Definition

A glycosylated decoy receptor fusion protein that is composed of the vascular endothelial growth factor receptor-1 (VEGFR1; VEGFR-1) backbone and fused to fragments of Fc region, with potential anti-angiogenic, immunomodulating and antineoplastic activities. Upon administration, Fc-VEGFR1 fusion protein PB101 targets, binds to and neutralizes placental growth factor (PlGF; PGF) and VEGF-A and VEGF-B, thereby inhibiting the binding of PlGF and VEGF-A and -B to VEGFR-1 and prevents subsequent VEGFR-1 phosphorylation and VEGFR1-mediated signaling. This may result in the inhibition of tumor angiogenesis and, by blocking blood flow, inhibits tumor cell proliferation. By simultaneously inhibiting both VEGF and PlGF signaling within the tumor microenvironment (TME), PB101 modulates the immunosuppressive TME and enhances CD8-positive T-cell infiltration into the tumor. Both PGF, a member of the VEGF sub-family, and VEGF play key roles in angiogenesis, and are upregulated in many cancers. Tumor vasculature plays an important role in promoting tumor progression and immune evasion.