Necroptosis-Inducible Polymeric Nanobubbles for Enhanced Cancer Sonoimmunotherapy

Area of Science:

• Biomedical Engineering
• Cancer Research
• Immunology

Background:

• Necroptosis is a programmed cell death pathway that can stimulate antitumor immune responses.
• Clinical applications of necroptosis are limited because cancer cells often downregulate RIPK3, a key enzyme.
• Developing strategies to induce necroptosis independently of RIPK3 is crucial for cancer therapy.

Purpose of the Study:

• To develop nanobubbles (NBs) capable of inducing RIPK3-independent necroptosis.
• To investigate the potential of these NBs to enhance antitumor immunity.
• To evaluate the combination therapy of NBs with immune checkpoint blockade in a preclinical cancer model.

Main Methods:

• Preparation of nanobubbles using PEGylated carboxymethyl dextran and chlorin e6, loaded with perfluoropentane.
• Ultrasound-triggered acoustic cavitation to induce cell membrane rupture and necroptosis.
• Assessment of damage-associated molecular pattern release, immune cell activation (dendritic cells, CD8+ T cells), and tumor regression in vitro and in vivo.
• Combination therapy with immune checkpoint blockade in an RIPK3-deficient CT26 tumor model.

Main Results:

• Ultrasound-activated NBs induced RIPK3-independent necroptosis and cell membrane disintegration.
• NBs promoted the release of damage-associated molecular patterns, enhancing dendritic cell maturation and CD8+ T cell activation.
• Combination therapy with NBs and immune checkpoint blockade resulted in complete primary tumor regression and activity against metastatic tumors in a preclinical model.
• The developed NBs effectively trigger immunogenic cell death in cancer cells, even in the absence of RIPK3.

Conclusions:

• Nanobubbles can induce RIPK3-independent necroptosis, offering a novel strategy to overcome a common resistance mechanism in cancer.
• This approach effectively enhances antitumor immunity by promoting immunogenic cell death and activating key immune cells.
• The combination of these nanobubbles with immune checkpoint blockade shows significant therapeutic potential for treating RIPK3-deficient tumors, including metastatic disease.