Figure 6.

H22-dPBD eliminates TAMs and inhibits the development of solid tumors. (A) Experimental scheme of the generation and therapeutic treatment of solid tumor-bearing humanized mice with ADCs. At day 0, HSC4 cells (1.5×10⁶ cells/mouse) were subcutaneously transplanted in hIL-6 Tg NOG mice humanized with UCB-derived Lin^-CD34⁺ cells. DNP- or H22-dPBD (0.5 µg/mouse) were intravenously injected to the mice once a week from day 7 and tumor sizes were measured every 4 days from day 7. The mice were sacrificed at day 28 and tumor weights and cells infiltrating the tumors were evaluated. mo: months. (B) Ratio of hCD45⁺ and mCD45⁺ cells in total leukocytes in the tumor. (C) Frequency of monocytes in circulating hCD45⁺ cells at day 28. (D) Representative FCM plots of tumor-infiltrating hCD45⁺ cells. Frequencies of CD163^hiCD14⁺ TAM-like cells are shown. (E) Histological evaluation of tumor-infiltrating CD163⁺ cells in DNP-dPBD- or H22-dPBD-treated mice. Scale bars: 200 μm. (F) Number and frequency of TAMs in DNP-dPBD- or H22-dPBD-treated mice. (G) Numbers of total hCD45⁺ cells and hCD45⁺CD3^-CD19^-CD56^-CD14^- (non-lymphoid, non-monocytic) cells in the tumor. (H) Time-course analysis of tumor development. Tumor volumes were calculated according to the following formula; 0.5 × length × (width)². Statistical analysis was performed on data at day 27. Averages of tumor size in each group were shown. (I) Tumor weights of DNP-dPBD- or H22-dPBD-treated mice at day 28. Error bars represent standard deviation of the mean. Each point in the bar graphs shows the value for an individual mouse (DNP-treated group: n=8, H22-treated group: n=6). Student’s t-test was performed to assess statistical significance. *p < 0.05, **p < 0.01; n.s, not significant. Data are representative of three independent experiments (D, E) or are pooled from two independent experiments (B, C, F–I). Data points more than two standard deviations from the mean were excluded as outliers (H, I).