Expression of MAGE-A and NY-ESO-1 cancer-testis antigens is enriched in triple-negative invasive breast cancers

Abstract

Aims

A better understanding of the expression of cancer testis antigens (CTA) in breast cancer might identify new immunotherapy options, especially for triple-negative (TN) tumours, which lack expression of conventional therapeutic targets ER, PR and HER2 (receptors for Oestrogen, Progesterone and Human epidermal growth factor). The aim of this study was to quantify the expression of MAGE-A and NY-ESO-1 CTAs in breast cancer, and relate this to known clinicopathologic parameters.

Methods and results

We surveyed MAGE-A and NY-ESO-1 protein expression in an unselected cohort of 367 breast tumours (out of which 65 tumours were TN), with accompanying clinical follow-up data, using immunohistochemistry (IHC) analysis of tissue microarrays. Relevant to their potential as vaccine targets in breast cancer, MAGE-A was expressed in 13% of cases, and NY-ESO-1 in 3.8%, with the majority of tumours exhibiting fairly homogeneous staining within individual tissue cores (~85% of cases with staining in >75% tumour cells). Most NY-ESO-1 positive cases also expressed MAGE-A (p=2.06x10^-9), and both were strongly associated with the TN phenotype (p<0.0001); particularly the most proliferative and poorly differentiated cases displaying genomic instabililty. This was characterised by co-expression of c-kit, TTK and overexpression of p53.

Conclusions

MAGE-A and NY-ESO-1 are frequently expressed in TNBC (~47% and 17% of TN cases, respectively), suggesting that targeting them could be feasible in this patient group. Expression is reasonably homogeneous in positive cases suggesting that IHC analysis of tissue biopsies would be a reliable companion biomarker.

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