Regulatory T (Treg) cells maintain immune homeostasis by inhibiting abnormal/overactive immune responses to both autogenic and nonautogenic antigens. Treg cells play an important role in immune tolerance, autoimmune diseases, infectious diseases, organ transplantation, and tumor diseases. Treg cells have two functional characteristics: T cell anergy and immunosuppression. Treg cells remain immune unresponsive to high concentrations of interleukin-2 and anti-CD3 monoclonal antibodies. In addition, the activation of Treg cells after TCR-mediated signal stimulation inhibits the activation and proliferation of effector T cells. In the process of tumor development, Treg cells accumulate locally in the tumor and lead to tumor escape by inducing anergy and immunosuppression. It is believed that targeted elimination of Treg cells can activate tumor-specific effector T cells and improve the efficiency of cancer immunotherapy. Therefore, inhibition/clearance of Treg cells is a promising strategy for enhancing antitumor immunity. Here, we review studies of cancer immunotherapies targeting Treg cells.

Immune checkpoint inhibitors (ICIs) are an integral antitumor therapy for many malignancies. Most patients show very good tolerability to ICIs; however, serious immune-related adverse events (irAEs) with ICIs have been well documented and prevent some patients from continuing ICIs or even become the direct cause of patient death. Cytopenia is a rare irAE but can be life-threatening. Here, we present the case of a 66-year-old male patient with metastatic lung adenocarcinoma who received two doses of chemotherapy + PD-1 antibody tislelizumab and developed pancytopenia after each dose. Although the first episode of pancytopenia resolved with a treatment regimen of granulocyte colony-stimulating factor (G-CSF), thrombopoietin (TPO), and red blood cell and platelet transfusion, the second episode showed extreme resistance to these treatments and improved only after the administration of steroids. His second pancytopenia episode resolved after a long course of treatment with methylprednisolone, G-CSF, TPO, hetrombopag and multiple red blood cell and platelet transfusions. However, he suffered a cerebral infarction when his platelet count was in the normal range and gradually recovered 1 week later. This case highlights the importance of the early recognition and management of hematological irAEs.

The clinical significance of palliative interventional therapy in the management of patients with advanced hilar cholangiocarcinoma (HCCA; stages III–IV) has yet to be studied. The present work was aimed to compare the clinical outcomes of the patients treated with surgery or interventional therapy. A total of 90 patients with advanced HCCA, who admitted Fuyang First People's Hospital from May 2015 to February 2016, were enrolled. Forty-five of them were assigned to the experimental group receiving biliary drainage as the interventional therapy, and the remaining 45 patients were designated as the conventional group receiving radical/palliative surgery. Before and after the treatment total bilirubin from blood was measured. The length of treatment and medical cost were also examined. All patients were followed up for at least 1 year after the treatment. For both the experimental and conventional groups, the serum bilirubin levels after treatment were significantly lower than those before treatment (P < .05); however, no significant differences between groups were seen. There were no significant differences between experimental and conventional groups in the incidence of postoperative complications and survival outcomes. Of note, the length of treatment of the experimental group was substantially shorter than that of the conventional group (P < .05). The medical expense of the experimental group was only about one-third of that of the conventional group (P < .05). Although the interventional therapy does not improve patients’ survivals and reduce the incidence of complications, it significantly shortens the treatment length, reducing substantially the medical expense. This finding provides new insights into the treatment strategy for patients with advanced HCCA.

The ongoing ENPOWER study exploring the efficacy and safety of the recombinant human endostatin (endostar) combined with programmed cell death 1 antibody sintilimab and chemotherapy showed encouraging efficacy and safety in advanced non-squamous non-small cell lung cancer. To evaluate the real-world efficacy and safety of endostar combined with immune checkpoint inhibitor and chemotherapy (EIC) for advanced non-squamous non-small cell lung cancer patients negative for actionable molecular biomarkers (NSCLCnm), patients with advanced NSCLCnm hospitalized to Zhejiang Provincial People’s Hospital from January 2020 to December 2022 were screened for eligibility. The included patients were analyzed for the objective response rate (ORR) and disease control rate (DCR). The pre- and posttreatment expression levels of serum tumor associated biomarkers, chemokines and subpopulations of immune cells in peripheral blood were compared. For the 31 patients with advanced NSCLCnm treated with EIC, the median follow-up and treatment cycles were 18.0 months and 4, respectively. The ORR and DCR were 38.7% and 90.3%, respectively. For those who received EIC as first-line treatment, the ORR and DCR were 63.2% and 94.7%, respectively. EIC significantly decreased expression levels of carcinoma antigen 125, carcinoma embryonic antigen and cytokeratin 19 (P<0.05) in patients who were partial remission or stable disease. Among the 31 patients, 27 (87.1%) experienced at least 1 treatment-related adverse events, and 13 (41.9%) had the treatment-related adverse events of grade 3 or higher. No antiangiogenesis-related adverse events were observed. The current study showed that EIC was potentially effective for patients with NSCLCnm, especially when used as first-line therapy, and well tolerated.