ERBB2 and neoplasm: While free MMAE indiscriminately radiosensitized independent of tumor receptor status, antibody conjugation specified MMAE radiosensitization to target-receptor enriched tumors, i.e. cetuximab conjugated MMAE radiosensitized EGFR expressing but not EGFR negative cancer cells while trastuzumab conjugated MMAE radiosensitized HER2 expressing but not HER2 negative cancer cells50.