Low CREBBP expression is associated with adverse long-term outcomes in paediatric acute lymphoblastic leukaemia.

Objectives: CREBBP alterations are associated with many diseases including leukaemia. However, CREBBP expression and its clinical relevance in paediatric acute lymphoblastic leukaemia have not been elucidated.

Methods: We studied CREBBP mRNA expression in 349 patients treated with either the BCH-2003 or CCLG-2008 protocol. Using a receiver operating characteristic curve, patients were divided into low- or high-CREBBP. The association among clinicobiological characteristics, outcomes and CREBBP level was analysed.

Results: Low expression of CREBBP (<1.0) at diagnosis was found in 97.7% of patients and increased significantly after complete remission. Low-CREBBP patients were associated with unfavourable clinical presentations, poor prednisone response and high minimal residual disease (>10 ) after induction. We found significantly poorer event-free survival (EFS) and overall survival (OS) in low-CREBBP group whether administered BCH-2003 or CCLG-2008. Low-CREBBP was an inferior independent prognostic factor in BCH-2003; patients with low-CREBBP had better outcomes on an intermediate-risk regimen than a standard-risk regimen involving the CCLG-2008 protocol. Patients stratified to high-risk with low-CREBBP had the worst EFS and OS.

Conclusions: These findings indicate that low-CREBBP is predictive of unfavourable outcomes; thus, a more intensive treatment protocol is necessitated for standard-risk patients with insufficient CREBBP and that a specific target therapy is necessitated for high-risk patients.