Abstract P3-11-14: Circulating lymphocytes and pathologic complete response rate among patients with early stage triple negative breast cancer treated with neoadjuvant chemotherapy
Authors: Talamantes SM , Costa RL , Rademaker A , Santa-Maria CA 
Published: May 2019

Background: Chemotherapy can affect circulating immune cells. Low lymphocyte counts have been associated with worse prognosis in many cancers and inferior responses to immune checkpoint therapy. The effects of neoadjuvant chemotherapy on the immune system and its association with clinical outcomes in breast cancer is not well described.

Methods: A database was constructed of patients diagnosed with early stage triple negative breast cancer (TNBC) treated with neoadjuvant chemotherapy. Clinicopathologic information was extracted from the local electronic tumor registry or by chart review. Circulating lymphocyte and monocyte counts were assessed at the time of diagnosis, after neoadjuvant chemotherapy, and prior to surgery (all values in K/cu mm). These were correlated with clinicopathologic data, pathologic complete response (pCR) rates, and disease free survival (DFS) using rank sum test and Spearman correlation, t-test and log rank test, respectively.

Results: From 2000-2015, 426 patients with breast cancer treated with neoadjuvant chemotherapy were sequentially identified by an institutional electronic database. After excluding those who did not actually receive neoadjuvant therapy, were a subtype other than TNBC, and had missing receptor status or blood counts, 95 patients met eligibility for analysis. The median age of patients was 50 (range 26-79); 63 (66%) patients were treated with anthracyclines plus taxanes, 29 (31%) platinum-based chemotherapy, 2 (2%) with only anthracyclines, and 1 (1%) with only taxanes; 32 (34%) patients achieved a pCR; and 33 (35%) patients had recurrence events. Median follow up time was 47 months (range 13-123). No significant associations were found between pCR and changes in lymphocyte or monocyte count (mean lymphocyte reduction 0.74 in those with no-pCR versus 0.60 in those with pCR, p=0.30; mean monocyte reduction 0.0 in those with no-pCR versus 0.016 in those with pCR, p=0.78). There was no correlation between changes in lymphocytes or monocytes with DFS. Baseline lymphocytes or monocytes also did not correlate with pCR or DFS. Notably, there was a correlation between monocytes after neoadjuvant chemotherapy and pCR (mean monocyte level was 0.56 in those with no-pCR versus 0.46 in those with pCR, p=0.049) and DFS (median DFS in highest monocyte quartile 30 months versus in lowest quartile 107 months, p=0.022).

Conclusions: Our results suggest that transient lymphopenia from chemotherapy is not associated with clinical outcomes. However, we observed lower absolute circulating monocyte counts after neoadjuvant chemotherapy were associated with better clinical outcomes. Further research assessing the role of circulating immune cells is required to understand the effects of neoadjuvant chemotherapy on clinical outcomes, which may help inform immunotherapy-based strategies.

Citation Format: Talamantes SM, Costa RL, Rademaker A, Santa-Maria CA. Circulating lymphocytes and pathologic complete response rate among patients with early stage triple negative breast cancer treated with neoadjuvant chemotherapy [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 P3-11-14.