC. Twenty four patients (35%) were CTC positive. Three year overall survival was evaluated in 4 groups of patients: pCR and no CTCs (n=20), pCR and CTC positive (n=4), non-pCR and no CTCs (n=24) and non-pCR and CTC positive (n=20). Three year overall survival was higher in the pCR and no CTCs cohort (100%), compared to pCR and CTC positive (50%), non-pCR and no CTCs (83%), non-pCR and CTC positive (19%); log rank p<0.0001. In the non-pCR and CTC positive patient cohorts, the presence of CTCs was associated with significant risk of death at 3 years [hazard ratio of 12.3 (95% CI 3.4-454, p=0.00002)], whereas a favorable, but non-significant trend was noted for pCR [hazard ratio of 0.2 (95% CI 0.0, 1.4, p=0.11)]. Conclusion: The identification of CTCs after NAC has prognostic significance beyond that of pCR, and should be considered in evaluation of patients for clinical trials of adjuvant therapies. Citation Format: Lucci A, Hall C, Hess K, Ravenberg E, Clayborn A, Mittendorf E, Rauch G, Candelaria R, Moulder S, Thompson A. Circulating tumor cells (CTCs) after neoadjuvant chemotherapy for triple negative breast cancer (TNBC) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-01-01.