Erythropoietin (EPO) has no direct effect on tumor growth or angiogenesis in animal models

Abstract

9530 Background: Erythropoietin (EPO) increases tumor oxygenation in several pre-clinical models. This improvement in oxygenation should lead to enhanced treatment responses. However, EPO has failed to show improved treatment outcomes in 2 recent, randomized clinical trials involving non-anemic patients with head and neck and metastatic breast cancer. In this study we characterize the direct effects of EPO on tumor growth and angiogenesis in both breast and colorectal carcinoma. Methods: Effects of EPO (Ortho Biotech, Raritan, NJ) on murine tumor growth (CT-26 and R3230) in over 200 non-anemic rodents randomized to either EPO or control was measured. EPO receptor expression was determined using standard IHC in both tumor types before and after treatment. Tumor proliferation, assessed by Ki-67 IHC staining, was also determined. In vivo angiogenesis was measured by vascular length density (VLD) and was calculated from intravital microscopy images of R3230 tumors grown in mammary window chambers. Results: EP...