Combining CTLA-4 and angiopoietin-2 blockade in patients with advanced melanoma: a phase I trial

Advances in tumor vascular growth inhibition

Tumor growth and metastasis require neovascularization, which is dependent on a complex array of factors, such as the production of various pro-angiogenic factors by tumor cells, intercellular signaling, and stromal remodeling. The hypoxic, acidic tumor microenvironment is not only conducive to tumor cell proliferation, but also disrupts the equilibrium of angiogenic factors, leading to vascular heterogeneity, which further promotes tumor development and metastasis. Anti-angiogenic strategies to inhibit tumor angiogenesis has, therefore, become an important focus for anti-tumor therapy. The traditional approach involves the use of anti-angiogenic drugs to inhibit tumor neovascularization by targeting upstream and downstream angiogenesis-related pathways or pro-angiogenic factors, thereby inhibiting tumor growth and metastasis. This review explores the mechanisms involved in tumor angiogenesis and summarizes currently used anti-angiogenic drugs, including monoclonal antibody, and small-molecule inhibitors, as well as the progress and challenges associated with their use in anti-tumor therapy. It also outlines the opportunities and challenges of treating tumors using more advanced anti-angiogenic strategies, such as immunotherapy and nanomaterials.

IBI310 (anti-CTLA-4 antibody) monotherapy or in combination with sintilimab in advanced melanoma or urothelial carcinoma

IBI310 is a recombinant fully human IgG1 antibody against cytotoxic T lymphocyte antigen 4. This study was conducted to evaluate IBI310 monotherapy or combination therapy with sintilimab in the patients with advanced melanoma or urothelial carcinoma (UC). Patients in phase 1a received IBI310 at 0.3/1/2/3 mg/kg intravenously (IV) every 3 weeks (Q3W) following the accelerated titration and 3 + 3 escalation design. Patients in phase 1b received IBI310 (1/2/3 mg/kg IV, Q3W) plus sintilimab (200 mg IV, Q3W) for four cycles, followed by sintilimab maintenance therapy. The phase 1b expansion of IBI310 plus sintilimab was performed in patients with advanced melanoma or UC. Overall, 53 patients were enrolled, including 10 patients with melanoma in phase 1a, 34 with melanoma, and 9 with UC in phase 1b. Overall, 94.3% of patients (50/53) experienced at least one treatment-related adverse event (TRAE) with most being grade 1-2; 26.4% of patients (14/53) experienced grade 3 or higher TRAEs. In phase 1a, the disease control rate (DCR) was 50.0% (95% confidence interval [CI], 18.7%-81.3%). In phase 1b, the objective response rate (ORR) and DCR were 17.6% (95% CI, 6.8%-34.5%) and 44.1% (95% CI, 27.2%-62.1%), respectively, for melanoma, and were 22.2% (95% CI, 2.8%-60.0%) and 66.7% (95% CI, 29.9%-92.5%), respectively, for UC. IBI310 monotherapy or combination therapy with sintilimab was well tolerated with favorable antitumor activity across patients with advanced melanoma and UC.

Bifidobacterium modulation of tumor immunotherapy and its mechanism

The advent of tumor immunotherapy in patients has revolutionized the treatment of tumors and significantly improved survival rates for a wide range of tumors. However, the full therapeutic potential of immune checkpoint inhibitors (ICIs) has yet to be realized, as not all patients have a lasting survival benefit from them, and a significant proportion of patients show primary or acquired resistance to immunotherapy. Bifidobacterium is one of the most common probiotics, and its antitumor and immunomodulatory effects have been demonstrated in recent years, but its immunomodulatory effects in tumors, especially on ICIs and in combination, have not been extensively studied in clinical practice, and its effects on the immune system and the mechanisms that modulate immunotherapy are largely unknown. Therefore, this review will focus on the immunomodulatory effects of Bifidobacteria in malignancies and the possible mechanisms of action of Bifidobacteria on immunotherapy in the hope of providing a basis for further research and better application of Bifidobacteria in clinical practice.

Angiopoietin-2-Dependent Spatial Vascular Destabilization Promotes T-cell Exclusion and Limits Immunotherapy in Melanoma

