The active ingredient in a drug that is used to treat chronic lymphocytic leukemia (CLL), to treat slow-growing B-cell non-Hodgkin lymphoma (NHL) that has gotten worse within 6 months of treatment with other anticancer drugs, and is being studied in the treatment of other types of cancer. Bendamustine may damage the DNA in cancer cells and cause them to die. It is a type of alkylating agent and a type of antimetabolite.