Fig. 4: Epacasome-2 potentiated PD-1 blockade in B16–F10 tumour mice via inhibiting IDO1 and eliciting potent CTL responses.

a Drug administration timeline scheme in subcutaneous (s.c.) B16–F10 tumour model (n = 6 mice, tumours: ~100 mm³). Mice were intravenously injected with Epacasome-2 or free EPA (p.o. or i.v.) at eq. 41 mg EPA/kg on days 8, 10, 12 and 14 alone or combined with i.p. α-PD-1 (BioXCell, clone RMP1-14, 100 µg per mouse per 3 day for 3 times) from day 8^{39, 69}. b Individual tumour growth curves. c, d Average tumour size growth curves of EPA formulation alone (c) or combined with α-PD-1 (d). e Kaplan–Meier survival curves. f, g An independent efficacy study in B16–F10 tumour mice as (a). f, g The ratio of Trp (nM)/kyn (nM) concentration in plasma (f) and tumours (g), (n = 6 mice). h–n Quantification analysis of intratumoural CD45⁺/CD11b⁺/F4/80⁺/CD206⁻ M1 and CD45⁺/CD11b⁺/F4/80⁺/CD206⁺ M2 TAMs cells (h)^{46, 49}, CD45⁺/CD11b⁺/Gr-1⁺ MDSC cells (i), CD3⁺/CD4⁺/Foxp3⁺/CD25⁺ Tregs (j), CD45⁺/CD11c⁺/CD80⁺/CD86⁺ DCs (k), CD45⁺/CD11c⁺/CD103⁺ DCs (l), Granzyme B⁺ (m) or IFN-γ⁺/CD3⁺/CD8⁺ (n) T cells from three random chosen tumours by flow cytometry. The representative flow cytometric plots and gating strategies were placed in Supplementary Figs. 12b, 20 and 22. Data in (c, d, f–n) are expressed as mean ± s.d. Statistical significance was determined by one-way ANOVA followed by Tukey’s multiple comparisons test; survival curves were compared using the log-rank Mantel–Cox test. Source data are provided as a Source Data file.