GS-3583

GS-3583 is a novel FLT3 agonist Fc fusion protein developed by Gilead Sciences. It acts as an agonist of the Fms-like tyrosine kinase 3 (FLT3) receptor, a hematopoietic growth factor receptor expressed on myeloid and lymphoid progenitor cells. By stimulating the FLT3 pathway, GS-3583 promotes the expansion of conventional dendritic cells (cDCs), particularly subtype 1 (cDC1), which are crucial for priming and expanding tumor-specific CD8+ T cells and enhancing antitumor immune responses. In clinical studies, systemic administration of GS-3583 led to transient, dose-dependent increases in cDC1 cells in healthy volunteers and patients with advanced solid tumors[1][4][6]. The drug was generally well tolerated in early-phase trials but development was discontinued after phase I due to safety concerns including treatment-related adverse events such as secondary malignancies[5][6].