<unk> (oral) is a anti neoplastic that is FDA approved for the treatment of B-cell chronic lymphocytic leukemia (CLL). There is a Black Box Warning for this drug as shown here.  Common adverse reactions include myelosuppression (neutropenia, thrombocytopenia and anemia), fever and chills, infection, and nausea and vomiting. Other commonly reported events include malaise, fatigue, anorexia, and weakness.
Fludarabine 
Vidarabine
Clofarabine
Nelarabine
Cladribine
Cytarabine
Mafosfamide
Floxuridine