Baseline and early treatment factors are not clinically useful for predicting individual response to erythropoietin in anemic cancer patients

Abstract

Recombinant human erythropoietin (rHuEPO) is an effective treatment for anemia in patients with cancer, and recent studies show that over two-thirds of patients can be expected to respond with a large increase (>2 g/dl) in hemoglobin concentration. However, it would be helpful to identify likely responders and nonresponders before initiating treatment. Previous studies have suggested that high pretreatment endogenous erythropoietin levels are associated with a lower response to erythropoietin, especially in certain patient groups, such as patients with hematological malignancies, non-chemotherapy patients, or patients with myelodysplastic syndrome. Various algorithms have therefore been developed to predict patient response to rHuEPO using baseline serum erythropoietin levels and other baseline factors. We performed an analysis of data pooled from four randomized clinical trials of 604 patients with non-myeloid malignancies, examining the clinical usefulness of pretreatment and early treatment factors for predicting response to erythropoietin. The analysis confirms several other reports that the most predictive models combined pretreatment and early treatment factors, including change in hemoglobin at 4 weeks, but even these models did not increase sensitivity above 85% (total response in unselected patients was 68.1%), while specificity remained poor. We conclude that clinically useful prediction of response to erythropoietin is not possible using baseline or early response variables because of poor sensitivity and specificity of prediction compared with generally accepted clinical tests.