Radiovirotherapy of orthtopic myeloma tumors in syngeneic, immunocompetent mice. C57BL6/KaLwRij mice with disseminated myeloma were treated with VSV(Δ51)-NIS (2 doses of 2.5 × 10⁸ TCID₅₀/dose) without or with ¹³¹I (1 mCi/mouse intraperitoneally 24 hours after virus administration). (A) Median survival of mice is shown as Kaplan-Meier plots. Arrows indicate virus injections and arrowhead indicate ¹³¹I injection. (B) Myeloma burden of various cohorts was determined by measuring serum IgG2b levels on day 29 after tumor engraftment (n = 4 per group, average values are shown by line).