A compound of Formula (I) or a pharmaceutically acceptable salt thereof, where: Q can be 5-methylpyridazin-3-yl, 5-chloropyridazin-3-yl, 6-methylpyridazin-3-yl, or 6-fluoropyridazin-3-yl; R can be hydrogen, fluoro, or methoxy; R1 can be hydrogen, methoxy, difluoromethoxy, or trifluoromethoxy; and R2 can be methyl or ethyl. The compound of formula (I) can inhibit glutaminase, e.g., GLS1.