33P - The multi-switching activity of circulatory neutrophils in patients with Early Breast Cancer

Background

Patients with Breast Cancer (BC) often display elevated levels of circulating neutrophils (Ns). Evidence from mouse models of Early Breast Cancer (EBC) shows that Ns can either have a tumour promoting or inhibitory role. CD62L (L-selectin) is a cell adhesion molecule found on the surface of Ns which helps them bind to the endothelium and migrate into tissues and is also rapidly shed upon N activation. There is limited knowledge whether different circulatory N subsets are present in patients with BC and if this is influenced by BC subtype. In order to address these questions, we phenotyped Ns from BC patients.

Methods

We investigated changes in CD62L expression via flow cytometry in Ns from patients and healthy volunteers (HVs). Since kinases govern many aspects of intracellular signalling, we also assessed the kinase activity (n = 340 kinases) within Ns using a Pamgene kinase assay. We recruited 44 patients with EBC (14 Node +, 30 node -; 10 T1 and 26 T2 and 8 T3) and paired HVs (age matched) to compare the phenotype of Ns isolated from blood. We recruited patients 15 with oestrogen receptor-positive (ER+) and HER2- BC, 7 patients with ER + HER2 – BC, 8 patients with ER- HER2- BC and 6 patients with triple-negative BC between June 2018 and June 2021. No patient had overt metastatic disease and all were screened for exclusion factors.

Results

ER+ patients had lower level of CD62L^low N subsets compared to HVs (P< 0.0019). There was a significant increase in CD62L^low N subsets (2-fold higher) for ER- patients compared to HVs (P< 0.0331). There was a general upregulation in neutrophil kinase activity for patients with ER+ HER2 – BC compared to paired HVs. The presence of HER2+ resulted in a general downregulation in the tyrosine kinase neutrophil activity for BC patients (regardless of ER status) compared to paired HVs. The functional implications of these differences in kinase activity are being actively investigated.

Conclusions

We have detected changes in CD62L expression and kinase activity within circulatory Ns in patients with EBC and the nature of these changes appear to be intrinsically linked to ER subtype. These findings may have important implications for use as part of an early diagnostic multi-omic platform.

Legal entity responsible for the study

Imperial College London.

Funding

Medical Research Council.

Disclosure

All authors have declared no conflicts of interest.