Prognostic significance of PRAME expression based on immunohistochemistry for diffuse large B-cell lymphoma patients treated with R-CHOP therapy.

The preferentially expressed antigen of melanoma (PRAME), a tumor-associated antigen, is considered a prognostic marker for various human malignancies. The prognostic significance of PRAME expression for diffuse large B-cell lymphoma (DLBCL) patients treated with rituximab-containing chemotherapy has not been evaluated to date, and the ability of immunohistochemistry (IHC) to detect PRAME expression in these patients has not yet been studied, although IHC is simple to perform in clinical practice. We evaluated the prognostic significance of PRAME expression based on IHC analysis in 160 DLBCL patients treated with R-CHOP therapy. There was a significant association between higher PRAME expression and shorter progression-free survival (PFS), and a trend toward shorter overall survival (OS) in patients with higher PRAME expression than that in patients with lower PRAME expression (5-year PFS, 48.1 vs. 61.1 %; 5-year OS, 65.6 vs. 79.1 %). Patients with high PRAME expression tended to have lower chemotherapeutic responses. Thus, IHC is useful for detecting and assessing PRAME expression in DLBCL. Further, we found a positive correlation between IHC and quantitative real-time RT-PCR measurements of PRAME expression. Our findings indicate that IHC results of PRAME expression can be a novel prognostic maker in DLBCL patients treated with R-CHOP therapy.