Fig. 5. Combining chemotherapy and PD-L2 blockade holds translational potential.
a, Tumor growth in PyMT mice treated weekly (from week 9 until week 12) with αPD-L2 alone (TY25, 10 mg kg−1) or the same dose of isotype control every 3 days, doxorubicin alone or a combination of both as indicated. αPD-L2 monotherapy (n = 3 mice); PBS and doxorubicin + IgG groups (n = 4); doxorubicin + αPD-L2 (n = 5). Two-way ANOVA. Inverted red triangles indicate day of doxorubicin treatment. b,c, SA-β-gal, CD3, CD4 and CD8 staining of untreated tumors and tumors treated with doxorubicin alone or in combination with αPD-L2 blocking antibody (TY25, 10 mg kg−1) or the same dose of isotype control (b), as in a, and analyzed at week 13 (c). Vehicle-treated group (n = 4); doxorubicin-treated groups (n = 5). Representative images are shown. Statistical significance shown versus the rest of the experimental conditions. One-way ANOVA with Tukey post-hoc test. Scale bar, 100 μm. d, SA-β-gal and PD-L2 costaining in tumor samples from PyMT mice treated weekly with doxorubicin (4 mg kg−1) at postnatal weeks 9–12. The indicated groups were treated with αPD-L2 (TY25, 10 mg kg−1), or the same dose of IgG isotype control, every 3 days. Representative images and quantification are shown. Samples were obtained at postnatal week 13 (that is, 7 days after the last doxorubicin dose). Vehicle-treated group (n = 4 mice); doxorubicin-treated groups (n = 5 mice). A one-way ANOVA was used for significant changes versus the rest of the conditions. Scale bar, 100 μm. e, SA-β-gal staining, p21 mRNA levels, PD-L2 mRNA levels and PD-L2 protein levels measured using fluorescence-activated cell sorting (FACS), with and without bleomycin treatment, in human head and neck cancer primary culture from patient VHIO-008. Gene expression (n = 4 independent replicates); FACS (n = 1). Scale bar, 50 μm. Two-sided t-tests were used.