Fig. 6

An increase in tumor-infiltrating CD8⁺ T cells is not sufficient to explain the radio-sensitizing effect of MRTX1257. A BALB/c mice were subcutaneously inoculated with CT26 WT cells or CT26 KRAS G12C^+/+ cells. Once the tumors reached an average volume of 90–100 mm³, mice received via oral administration 50 mg/kg of MRTX1257 or vehicle. The day after, mice received a single fraction of 6 Gy on the tumor mass. MRTX1257 at the dose of 50 mg/kg or vehicle were then administered at D1 and D3 after RT. At D4 after RT, mice were sacrificed, tumors were harvested and then fixated using paraformaldehyde (PFA) 4%. Immunohistochemistry analyses for CD8 and then the quantification of CD8⁺ cells were performed. B Photographs at magnification 1.5X of 4 µm-thick CT26 KRAS^G12C+/+ (left) or CT26 WT (right) tumor slices stained with anti-CD8 antibody. C Quantification of CD8⁺ cells per mm² in CT26 KRAS^G12C+/+ tumor slices. Each point is representative of a single tumor. Mean ± standard-errors to mean (SEM). n = 3–5 tumors/group. *: p < 0.05 (one-way ANOVA). D Quantification of CD8⁺ cells per mm² in CT26 WT tumor slices. Each point is representative of a single tumor. Mean ± standard-errors to mean (SEM). n = 3 tumors/group. Ns: non-significant (one-way ANOVA)