Cancer testis antigen Sperm Protein 17 as a new target for triple negative breast cancer immunotherapy

Area of Science:

• Oncology
• Immunology
• Molecular Biology

Background:

• Breast carcinoma poses a significant health challenge, with current treatments often ineffective for metastatic disease and triple-negative breast cancer (TNBC).
• Novel, less toxic therapies are urgently needed, particularly for TNBC, which is unresponsive to hormonal and antibody treatments.
• Cancer-testis antigens (CTA) are highly immunogenic and cancer-specific, making them promising targets for cancer immunotherapy.

Purpose of the Study:

• To evaluate Sperm Protein 17 (SP17) expression in breast cancer, including TNBC.
• To determine if SP17 can elicit an immune response and generate SP17-specific cytotoxic T lymphocytes (CTL) for potential immunotherapy.

Main Methods:

• SP17 expression was analyzed in breast cancer cell lines, primary invasive ductal carcinomas (including TNBC), and adjacent non-neoplastic breast tissue.
• The generation of SP17-specific CTLs was assessed *in vitro*.
• Anti-SP17 antibodies in patient sera were detected.

Main Results:

• SP17 is expressed in breast cancer cell lines and primary tumors, notably in the TNBC subtype.
• SP17 expression was absent in adjacent non-tumoral breast tissue but present in male germinal cells.
• Specific anti-SP17 antibodies were detected in patients' sera, and SP17-specific CTLs were generated *in vitro*.
• These SP17-specific CTLs demonstrated efficient killing of breast cancer cells.

Conclusions:

• SP17 is a promising tumor-associated antigen (TAA) for breast cancer immunotherapy, especially for TNBC.
• The presence of anti-SP17 antibodies and the generation of SP17-specific CTLs support SP17 as a viable target for immunotherapeutic strategies.
• Targeting SP17 could lead to novel, less toxic treatments for breast cancer, including the challenging TNBC subtype.