Clinical significance of microvessel density in multiple myeloma patients

Microvessel Density as a Surrogate Prognostic Marker in Patients with Multiple Myeloma: A Meta-Analysis

BACKGROUND/AIMS

Bone marrow (BM) angiogenesis is considered a hallmark of multiple myeloma (MM) development and progression, and can be quantified with the use of microvessel density (MVD). The purpose of this study is to provide a review and a meta-analysis of the current literature regarding the prognostic value of MVD in the overall survival (OS) of MM patients.

METHODS

MEDLINE was screened for studies evaluating the OS of MM patients with regard to their MVD count in BM trephine. The pooled hazard ratio (HR) and its associated 95% confidence interval (CI) among MM patients with a high and low MVD count was the primary end point. Secondary outcomes included odds ratios (OR) for 12-, 36-, and 60-month survival.

RESULTS

Ten eligible trials were identified for the analysis of the primary end point and 9 for the secondary end points. Pooled HR for OS was 1.85 (95% CI: 1.25-2.73, p = 0.002). The pooled OR of survival were 1.59 (95% CI: 1.02-2.46, p = 0.04) at 12 months, 2.90 (95% CI: 1.68-5.03, p = 0.0001) at 36 months, and 3.42 (95% CI: 2.41-4.85, p < 0.00001) at 60 months, in favor of the low MVD group.

CONCLUSION

This meta-analysis provides persuasive evidence that MVD has significant impact on the clinical outcome of MM patients.

Adverse prognostic impact of bone marrow microvessel density in multiple myeloma

Background

Angiogenesis is important for the proliferation and survival of multiple myeloma (MM) cells. Bone marrow (BM) microvessel density (MVD) is a useful marker of angiogenesis and is determined by immunohistochemical staining with anti-CD34 antibody. This study investigated the prognostic impact of MVD and demonstrated the relationship between MVD and previously mentioned prognostic factors in patients with MM.

Methods

The study included 107 patients with MM. MVD was assessed at initial diagnosis in a blinded manner by two hematopathologists who examined three CD34-positive hot spots per patient and counted the number of vessels in BM samples. Patients were divided into three groups according to MVD tertiles. Cumulative progression-free survival (PFS) and overall survival (OS) curves, calculated by using Kaplan-Meier method, were compared among the three groups. Prognostic impact of MVD was assessed by calculating Cox proportional hazard ratio (HR).

Results

Median MVDs in the three groups were 16.8, 33.9, and 54.7. MVDs were correlated with other prognostic factors, including β2-microglobulin concentration, plasma cell percentage in the BM, and cancer stage according to the International Staging System. Multivariate Cox regression analysis showed that high MVD was an independent predictor of PFS (HR=2.57; 95% confidence interval, 1.22-5.42; P=0.013). PFS was significantly lower in the high MVD group than in the low MVD group (P=0.025). However, no difference was observed in the OS (P=0.428).

Conclusions

Increased BM MVD is a marker of poor prognosis in patients newly diagnosed with MM. BM MVD should be assessed at the initial diagnosis of MM.

Review of the Effects of Anti-Angiogenic Compounds on the Epiphyseal Growth Plate

The formation of new blood vessels from a pre-existing vascular bed, termed “angiogenesis,” is of critical importance for the growth and development of the animal since it is required for the growth of the skeleton during endochondral ossification, development and cycling of the corpus luteum and uterus, and for the repair of tissues during wound healing. “Vasculogenesis,” the de novo formation of blood vessels is also important for the proper function and development of the vascular system in the embryo. New blood vessel formation is a prominent feature and permissive factor in the relentless progression of many human diseases, one of the most important examples of which is neoplasia. It is for this reason that angiogenesis is considered to be one of the hallmarks of cancer. The development of new classes of drugs that inhibit the growth and proper functioning of new blood vessels in vivo is likely to provide significant therapeutic benefit in the treatment of cancer, as well as other conditions where angiogenesis is a strong driver to the disease process. During the preclinical safety testing of these drugs, it is becoming increasingly clear that their in vivo efficacy is reflected in the profile of “expected toxicity” (resulting from pharmacology) observed in laboratory animals, so much so, that this profile of “desired” toxicity may act as a signature for their anti-angiogenic effect. In this article we review the major mechanisms controlling angiogenesis and its role during endochondral ossification. We also review the effects of perturbation of endochondral ossification through four mechanisms—inhibition of vascular endothelial growth factor (VEGF), pp60 c-Src kinase and matrix metalloproteinases as well as disruption of the blood supply with vascular targeting agents. Inhibition through each of these mechanisms appears to have broadly similar effects on the epiphyseal growth plate characterised by thickening due to the retention of hypertrophic chondrocytes resulting from the inhibition of angiogenesis. In contrast, in the metaphysis there are differing effects reflecting the specific role of these targets at this site.

