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Blockade of immune checkpoint pathways by programmed cell death protein 1 (PD-1) antibodies has demonstrated broad clinical efficacy against a variety of malignancies. Sintilimab, a highly selective, fully human monoclonal antibody (mAb), blocks the interaction of PD-1 and its ligands and has demonstrated clinical benefit in various clinical studies. Here, we evaluated the affinity of sintilimab to human PD-1 by surface plasmon resonance and mesoscale discovery and evaluated PD-1 receptor occupancy and anti-tumor efficacy of sintilimab in a humanized NOD/Shi-scid-IL2rgamma (null) (NOG) mouse model. We also assessed the receptor occupancy and immunogenicity of sintilimab from clinical studies in humans (9 patients with advanced solid tumor and 381 patients from 4 clinical studies, respectively). Sintilimab bound to human PD-1 with greater affinity than nivolumab (Opdivo®, MDX-1106) and pembrolizumab (Keytruda®, MK-3475). The high affinity of sintilimab is explained by its distinct structural binding mode to PD-1. The pharmacokinetic behavior of sintilimab did not show any significant differences compared to the other two anti-PD-1 mAbs. In the humanized NOG mouse model, sintilimab showed superior PD-1 occupancy on circulating T cells and a stronger anti-tumor effect against NCI-H292 tumors. The strong anti-tumor response correlated with increased interferon-γ-secreting, tumor-specific CD8+ T cells, but not with CD4+ Tregs in tumor tissue. Pharmacodynamics testing indicated a sustained mean occupancy of ≥95% of PD-1 molecules on circulating T cells in patients following sintilimab infusion, regardless of infusion dose. Sintilimab infusion was associated with 0.52% (2/381 patients) of anti-drug antibodies and 0.26% (1/381 patients) neutralizing antibodies. These data validate sintilimab as a novel, safe, and efficacious anti-PD-1 mAb for cancer immunotherapy.

Background Deciphering intra‐ and inter‐tumoural heterogeneity is essential for understanding the biology of gastric cancer (GC) and its metastasis and identifying effective therapeutic targets. However, the characteristics of different organ‐tropism metastases of GC are largely unknown. Methods Ten fresh human tissue samples from six patients, including primary tumour and adjacent non‐tumoural samples and six metastases from different organs or tissues (liver, peritoneum, ovary, lymph node) were evaluated using single‐cell RNA sequencing. Validation experiments were performed using histological assays and bulk transcriptomic datasets. Results Malignant epithelial subclusters associated with invasion features, intraperitoneal metastasis propensity, epithelial–mesenchymal transition‐induced tumour stem cell phenotypes, or dormancy‐like characteristics were discovered. High expression of the first three subcluster‐associated genes displayed worse overall survival than those with low expression in a GC cohort containing 407 samples. Immune and stromal cells exhibited cellular heterogeneity and created a pro‐tumoural and immunosuppressive microenvironment. Furthermore, a 20‐gene signature of lymph node‐derived exhausted CD8+ T cells was acquired to forecast lymph node metastasis and validated in GC cohorts. Additionally, although anti‐NKG2A (KLRC1) antibody have not been used to treat GC patients even in clinical trials, we uncovered not only malignant tumour cells but one endothelial subcluster, mucosal‐associated invariant T cells, T cell‐like B cells, plasmacytoid dendritic cells, macrophages, monocytes, and neutrophils may contribute to HLA‐E‐KLRC1/KLRC2 interaction with cytotoxic/exhausted CD8+ T cells and/or natural killer (NK) cells, suggesting novel clinical therapeutic opportunities in GC. Additionally, our findings suggested that PD‐1 expression in CD8+ T cells might predict clinical responses to PD‐1 blockade therapy in GC. Conclusions This study provided insights into heterogeneous microenvironment of GC primary tumours and organ‐specific metastases and provide support for precise diagnosis and treatment.

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Anti-programmed cell death-1 (PD-1)/programmed cell death-ligand 1 (PD-L1) antibodies are currently used in the clinic to interupt the PD-1/PD-L1 immune checkpoint, which reverses T cell dysfunction/exhaustion and shows success in treating cancer. Here, we report a histone demethylase inhibitor, 5-carboxy-8-hydroxyquinoline (IOX1), which inhibits tumour histone demethylase Jumonji domain-containing 1A (JMJD1A) and thus downregulates its downstream β-catenin and subsequent PD-L1, providing an antibody-independent paradigm interrupting the PD-1/PD-L1 checkpoint. Synergistically, IOX1 inhibits cancer cells’ P-glycoproteins (P-gp) through the JMJD1A/β-catenin/P-gp pathway and greatly enhances doxorubicin (DOX)-induced immune-stimulatory immunogenic cell death. As a result, the IOX1 and DOX combination greatly promotes T cell infiltration and activity and significantly reduces tumour immunosuppressive factors. Their liposomal combination reduces the growth of various murine tumours, including subcutaneous, orthotopic, and lung metastasis tumours, and offers a long-term immunological memory function against tumour rechallenging. This work provides a small molecule-based potent cancer chemo-immunotherapy.

