Prevalence and prognostic and predictive relevance of PRAME in breast cancer

Preferentially expressed antigen of melanoma (PRAME) has been described as a potential candidate for immunotherapeutic targeting. However, the prognostic and predictive relevance of PRAME in breast cancer has never been investigated. PRAME gene expression was evaluated in 103 breast tumour biopsies, using quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR). Normal breast tissue was also analysed for comparative purposes. All qRT-PCRs were performed in triplicate. Kaplan-Meier survival curves, Chi-squared and Cox Regression analyses were used to identify associations between PRAME expression and patients' clinicopathological and survival data. PRAME mRNA was detected in approximately 53% of tumour specimens and 37% of normal breast specimens. Kaplan-Meier analysis showed expression of PRAME to correlate significantly with unfavourable disease outcome for patients, in terms of both their disease-free survival (p = 0.0004) and overall survival (OS) (p = 0.0052) times from diagnosis. Multivariate analysis indicated PRAME expression to be an independent prognostic factor for shortened disease-free survival (p = 0.026) and OS (p = 0.02). Furthermore, for patients who received adjuvant chemotherapy, significantly (p = 0.0291) shorter relapse-free survival was achieved for those whose tumour expressed PRAME, compared to those that did not express this transcript. Our results suggest that PRAME mRNA expression may be a useful prognostic and predictive marker for breast cancer.