Discussion
non-small cell lung cancer, ER+ tumours, melanoma, breast cancer, tumours, TNBC, immune-suppressed tumour
NON-SMALL CELL LUNG CANCER, MELANOMA, BREAST CANCER, TUMOURS, CYTOTOXICITY, HER2+ BREAST CANCER
We report that neo-adjuvant treatment reduced the direct cytotoxic and ADCC capacity of circulating immune cells for all patients on the ICORG 10-05 trial, irrespective of FCGR SNP status. This corresponded with post-treatment increases in circulating CD8+ and CD4+ T cells, and decreased levels of NK cells, monocytes and B cells. When assessed in the context of treatment response, these changes were predominantly associated with patients who did not achieve a pCR. In addition, functionally pembrolizumab-responsive ADCC-capable immune cells were only detected in the pre-therapy blood of patients who did not achieve a pCR, had lower TIL levels and were more likely to have ER+ tumours.This study is the first to genotype, phenotype and functionally assess patient PBMCs in vitro in the context of pCR following 6 rounds of neo-adjuvant anti-HER2 targeted therapy/docetaxel/carboplatin. We found no statistically significant evidence that the HER2-targeted therapy given influenced the in vitro cytotoxicity or immune profile of samples (Supplementary Figs. Previous studies, such as those from Gennari et al. and Varchetta et al., have shown an increase in trastuzumab-mediated ADCC capabilities of patient immune cells in vitro after receiving neo-adjuvant trastuzumab monotherapy [The increase in post-therapy T cell levels indicates a triggering of an adaptive immune response. When assessed by pCR, it was found that the No pCR cohort was making the biggest contribution to the observed post-treatment changes for all immune cell subtypes (Fig. Our results highlight functional assessment of immune cells as an important adjunct to phenotypic analysis, which in this case did not definitively identify PD-1+CD16+ NK cells or monocytes as markers of treatment response in the population as a whole (Fig. The reduced TIL count in tumours from patients with PBMCs that responded to pembrolizumab in vitro is an important indication that the circulating immune cells are associated with an immune-suppressed tumour microenvironment (Fig. It should also be noted that the presence of PD-1-inhibited immune cells could also identify patients who will benefit from the addition of anti-PD-1 immune checkpoint inhibitors in the neo-adjuvant setting. Clinical trials examining checkpoint inhibitors in breast cancer are established, with anti-PD-L1 therapy atezolizumab approved to treat TNBC following the IMpassion130 trial [In summary, we hypothesise that circulating anti-PD-1-sensitive ADCC-capable immune cells identify immune-suppressed tumour phenotypes and could function as a biomarker of response to standard chemotherapy regimens and immune checkpoint inhibitors. Current efforts are focussed on prospective collection of pre-treatment blood samples from early stage HER2+ breast cancer patients and non-small cell lung cancer and melanoma patients scheduled to receive immune checkpoint therapy to provide larger datasets to assess the potential of the functional biomarker assay described in this study.