(-)-Cyclocytidine hydrochloride is primarily used in the field of oncology as an antineoplastic agent. It is effective in inhibiting the growth of cancer cells, particularly in leukemia and other types of tumors. The compound works by interfering with the synthesis of DNA and RNA, thereby preventing the proliferation of malignant cells. It is often administered in combination with other chemotherapy drugs to enhance its efficacy and reduce the likelihood of drug resistance. Additionally, it has been studied for its potential use in antiviral therapies, where it shows promise in inhibiting the replication of certain viruses. The compound's ability to target rapidly dividing cells makes it a valuable tool in both cancer treatment and antiviral research.