Figure 3 from CD70-Targeting CAR NK Cells Overcome BCMA Downregulation and Improve Survival in High-risk Multiple Myeloma Models

Armoring NK cells with CAR27/IL-15 results in enhanced antitumor activity against multiple myeloma. A, Schematic of the retroviral vector used to transduce CB-NK cells. B, Flow cytometry histogram assay of CD70 surface protein levels in NCI-H929 (blue) and MM.1S (magenta) cells. C,51Cr release assay of NT or CAR27/IL-15 NK cells against CD70+ MM.1S or (D) CD70− NCI-H929 tumor cells at different E:T ratios and measured 4 hours after coincubation (n = 3). E, MM.1S tumor cells transduced to express mKATE were cultured alone or with NT, IL-15, or CAR27/IL-15 NK cells. The number of MM.1S cells was measured over time with sequential images from the Incucyte machine. Representative images from 0 Hours (baseline) and after 24 Hours after coculture are shown. White bar, 400 μm. F, The percentage of initial MM.1S cells from panel (E) is plotted for each group over 30 hours. Bar graph (right) shows the AUC analysis. G, The Incucyte killing assay was repeated for NT and CAR27/IL-15 NK cells against the CD70-positive U266B1 myeloma cell line. Bar graph (right) shows the AUC analysis. Data are represented as mean ± SD. Data for the AUC graphs are represented as mean ± SEM. The P values were determined by two-way ANOVA with Sidak’s multiple comparisons (C), one-way ANOVA with Tukey multiple comparison (F), and unpaired t test (G). ***, P ≤ 0.001. ICD, intracellular domain; LTR, long terminal repeats; TMD, transmembrane domain.