PRAME Expression and Its Clinical Relevance in Hodgkin's Lymphoma

Although Hodgkin's lymphoma (HL) is one of the most curable cancers in adult patients, new targets have to be defined in cases resistant to traditional chemotherapy. The preferentially expressed antigen of melanoma (PRAME) is a cancer testis antigen and its expression is very scarce or absent in normal tissues. For this reason PRAME is a promising candidate for tumor immunotherapy. The aim of this study is to understand the correlation of PRAME expression with prognostic factors in HL, to determine the utility of PRAME as a targeted molecule for immunotherapy and to compare real-time polymerase chain reaction (real-time PCR) and immunohistochemistry (IHC) for the detection of PRAME.

In 82 patients, PRAME was studied using real-time PCR and IHC. Data analyses were performed using statistical methods such as t test, Mann-Whitney U test, χ 2 test, Kaplan-Meier method, log-rank test and Cox regression analysis.

PRAME was detected in 15 (18.3%) patients using IHC and in 8 (9.8%) patients using real-time PCR. A correlation was found between PRAME positivity and higher International Prognostic Score (p = 0.039). PRAME positivity detected using real-time PCR was found to be correlated with shorter disease-free survival (DFS) and overall survival (OS, p = 0.0005).

The demonstration of PRAME especially in histiocytes and Reed-Sternberg cells may provide guidance for immunotherapy. Although PRAME positivity increases the risk for death (3.56), independent risk factors that affected DFS and OS occurred in advanced age and high-risk groups.

Although real-time PCR is sensitive in the detection of PRAME, IHC can be another useful method. Despite the need for studies conducted on larger patient samples, PRAME expression is considered as a poor prognostic parameter in HL.