The effects of efaproxyn™ (Efaproxiral) on subcutaneous RIF-1 tumor oxygenation and enhancement of radiotherapy-mediated inhibition of tumor growth in mice

Abstract Hou, H., Khan, N., Grinberg, O. Y., Yu, H., Grinberg, S. A., Lu, S., Demidenko, E., Steffen, R. P. and Swartz, H. M. The Effects of Efaproxyn™ (Efaproxiral) on Subcutaneous RIF-1 Tumor Oxygenation and Enhancement of Radiotherapy-Mediated Inhibition of Tumor Growth in Mice. Radiat. Res. 168, 218–225 (2007). Efaproxiral, an allosteric modifier of hemoglobin, reduces hemoglobin-oxygen binding affinity, facilitating oxygen release from hemoglobin, which is likely to increase tissue pO2. The purpose of this study was to determine the effect of efaproxiral on tumor oxygenation and growth inhibition of RIF-1 tumors that received X radiation (4 Gy) plus oxygen breathing compared to radiation plus oxygen plus efaproxiral daily for 5 days. Two lithium phthalocyanine (LiPc) deposits were implanted in RIF-1 tumors in C3H mice for tumor pO2 measurements using EPR oximetry. Efaproxiral significantly increased tumor oxygenation by 8.4 to 43.4 mmHg within 5 days, with maximum increases at 22–31 min after treatme...