High expression of PD-L1 marks the poor prognosis of pancreatic ductal adenocarcinomas (PDAC). However, the regulatory mechanism of PD-L1 remains elusive. We recently reported that cancer Forkhead box protein 3 (Cancer-FOXP3 or C-FOXP3) promoted immune evasion of PDAC by recruiting Treg cells into PDAC via upregulation of CCL5. In this study, we confirmed that PD-L1 was overexpressed in PDAC samples from two independent cohorts of patients with radical resection. Moreover, C-FOXP3 was colocalized and correlated with the expression of PD-L1 in tumor cells at the mRNA and protein levels, and this finding was confirmed by the The Cancer Genome Atlas (TCGA) database. Chromatin immunoprecipitation (ChIP) revealed that C-FOXP3 directly bound to the promoter region of PD-L1 in pancreatic cancer cells. Furthermore, overexpression of C-FOXP3 activated the luciferase reporter gene under the control of the PD-L1 promoter. However, mutation of the binding motif-a completely reversed the luciferase activity. In addition, C-FOXP3-induced upregulation of PD-L1 effectively inhibited the activity of CD8 + T cells. Based on our recent finding that the CCL-5 antibody achieved a better response to PDAC models with high C-FOXP3 levels, we further demonstrated that the PD-L1 antibody strengthened the antitumor effect of CCL-5 blockade in xenograft and orthotopic mouse models with high C-FOXP3 levels. In conclusion, C-FOXP3 directly activates PD-L1 and represents a core transcription factor that mediates the immune escape of PDAC. Combined blockade of PD-L1 and CCL-5 may provide an effective therapy for patients with PDAC that have high C-FOXP3 levels.

Immune checkpoint inhibitors have greatly improved the prognoses of diverse advanced malignancies, including gastric and gastroesophageal junction (G/GEJ) cancer. However, the role of anti-programmed cell death protein-1 treatment in the neoadjuvant setting remains unclear. This phase 2 study aimed to evaluate sintilimab plus CapeOx as a neoadjuvant regimen in patients with advanced resectable G/GEJ adenocarcinoma. Eligible patients with resectable G/GEJ adenocarcinoma stage cT3-4NanyM0 were enrolled. Patients received neoadjuvant treatment with sintilimab (3 mg/kg for cases <60 kg or 200 mg for those ≥60 kg on day 1) plus CapeOx (oxaliplatin at 130 mg/m2 on D1 and capecitabine at 1000 mg/m2 two times per day on D1–D14) every 21 days, for three cycles before surgical resection, followed by adjuvant treatment with three cycles of CapeOx with the same dosages after surgical resection. The primary endpoint was pathological complete response (pCR) rate. Secondary endpoints included objective response rate, tumor regression grade per Becker criteria, survival and safety. As of July 30, 2020, 36 patients were enrolled. Totally 7 (19.4%) patients had GEJ cancer, and 34 (94.4%) patients were clinical stage III cases. A total of 35 (97.2%) patients completed three cycles of neoadjuvant treatment, and 1 patients received two cycles due to adverse events. All patients underwent surgery and the R0 resection rate was 97.2%. In this study, pCR and major pathological response were achieved in 7 (19.4%, 95% CI: 8.8% to 35.7%; 90% CI: 10.7% to 33.1%) and 17 (47.2%, 95% CI: 31.6% to 64.3%) patients, respectively. Thirty-one patients received adjuvant treatment. By December 20, 2021, three patients died after disease relapse, and two patients were alive with relapse. Median disease-free survival (DFS) and overall survival (OS) were not reached. The 1-year DFS and OS rates were 90.3% (95% CI: 80.4% to 100.0%) and 94.1% (95% CI: 86.5% to 100.0%), respectively. The most common (>1 patient) grade 3 treatment-related adverse events during neoadjuvant treatment were anemia and neutropenia (n=5 each, 13.9%). No serious adverse events (AEs) or grade 4–5 AEs were observed. Sintilimab plus oxaliplatin/capecitabine showed promising efficacy with encouraging pCR rate and good safety profile in the neoadjuvant setting. This combination regimen might present a new option for patients with locally advanced, resectable G/GEJ adenocarcinoma. Trial registration; NCT04065282.