Figure 7. PERK inhibition reduces CD8⁺ TIL mtROS and augments anti-PD-1 therapy.

(A) Representative FACS plot and quantification of mtROS/PD-1⁺ CD8⁺ T cells from PBMC and tumor of three patients with pleomorphic undifferentiated high grade deep (PU HGD) sarcoma. Gates are set from isotype controls. PERK inhibitor (PERK I) or vehicle control was administered for 1 week (days 7-14) to mice bearing MCA-205-OVA sarcomas. (B) Representative FACS plots and quantification of mtROS/PD-1 TILs gated from CD45⁺/ CD8⁺ populations. Gates are set from isotype control data. (C) Absolute number of CD45⁺/PI⁻/ CD8⁺ TILs calculated per gram of tumor weight. Bar graphs represent 4-5 mice per group and are shown as SEM. Individual experiments repeated twice. Students t test, *p<0.05, ***p<0.001. PERK I or vehicle control was administered beginning after 7 days of tumor growth to mice bearing MCA-205-OVA sarcomas and anti-PD-1 or isotype antibody was administered on day 12 and every four days thereafter. Anti-CD8 was administered every 2-3 days beginning 5 days after tumor inoculation. (D) Composite and (E) individual graphs of tumor growth measured every other day for 40 days with complete response (CR) listed per group, composite data represented as SEM. Linear regression of combination measured against anti-PD-1 therapy, ****p<0.0001. (F) Survival to 41 days or tumor size of 200mm² was recorded, Log-rank test, **p<0.01 survival proportions of anti-PD-1 therapy (28%) versus combination therapy (100%). Combination experiment repeated twice, anti-CD8 depletion condition performed once.