Fig. 7.

Low-dose mitoxantrone recalls activated CD8⁺ T cells and NK cells in PDOTS when combined with TGFβ and PD-1 blockade. A Experimental scheme. Explanted human tumors are reduced to small pieces, cultured to form PDOTS and then co-cultured with autologous PBMC in ULA plates or microfluidic devices. A representative image of PDOTS cultured in ULA plate is shown. Original magnification, 20x. Scale bar, 30 μm. B Representative images of PDOTS derived from P5, P6 and P7 NB patients, respectively. Original magnification, 20x. Scale bar, 30 μm. C, D Flow-cytometry analyses of granzyme B expression by CD8⁺ T cells (C) and NK cells (D) from autologous PBMC co-cultured 24 hours with drug-treated PDOTS. E Representative images of the migration of red-labeled autologous PBMCs in microfluidic devices to drug-treated and untreated PDOTS after 24 hours of co-culture. The number of PBMCs migrating versus drug-treated and untreated PDOTS was assessed by ImageJ software. Data are shown as fold change ± SD. Levels of significance for comparison between samples were determined by two-tailed Student’s t test. F A schematic representation depicting the transition from an immunosuppressive (CTR) to a tumor friendly microenvironment driven by MTP treatment. CTR, vehicle control; MTX, mitoxantrone; MTP, mitoxantrone, anti-TGFβ and anti-PD-1; GZMB, granzyme B. Statistically significant P values are shown