T-cell position in the tumor microenvironment determines the probability of target encounter and tumor killing. CD8+ T-cell exclusion from the tumor parenchyma is associated with poor response to immunotherapy, and yet the biology that underpins this distinct pattern remains unclear. Here we show that the vascular destabilizing factor angiopoietin-2 (ANGPT2) causes compromised vascular integrity in the tumor periphery, leading to impaired T-cell infiltration to the tumor core. The spatial regulation of ANGPT2 in whole tumor cross-sections was analyzed in conjunction with T-cell distribution, vascular integrity, and response to immunotherapy in syngeneic murine melanoma models. T-cell exclusion was associated with ANGPT2 upregulation and elevated vascular leakage at the periphery of human and murine melanomas. Both pharmacologic and genetic blockade of ANGPT2 promoted CD8+ T-cell infiltration into the tumor core, exerting antitumor effects. Importantly, the reversal of T-cell exclusion following ANGPT2 blockade not only enhanced response to anti-PD-1 immune checkpoint blockade therapy in immunogenic, therapy-responsive mouse melanomas, but it also rendered nonresponsive tumors susceptible to immunotherapy. Therapeutic response after ANGPT2 blockade, driven by improved CD8+ T-cell infiltration to the tumor core, coincided with spatial TIE2 signaling activation and increased vascular integrity at the tumor periphery where endothelial expression of adhesion molecules was reduced. These data highlight ANGPT2/TIE2 signaling as a key mediator of T-cell exclusion and a promising target to potentiate immune checkpoint blockade efficacy in melanoma.

SIGNIFICANCE

ANGPT2 limits the efficacy of immunotherapy by inducing vascular destabilization at the tumor periphery to promote T-cell exclusion.

Melanoma Tumour Vascularization and Tissue-Resident Endothelial Progenitor Cells

The aggressiveness of solid cancers, such as melanoma, relies on their metastatic potential. It has become evident that this key cause of mortality is largely conferred by the tumour-associated stromal cells, especially endothelial cells. In addition to their essential role in the formation of the tumour vasculature, endothelial cells significantly contribute to the establishment of the tumour microenvironment, thus enabling the dissemination of cancer cells. Melanoma tumour vascularization occurs through diverse biological processes. Vasculogenesis is the formation of de novo blood vessels from endothelial progenitor cells (EPCs), and recent research has shown the role of EPCs in melanoma tumour vascularization. A more detailed understanding of the complex role of EPCs and how they contribute to the abnormal vessel structures in tumours is of importance. Moreover, anti-angiogenic drugs have a limited effect on melanoma tumour vascularization, and the role of these drugs on EPCs remains to be clarified. Overall, targeting cancer vasculature remains a challenge, and the role of anti-angiogenic drugs and combination therapies in melanoma, a focus of this review, is an area of extensive exploration.

Ang2-Targeted Combination Therapy for Cancer Treatment

Angiopoietin-2 (Ang2), a member of the angiopoietin family, is widely involved in the process of vascular physiology, bone physiology, adipose tissue physiology and the occurrence and development of inflammation, cardiac hypertrophy, rheumatoid, tumor and other diseases under pathological conditions. Proliferation and metastasis of cancer largely depend on angiogenesis. Therefore, anti-angiogenesis has become the target of tumor therapy. Due to the Ang2 plays a key role in promoting angiogenesis and stability in vascular physiology, the imbalance of its expression is an important condition for the occurrence and development of cancer. It has been proved that blocking Ang2 can inhibit the growth, invasion and metastasis of cancer cells. In recent years, research has been constantly supplemented. We focus on the mechanisms that regulate the expression of Ang2 mRNA and protein levels in different cancers, contributing to a better understanding of how Ang2 exerts different effects in different cancers and stages, as well as facilitating more specific targeting of relevant molecules in cancer therapy. At the same time, the importance of Ang2 in cancer growth, metastasis, prognosis and combination therapy is pointed out. And finally, we will discuss the current investigations and future challenges of combining Ang2 inhibition with chemotherapy, immunotherapy, and radiotherapy to increase its efficacy in cancer patients. This review provides a theoretical reference for the development of new targets and effective combination therapy strategies for cancer treatment in the future.

Normalization of tumor vasculature: A potential strategy to increase the efficiency of immune checkpoint blockades in cancers

Immune checkpoint inhibitors (ICIs) eliminate tumor cells by reactivating CD8 + T cells using the cytotoxic effects of the immune system. However, in this process, tumor angiogenic factors and abnormal formation of tumor blood vessels are not conducive to the treatment of ICIs. In the tumor microenvironment (TME), proangiogenic factors prevent dendritic cell maturation, reduce T cell infiltration, and recruit inhibitory immune cells such as regulatory T (Treg) cells. Abnormal tumor blood vessels also prevent immune cells and chemotherapy drugs from reaching the target effectively and lead to poor perfusion and severe hypoxia of the tumor. Treatment with antiangiogenic inhibitors can block the transmission of abnormal angiogenesis signals and promote the normalization of tumor vasculature. Therefore, the combination of antiangiogenic inhibitors and ICIs is used in clinical therapy. Combination therapy has been proven theoretically feasible in preclinical trials, and many clinical trials have been completed to confirm its safety and efficacy.

Lactobacillus kefiranofaciens ZW18 from Kefir enhances the anti-tumor effect of anti-programmed cell death 1 (PD-1) immunotherapy by modulating gut microbiota

The research of probiotics assisting PD-1 inhibitors in anti-tumor has attracted widespread attention. Therefore, it is significative to find new probiotic strains with PD-1 inhibitors promoting effect. This study aims...