Harnessing Bacterial Agents to Modulate the Tumor Microenvironment and Enhance Cancer Immunotherapy

Area of Science:

• Oncology
• Immunology
• Microbiology

Background:

• Cancer immunotherapy harnesses the immune system but is often limited by the immunosuppressive tumor microenvironment (TME).
• The TME comprises diverse cells that suppress antitumor responses and promote immune evasion.
• Developing strategies to modify the TME is crucial for improving immunotherapy efficacy.

Purpose of the Study:

• To review innovative strategies for modifying the TME to enhance cancer immunotherapy outcomes.
• To explore the therapeutic potential of engineered bacteria in overcoming TME-mediated immune suppression.
• To highlight how bacterial therapeutics can be utilized to improve immunotherapy efficacy.

Main Methods:

• Review of current literature on tumor microenvironment modification and bacterial therapeutics.
• Analysis of engineered bacteria's mechanisms for TME targeting and therapeutic payload delivery.
• Examination of combination strategies involving bacterial therapies and other immunotherapies.

Main Results:

• Engineered bacteria can selectively accumulate in tumors, exploiting TME characteristics like abnormal vasculature.
• Genetically modified bacteria can deliver therapeutic agents (e.g., immune checkpoint inhibitors, cytokines) directly to tumor sites.
• Bacterial therapeutics can target immunosuppressive cells (e.g., myeloid-derived suppressor cells, tumor-associated macrophages) within the TME.

Conclusions:

• Engineered bacteria represent a promising strategy to reshape the TME and enhance cancer immunotherapy.
• Combining bacterial therapies with immune checkpoint inhibitors or adoptive cell transfer can counteract immune suppression.
• Bacterial agents offer a potential new modality for treating tumors resistant to conventional treatments.