TH-302-loaded nanodrug reshapes the hypoxic tumour microenvironment and enhances PD-1 blockade efficacy in gastric cancer

Background: Hypoxia, a common characteristic of the tumour microenvironment, is involved in tumour progression and immune evasion. Targeting the hypoxic microenvironment has been implicated as a promising antitumour therapeutic strategy. TH-302 can be selectively activated under hypoxic conditions. However, the effectiveness of TH-302 in gastric cancer combined immunotherapy remains unclear.

Methods: We designed mPEG-PLGA-encapsulated TH-302 (TH-302 NPs) to target the hypoxic area of tumour tissues. A particle size analyzer was used to measure the average size and zeta potential of TH-302 NPs. The morphology was observed by transmission electron microscopy and scanning electron microscopy. The hypoxic area of tumour tissues was examined by immunofluorescence assays using pimonidazole. Flow cytometry analysis was performed to measure the levels of TNF-α, IFN-γ, and granzyme B. The synergistic antitumour activity of the combination of TH-302 NPs with anti-PD-1 (α-PD-1) therapy was assessed in vitro and in vivo. Haematoxylin and eosin staining of major organs and biochemical indicator detection were performed to investigate the biological safety of TH-302 NPs in vivo.

Results: TH-302 NPs inhibited the proliferation and promoted the apoptosis of gastric cancer cells under hypoxic conditions. In vitro and in vivo experiments confirmed that TH-302 NPs could effectively alleviate tumour hypoxia. TH-302 NPs exhibited high bioavailability, effective tumour-targeting ability and satisfactory biosafety. Moreover, the combination of TH-302 NPs with α-PD-1 significantly improved immunotherapeutic efficacy in vivo. Mechanistically, TH-302 NPs reduced the expression of HIF-1α and PD-L1, facilitated the infiltration of CD8+ T cells and increased the levels of TNF-α, IFN-γ, and granzyme B in tumours, thereby enhancing the efficacy of α-PD-1 therapy.

Conclusion: TH-302 NPs alleviated the hypoxic tumour microenvironment and enhanced the efficacy of PD-1 blockade. Our results provide evidence that TH-302 NPs can be used as a safe and effective nanodrug for combined immunotherapy in gastric cancer treatment.

 

Comments:

The study you've outlined is quite fascinating! It seems like the research delves into a novel approach for tackling the challenges posed by the hypoxic tumor microenvironment in gastric cancer and exploring the potential synergies between TH-302 nanoparticles and PD-1 blockade in immunotherapy.

TH-302's selective activation under hypoxic conditions appears promising, especially in targeting the hypoxic areas of tumor tissues. The encapsulation of TH-302 into mPEG-PLGA nanoparticles seems to have facilitated effective delivery and enhanced its therapeutic efficacy.

The observed inhibition of proliferation and promotion of apoptosis in gastric cancer cells under hypoxic conditions by TH-302 NPs are significant findings. Equally important is the confirmation of its ability to alleviate tumor hypoxia both in vitro and in vivo, potentially paving the way for better treatment outcomes.

The results indicating high bioavailability, effective tumor-targeting ability, and satisfactory biosafety of TH-302 NPs are encouraging, particularly in the context of its application in combined immunotherapy. The demonstrated enhancement of immunotherapeutic efficacy in vivo when combined with α-PD-1 therapy showcases the potential synergy between TH-302 NPs and immune checkpoint blockade.

Understanding the mechanistic insights behind TH-302 NPs' action, including the reduction in HIF-1α and PD-L1 expression, facilitation of CD8+ T cell infiltration, and elevation of TNF-α, IFN-γ, and granzyme B levels within tumors, provides valuable insights into how this combination therapy may work.

The conclusion drawn from this research suggests that TH-302 NPs hold promise as a safe and effective nanodrug for combined immunotherapy in treating gastric cancer. This could potentially offer a new avenue for therapeutic strategies, especially considering the challenges posed by the tumor microenvironment.

Further research and clinical trials could help validate these findings and potentially pave the way for the development of more effective treatment options for gastric cancer patients.

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