A novel sulfonamide compound with potential antineoplastic activity. Indisulam inhibits cyclin-dependent kinases (CDK), which regulate cell cycle progression and are usually over-expressed in cancerous cells. Inhibition of CDK results in G1/S phase arrest of the cell cycle, and may lead to induction of apoptosis and inhibition of tumor cell proliferation. In addition, indisulam also inhibits carbonic anhydrases (CA), especially isoforms IX and XII that are involved in aqueous humor production and are highly overexpressed in some types of cancers. Inhibition of CA IX and XII results in interference with ion exchange and pH in hypoxic tumor tissue and preventing chemoresistance to weakly basic antineoplastic agents.