Hypoxia inducible factor-1 alpha and multiple myeloma.

Rapid tumor growth creates a state of hypoxia in the tumor microenvironment and results in release of hypoxia inducible factor-1 alpha (HiF-1α) in the local milieu. Hypoxia inducible factor activity is deregulated in many human cancers, especially those that are highly hypoxic. In multiple myeloma (MM) in initial stages of disease establishment, the hypoxic bone marrow microenvironment supports the initial survival and growth of the myeloma cells. Hypoxic tumour cells are usually resistant to radiotherapy and most conventional chemotherapeutic agents, rendering them highly aggressive and metastatic. Therefore, HIF is an attractive, although challenging, therapeutic target in MM directly or indirectly in recent years.

Synergistic effect of vascular endothelial growth factor and angiopoietin-2 on progression free survival in multiple myeloma.

Bone marrow neoangiogenesis plays an important role in multiple myeloma (MM) and depends on the interplay of angiogenic cytokines. We investigated the levels of angiogenic cytokines such as vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), angiopoietin (Ang)-1, Ang-2 and hypoxia inducible factor-1 alpha (HiF-1α) in MM patients and their association with treatment outcome. Serum levels and mRNA expression of VEGF, Ang-2, Ang-1, bFGF and HiF-1α were evaluated in 71 MM patients using enzyme-linked immunosorbent assay and reverse transcriptase polymerase chain reaction. In multivariate Cox regression analysis, serum levels of VEGF≥756 pg/ml (HR 2.2, 95% CI 1.02-4.91; p=0.045) and relative mRNA expression levels of Ang-2≥0.93 (HR 21.0, 95% CI 6.27-70.45; p<0.001) were predictive of inferior progression free survival (PFS) and patients with concomitant increase in VEGF and Ang-2 had poor outcome compared to the rest of the patients (HR 32.6, 95% CI 7.20-148.36; p<0.001). These results suggest that VEGF and Ang-2 act in synergy and their expression levels at presentation are predictive of PFS in MM.

Angiopoietins as biomarker of disease activity and response to therapy in multiple myeloma.

Tumor angiogenesis is a complex process involving interplay of several angiogenic regulators. In the present study, mRNA expression and circulating levels of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), hypoxia inducible factor (HiF)-1α, circulating endothelial progenitor cells (cEPCs) and bone marrow microvessel density (MVD) were evaluated in multiple myeloma (MM). Compared to healthy controls, the levels of VEGF, bFGF, Ang-2, HiF-1α and cEPCs were significantly higher and Ang-1 and Ang-1/Ang-2 were lower in MM (p < 0.01). cEPC numbers correlated with Ang-1 (p = 0.03), Ang-2 (p = 0.01) and VEGF (p = 0.002). On multivariate analysis, reduced Ang-1/Ang-2 ratio (p = 0.005) at baseline was an independent predictor for response to therapy. After therapy, a decrease in Ang-2 (p < 0.001) and an increase in Ang-1/Ang-2 ratio (p = 0.003) were observed in responders. This study highlights the role of angiopoietins in MM which may, thus, be evaluated as potential targets for anti-angiogenic therapy in future.

Circulating endothelial progenitor cells as potential prognostic biomarker in multiple myeloma.

Recent studies suggest that endothelial progenitor cells (EPCs) are mobilized from bone marrow to the peripheral circulation and aid in tumor neovascularization. In this study, circulating EPC (cEPC) numbers were assessed and correlation with clinical and laboratory parameters was determined in 75 patients with multiple myeloma (MM). Higher numbers of cEPCs (defined as CD45-/dim CD34+CD133+CD31+cells) were observed in MM as compared to healthy controls (n = 10; p < 0.001), which increased progressively from stage I to stage III (p < 0.001). A significant decline in cEPC numbers after therapy was observed in patients who attained at least a partial response (n = 47; p < 0.001). cEPCs correlated with response duration, at a baseline cut-off value of 19.6 cEPCs/µL (p = 0.006) and 6.5 cEPCs/µL after therapy (p < 0.001). This study suggests that cEPC numbers and changes in their levels may serve as a potential biomarker of disease severity, response to therapy and treatment outcome in MM.

Flow cytometric immunophenotyping and minimal residual disease analysis in multiple myeloma.

Presence of normal plasma cells (PCs), hemodilution of bone marrow aspirate, and changes in the immunophenotype are important considerations in minimal residual disease (MRD) assessment in multiple myeloma (MM). We evaluated 124 subjects-107 with MM, 11 with Hodgkin lymphoma, and 6 allogeneic stem cell transplantation donors-for the immunophenotype of neoplastic, reactive, and normal PCs respectively. Of the patients with MM, 36 were evaluated for MRD and 23 for a change in immunophenotype after chemotherapy. The immunophenotype of normal and reactive PCs was similar and differed from that of neoplastic PCs with respect to CD19, CD45, CD56, CD52, CD20, and CD117. At least 2 antigens were aberrantly expressed in all cases and 3 in 90.7% of MM cases. A change in the immunoprofile of PCs was observed in 18 (78%) of 23 cases. By using flow cytometry, we detected MRD in all samples, and a neoplastic PC index (percentage of neoplastic PCs/total bone marrow PCs) of less than 30 could differentiate immunofixation (IFx)- from IFx+ samples (complete and partial responders, respectively).

Analysis of bone marrow plasma cells in patients with solitary bone plasmacytoma.

Local radiotherapy is the treatment of choice for solitary bone plasmacytoma (SBP) and the role of adjuvant systemic chemotherapy in preventing progression to multiple myeloma (MM) is controversial. The purpose of this study was to examine the presence of systemic disease in the form of neoplastic plasma cells (PC) in bone marrow of patients with SBP. Flow cytometric immunophenotyping of PC was carried out on bone marrow aspirate of 7 patients using monoclonal antibodies: CD19 FITC, CD45 FITC, CD20 FITC, CD52 PE, CD117 PE, CD56 PE, CD38 PerCP-Cy5.5, CD138 APC, anti-kappa (κ) FITC and anti-lambda (λ) PE. The neoplastic as well as normal PC were identified in bone marrow aspirate of all the patients at the time of diagnosis; the neoplastic PC ranged from 0.1%to 0.7% of all BM cells and 33.5% to 89.7% of total BMPC. The κ:λ ratio was normal in all the samples ranging from 0.5% to 1.6%. The present work shows the presence of systemic disease in the form of neoplastic PC in bone marrow of patients with SBP. Prospective studies would be required to study if the levels of neoplastic PC in the bone marrow may help us identify patients who are likely to progress to overt MM and benefit from systemic chemotherapy.