Low-dose decitabine enhances the effect of PD-1 blockade in colorectal cancer with microsatellite stability by re-modulating the tumor microenvironment

PD-1 blockade has demonstrated impressive clinical outcomes in colorectal cancers that have high microsatellite instability.However,the therapeutic efficacy for patients with tumors with low microsatellite instability or stable microsatellites needs further improvement.Here,we have demonstrated that low-dose decitabine could increase the expression of immune-related genes such as major histocompatibility complex genes and cytokine-related genes as well as the number of lymphocytes at the tumor site in CT26 colorectal cancer-bearing mice.A more significant inhibition of tumor growth and a prolongation of survival were observed in the CT26 mouse model after treatment with a combination of PD-1 blockade and decitabine than in mice treated with decitabine or PD-1 blockade alone.The anti-tumor effect of the PD-1 blockade was enhanced by low-dose decitabine.The results of RNA sequencing and whole-genome bisulfite sequencing of decitabine-treated CT26 cells and tumor samples with microsatellite stability from the patient tumor-derived xenograft model have shown that many immune-related genes,including antigen-processing and antigen-presenting genes,were upregulated,whereas the promoter demethylation was downregulated after decitabine exposure.Therefore,decitabine-based tumor microenvironment re-modulation could improve the effect of the PD-1 blockade.The application of decitabine in PD-1 blockade-based immunotherapy may elicit more potent immune responses,which can provide clinical benefits to the colorectal cancer patients with low microsatellite instability or stable microsatellites.

Application of sintilimab combined with anlotinib hydrochloride in the clinical treatment of microsatellite stable colorectal cancer

BACKGROUND Microsatellite stable(MSS)colorectal cancer(CRC)is a common type of tumor with limited treatment options.Sintilimab and anlotinib hydrochloride are two extensively studied anticancer drugs.AIM To probe the clinical value of combining sintilimab with anlotinib hydrochloride in MSS CRC treatment.METHODS During the period spanning from April 2019 to April 2022,Zhejiang Provincial People’s Hospital accommodated a cohort of 92 patients diagnosed with MSS CRC who were classified into two distinct groups in our study,the observation group and the control group.The control group was administered anlotinib hy-drochloride as their designated therapy,whereas the observation group received the additional treatment of sintilimab in conjunction with the therapy assigned to the control group.The administration of treatment occurred in cycles consisting of a duration of 3 wk,and the evaluation of effectiveness took place subsequent to the completion of two consecutive cycles of treatment within both groups.A comparative analysis between the two groups was conducted to assess the short-term efficacy and ascertain the incidence of adverse events transpiring throughout the duration of the treatment period.Changes in the levels of carcinoembryonic Life Questionnaire-Core 30 were compared between the two groups prior to and subsequent to therapy.Finally,a 1-year follow-up was conducted for both groups of patients,and the survival status was recorded and analyzed.RESULTS The short-term effectiveness displayed by the observation group surpassed that exhibited by the control group,with a statistically significant discrepancy(76.09%vs 50.00%),reaching a significance level denoted as P<0.05.Following the administration of treatment,the observation group manifested a considerable reduction in numerous serum indicators,which were found to be lower than the corresponding pretreatment levels within the same group as well as the post-treatment levels observed in the control group(P<0.05).Post-treatment,the T lymphocyte subset levels within the observation group demonstrated a remarkable amelioration,surpassing the corresponding pre-treatment levels observed within the same group as well as the post-treatment levels observed in the control group(P<0.05).Subsequent to the therapeutic intervention,the observation group showcased a notable amelioration in the scores associated with multiple dimensions of life quality.These scores outperformed the pretreatment scores within the same group as well as the post-treatment scores observed in the control group(P<0.05).The safety levels of drug use in the two group were comparable(19.57%vs 13.04%),and no distinct difference was observed upon comparison(P>0.05).After the completion of treatment,both groups of patients underwent a 1-year follow-up outside the hospital.Throughout this period,1 patient within the observation group and 2 patients within the control group became untraceable and were lost to follow-up.During the follow-up period of the observation group,12 patients died,resulting in a survival rate of 73.33%(33/45),while in the control group,21 patients died,resulting in a survival rate of 52.27%(23/44).The implementation of Kaplan-Meier survival analysis revealed a conspicuous contrast in survival rates exhibited by the two groups(log-rank=4.710,P=0.030).CONCLUSION The combination of sintilimab and anlotinib hydrochloride demonstrated favorable efficacy in the treatment of MSS CRC patients,leading to improvements in patient immunity and prognosis.Additionally,it exerted inhibitory effects on the expression of carcinoembryonic antigen,CA199,and CA125.

