A compound of Formula (I): or a pharmaceutically acceptable salt thereof, is described. Q can be pyridazin-3-yl, 6-fluoropyridazin-3-yl; R1 can be H; R2 and R3 can each independently be C1-C6 alkyl, or R2 and R3 taken together are —(CH2)3—; or R1 and R2 taken together can be —(CH2)2— and R3 can be —CH3; R4 halo, —CH3, —OCH3, —OCHF2, —OCF3, or —CN; and n can be 0, 1, or 2. The compound of formula (I) can inhibit glutaminase, e.g., GLS1.