Nelmastobart

**Semantic type:** Amino Acid, Peptide, or Protein|Immunologic Factor|Pharmacologic Substance

**Definition:** A humanized monoclonal antibody directed against the immune checkpoint protein butyrophilin 1A1 (BTN1A1), with potential immune checkpoint inhibitory and antineoplastic activities. Upon administration, nelmastobart targets and binds to the extracellular domain of human BTN1A1, which prevents the formation of the BTN1A1-galectin-9 (Gal9)-programmed cell death protein 1 (PD-1) complex, and inhibits downstream signaling pathways. This may restore immune function through the activation of T-cells and T-cell-mediated immune responses against tumor cells. The BTN1A1-Gal9-PD-1 axis suppresses T-cell receptor (TCR) signaling and T-cell activation. BTN1A1 does not bind to PD-1 directly but interacts with PD-1 through Gal9. BTN1A1, a member of the butyrophilin superfamily of immunomodulators, is upregulated in a variety of tumor cell types.

**Synonyms:** - Anti-BTN1A1 Monoclonal Antibody hSTC810 - Anti-Butyrophilin 1A1 Monoclonal Antibody hSTC810 - NELMASTOBART - hSTC 810 - hSTC-810 - hSTC810