Used primarily in chemotherapy, this compound treats chronic lymphocytic leukemia (CLL) and certain lymphomas due to its alkylating action that interferes with DNA replication in cancer cells. It is valued for its oral bioavailability, allowing convenient outpatient treatment. Also employed in autoimmune diseases like nephrotic syndrome, especially in children, when standard therapies fail. Its immunosuppressive properties help reduce abnormal immune activity in such conditions. Due to its long half-life and slow action, it is often used in low, continuous doses to maintain remission. Commonly considered in elderly patients or those with comorbidities where less aggressive regimens are preferred.