Long-Term Antitumor CD8⁺ T Cell Immunity Induced by Endogenously Engineered Extracellular Vesicles

Area of Science:

• Immunology
• Molecular Biology
• Oncology

Background:

• Extracellular vesicles (EVs) are emerging as a platform for drug delivery and immunotherapy.
• Engineering EVs for antigen presentation can enhance antigen-specific T cell responses.
• Previous work demonstrated Nefmut/HPV16-E7 fusion protein induced E7-specific CD8+ T cell response.

Purpose of the Study:

• To optimize and extend the anti-HPV16 CD8+ T cell immune response induced by engineered EVs.
• To evaluate the therapeutic antitumor efficacy of these engineered EVs over time.
• To assess the potential for long-term protective immunity against HPV-induced tumors.

Main Methods:

• In vivo engineering of EVs using a DNA vector expressing a mutated HIV-1 Nef protein (Nefmut) fused to HPV16 antigens (E6 and E7).
• Co-injection of DNA vectors expressing Nefmut fused with E6 and E7 into mice.
• Evaluation of anti-HPV16 CD8+ T cell immune response and therapeutic antitumor efficacy in a mouse model.
• Tumor cell implantation, immunization, survival analysis, tumor clearance assessment, and re-challenge experiments.

Main Results:

• Co-injection of Nefmut-E6/E7 vectors generated a stronger anti-HPV16 immune response than single vectors.
• Mice immunized with engineered EVs survived HPV16-E6/E7 tumor cell implantation, while control groups did not.
• A significant portion of immunized mice (7/12) cleared existing tumors.
• Cured mice developed resistance to subsequent tumor re-challenge, indicating durable immunity.
• Both E6- and E7-specific CD8+ T cell immunities were detectable long-term.

Conclusions:

• Engineered EVs effectively induce antigen-specific CD8+ T cell immunity against HPV-induced tumors.
• This approach demonstrates therapeutic efficacy in treating established tumors and provides long-term protection.
• The engineered EV system holds promise for treating metastatic and relapsing tumors.