UNC2025 hydrochloride is a potent, ATP-competitive, highly orally active Mer Flt3 inhibitor. It has IC50 values of 0.74 nM and 0.8 nM, respectively, for Mer and Flt3. UNC2025 hydrochloride demonstrates over 45-fold selectivity for MERTK compared to Axl (IC50 = 122 nM; Ki = 13.3 nM). Additionally, UNC2025 hydrochloride exhibits excellent PK properties, making it suitable for investigating acute leukemia.