Vascular endothelial growth factor secretion is an independent prognostic factor for relapse-free survival in pediatric acute myeloid leukemia patients

Substantial improvements in long-term survival have been made with acute myeloid leukemia (AML). However, the overall success rate in treatment of AML is around 50%, despite intensive chemotherapeutic regimens. AML cell survival seems to be related to vascular endothelial growth factor (VEGF). The purpose of this study was to investigate whether VEGF production by AML cells is a prognostic factor for therapeutic outcome and whether this is independent of known prognostic factors such as WBC count, French-American-British (FAB) classification, and risk assessment in which the presence of t(8;21), t(15;17), and inv(16) or FAB M3 defines a low-risk group. Pretreatment levels were measured in the supernatant of AML cells obtained from 47 children with newly diagnosed AML treated between 1988 and 1998. All patients were treated with intensive chemotherapeutic protocols from the Dutch Childhood Leukemia Study Group [DCLSG (DCLSG-ANLL87, DCLSG-ANLL92/94, and DCLSG-ANLL97)]. VEGF was measured at the mRNA level with reverse transcription-PCR and at the protein level using a VEGF immunoassay. VEGF in the supernatant from AML cells was highly variable and in concordance with reverse transcription-PCR results. The low-risk group had significantly lower VEGF levels compared with all others (P = 0.002). VEGF levels were significantly increased in AML FAB M4/M5 versus AML patients with FAB M1/M2/M3/M4eo (P = 0.011), who are reported to have a longer remission duration. Subsequently, the influence of different variables on therapeutic outcome was analyzed. No differences were found in overall survival. But within the limits of the small patient population, VEGF levels as well as age at diagnosis had an independent significant effect on relapse-free survival (P = 0.032 and P = 0.029, respectively) in multivariate analysis.