Oxygen microbubbles improve radiotherapy tumor control in a rat fibrosarcoma model - A preliminary study

Area of Science:

• Oncology
• Biomedical Engineering
• Radiotherapy Research

Background:

• Solid tumors often exhibit hypoxia, a condition linked to poor treatment outcomes and increased metastasis.
• Tumor hypoxia necessitates higher radiation therapy (RT) doses for equivalent tumor control, impacting treatment efficacy.
• Even small tumors (<2-3 mm3) contain significant hypoxic regions, posing a challenge for conventional therapies.

Purpose of the Study:

• To investigate the potential of lipid-stabilized oxygen microbubbles (OMBs) to enhance the therapeutic ratio of RT.
• To evaluate the efficacy of OMBs in increasing tumor oxygen levels and improving treatment outcomes in a preclinical cancer model.

Main Methods:

• In vitro assessment of dissolved oxygen levels in water with OMBs and nitrogen microbubbles (NMBs).
• In vivo evaluation of OMBs' effect on tumor oxygenation in a rat fibrosarcoma model.
• Assessment of tumor control following intra-tumoral injection of OMBs or NMBs prior to RT.

Main Results:

• OMBs, unlike NMBs, significantly increased dissolved oxygen in vitro.
• Intra-tumoral OMB injections increased tumor oxygen levels in vivo.
• OMB treatment, but not NMB, significantly improved tumor control following RT, with efficacy dependent on initial tumor volume.

Conclusions:

• Lipid-stabilized oxygen microbubbles show promise for overcoming tumor hypoxia and enhancing RT efficacy.
• OMBs represent a potential strategy to improve cancer treatment outcomes by addressing a critical challenge in solid tumors.
• The findings support further investigation of OMBs as an adjunct therapy to radiation for hypoxic tumors.