Study On Antitumor Effect Of Hydrostatin-SN10 Combined With PD-1 And CTLA-4

Tumor immunotherapy represented by PD-1 monoclonal antibody and CTLA-4monoclonal antibody has made great progress in clinical practice,but it has been found that overactivation of patients’ immune system activity can cause strong immunerelated adverse reaction events(ir AE),such as cardiotoxicity,gastrointestinal toxicity and skin toxicity.It has been reported that TNF-α monoclonal antibody can significantly relieve ir AE colitis induced by PD-1/CTLA-4 dual antibody combination(ICB)in mice,and enhance the anti-tumor efficacy of combination therapy to a certain extent.However,monoclonal antibodies to TNF-α completely block the biological function of TNF-α,namely,TNF/TNFR1 and TNF/TNFR2 signal transduction,thereby affecting systemic immune homeostasis and immune monitoring function,leaving patients vulnerable to new autoimmune diseases such as tuberculosis,upper respiratory infections,and lupus.TNF/TNFR1 mainly transmits pro-inflammatory and apoptotic signals,while TNF/TNFR2 is more involved in maintaining immune homeostasis.Therefore,TNF/TNFR1 was selectively blocked to relieve the excessive immune response caused by PD-1/CTLA-4 antibody,and TNF/TNFR2 signal was opened to regulate Th17/Treg and maintain the immune balance.It can more effectively reduce ir AE colitis caused by PD-1/CTLA-4 double antibody.Therefore,it is of great significance to investigate the role of selective blocking of TNF/TNFR1 signaling pathway in coordination with PD-1/CTLA-4 double antibodies in anti-tumor treatment.In our previous study,we obtained a target-specific and selective TNFR1 antagonistic peptide Hydrostatin-SN10(SN10),which only binds to TNFR1 and does not bind to TNF-α and TNFR2.Has completed the preclinical study for the treatment of inflammatory bowel disease,is about to enter the clinical phase I.This study investigated the antitumor effect of selective TNFR1 antagonistic peptide SN10 in coordination with PD-1/CTLA-4 double antibody.This study was mainly divided into three parts.The first part was to establish a PD-1/CTLA-4 anti-induced ir AE colitis mouse model,and to clarify the therapeutic effect of SN10 on ir AE colitis from the aspects of mouse body weight,disease activity index,spleen index,colon ultrasound,inflammatory factor expression,histopathology and malondialdehyde release.The second part is to establish MC38 colorectal cancer model,and investigate whether SN10 affects the dual antitumor effect of PD-1/CTLA-4 from the tumor volume and survival rate of mice.The third part was to establish a MC38 colorectal cancer model accompanied by ir AE colitis.The antitumor effect of SN10 synergistic PD-1/CTLA-4 double antibody was discussed from the aspects of tumor volume,tumor weight,survival rate,histopathology,PD-1 receptor expression and CD8+T cell expression in tumor microenvironment.The conclusion is as follows:1.ir AE colitis model mice showed obvious depression,loss of appetite,diarrhea,hematochezia and other symptoms,indicating that the mice suffered from ir AE colitis.800μg/kg SN10 significantly inhibited the expressions of pro-inflammatory factors TNF-α,IL-6 and IL-1β,and decreased the plasma concentration of MDA in ir AE colitis mice.The symptoms of colon tissue and intestinal wall thickening,pathological structural changes,crypt disorder,goblet cell disappearance,mucosal injury,inflammatory cell infiltration and intestinal wall thickening were alleviated.2.The MC38 colorectal cancer mouse model was established,and 800μg/kg SN10 combined with ICB did not affect the antitumor effect of PD-1/CTLA-4 double antibody.3.A MC38 colorectal cancer mouse model with ir AE colitis was established.800μg/kg SN10 combined with ICB inhibited tumor growth,reduced tumor weight,increased tumor survival rate,significantly inhibited PD-1 receptor expression,and increased CD8+T cell expression in tumor microenvironment.The effect of ICB was better than that of ICB alone.The results showed that SN10 can enhance the anti-tumor effect of PD-1/CTLA-4 and relieve the corresponding side effect--ir AE colitis,which has a good clinical application prospect and provides more options for clinical drug use.