Immunological Mechanisms Responsible for Radiation-Induced Abscopal Effect

Area of Science:

• Immunology
• Radiation Oncology
• Cancer Therapy

Background:

• Radiotherapy has historically been a local tumor treatment for over a century.
• Systemic antitumor effects, such as the abscopal effect, were observed but considered rare and unpredictable.
• The emergence of immunotherapy has renewed interest in radiotherapy's potential for systemic effects.

Purpose of the Study:

• To review the immunological mechanisms underlying radiotherapy's ability to promote systemic antitumor effects.
• To explore how focal radiation can stimulate T cell responses for tumor rejection.
• To understand radiation's role in overcoming primary and acquired resistance to cancer immunotherapy.

Main Methods:

• Literature review of immunological mechanisms.
• Analysis of studies combining radiotherapy and immunotherapy.
• Examination of T cell-mediated responses to focal radiation.

Main Results:

• Focal radiotherapy can induce systemic antitumor responses, including the abscopal effect.
• Radiotherapy enhances T cell activation and infiltration in non-irradiated tumors.
• Combinations of radiotherapy and immune checkpoint blockade show remarkable systemic effects in patients.

Conclusions:

• Radiotherapy, particularly in conjunction with immunotherapy, can overcome cancer resistance.
• Understanding the immunological mechanisms is key to optimizing radiation-based immunotherapy.
• Focal radiation can be strategically used to promote systemic T cell responses for tumor rejection.