Therapeutic efficacy of MV-NIS with or without radioiodine for multiple myeloma. (A) Radiovirotherapy results in faster tumor eradication compared with the virus alone in the susceptible tumor cell line KAS-6/1. (B) Radiovirotherapy for MM1 cell line–derived tumors that are not eradicated by MV-Edm. ¹³¹I by itself or MV-Edm with or without ¹³¹I does not eradicate the tumors. MV-NIS by itself does not slow tumor growth but in combination with ¹³¹I results in tumor eradication in all mice. There were 5 mice treated per arm of the study (30 mice total). The vertical arrows represent the time of vector and isotope injection. Radiovirotherapy is associated with prolonged survival in the treated mice. Error bars indicate SD.