Femoral Head Growth Plate Dysplasia and Fracture in Juvenile Rabbits Induced by Off-target Antiangiogenic Treatment

Epiphyseal growth plate dysplasia (chondrodysplasia) might be considered as the pathognomonic feature of antiangiogenic treatment in preclinical species as it is reliably and dose-responsively induced in rodents and monkeys with vascular endothelial growth factor receptor (VEGFR) inhibitors, fibroblast growth factor (FGF) receptor inhibitors, matrix metalloproteinase inhibitors, and vascular targeting agents. Here we report epiphyseal growth plate dysplasia in juvenile rabbits treated with an oral spleen tyrosine kinase inhibitor induced by off-target antiangiogenic inhibition of VEGF and FGF family kinase receptors. Epiphyseal growth plate dysplasia resulted in weakening and fracturing of the femoral head physis in 6 of 10 male and 1 of 10 female animals as well as microfracturing and dysplasia of the distal femoral articular cartilage in 1 male animal. Fracture lines ran through the zone of hypertrophic cartilage (as well as adjacent zones), were orientated parallel to the physeal plane, and often involved displacement of the femoral head. We would suggest that the high prevalence of growth plate fracture in the rabbit may represent a potential additional adverse risk to those already established for children treated with antiangiogenic therapy.

Prognostic value of bone marrow microvessel density and angiogenic cytokines in patients with multiple myeloma undergoing autologous stem cell transplant

Angiogenesis is important for the proliferation and metastasis of most malignant neoplasms including multiple myeloma (MM). The aim of this study was to evaluate the role of bone marrow angiogenesis and angiogenic cytokines in patients with MM prior to and after autologous stem cell transplant (ASCT). Twenty-nine patients with MM who underwent ASCT had serial samples of serum and bone marrow biopsies at diagnosis, prior to ASCT, and at the 3rd and 6th months post-transplant. Besides bone marrow microvessel density (MVD), serum angiogenic cytokines including vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) and markers of disease activity such as interleukin-6 (IL-6), IL-1β, C-reactive protein (CRP), β(2)-microglobulin, and bone marrow plasma cells (BMPCs) were also determined. Bone marrow MVD, serum levels of IL-6, CRP, and β(2)-microglobulin, and BMPCs decreased significantly from diagnosis to the 6th month post-transplant (p < 0.05). Serum FGF and IL-1β levels decreased significantly until 3 months post-transplant, however lost this significance at the 6th month. Serum VEGF levels did not vary significantly during follow-up. MVD, serum angiogenic cytokine levels, and parameters reflecting disease activity were similar in responders and non-responders to induction chemotherapy. Cytokines and MVD both at diagnosis and prior to transplant did not show any correlation with overall survival (OS) and progression-free survival (PFS) after a median follow-up of 55 months after transplant (p > 0.05). Our findings suggest that bone marrow MVD decreases significantly with ASCT in MM, however without an impact on OS and PFS.

Prognostic value of bone marrow angiogenesis in multiple myeloma: use of light microscopy as well as computerized image analyzer in the assessment of microvessel density and total vascular area in multiple myeloma and its correlation with various clinical, histological, and laboratory parameters

We studied the prognostic value of parameters of angiogenesis on bone marrow biopsies in newly diagnosed multiple myeloma (MM) patients. Angiogenesis parameters studied were the microvessel count done manually on light microscopy (MVD-A), microvessel count done by using computerized image analyzer (MVD-B), and total vascular area (TVA) measured by computerized image analyzer. One hundred ten newly diagnosed cases of MM treated at Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, were analyzed with respect to clinical features, laboratory findings, histological features, angiogenesis parameters, and responses to the treatment on follow-up. Twenty age- and sex-matched controls were studied for comparing with angiogenesis of the test cases. Bone marrow microvessels were examined using immunohistochemical staining for CD34. MVD-A (range 4.9-85.2; mean 28.2; SD 19.4), MVD-B (range 2.0-26.9; mean 11.7; SD 5.9), and TVA measured in percentage (range 0.1-17.1; mean 2.4; SD 2.5) were measured for test cases (n = 110). Grading of angiogenesis parameters of the test cases were done; such that angiogenesis parameters of controls (taken as baseline) were grade I. There was a statistically highly significant correlation between (MVD-A vs MVD-B, pcc = 0.92; MVD-A vs TVA, pcc = 0.78; MVD-B vs TVA, pcc = 0.76). The myeloma cases had significantly higher angiogenesis parameters when compared with controls (Kruskall-Wallis test, P < 0.001). "Complete responders" (n = 38/110) had significant lower angiogenesis (Mann-Whitney U test, P < 0.001) than "nonresponders" (n = 72/110). On treatment follow-up "rapid disease progressors" had the highest levels of angiogenesis (mean rank for MVD-A = 84.7, MVD-B = 82.1, and TVA = 81.1). On multivariate (logistic regression) analysis, factors found to have independent prognostic significance in complete responders (adjusted odd ratio (95% CI, P value)] were: (a) MVD-B grade I [0.134 (0.10-0.16, P < 0.001)], (b) clinical substage A [0.163 (0.12-0.19, P = 0.008)], (c) Bartl's histological stage II & I [0.262 (0.2-0.32, P = 0.021)], (d) MVD-A grade I [0.28 (0.22-0.36, P = 0.03)], (e) beta2 microglobulin levels less than 3,400 ng/dl [0.31 (0.23-0.42, P = 0.04)]. Kaplan-Meier survival analysis for myeloma-related death (n = 16) shows a mean survival time (in months) of 24.75; SE = 3; 95% CI = 21-28. We conclude that MVD (particularly MVD-B) is a very good predictor for the complete response in patients of MM and should be done routinely on bone marrow biopsies.

