Mucin-16 (MUC16) (MUC16)

Mucin-16 (MUC16), widely recognized by its clinical biomarker name Cancer Antigen 125 (CA125), is a massive transmembrane glycoprotein that serves as a key therapeutic target in gynecological and other epithelial malignancies (UniProt Q8WXI7). The protein features an extensive extracellular domain composed of multiple tandem repeats, which are frequently overexpressed and shed into the systemic circulation in patients with ovarian cancer (PubMed: 25103343). Biologically, MUC16 facilitates tumor progression by promoting cell-cell adhesion through interactions with mesothelin and by providing a protective barrier that shields cancer cells from immune surveillance (PubMed: 29351553). Therapeutic strategies targeting the CA125 domain include monoclonal antibodies like oregovomab, which aims to induce an endogenous immune response, and antibody-drug conjugates (ADCs) such as sofituzumab vedotin designed for intracellular toxin delivery (ClinicalTrials.gov). Additionally, next-generation approaches like CAR-T cell therapies are being developed to overcome the challenges of the immunosuppressive tumor microenvironment associated with MUC16 expression. A primary hurdle in targeting MUC16 is the high level of shed CA125, which can act as a decoy receptor, sequestering drugs in the blood and limiting their penetration into solid tumor masses (PubMed: 31631468).

Other names

CA125Cancer antigen 125Ovarian cancer-associated antigen CA125MUC-16FLJ14303

Therapeutic agents targeting the MUC16 extracellular domain utilize several mechanisms: monoclonal antibodies like oregovomab induce antibody-dependent cellular cytotoxicity (ADCC) and prime the immune system for a T-cell mediated response; antibody-drug conjugates (ADCs) such as sofituzumab vedotin bind the CA125 repeats to facilitate internalization and intracellular release of cytotoxic payloads; and chimeric antigen receptor (CAR) T-cells are engineered to recognize the MUC16 extracellular domain to induce direct T-cell mediated lysis of malignant cells (PubMed: 25103343, PubMed: 31631468).