Clinical Impact of Different Levels of VEGF-C on Leukemic Blasts in the Bone Marrow and Peripheral Blood of Acute Myeloid Leukemia
Authors: Lee Sung-Eun , Lee Ji Yoon , Han A-Reum , Min Woo-Sung , Kim Heeje 
Published: October 2019

Abstract
Background: Vascular endothelial growth factor-C (VEGF-C) is a lymph-angiogenic growth factor and in general, transmits intracellular signals, resulting in cell proliferation and survival. Previous studies have reported that VEGF-C is important for cancer progression based on the autocrine VEGF-C loop promoting the invasion and metastasis of cancer cells as well as the spread of cancer cells by active recruitment of new lymphatics by tumor-derived VEGF-C. Acute myeloid leukemia (AML) blasts express VEGF-C and its receptors. A few studies demonstrated that high VEGF-C mRNA expression of AML blasts were related to increased in vitro and in vivo drug resistance and could predict adverse long-term outcomes. However, whether the expression of VEGF-C in the bone marrow (BM) and peripheral blood (PB) has a similar role in the pathophysiology of AML remains unclear.
Methods: In this study, we analyzed plasma levels of VEGF-C in both BM and PB samples of AML patients. The levels of VEGF-C were measured using a commercially available ELISA in the newly diagnosed AML patients (58 in BM, 26 in PB), patients in complete remission (CR) (26 in BM, 20 in PB), and refractory/relapsed AML (15 in BM, 10 in PB). In addition, response after 1st induction chemotherapy was assessed in 67 evaluable patients and to create the predictive model for an achievement of CR, logistic regression was used after log transformation of VEGF-C levels.
Results: In the BM of patients with newly diagnosed AML, the level of VEGF-C was 47.87 ± 12.4 pg/ml which was significantly lower than that of refractory/relapsed AML [518.3 ± 320.0 pg/ml (P=0.005)] but there was no difference, compared to that of patients in CR [44.57 ± 8.44 pg/ml (P = 0.865)]. In contrast no trend was observed in the PB samples. Next, to create the predictive model for an achievement of CR, sixty-seven evaluable patients who received standard induction chemotherapy were analyzed. Thirty-seven men and 30 women were included. With a median age of 49 years (range, 20-78), the distribution of favorable, intermediate-I, intermediate-II, and adverse cytogenetic risk (ELN) were 25%, 31%, 21%, and 22%, respectively. The patients with continuous values of Log10VEGF-C were divided into 2 groups (low vs. high levels) by a ROC curve analysis. Univariate analysis showed that high levels in BM samples were associated with achievement of CR after 1st induction chemotherapy. Ultimately, multivariate analyses revealed that low levels of Log10VEGF-C showed a trend for failure to achieve a response of CR (RR of 0.24, P = 0.065) and intermediate II/adverse cytogenetic risk was associated with a failure of CR, compared to favorable/intermediate I (RR of 0.21, P = 0.036). In contrast, in the PB samples, a low value of Log10VEGF-C was an independent factor for achievement of CR (RR of 28.7, P = 0.043).
Conclusion: Our data demonstrate that the high VEGF-C level in the BM samples at diagnosis was associated with a trend toward higher CR rate and high VEGF-C level in the PB samples was significantly related to a failure of CR, suggesting discrepancy of the role of VEGF-C level in the BM and PB. Further studies on the different mechanism of the VEGF-C/VEGF-receptor pathway in the BM and PB are warranted.

Disclosures
No relevant conflicts of interest to declare.