Inspired by their potency and overall physicochemical properties, we chose to next evaluate the in-cell selectivity of 40 and 46 using panels of 192-240 kinase NanoBRET assays 44 at a concentration of 1 µM. This concentration is well above the PIKfyve NanoBRET IC50 of these compounds and was selected to identify kinases that bind with weaker affinity, allowing us to define the selectivity window and appropriate in vitro dosing range for each compound. The results, which are expressed as percent occupancy of a kinase by the test compound at 1 µM, are summarized in Figure . Compound 40 bound to MYLK4, MKNK2, and CDK10 and compound To supplement this data, we also sent 40 and 46 to be profiled in enzymatic assays for TTBK1 and TTBK2. These kinases were not included in the 192-member panel, and we have demonstrated binding of related indolyl pyrimidinamine analogues to TTBK1 and TTBK2. When evaluated at 1 µM, both 40 and 46 demonstrated ≤8% inhibition of TTBK1 and TTBK2 and were thus considered to be inactive versus these two kinases.