SP17 (Sperm Protein 17) is a testis-specific protein first identified in spermatozoa, where it plays a role in sperm-egg interaction by binding to zona pellucida glycoproteins. Structurally, it contains a conserved N-terminal heparin-binding domain and a C-terminal region homologous to the RFC (Recombination Factor C) family. While primarily expressed in germ cells, SP17 has been detected ectopically in various cancers, including multiple myeloma, ovarian cancer, and squamous cell carcinomas, suggesting potential oncogenic roles. Its aberrant expression in malignancies has been linked to epigenetic dysregulation, particularly hypomethylation of promoter regions.
SP17 antibodies have emerged as valuable tools for both research and clinical applications. In diagnostics, they help detect SP17 overexpression in tumor tissues or serum, aiding cancer subtyping and monitoring. Therapeutically, SP17 is investigated as a target for immunotherapy due to its cancer-specific expression pattern. Preclinical studies explore SP17-directed CAR-T cells and antibody-drug conjugates, showing reduced tumor burden in xenograft models. However, challenges persist, including heterogeneous SP17 expression across tumors and potential off-target effects in males due to residual testicular expression. Current research focuses on optimizing antibody specificity and evaluating combinatorial approaches with checkpoint inhibitors to enhance anti-tumor efficacy.