or a pharmaceutically acceptable salt thereof, where: Q can be 1,2,4-triazin-3-yl, pyridazin-3-yl, 6-methylpyridazin-3-yl, or 6-fluoropyridazin-3-yl； R1 can be hydrogen, methoxy, trifluoromethoxy, oxetan-3-yl, 3-fluoroazetidin-1-yl, 3-methoxyazetidin-1-yl, or 3,3-difluoroazetidin-1-yl； R2 can be hydrogen or fluoro； R3 can be hydrogen or methoxy； and R4 can be methoxy, ethoxy, or methoxymethyl； provided that when R1 is hydrogen, methoxy or trifluoromethoxy, then R3 is not hydrogen, and/or R4 is methoxymethyl. The compound of formula (I) can inhibit glutaminase, e.g., GLS1.
