Used primarily in chemotherapy, especially for chronic myeloid leukemia (CML). Often part of conditioning regimens before bone marrow or stem cell transplantation to eliminate cancer cells and suppress the immune system to prevent graft rejection. Its ability to cross the blood-brain barrier makes it useful in certain central nervous system cancers. Also investigated for use in myeloablative therapy due to its potent alkylating action on DNA, which inhibits cell division and leads to cancer cell death.