IGF1 and glioblastoma: Radiotherapy (RTx) remains a cornerstone of the standard-of-care (SOC) for GBM and BCBM but induces IGF1/IGF1R signaling, triggering radio-resistance and recurrence.24 As expected, combining oHSV with RTx significantly increased cytotoxicity across GBM and BC cells, either additively or synergistically, as measured by MTT assay (Fig. 4A, Supplemental Statistics).