Supplementary Figure 9 from Intermittent MEK Inhibition with GITR Costimulation Rescues T-cell Function for Increased Efficacy with CTLA-4 Blockade in Solid Tumor Models

Supplementary Figure 9. Intermittent CKI27 treatment and GITR engagement relieves suppressive effects of MEK inhibition on T cell proliferation, cytokine production, and effector function. (A-C) Human PBMCs were labelled with CTV, sub-optimally stimulated with 1:25 or 1:100 CD3/CD28 Dynabeads, and treated with DMSO, continuous CKI27 (96hr), washout CKI27 (24hr on, 72hr off), and/or GITR-L; n=2-3. (A) % proliferation of CTVlow CD8+ and CD4+ T cells. (B) FACS analysis of co-inhibitory, co-stimulatory, and activation markers on CD8+ and CD4+ T cells. Heatmaps represent fold changes of positive percentages of each marker normalized to DMSO. (C) Cytokine analysis of supernatants collected from all PBMCs. Heatmap represents fold changes of concentrations (pg/mL) of proteins normalized to DMSO. Two-way ANOVA test with Bonferroni’s correction for multiple comparisons was used. Significance levels are indicated by asterisks (*p ≤ 0.05; **p ≤ 0.01; ***p ≤ 0.001; ****p ≤ 0.0001)