Used primarily in the treatment of chronic lymphocytic leukemia (CLL), fludarabine phosphate is effective in inducing remission in patients with this type of cancer. It is often used when the disease has progressed or has not responded to other treatments like alkylating agents. Due to its mechanism of interfering with DNA synthesis and repair, it targets rapidly dividing cancer cells. It is administered intravenously and is valued for its ability to cross the blood-brain barrier, making it useful in certain central nervous system malignancies. Its use is generally limited by potential side effects, including immunosuppression, which increases the risk of serious infections.