Purpose: The effect of recombinant human erythropoietin (rhEPO) on the radiosensitivity of human tumor xenografts growing in anemic and nonanemic nude mice was studied.
Methods and materials: Anemia was induced by total body irradiation ([TBI], 2 x 4 Gy) of mice before tumor implantation into the subcutis of the hind leg. The development of anemia was prevented by rhEPO (750 U/kg s.c.) given 3 times weekly starting 2 weeks before TBI. Fourteen days after fractionated TBI (tumor volume of approx. 40 mm(3)), single-dose irradiation of the tumor with varying doses was performed so that in full dose-response relationship for the probability of tumor cure was obtained.
Results: Radiation-induced anemia (hemoglobin concentration [cHb] = 9.9 g/dl) led to a reduced radiosensitivity compared to controls [49.4 vs. 40.1 Gy radiation dose to control 50% of the tumors (TCD50)]. Upon rhEPO treatment for anemia prevention (cHb = 13.3 g/dl), the TCD50 was 39.8 Gy, illustrating restored radiosensitivity compared to anemic mice.
Conclusion: These data provide further experimental evidence for restored radiosensitivity upon prevention of anemia with rhEPO.