Tumor-associated antigens identified early in mouse mammary tumor development can be effective vaccine targets

Area of Science:

• Oncology
• Immunology
• Cancer Vaccines

Background:

• Serological analysis of cDNA expression libraries (SEREX) identified breast cancer antigens that elicit immune responses but offer limited clinical benefit.
• Previous vaccine strategies focused on modifying adjuvants and delivery methods, neglecting the potential impact of antigen selection based on disease stage.

Purpose of the Study:

• To investigate if the antigen repertoire differs between early and late-stage breast cancer.
• To determine if breast cancer antigens identified from early-stage tumors elicit a more effective anti-tumor response compared to those from late-stage tumors.

Main Methods:

• Utilized the transgenic TgMMTV-neu mouse model to compare antigen repertoires in early versus late-stage breast cancer.
• Conducted SEREX screens on mice with early and late-stage tumors to identify distinct antigens.
• Vaccinated mice with identified early-stage antigens (Pdhx, Stk39, Otud6B) and late-stage antigens (Swap70, Gsn, Arhgef2) to assess anti-tumor effects.
• Evaluated the essentiality of early-stage antigens for tumor survival by silencing their protein expression in mouse and human breast cancer cell lines.
• Correlated the overexpression of early and late-stage antigens in human breast cancer patients with patient prognosis.

Main Results:

• Three early-stage antigens (Pdhx, Stk39, Otud6B) significantly inhibited tumor growth when used in vaccines (p < 0.0001).
• Antigens identified from late-stage tumors (Swap70, Gsn, Arhgef2) failed to inhibit tumor growth when formulated as vaccines.
• Early-stage antigens were crucial for tumor cell survival, with silencing increasing apoptosis and decreasing survival in both mouse and human cancer cell lines.
• Overexpression of early-stage antigens in human breast cancer correlated with a worse prognosis (p = 0.03), while late-stage antigens did not significantly impact prognosis (p = 0.09).

Conclusions:

• Antigens expressed during early breast tumor development are functionally critical for tumor growth and survival.
• Early-stage breast cancer antigens represent more promising targets for therapeutic vaccine development than late-stage antigens.
• Targeting early-stage antigens may offer a more effective strategy for improving clinical outcomes in breast cancer treatment.