Combined Therapy Of Radiofrequency Ablation And TIM-3 Blockade Exerts Synergistic Anti-tumor Effect

Objective Our previous study demonstrated that Programmed death-1(PD-1)/PD-L1 signaling pathway plays a crucial role in dampening RFA-elicited anti-tumor immune responses.However,this cannot elucidate the explicit mechanism of such immune inhibition.Then we noticed an up-regulation of TIM-3 expression in mouse RFA model along with going deep into our research.Here,we tried to further explain this phenomenon,meanwhile we evaluated the anti-tumor efficacy of combining RFA and TIM-3 blockade therapy.Methods Mouse CT26 RFA model was developed and treated accordingly.The tumor size was measured and the survival time was recorded in order to acquire tumor growth and mouse survival curves.In mouse CT26 RFA model,T-cell immune response and TIM-3/Galectin-9?IFN-? expression were characterized,the synergistic effect of RFA and TIM-3 blockade was examined in the mouse RFA model.The MDSCs were harvested by flow sorting,and then TIM-3 was blocked in vitro.qRT-PCR was applied in mRNA expression of MDSCs-related cytokines and transcription factors.Results RFA treatment initially induced an enhanced T-cell-mediated immune response in tumor mircoenvironment.Nevertheless,tumor quickly overcame the immune response and restored rapid growth,along with TIM-3 up-regulation and MDSCs accumulation in tumor in situ.Surprisingly,we found that the blockade of TIM-3 was capable of reversing MDSCs accumulation.Furthermore,we demonstrated that combining RFA and TIM-3 antibodies significantly boosted T-cell immune response,resulting in stronger anti-tumor immunity and better prognosis.TIM-3 participated in the regulation of MDSCs differentiation and immunosuppressive function in TME by up-regulating STAT3,STAT1 and NF-?B expression,the expression of these molecules were down-regulated when TIM-3 was blocked,thereby reducing MDSCs accumulation,preventing immunosuppression,and stimulating anti-tumor immune response.Conclusions TIM-3 plays an important role in shaping RFA-induced adaptive immune responses in tumor in situ,which is closely related to MDSCs differentiation and immunosuppressive function.The combined therapy of RFA and TIM-3 blockade may exert synergistic anti-tumor effect.