# Combined carbon ion radiotherapy and immunotherapy: leveraging the immunological advantages of carbon ion

## TL;DR

This paper reviews how combining carbon ion radiotherapy with immunotherapy can improve cancer treatment by leveraging the immunological benefits of carbon ion therapy.

## Contribution

The paper provides a comprehensive review of combining carbon ion radiotherapy with immunotherapy, highlighting new preclinical and clinical insights.

## Key findings

- Carbon ion radiotherapy enhances immune cell infiltration and antigen exposure in tumors.
- Combining carbon ion radiotherapy with immunotherapy can shift the tumor microenvironment from immunosuppressive to immunostimulatory.
- Preclinical and clinical studies support the potential of this combined treatment modality.

## Abstract

Immunotherapy represents a systemic approach to cancer treatment; however, its effectiveness can be limited by intrinsic tumor resistance or immunosuppressive mechanisms within the tumor microenvironment. In contrast, carbon ion radiotherapy (CIRT) demonstrates considerable immunomodulatory potential owing to its distinct biological properties. The exposure of tumor-associated antigens, increased immune cell infiltration and activity, and modifications in the immune microenvironment after CIRT provide a mechanistic rationale for combining CIRT with immunotherapy. Furthermore, strategies aimed at converting the tumor microenvironment from immunosuppressive to immunostimulatory, or those targeting immune checkpoints, are currently under active exploration. This review summarizes the latest advances in combining heavy ion radiotherapy with immunotherapy, encompassing both preclinical and clinical studies. Based on the immunological advantages of CIRT, it provides a comprehensive summary and in-depth exploration of the potential of this combined treatment modality for future clinical applications, along with a theoretical foundation to support it.