R992

R992 is a small molecule inhibitor developed by Rigel Pharmaceuticals that selectively targets the MERTK (Mer) receptor tyrosine kinase. It belongs to the TAM (Tyro3, Axl, Mer) receptor family and demonstrates 8-fold selectivity over Tyro3 and 13-fold selectivity over Axl. In preclinical models of multiple myeloma, R992 has shown the ability to inhibit myeloma cell proliferation and induce apoptosis by blocking MERTK signaling. Additionally, it addresses myeloma-associated bone disease by inhibiting osteoclast differentiation, thereby promoting bone formation. While it has demonstrated dose-dependent growth inhibition and prolonged survival in mouse models, R992 remains a research compound and is not currently approved for clinical use.