Syndecan-1 and angiogenic cytokines in multiple myeloma: correlation with bone marrow angiogenesis and survival

Angiogenesis is a complex process involved in the proliferation and metastasis of malignant tumours, and partly triggered by the secretion of various angiogenic factors by tumour cells or cells in the stromal environment. We investigated the correlation between bone marrow angiogenesis, estimated as microvessel density (MVD), and interleukin-6 (IL-6), basic fibroblastic growth factor (bFGF), hepatocyte growth factor (HGF) and syndecan-1 in 67 patients with newly diagnosed multiple myeloma, and evaluated the prognostic value of these parameters. Circulating levels of IL-6, bFGF, HGF and syndecan-1 were significantly higher in patients than in controls. Moreover, in patients, bone marrow levels of bFGF, HGF and syndecan-1 were higher than peripheral blood levels. Positive correlations were found between MVD and syndecan-1 blood levels (r = 0.33, P = 0.017), syndecan-1 bone marrow levels (r = 0.49, P = 0.046) and HGF blood levels (r = 0.36, P = 0.008) respectively. High MVD and high blood levels of IL-6, HGF and syndecan-1 were predictive of a shorter survival. In a multivariate survival analysis MVD and blood levels of IL-6 retained independent prognostic significance, while in a survival analysis without MVD the peripheral blood levels of HGF and syndecan-1 were strong independent prognostic factors.

Prognostic value of bone marrow angiogenesis in patients with multiple myeloma undergoing high-dose therapy

Bone marrow (BM) angiogenesis is increased in multiple myeloma and is an important prognostic factor. However, prior studies were mainly done on patients receiving conventional chemotherapy and there is limited data on its prognostic value in patients undergoing high-dose therapy (HDT) as initial therapy. We studied BM angiogenesis in terms of microvessel density (MVD) in 88 newly diagnosed patients, who were uniformly treated, with 3-4 cycles of induction chemotherapy followed by HDT. We examined if MVD at diagnosis was predictive of response to induction therapy or to subsequent HDT. In addition, we also examined its prognostic value in these patients. The median MVD for primary refractory patients was 28 (range, 2-84) compared to 27 (range, 2-99) for responding patients (P=0.7). The median progression-free survival (PFS) was 21 months for those with high-grade angiogenesis compared to 42 months for those with low-grade angiogenesis, P=0.017. The median overall-survival (OS) from diagnosis was 40 months for those with high-grade angiogenesis and not yet reached, for those with low-grade angiogenesis, P=0.007. BM MVD at the time of initial diagnosis is an important prognostic factor for OS and PFS in patients undergoing autologous transplantation as frontline therapy for myeloma.

Absence of clinical prognostic value of vascular endothelial growth factor and microvessel density in multiple myeloma

Vascular endothelial growth factor (VEGF) is considered a potent stimulator of angiogenesis. In multiple myeloma (MM), it has been reported that bone marrow angiogenesis parallels tumor progression and correlates with a poor prognosis. To investigate the role of angiogenesis in MM, we investigated VEGF expression and microvessel density (MVD) in the bone marrow of 75 MM patients by immunohistochemical methods. VEGF expression was observed in 87.3% (62 of 71) of patients. MVD was 69.42 +/- 9.67 (mean +/- SE) compared with the normal control values of 26.81 +/- 2.85. MVD values were 73.98 +/- 11.27 and 36.04 +/- 6.99 in the VEGF-positive and VEGF-negative groups, respectively. The MVD of patients in the VEGF-positive group was significantly higher than in the VEGF-negative group (P = .045). However, there were no significant differences in various clinical parameters, such as age, sex, hemoglobin, platelet count, serum levels of albumin, calcium, creatinine, and beta2-microglobulin, and bone marrow plasma cell percentage, between the VEGF-positive and VEGF-negative groups. Multivariate analysis revealed that age, hemoglobin, platelet count, serum levels of albumin and creatinine, and bone marrow plasma cell percentage were correlated with overall survival, whereas VEGF expression or MVD was not. In conclusion, our results suggest that VEGF is highly expressed and that MVD is increased in MM, indicating that angiogenesis may play a role in MM. Although MVD in the bone marrow of the VEGF-positive group is significantly higher compared with the VEGF-negative group (P = .045), VEGF is not correlated with overall survival. Further studies that include other angiogenic factors are needed to determine the functional role of angiogenesis in MM.

