The average Gleostine cash price is about $2,743.36 for a supply of: Capsule 10 MG 30 pcs. Get our free Gleostine coupon and be eligible to receive a discount. You can reduce your Gleostine cost by up to 75% with our free Gleostine discount card. Bring it to a participating pharmacy near you to save on your prescription medication.Treating certain types of cancer. Gleostine is an alkylating agent used to treat cancer. It works by stopping or slowing the growth of cancer cells.