Bone Marrow Microvessel Density (MVD) in Adult Acute Myeloid Leukemia (AML): Therapy Induced Changes and Effects on Survival

Based on the strong evidence in favor of an increase in microvessel density (MVD) in hematological malignancies, we evaluated VEGF immunoreactivity and MVD measurement in bone marrow biopsies of 36 AML patients at diagnosis and following therapy. MVD assessment was based on CD31, CD34 expressing vessels. The values were calculated for only one marker if the other vascular marker was positive on blasts, otherwise both markers were used. VEGF immunoreactivity was also scored. Comparison of MVD values of 36 AML patients with 18 non-malignant controls showed a significantly higher MVD in AML (CD31: P = 0.004, CD34: P < 0.001), which is independent of other variables such as cellularity or blast percentage. Following induction chemotherapy, the responders showed a significant decrease in blast counts (P < 0.001), cellularity (P = 0.001) and MVD (P = 0.050) quantification with CD31. Higher baseline MVD (CD34) values were associated with shorter overall survival (P = 0.0027). These results are encouraging for inclusion of MVD enumeration in bone marrow examinations of AML patients at diagnosis as an additional prognostic factor.