XL177A

XL177A is a potent and selective small molecule inhibitor of the deubiquitylating enzyme USP7 (Ubiquitin-specific-processing protease 7). Developed at the Dana-Farber Cancer Institute, XL177A is being investigated for its potential to treat multiple myeloma, particularly in cases resistant to proteasome inhibitors. The drug works by inducing apoptosis in myeloma cells and stimulating anti-tumor immunity. Specifically, it activates plasmacytoid dendritic cells (pDCs), which in turn enhances the cytolytic activity of CD8+ T cells and NK cells against myeloma targets. Additionally, XL177A has been shown to decrease the population of immunosuppressive regulatory T cells (Tregs) in the bone marrow microenvironment.