Fig. 2: Locally delivered αCD45-IL-15 is retained in the tumor and TDLNs with negligible systemic exposure.

a, Study diagram. b–d, C57BL/6J mice (n = 4 mice per group) were inoculated with 10⁶ MC38 cells in the flank and 10 d later administered AF647-labeled αCD45-IL-15 or IgG-IL-15 at a 1-, 10- or 60-µg dose. After 24 h, organs were harvested, lysed and analyzed for cytokine signal by fluorescence spectroscopy measurements. Concentrations were calculated using a standard curve. The dashed lines represent the limit of detection. b, Tumor concentrations of dosed immunocytokines. c, TDLN concentrations of dosed immunocytokines. d, Serum concentrations of dosed immunocytokines. e–j. C57BL/6J mice (n = 4 mice per group) were inoculated with 10⁶ MC38 (e–g and i) or MC38-ZsGreen (h and j) cells in the flank and, 10 d later, administered AF647-labeled αCD45-IL-15 or IgG-IL-15 at a 10-µg dose i.t., followed by analysis of cytokine biodistribution 24 h later by flow cytometry and microscopy. e, Representative contour plots of antibody–cytokine fusion binding to CD45⁺ TILs. f, Frequencies of AF647⁺ TILs. g, AF647 MFI on TILs. h, Representative confocal images of tumors. Scale bar, 200 μm. i, AF647 labeling on TDLN immune cells. j, Representative histological images of TDLNs. Scale bar, 100 μm. Shown are mean ± s.d. from n = 4 mice per group. P values were determined by two-way (b–d) or one-way (f, g and i) ANOVA followed by Tukey’s multiple-comparison test. Exact P values are denoted in the figure; NS, not significant (P > 0.05).

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