Figure 1.

Autologous Stem Cell Transplantation in Conjunction with Ex Vivo MYXV Virotherapy Increases Survival and Decreases Myeloma Tumor Burden

(A and B) In vitro infection and killing of target MM cells. BALB/c whole BM leukocytes were isolated from tibias and femurs. Peripheral blood was isolated via terminal cardiac puncture and subjected to Ficoll-Paque purification in order to isolate mononuclear cells (PBMCs). Both BM cells (A) and PBMCs (B) were either mock-treated (i.e., no virus) or treated ex vivo with vMyx-M135KO-GFP (MOI of 10) for 1 h at 37°C to allow virus adsorption. For in vitro studies (A and B), mock- and MYXV-treated cells were incubated overnight in complete RPMI 1640 media at 37°C to assess for virus infection. After 18 h, the MYXV-loaded donor leukocytes were mixed with target MOPC315.BM.DsRed MM cells to a donor cell-to-target cell ratio of 10:1. Levels of infection and killing of MM (CD138⁺) cells were accessed using flow cytometry after 24 or 48 h post-admixture. Error bars represent the mean ± standard deviation (SD). At least three independent experiments were performed in order to generate these in vitro data. (C–E) In vivo treatment of MM MRD. (C) Schematic overview of the experimental workflow including treatment timeline of the experimental cohorts. (D) Kaplan-Meier survival curves in days from the initiation of the experiment. (E) Flow cytometry plots showing the myeloma tumor burden from target organs such as BM, spleen, and CD138⁺/DsRed solid tumors, shown as the mean ± SD. At least five independent cohort sets were performed in order to generate the in vivo data as shown. p values are reported as non significant (ns) if p > 0.05, and significant if ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.001, ∗∗∗∗p ≤ 0.0001.