PD-1 Immune Checkpoint Blockade Promotes Therapeutic Cancer Vaccine to Eradicate Lung Cancer

Area of Science:

• Oncology
• Immunology
• Cancer Research

Background:

• Activating immune responses against cancer is crucial, especially with the rise of immune checkpoint inhibitors.
• Therapeutic vaccination offers a promising strategy to generate specific anti-tumor immune responses.

Purpose of the Study:

• To evaluate the efficacy of combining PD-1 blockade with a CCL21-DC tumor lysate vaccine in a murine lung cancer model.
• To determine the impact of this combination therapy on tumor burden, T cell activity, and immunological memory.

Main Methods:

• Utilized a K-RasG12Dp53null murine lung cancer model.
• Assessed tumor burden, tumor-infiltrating T cell (TIL) cytolysis, and immune cell populations via flow cytometry and immunohistochemistry.
• Employed CD4 and CD8 depletion to elucidate the role of T cells in the therapeutic response.

Main Results:

• The combination of anti-PD-1 and CCL21-DC tumor lysate vaccine led to 80% tumor eradication in established tumors.
• Treatment increased perforin and granzyme B expression and enhanced TIL activity within the tumor microenvironment.
• Complete tumor eradication induced durable immunological memory, conferring protection against tumor re-challenge and ensuring cancer-recurrence-free survival.
• Monotherapy with either PD-1 blockade or the vaccine reduced tumor burden but did not achieve eradication.

Conclusions:

• Immune checkpoint blockade, specifically PD-1 blockade, significantly enhances the efficacy of therapeutic cancer vaccines.
• The combination of PD-1 blockade and CCL21-DC tumor lysate vaccine demonstrates potent anti-tumor activity and potential for treating lung cancer.