Alternative Radiotherapy Delivery Approaches to Modulate Radiation Response

Area of Science:

• Radiation oncology
• Immunology
• Preclinical research

Background:

• Spatially fractionated radiotherapy (SFRT) and FLASH radiotherapy (RT) are advanced dose delivery techniques aiming to enhance the therapeutic ratio in radiation oncology.
• The underlying biological mechanisms, particularly concerning normal tissue sparing and tumor control, remain largely unelucidated.
• Understanding the immunological effects of these novel RT modalities is crucial for their clinical translation.

Purpose of the Study:

• To introduce preclinical research technologies for SFRT and FLASH-RT using photon beams.
• To review and discuss the observed immunological anti-tumor responses in animal models for both SFRT and FLASH-RT.
• To assess the potential of SFRT and FLASH-RT to generate beneficial anti-tumor immunity.

Main Methods:

• Description of preclinical research technologies, including carbon nanotubes, modified small animal irradiators, and line-focused x-ray tubes for SFRT and FLASH-RT.
• Review of existing literature on immunological anti-tumor responses in various animal models exposed to SFRT and FLASH-RT.
• Comparative analysis of immune modulation by SFRT and FLASH-RT versus conventional RT.

Main Results:

• Preclinical technologies for photon-based SFRT and FLASH-RT are presented.
• Both SFRT and FLASH-RT have been shown to modulate the tumor immune microenvironment in preclinical models.
• The extent to which the generated anti-tumor immunity surpasses that of conventional RT is not yet clearly established.

Conclusions:

• SFRT and FLASH-RT represent promising advancements in radiation delivery with the potential to improve therapeutic outcomes.
• While these techniques modulate the tumor immune microenvironment, further research is needed to fully understand their immunogenicity.
• Future preclinical studies should focus on elucidating specific aspects of SFRT- and FLASH-RT-mediated anti-tumor immunity for potential clinical application in cancer patients.