Expression of NY-ESO-1, MAGE-A3, PRAME and WT1 in different subgroups of breast cancer: An indication to immunotherapy?

Objectives: Cancer Testis Antigens are immunogenic tumor-specific proteins. We investigated NY-ESO-1, MAGE-A3 and PRAME, in addition to WT1 expression in different Breast Cancer (BC) subtypes. We then evaluated the expression rate of NY-ESO-1 in early Triple Negative breast cancer (TNBC), and investigated whether its expression would be maintained or lost in the metastatic setting to explore possible immunotherapy indication.

Materials and methods: Three subgroups of BC patients were selected by the expression of ER, PgR and Her2. Tissue microarray was performed on a total of 92 Invasive BC. Sections were stained for NY-ESO-1, MAGE-A3, PRAME and WT1. The second cohort was composed by 26 metastatic TNBC patients from whom both the primary and secondary lesion tissues were available. Sections were stained for NY-ESO-1.

Results: NY-ESO-1 was the only differentially expressed antigen and was absent in ER+ and ER-PgR + tumors, as for an exclusive expression of either NY-ESO-1 or at least one hormonal receptor (HR+). NY-ESO-1 was particularly represented in TNBC. No correlation has been found between MAGE-A3 and PRAME expression and subtype WT1 had low expression, except in the Her2+ group. In the second cohort, NY-ESO-1 was expressed in 12 and 24% of primary and metastatic lesions respectively.

Conclusions: This study defines a distinction between HR+ and HR-tumors through NY-ESO-1 expression. TNBC subgroup has the highest frequency of NY-ESO-1+ cases, and it could be the candidate population for the development of anti-NY-ESO-1 vaccine, both in the adjuvant or metastatic setting, and for the selection of cases suitable for immunotherapy.