Eradication of medullary and meningeal KMT2Ar-ALL by bispecific CAR-iNKT cells. (A-B) Leukemia burden as assessed by bioluminescence imaging (BLI) and overall survival of SEM leukemia-bearing mice treated with 106 mono- or bispecific CAR-iNKT cells on day 6 after leukemia transfer. (C) Schematic of experiments shown in panels D-I. (D-F) Representative BLI images (D), leukemia burden (E), and overall survival (F) in mice treated with 5 × 106 bispecific CAR-iNKT cells 6 days after IV leukemia cell transfer (n = 7 mice per group). (G-I) Representative BLI images (G), leukemia burden (H), and overall survival (I) in mice treated with 107 bispecific CAR-iNKT cells 12 days after IV leukemia cell transfer (n = 5 mice per group). (B, F, I) Kaplan-Meier curves were plotted for overall survival, with differences assessed by log-rank test (n = 5-7 mice per group). ∗∗P < .01; ∗∗∗P < .001; ∗∗∗∗P < .0001. (J) Left: Coronal sections of representative mouse brains and immunohistochemistry from end of experiment untreated control and bispecific CAR-iNKT cell 5 × 106 treated mice (as shown in D-F) stained with antihuman CD19 mAb. Imaging region indicated by green box. Scale bar, 100 μm. Right: Cumulative meningeal infiltration grade scores. (K) Schematic of experiment for data shown in panels L-M. (L) Coronal sections of representative mouse brains from untreated mice euthanized on day 16, untreated mice euthanized at termination on days 21 to 23, and from day 16 treated mice euthanized either on day 36 or day 50. Top panels: hematoxylin and eosin staining; bottom panels: immunohistochemistry against human CD19. Day 16 area indicated by black box, and the other 2 groups by red box (left). Scale bar, 100 μm. (M) Cumulative meningeal infiltration grade scores in untreated mice euthanized on day 16, untreated mice euthanized at termination on days 21 to 23, and in day 16 treated mice euthanized either on day 36 or day 50. Mann-Whitney or 1-way ANOVA. ∗∗P < .01; ∗∗∗P < .001; ∗∗∗∗P < .0001. Bi, bispecific; UT, untreated.
