Antitumor effect of anti-vascular therapy with STING agonist depends on the tumor microenvironment context

Recent Progress in Photothermal, Photodynamic and Sonodynamic Cancer Therapy: Through the cGAS-STING Pathway to Efficacy-Enhancing Strategies

Photothermal, photodynamic and sonodynamic cancer therapies offer opportunities for precise tumor ablation and reduce side effects. The cyclic guanylate adenylate synthase-stimulator of interferon genes (cGAS-STING) pathway has been considered a potential target to stimulate the immune system in patients and achieve a sustained immune response. Combining photothermal, photodynamic and sonodynamic therapies with cGAS-STING agonists represents a newly developed cancer treatment demonstrating noticeable innovation in its impact on the immune system. Recent reviews have concentrated on diverse materials and their function in cancer therapy. In this review, we focus on the molecular mechanism of photothermal, photodynamic and sonodynamic cancer therapies and the connected role of cGAS-STING agonists in treating cancer.

Combination of STING agonist with anti-vascular RGD-(KLAKLAK)2 peptide as a novel anti-tumor therapy

Immunotherapy is one of the most promising anti-cancer treatment. It involves activating the host's own immune system to eliminate cancer cells. Activation of cGAS-STING pathway is promising therapeutic approach for cancer immunotherapy. However, in human clinical trials, targeting cGAS-STING pathway results in insufficient or unsustainable anti-tumor response. To enhance its effectiveness, combination with other anti-cancer therapies seems essential to achieve synergistic systemic anti-tumor response.The aim of this study was to evaluate whether the combination of STING agonist-cGAMP with anti-vascular RGD-(KLAKLAK)2 peptide results in a better anti-tumor response in poorly immunogenic tumors with various STING protein and αvβ3 integrin status.Combination therapy inhibited growth of murine breast carcinoma more effectively than melanoma. In melanoma, the administration of STING agonist alone was sufficient to obtain a satisfactory therapeutic effect. In both tumor models we have noted stimulation of innate immune response following cGAMP administration alone or in combination. The largest population of immune cells infiltrating the TME after therapy were activated NK cells. Increased infiltration of cytotoxic CD8+ T lymphocytes within the TME was only observed in melanoma tumors. However, they also expressed the "exhaustion" PD-1 receptor. In contrast, in breast carcinoma tumors each therapy caused the drop in the number of infiltrating CD8+ T cells.The obtained results indicate an additional therapeutic benefit from combining STING agonist with an anti-vascular agent. However, this effect depends on the type of tumor, the status of its microenvironment and the expression of specific proteins such as STING and αvβ3 family integrin.

Therapeutic In Situ Cancer Vaccine Using Pulsed Stereotactic Body Radiotherapy-A Translational Model

Both radiation and cancer therapeutic vaccine research are more than 100 years old, and their potential is likely underexplored. Antiangiogenics, nanoparticle targeting, and immune modulators are some other established anticancer therapies. In the meantime, immunotherapy usage is gaining momentum in clinical applications. This article proposes the concept of a pulsed/intermittent/cyclical endothelial-sparing single-dose in situ vaccination (ISVRT) schedule distinguishable from the standard therapeutic stereotactic body radiotherapy (SBRT) and stereotactic radiosurgery (SRS) plans. This ISVRT schedule can repeatedly generate tumor-specific neoantigens and epitopes for primary and immune modulation effects, augment supplementary immune enhancement techniques, activate long-term memory cells, avoid extracellular matrix fibrosis, and essentially synchronize with the vascular normalized immunity cycle. The core mechanisms of ISVRT impacting in situ vaccination would be optimizing cascading antigenicity and adjuvanticity. The present proposed hypothesis can be validated using the algorithm presented. The indications for the proposed concept are locally progressing/metastatic cancers that have failed standard therapies. Immunotherapy/targeted therapy, chemotherapy, antiangiogenics, and vascular-lymphatic normalization are integral to such an approach.