Tumor treatment by pHLIP-targeted antigen delivery

Area of Science:

• Biotechnology
• Immunology
• Oncology

Background:

• Targeted antigen delivery can activate the immune system against cancer cells.
• pH Low Insertion Peptides (pHLIPs) respond to tumor acidity, inserting into cancer and immune cell membranes for targeted delivery.

Purpose of the Study:

• To investigate the targeted delivery of various epitopes, including a hemagglutinin (HA) peptide, to tumors using pHLIPs.
• To evaluate the immunogenicity and therapeutic efficacy of HA-pHLIP agents in preclinical cancer models.

Main Methods:

• Developed double-headed HA-pHLIP agents with linked HA epitopes via polymer chains.
• Vaccinated mice with HA-pHLIP agents and various adjuvants, assessing anti-HA antibody titers and tumor targeting.
• Evaluated tumor regression in 4T1 breast and B16F10 melanoma models.

Main Results:

• HA-pHLIP agents successfully targeted tumor cells, with epitopes exposed for 24-48 hours before internalization.
• Vaccination induced high titers of anti-HA antibodies, which complexed with HA-pHLIP for tumor targeting and hepatic clearance.
• Significant regression of triple-negative breast and melanoma tumors was observed in immunized mice.

Conclusions:

• pHLIP-targeted antigen therapy effectively induces anti-tumor immunity and tumor regression.
• Potential limitations include waning antibody titers, suggesting the need for booster vaccinations.
• This approach offers a promising therapeutic strategy for cancers unresponsive to conventional immunotherapies.