Prediction of response to recombinant human erythropoietin (rHuEpo) in anemia of malignancy

Background. Since only a portion of anemic patients outside the uremia setting benefit from erythropoietin treatment, a reliable means of predicting potential responders and nonresponders would be very useful. Materials and Methods. We retrospectively reviewed the clinical records of 58 patients with refractory anemia associated with various malignant disorders who had been treated with subcutaneous rHuEpo. The starting rHuEpo dose was 375 U/kg/week for 4 weeks, and was increased to 750 U/kg/week for another 4 weeks if no response was observed. Response was defined as a Hb increase greater than or equal to 2 g/dL with no need for blood transfusion. We examined the value of various laboratory parameters (baseline levels, 2-week and 4-week changes) as predictors of response. Endogenous erythropoietin production was evaluated by its serum level and erythroid activity was assessed through reticulocyte count and circulating transferrin receptor. Results. Forty-eight individuals were evaluable, 58% of whom responded to rHuEpo within 8 weeks. Multiple regression analysis showed that 53% of the variation in the 8-week Hb concentration was explained by variations in baseline serum erythropoietin and the 2-week change in serum transferrin receptor (p < 0.001). Based on these two parameters, response prediction in individual patients would have resulted in a sensitivity of 96%, a specificity of 79% and an overall accuracy of 88%. In addition, 58% of the variation in the 8-week Hb was explained by variations in the 4-week changes in Hb and reticulocyte count (p < 0.001). Utilizing these latter parameters and baseline serum erythropoietin, response prediction in individual patients would have resulted in a sensitivity of 92%, a specificity of 82% and an overall accuracy of 88%. Conclusions. This retrospective analysis suggests that response to rHuEpo can be reasonably predicted by pretreatment serum erythropoietin together with early changes in simple laboratory parameters.