54PWT1, NY-ESO-1 AND PRAME EXPRESSION IN BREAST CANCER SUBTYPES

Background: Tumor associated antigens (TAA) are frequently expressed in several cancer types. Several clinical trials with vaccines containing the TAA NY-ESO-1, WT1 and PRAME are actually accruing patients with lung, ovarian, breast cancer and melanoma. Very few studies investigated the expression of NY-ESO 1, PRAME and WT1 antigens in breast cancer. The aim of this study was to assess the immunoreactivity for TA antigens NY-ESO-1, PRAME and WT-1 in a large series of breast cancer tumor samples classified, according to immunophenotype in: triple negative (ER and PgR absent and HER2 negative), Luminal A like (ER positive and low Ki67), luminal B like (ER positive and Ki67 high and\\or PgR negative or low), lobular type and HER2 positive human breast cancers subtypes. Patients and methods: We collected information through the institutional clinical database on all consecutive breast cancer patients who underwent surgery at the European Institute of Oncology, Milan, Italy, between June 1995 and July 2002. A total of 250 selected invasive breast cancers including 50 luminal B-like, 50 triple-negative, 50 ER positive lobular type, 50 luminal A- like and 50 HER2 positive breast cancers, were examined for NY-ESO-1, WT-1 and PRAME antigens expression by immunohistochemistry (IHC). Results: A significantly higher expression of NY-ESO-1 and WT-1 antigens was detected in triple negative breast cancers compared with Luminal A-like tumors (p = 0.023 and <0.001 respectively). NY-ESO-1 expression assessed by polyclonal antibodies was detected in 10 (20%) triple negative cancers as compared to 2 (4%) Luminal A-like tumors (p = 0.002).WT1 expression was confirmed in 28 (56%) triple negative tumor samples as compared to 10 (20%) Luminal A-like tumors (p = <0.0001). PRAME expression was detected in 17 (34%) HER2 positive tumor samples as compared to 12 (24%) lobular types, 16 (32%) luminal B and 1 (2%) triple negative breast cancers (p < 0.0001). Conclusion: NY-ESO-1 and WT1 antigens are expressed in triple negative breast cancers. NY-ESO-1 and WT1 antigen based vaccines or targeted therapies could be potentially useful in the clinical setting for this subpopulation of patients. Disclosure: All authors have declared no conflicts of interest.