SMPD1 and fibrosarcoma: While Ad5H2E-mVEGFR2-ASMase renders a 6 Gy radiosensitization, deescalating the ablative SDRT dose in MCA/129 fibrosarcoma allografts in mice from 20 Gy to 14 Gy (24), the gene therapy approach appears to be disfavored due to its complexity and higher cost.