Inducing Tumor Suppressive Microenvironments through Genome Edited CD47^-/- Syngeneic Cell Vaccination

Area of Science:

• Immunology
• Oncology
• Cancer Research

Background:

• Tumors evade immune detection via CD47 overexpression, a challenge for therapies due to universal CD47 expression and toxicity.
• CD47 blockade is a promising cancer immunotherapy strategy, but systemic toxicity limits its application.

Purpose of the Study:

• To investigate the immunomodulatory effects of vaccinating with genome-edited CD47-/- syngeneic tumor cells.
• To determine how the tumor microenvironment changes following vaccination with CD47-depleted melanoma cells.

Main Methods:

• Utilized genome-edited CD47-/- syngeneic mouse melanoma cells for vaccination.
• Assessed tumor growth rates, tumor-free survival, and characterized the tumor microenvironment post-vaccination.
• Analyzed immune cell populations including natural killer cells, regulatory T cells, M2 macrophages, and PD-L1 expression.

Main Results:

• Vaccination with CD47-depleted melanoma cells resulted in 33% of mice remaining tumor-free and a 5-fold reduction in tumor growth rates.
• The tumor microenvironment became highly anti-tumorigenic and homogenous after vaccination.
• Non-responsive tumors showed decreased natural killer cells, increased regulatory T cells and M2 macrophages, and high PD-L1 expression.

Conclusions:

• Inactivated CD47-depleted tumor cells can confer protection against melanoma in a preclinical model.
• The observed changes in the tumor microenvironment suggest a potential new immunotherapy for solid tumors.
• Targeting CD47 in combination with other immunomodulatory strategies may overcome treatment resistance.