Engineering PD-1-Presenting Platelets for Cancer Immunotherapy.

Area of Science:

• Oncology
• Immunology
• Biotechnology

Background:

• Radical surgery is a primary treatment for many cancers, but tumor relapse remains a significant challenge.
• Post-surgical consolidation therapy is crucial to prevent recurrence.
• Immune checkpoint inhibitors show promise as consolidation treatments.

Purpose of the Study:

• To investigate the potential of genetically engineered platelets as a post-surgical immunotherapy.
• To evaluate the efficacy of PD-1-expressing platelets in preventing tumor relapse.
• To assess the combined effect of PD-1 platelets and cyclophosphamide on the tumor microenvironment.

Main Methods:

• Megakaryocyte progenitor cells were genetically engineered to express programmed cell death protein 1 (PD-1).
• Engineered PD-1 platelets and their microparticles were designed to target tumor surgical wounds.
• A low dose of cyclophosphamide (CP) was loaded into PD-1 platelets to deplete regulatory T cells (Tregs).
• The effect on CD8+ T cells and tumor relapse was analyzed in the post-surgical tumor microenvironment.

Main Results:

• Engineered PD-1 platelets and microparticles accumulated in the tumor surgical wound.
• PD-1 platelets successfully reverted exhausted CD8+ T cells, leading to eradication of residual tumor cells.
• Combining PD-1 platelets with cyclophosphamide increased the frequency of reinvigorated CD8+ T cells.
• This combination therapy effectively prevented tumor relapse in the post-surgery setting.

Conclusions:

• Genetically engineered PD-1 platelets represent a novel strategy for post-surgical cancer consolidation therapy.
• PD-1 platelets can enhance anti-tumor immunity by reinvigorating exhausted T cells within the tumor microenvironment.
• Combination therapy with PD-1 platelets and low-dose cyclophosphamide offers a promising approach to prevent tumor recurrence after surgery.