Molecular insights into clinical trials for immune checkpoint inhibitors in colorectal cancer:Unravelling challenges and future directions

Colorectal cancer(CRC)is a complex disease with diverse etiologies and clinical outcomes.Despite considerable progress in development of CRC therapeutics,challenges remain regarding the diagnosis and management of advanced stage metastatic CRC(mCRC).In particular,the five-year survival rate is very low since mCRC is currently rarely curable.Over the past decade,cancer treatment has significantly improved with the introduction of cancer immunotherapies,specifically immune checkpoint inhibitors.Therapies aimed at blocking immune checkpoints such as PD-1,PD-L1,and CTLA-4 target inhibitory pathways of the immune system,and thereby enhance anti-tumor immunity.These therapies thus have shown promising results in many clinical trials alone or in combination.The efficacy and safety of immunotherapy,either alone or in combination with CRC,have been investigated in several clinical trials.Clinical trials,including KEYNOTE-164 and CheckMate 142,have led to Food and Drug Administration approval of the PD-1 inhibitors pembrolizumab and nivolumab,respectively,for the treatment of patients with unresectable or metastatic microsatellite instability-high or deficient mismatch repair CRC.Unfortunately,these drugs benefit only a small percentage of patients,with the benefits of immunotherapy remaining elusive for the vast majority of CRC patients.To this end,primary and secondary resistance to immunotherapy remains a significant issue,and further research is necessary to optimize the use of immunotherapy in CRC and identify biomarkers to predict the response.This review provides a comprehensive overview of the clinical trials involving immune checkpoint inhibitors in CRC.The underlying rationale,challenges faced,and potential future steps to improve the prognosis and enhance the likelihood of successful trials in this field are discussed.

Epidermal growth factor receptor stabilizes programmed death ligand 1 by glycosylation in colorectal cancer with microstatellite instability status

Programmed death ligand-1(PD-L1)is involved in inhibiting of T lymphocyte proliferation,producing cytokine,cytolytic activity,and suppressing of the immune response.Genes with molecular alterations involved in DNA mismatch repair promote cancer initiation and tumor progression.Clinical studies show that colorectal cancer(CRC)patients harboring microsatellite instability(MSI)have a higher anti-programmed cell death protein 1/PD-L1 immunotherapy response ratio compared with microsatellite stable subgroup patients.The underlying mechanism has however remained unclear.Here,we found that compared with microsatellite stable samples,PD-L1 was glycosylated and highly expressed both in MSI CRC cell lines and tissue samples.Specifically,PD-L1 was Nglycosylated at its N35,N192,N200,and N219 sites,and the four glycosylation sites were all responsible for PD-L1 degradation.Additionally,non-glycosylated PD-L1 underwent rapid degradation compared with glycosylated PD-L1 through the 26S proteasome pathway.The faster degradation of the non-glycosylated PD-L1 was ascribed to its binding to glycogen synthase kinase 3b via ubiquitination.This degradation phenotype was,however,not observed for glycosylated PD-L1.Significantly,glycosylated PD-L1 was up-regulated by activated epidermal growth factor receptor in MSI CRC cells.Together,our results indicate that epidermal growth factor receptor stabilized PD-L1 via glycosylation in MSI CRC cells,uncovering a novel role of PD-L1 in MSI CRC immunosuppression and disease progression.The study was approved by the Clinical Ethics Review Committee at the Six Affiliated Hospital of Sun Yat-sen University,China(Approval No.2019ZSLYEC-005).