Fig. 1: Smad4-mutant SCCs in mice and humans exhibit high TGFβ expression, and combined TGFβ inhibition and PD-L1 blockade durably eradicate Smad4-mutant (A223) SCCs.
a pg/mL per cell of secreted TGFβ measured by ELISA in untransformed mouse skin keratinocytes, A223 cells, LY2 cells, and A1419 cells (n = 6). P values are shown for multiple comparisons to A223 cells by one-way ANOVA (F = 328.8, df = 25). b TGFB1 mRNA expression z-scores in human HNSCC patient samples based on their SMAD4 mutant status of deleted (blue, n = 253), diploid (green, n = 205), or gained (orange, n = 30). P values are shown for multiple comparisons to diploid cells by one-way ANOVA (F = 8.445, df = 487). c Post-transplant tumor volume of A223 tumors in C57BL/6 mice treated with either 75 mg/kg LY2109761 p.o. per day (pink, n = 22), or carboxymethylcellulose vehicle control (black, n = 22) for 14 days. d Tumor volume on day 18 post-transplant of mice in (c). e Post-transplant tumor volume of A223 in athymic nude mice treated as in (c) (n = 10 per treatment group). f Tumor volume on day 17 post-transplant of mice in (e). g Survival post-injection of C57BL/6 mice bearing A223 tumors that were treated as in (c), with the addition of 200 μg anti-PD-L1 or its isotype control 3×/week for 2 weeks (vehicle/mock: black lines, LY2109761/mock: pink lines, vehicle/anti-PD-L1: blue lines, LY2109761/anti-PD-L1: green lines, n = 9 per treatment group); surviving mice (combination-treated n = 7, anti-PD-L1-treated n = 3) were rechallenged with A223 cells on day 147 (arrow) along with a cohort of naïve mice (dashed line, n = 5). h Tumor volume on day 25 post-transplant in mice from (g). Multiple comparisons were corrected with Tukey’s method for (a) and (b). Unpaired two-tailed t tests were performed for (d), (f), and (h), and survival comparisons were performed using the log-rank Mantel–Cox test. All error bars represent the SEM, except for b where the box represents the 25–75th percentile, whiskers represent the full range, and the line represents the median value.
