- Known central nervous system involvement by CLL. Screening laboratory values: Platelets less than 100 x 109/L (unless due to CLL involvement of the bone marrow). Neutrophils less than 1.5 x 109/L (unless due to CLL involvement of the bone marrow). Serum creatinine greater than 1.5 times the upper limit of normal (ULN); subjects with a serum creatinine greater than 1.5 x ULN will be eligible if the calculated creatinine clearance [Cockcroft, 1976] is greater than or equal to 30 mL/min. Total bilirubin greater than 1.5 times ULN (unless due to liver involvement by CLL or Gilbert's disease). Transaminases greater than 2.5 times ULN.