Pathologic complete response and serial circulating tumor cell monitoring during neoadjuvant therapy in nonmetastatic triple-negative breast cancer patients.

Abstract

e12111 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) influences rates of pathologic complete response in the breast and axillary nodes (pCR). We hypothesized that blood circulating tumor cell (CTC) identification before and/or after NAC (just before surgery) would be associated with pCR in non-metastatic TNBC patients. Methods: Blood was assessed for CTCs at baseline (pre-NAC) and after NAC (post-NAC), as part of an IRB approved study, ARTEMIS (2014 – 0185/PA15-1050). CTCs (per 7.5 ml blood) were identified using the Cell Search System (Menarini Silicon Biosystems). Samples > one cell having morphologic criteria for malignancy were deemed CTC+. Fisher exact test was used to evaluate associations between CTC detection and clinicopathologic characteristics, and Chi2 test was used to analyze associations between CTC detection pre- and post- NAC, and pCR. Results: Fifty-nine patients had pre-NAC and 43 patients had post-NAC CTC assessments. One or more CTC was detected in 13/59 (22%) patients pre-NAC and in 16/43 (37%) of post NAC samples. CTC detection was not associated with patient stage, tumor androgen receptor expression, vimentin expression, Ki-67 staining, or tumor-infiltrating lymphocyte levels. Pre-NAC CTC detection was not (chi2 P = 0.98), but post-NAC (chi2 P = 0.0017) CTC identification was negatively associated with pCR. Conclusions: CTC detection post-NAC was negatively associated with pCR in non-metastatic TNBC patients. These findings warrant larger studies studying serial CTC detection throughout treatment to assess response to NAC.