Acute serious infection, including hepatitis; hypothyroidism (TSH greater than 6.0 microunits/mL); folic acid deficiency (less than 0.9 ng/mL); vitamin B12 deficiency (less than 160 pg/mL) within one year prior to enrollment; severe renal insufficiency (creatinine clearance less than 25 mL/min, BUN greater than 40 mg/dL, or serum creatinine greater than 2.0 mg/dL); hepatic insufficiency (SGPT or SGOT greater than 3 x upper limit of normal, or total bilirubin greater than 2.0 mg/dL). Due to the serious adverse event transient agranulocytosis report in another study of CX516, patients will neutropenia or low normal white blood cell counts (greater than or equal to 3.5 K/microliter) will be excluded from this study.