SPH4336

SPH4336 is an oral, small molecule inhibitor that selectively targets cyclin-dependent kinase 4 (CDK4) and cyclin-dependent kinase 6 (CDK6). By inhibiting these kinases, SPH4336 prevents phosphorylation of the retinoblastoma protein (Rb) early in the G1 phase of the cell cycle, thereby blocking CDK-mediated G1-S-phase transition and inducing cell cycle arrest. This mechanism disrupts tumor cell proliferation. SPH4336 is being developed primarily for advanced solid tumors, including HR-positive metastatic breast cancer, HER2-negative breast cancer, well-differentiated/dedifferentiated liposarcomas, and central nervous system primary or metastatic tumors. The drug has received orphan drug designation from the US FDA for liposarcoma and has shown promising anti-tumor activity in preclinical models as well as tolerability in early clinical trials[1][2][7][8].