V-set domain-containing T-cell activation inhibitor 1 (B7-H4) (B7-H4)

V-set domain-containing T-cell activation inhibitor 1, commonly known as B7-H4, is a member of the B7 family of immune checkpoint proteins that plays a critical role in the negative regulation of T-cell-mediated immune responses [2, 7, 16]. It is a type I transmembrane glycoprotein that is significantly overexpressed in a wide range of solid tumors, including breast, ovarian, and endometrial cancers, while maintaining very limited expression in healthy tissues [1, 3, 18, 20]. This distinct expression profile makes B7-H4 a highly attractive target for antibody-drug conjugates (ADCs) like AZD8205 (puxitatug samrotecan), which use a specific antibody component to deliver cytotoxic payloads directly to malignant cells [5, 6, 13]. In the tumor microenvironment, B7-H4 suppresses T-cell proliferation and the production of inflammatory cytokines, thereby facilitating tumor immune evasion and correlating with poor clinical outcomes [16, 20, 21]. Therapeutic interventions targeting B7-H4 aim to either disrupt its immunosuppressive signaling to reactivate the immune system or utilize its surface presence for targeted delivery of potent anti-cancer agents [17, 19, 24].

Other names

VTCN1B7S1B7xB7h.5PRO1291VCTN1B7 superfamily member 1B7 homolog 4Immune costimulatory protein B7-H4

AZD8205 is an antibody-drug conjugate (ADC) that targets B7-H4. Its primary mechanism of action involves the binding of the anti-B7-H4 antibody component to the target protein on the surface of tumor cells, followed by internalization of the ADC-receptor complex [1, 5]. Once inside the cell, the linker is cleaved to release a topoisomerase I inhibitor payload, which induces DNA damage and subsequent apoptotic cell death [3, 10, 14]. Additionally, B7-H4 targeting can block the inhibitory signals sent to T-cells, potentially restoring anti-tumor immune responses [16, 17, 20].