AMG 701 combination treatment with lenalidomide effectively prevented myeloma regrowth in vivo. (A) Head-to-head comparison of AMG 701 and len monotherapy vs combination therapy in the H929 xenograft model in female SCID mice reconstituted with human CD3⁺ T cells isolated from buffy coats and expanded in vitro. Mice were treated from day 15, when mean tumor volume was 260 mm³ with bolus injections into the peritoneal cavity (vehicle or len) or the lateral tail vein (AMG 701). Control mice reconstituted with or without (w/o) T cells were treated with vehicle once daily from days 15 to 23 (q1dx9). AMG 701 was administered (0.25 mg/kg per administration) once weekly at days 15, 22, 29, 36, and 43; len (0.2 mg/kg per administration) once daily from days 15 to 46 (q1dx32); or both drugs. Eight mice were used in each group, except 5 mice in the vehicle without T-cell group. Values represent mean tumor sizes (mm³) ± SEMs. (B) Symbols indicate individual tumor volumes and lines indicate group mean values ± SDs at days 15, 24, and 43. One-way ANOVA with Tukey multiple comparison test was used for statistics analysis. (C) Using Kaplan-Meier and log-rank analysis, the median overall survival of animals was derived (vehicle, 18 days; vehicle without T cells, 19 days; AMG 701, 38 days; len, 45 days; AMG 701 plus len, >47 days). All 8 mice were alive in the combination therapy group at the end of 47-day follow-up. ***P < .001. n.s., not significant.