Bone marrow angiogenesis in multiple myeloma: effect of therapy

Recent studies have demonstrated that angiogenesis has a role in haematological malignancies, including multiple myeloma. Multiple myeloma is characterized by inevitable relapse after standard or high-dose chemotherapy. To study the effect of chemotherapy on bone marrow angiogenesis in patients with multiple myeloma, we used two methods to evaluate bone marrow angiogenesis in patients with newly diagnosed multiple myeloma, comparing these findings with those from bone marrow obtained after standard chemotherapy. Before therapy, an increased degree of bone marrow angiogenesis and a high bone marrow plasma cell labelling index (PCLI) were predictive of poorer survival. As estimated by microvessel density (MVD), the median survivals for patients with low-grade, intermediate-grade and high-grade angiogenesis were 77, 30 and 14 months respectively. After therapy, the MVD did not change significantly. However, when patients with at least a partial response were considered separately, they showed a decrease in MVD. Post-therapy PCLI was predictive of survival, but post-therapy MVD was not. There was good correlation between angiogenesis estimated by visual grading and that determined by MVD assessment. We conclude that the degree of bone marrow angiogenesis is a prognostic marker in patients with multiple myeloma and does not decrease significantly after therapy.

Microvessel density, a surrogate marker of angiogenesis, is significantly related to survival in multiple myeloma patients

We evaluated microvessel density (MVD) in bone marrow biopsies (BM) from multiple myeloma (MM) patients after staining with anti-CD34 and anti-CD105 antibodies (mAbs). The anti-CD105 mAb was significantly more sensitive than the anti-CD34 mAb in visualizing blood vessels both in controls and MM samples. MVD was significantly higher in MM than in controls with both anti-CD34 and anti-CD105 mAbs. Patients with low CD34+ MVD survived longer than patients with higher MVD (P = 0.01), whereas there was no difference in survival between patients with low and high CD105+ MVD. Multivariate analysis confirmed the independent significant association between CD34+ MVD and survival (P = 0.001).

Increased angiogenesis in bone marrow of children with acute lymphoblastic leukaemia has no prognostic significance

The importance of angiogenesis for the growth and viability of solid tumours has been established. Similarly, prognostic information may be gained from the extent of angiogenesis in these tumours. Haematopoietic malignancies should have equal requirements for angiogenesis and important prognostic information may be derived from quantification of bone marrow angiogenic activity. We retrospectively investigated 82 bone marrow trephine biopsies from 41 children with acute lymphoblastic leukaemia (ALL) at diagnosis and following treatment. Nine normal bone marrow trephines from age-matched children were also analysed as controls. The microvessels were stained immunohistochemically with anti-Factor VIII-related antigen (antivWF) and antithrombomodulin (anti-THR). Angiogenesis was quantified manually by two independent observers and was highly reproducible (Pearson's r = 0.91). Staining with anti-vWF and anti-THR was highly specific for microvessels and thetwo stains closely correlated (r = 0.68). Microvessel densities (MVD) at presentation were significantly increased in the majority of patients in comparison with controls (P < 0.0001) and MVD dropped towards normal in remission (P < 0.0001). Of interest, the difference in total vessel counts between leukaemic and normal/remission marrows was contributed solely by small microvessels. There was no significant difference in MVD at presentation or remission from children in poor prognostic groups or those who subsequently relapsed. Similarly, we could not find an association with age, sex, cytogenetic abnormality or disease phenotype.

Angiogenesis in hematologic malignancies and its clinical implications

Angiogenesis is defined as a neoformation of blood vessels of capillary origin. Hematopoiesis is closely linked with angiogenesis, for they share a common ancestor, the hemangioblast. Although it is well established that growth in solid tumors is dependent on angiogenesis, its role in hematologic malignancies has not yet been clarified. In this review, the direct evidence, ie, increased microvessel density, and the indirect evidence, ie, elevated level of angiogenic factors or overexpression of messenger RNA or protein of angiogenic factors, for and against the role of angiogenesis in the development and progression of hematologic malignancies are presented.