Prognostic significance of P2RY8‐CRLF2 and CRLF2 overexpression may vary across risk subgroups of childhood B‐cell acute lymphoblastic leukemia

The cytokine receptor-like factor 2 (CRLF2) gene plays an important role in early B-cell development. Aberrations in CRLF2 activate the JAK-STAT signaling pathway that contributes to B-cell acute lymphoblastic leukemia (B-ALL). The prognostic significance of CRLF2 overexpression and P2RY8-CRLF2 fusion in various B-ALL risk subgroups has not been well established. Two hundred seventy-one patients with newly diagnosed childhood B-ALL were enrolled from a Chinese population. The prevalence of CRLF2 overexpression, CRLF2-P2RY8 fusion, CRLF2 F232C mutation, and JAK2 and IL7R mutational status were analyzed, and the prognostic impact of CRLF2 overexpression and P2RY8-CRLF2 on B-ALL was evaluated by assessing their influence on overall survival and event-free survival. CRLF2 overexpression and P2RY8-CRLF2 were found in 19% and 10%, respectively, in the whole cohort. No correlation between CRLF2 overexpression and P2RY8-CRLF2 was observed. CRLF2 F322C and IL7R mutations were not detected in B-ALL cases overexpressing CRLF2, and no JAK2 mutations were found in the whole cohort either. The results showed that CRLF2 overexpression and P2RY8-CRLF2 were associated with a poor outcome in unselected B-ALL. Moreover, in an intermediate risk B-ALL subgroup P2RY8-CRLF2 was correlated with worse survival, whereas in high- and low-risk subgroups, CRLF2 overexpression predicted a poor outcome. Our findings suggest that P2RY8-CRLF2 is an independent prognostic indicator in intermediate risk B-ALL, while CRLF2 overexpression is correlated with an inferior outcome in high- or low-risk B-ALL. Our study demonstrates that the impact of P2RY8-CRLF2 and CRLF2 overexpression on B-ALL survival may differ across risk subgroups. © 2016 Wiley Periodicals, Inc.