Figure 2.

Preclinical evaluation of CAR T cell and BiTE immunotherapies using xenografts grown in rag2^Δ/Δ, il2rga ^−/− zebrafish. (A) Schematic of experimental design. (B–G) CAR T immunotherapy. (H–M) BiTE immunotherapy. (B–F)rag2^Δ/Δ, il2rga^−/− animals engrafted with GFP⁺ U87 glioma cells that coexpress EGFRvIII and administered CFSE-labeled untransduced control T cells, CD19 CAR T cells, or EGFRvIII CAR T cells (n ≥ 6 fish/arm). (G) Quantification of relative tumor cell growth following CAR T cell administration in EGFP⁺ JeKo-1 B cell lymphomas that express endogenous CD19. (H–L)rag2^Δ/Δ, il2rga^−/− animals engrafted with EGFP⁺ OVCAR-5 ovarian cancer cells that endogenously express EpCAM and monitored for tumor regressions following injection of CD8⁺ T cells and either EpCAM control antibody, CD19-CD3 blinatumomab, or EpCAM-CD3 solitomab BiTEs (n ≥ 7 fish/arm). (M) Quantification of relative tumor cell growth following BiTE administration in K562 CML cells engineered to express EGFP and CD19. Merged fluorescence and brightfield images of engrafted animals at 7 dpt (before treatment; left panels in B and H) and 21 dpt (after immunotherapy; right panels in B and H). H&E- (C and I), Ki67- (D and J), and TUNEL-stained (E and K) sections with quantification noted ±SD (n = 3 fish/arm). Waterfall plots quantifying relative tumor growth at 21 dpt with the epitope expressed noted in parenthesis (F, G, L, and M). ***, P < 0.001, Student’s t test compared with control treated fish. Scale bar equals 0.25 cm (B and H) and 50 µm (C–E and I–K). Blin, blinatumomab; CML, chronic myeloid leukemia; Sol, solitomab.