BACKGROUND. Angiogenesis is a constant hallmark of multiple myeloma (MM) progression. It has also been reported that bone marrow angiogenesis is a predictive factor of poor survival in newly diagnosed myeloma. The aim of the current study was to investigate the dynamics of bone marrow (BM) microvessel density (MVD) in patients undergoing high-dose therapy (HDT) and autologous stem cell transplantation (ASCT).

PATIENTS AND METHODS. 36 patients with newly diagnosed MM (22 in stage II and 14 in stage III according to Salmon and Durie) were included in the study – 21 male and 15 female, median age – 51 ys (range 31–67). All patients underwent HDT that included 3–4 cycles of induction therapy (VAD), stem cell mobilization with cyclophosphamide 6 g/m2 and G-CSF 5 mcg/kg, EDAP and single or tandem ASCT with melphalan 200 mg/ m2. The BM biopsies for histological and immunohistochemical analysis were performed at the time of diagnosis, after induction, after stem cell mobilization before the 1st ASCT and after the end of therapy (5 times during the treatment). The Control group consisted of normal BM donors (7 male and 3 female, median age 29, (17–59)) who underwent BM biopsy during BM harvesting for alloBMT. Blood vessels were highlighted by immunostaining of endothelial cells with a monoclonal antibody to CD34 (Novocastra Lab Ltd). The MVD was calculated in 10 fields using an 40x objective and 16x ocular lens.

RESULTS. At diagnosis in all MM pts, MVD was extremely high compared to normal donors (152±8 vs 74±4). A significant decrease of BM MVD was observed after each phase of therapy: after the induction therapy the MVD was 124±6; before the 1st ASCT – 109±5 and at the end of treatment – 97±3. There was a statistically significant increase of MVD after stem cell mobilization due to G-CSF (143±4). Although there was a marked decrease of BM MVD in MM pts with CR or VGPR, it nevertheless stayed significantly higher compared with control group (p<0,001). The analysis of probability of CR or VGPR duration after ASCT according to MVD at different phases of therapy showed that MVD at diagnosis and before the 1-st ASCT are important prognostic factors. Probability of duration of CR or VGPR was 63% in group with low MVD before the 1st ASCT compared with 15% in group with high MVD (p<0,02). MVD was revealed to be more powerful prognostic factor for progression free survival (PFS) then CR or VGPR achievement.

CONCLUSION. BM angiogenesis is increased in patients with MM. BM MVD is decreased during and after treatment however even after the completion of HDT and ASCT, the MVD is higher then in the normal control group. There is a statistically significant increase of MVD after stem cell mobilization with cyclophosphamide and G-CSF. MVD at the time of diagnosis and before the 1-st ASCT are important prognostic factors for overall-survival and PFS after ASCT. MVD before the 1-st ASCT appears to be a more powerful prognostic factor for PFS then remission rate.

Disclosures: No relevant conflicts of interest to declare.

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