Bone marrow angiogenesis in multiple myeloma: effect of therapy Shaji Kumar, Rafael Fonseca, Angela Dispenzieri, Martha Q. Lacy, John A. Lust, Thomas E. Witzig, Morie A. Gertz, Robert A. Kyle, Philip R. Greipp and S. Vincent Rajkumar Division of Hematology and Internal Medicine, Mayo Clinic, Rochester, MN, USA Received 5 February 2002; accepted for publication 27 May 2002 Summary. Recent studies have demonstrated that angio- genesis has a role in haematological malignancies, inclu- ding multiple myeloma. Multiple myeloma is characterized by inevitable relapse after standard or high-dose chemo- therapy. To study the effect of chemotherapy on bone marrow angiogenesis in patients with multiple myeloma, we used two methods to evaluate bone marrow angiogen- esis 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 pre- dictive 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. Keywords: angiogenesis, chemotherapy, microvessel den- sity, multiple myeloma, plasma cell labelling index. Angiogenesis, or the formation of new blood vessels from existing blood vessels (in contrast to vasculogenesis or de novo formation of blood vessels), occurs during normal growth, tissue healing and regeneration. The role of abnormal, increased angiogenesis in the development and spread of tumours is well recognized (Folkman, 1995, 1996). In humans, increased angiogenesis in various solid tumours has been associated with a poor prognosis (Weidner et al, 1992; Dickinson et al, 1994; Li et al, 1994; Gasparini et al, 1995, 1996; Vermeulen et al, 1995; Maeda et al, 1996). Initially described in the context of solid tumours, angiogenesis is now seen also to be important in the initiation and progression of haematological malignancies. As in solid tumours, new vessel formation (occurring in the bone marrow) seems to have an integral role in the pathophysiology of leukaemias (Perez-Atayde et al, 1997; Schneider et al, 1999; Aguayo et al, 2000; Hussong et al, 2000; Kini et al, 2000; Padro et al, 2000), myeloma (Vacca et al, 1994; Rajkumar & Greipp, 1999; Rajkumar et al, 2000a) and myelofibrosis with myeloid metaplasia (Mesa et al, 2000). Increased angiogenesis in bone marrow has been associated with a poor prognosis in acute leukaemia (Perez-Atayde et al, 1997; Schneider et al, 1999; Aguayo et al, 2000; Hussong et al, 2000; Kini et al, 2000; Padro et al, 2000) and multiple myeloma. Techniques have been developed for visualizing and estimating the number of microvessels in various tissues. Immunohistochemical staining for substances present in the blood vessel wall, such as CD34, von Willebrand factor (VWF), CD31 and others, allows excellent visualization of the microvessels (Vermeulen et al, 1996). Angiogenesis can be quantified in terms of the microvessel density (MVD) and the percentage of unit surface area occupied by the microvessels (Vacca et al, 1995; Bostwick et al, 1996). Different approaches have been adopted for estimating the degree of angiogenesis or MVD, including visual grading (Vermeulen et al, 1996; Rajkumar et al, 1999a), vessel count per defined area, use of grids for counting (Rajkumar et al, 2000a) and computer- ized-image subtraction analysis (Fox et al, 1995). To assess the effect of therapy on bone marrow angio- genesis, we examined the bone marrow MVD before and Correspondence: Dr S. V. Rajkumar, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA. E-mail: rajkumar.vincent@ mayo.edu British Journal of Haematology, 2002, 119, 665–671 Ó 2002 Blackwell Publishing Ltd 665