Fig. 1: PD-L1 is dispensible for αPD-1 efficacy against B16 melanoma in the aged host and αPD-L2 efficacy varies by host age and tumour type.

Tumour growth curves of a PD-L1^KO aged mice challenged subcutaneously with PD-L1^KO B16 murine melanoma and treated with αPD-1 (200 µg/mouse) or isotype control (200 µg/mouse) intraperitoneally every 4 days starting on day 7 (isotype n = 3 mice, αPD-1 n = 3 mice), b wild type young (isotype n = 5 mice, αPD-L2 n = 5 mice), c wild type aged mice (isotype n = 6 mice; αPD-L2 n = 6 mice) challenged subcutaneously with B16 murine melanoma and treated with αPD-L2 (200 µg/mouse) or isotype control (200 µg/mouse) intraperitoneally every 4 days starting on day 3, d wild type young (isotype n = 8 mice, αPD-L2 n = 6 mice), e wild type aged mice (isotype n = 6 mice; αPD-L2 n = 7 mice) challenged subcutaneously with NCH1 murine melanoma and treated with αPD-L2 or isotype control as above, f wild type young (isotype n = 6 mice, αPD-L2 n = 5 mice) or g wild type aged mice (isotype n = 5 mice, αPD-L2 n = 5 mice) harboring subcutaneous MB49 murine bladder cancer tumours treated with αPD-L2 or isotype control as above. Flow cytometry data of intratumoural h prevalence of IFNγ⁺CD45⁺ immune cells, i mean fluorescence intensity (MFI) of IFNγ in CD45⁺ immune cells, j prevalence of IFNγ⁺CD4⁺ T cells (CD45⁺CD3⁺B220^-), k MFI of IFNγ in CD4⁺ T cells, l prevalence of IFNγ⁺CD8⁺ T cells (CD45⁺CD3⁺B220^-), m MFI of IFNγ in CD8⁺ T cells, n prevalence of IFNγ⁺γδ TCR⁺γδ T cells (CD45⁺CD3⁺B220^-), and o MFI of IFNγ in γδ TCR+ γδ T cells (CD45⁺CD3⁺B220^-) from wild type young or wild type aged mice as indicated harboring MB49 tumours as above. Tumour growth curves of p wild type young (isotype n = 4 mice, αPD-L2 n = 4 mice) or q wild type aged mice (isotype n = 3 mice, αPD-L2 n = 4 mice) harboring orthotopic ID8agg murine ovarian cancer tumours treated with αPD-L2 (200 µg/mouse) or isotype control (200 µg/mouse) intraperitoneally every 4 days starting on day 3. r Comparison of tumour growth curves of ID8agg tumours in wild type aged versus young mice (young mice n = 4 mice; aged mice n = 3 mice). Standard error of mean indicated; p-values, (a–g, p–r) two-way ANOVA, (h–o) unpaired Student’s t-test.