| Exclusion Criteria: | 1) Burkitt's lymphoma, Lymphoblastic lymphoma, Chronic lymphocytic leukemia (Small lymphocytic lymphoma may be included).
2) Chemotherapy or radiation therapy or other investigational agents within 4 weeks prior to entering the study.
3) Previous radioimmunotherapy within 12 weeks.
4) Patient with active infections or HIV infection.
5) Known active viral hepatitis.
6) Known intolerance to infused protein products or maytansinoids (an anti-tumor medication that is a derivative of a natural plant).
7) Any serious active disease or co-morbid condition, which in the opinion of the principle investigator, will interfere with the safety or with compliance with the study.
8) Poor bone marrow reserve as defined by absolute neutrophil count < 1.5 x 10^9/L or platelets < 100 x 10^9/L.
9) Baseline QTc interval > 500 msec (determined as the median of three EKGs done within a 30-min period) (Grade >/= 3 NCI-CTC v3.0)
10) Poor organ function as defined by one of the following: a.) Total bilirubin > 1.5 x ULN (>3 x ULN for patients with liver involvement); b.) AST, ALT > 2.5 x ULN (> 5 x ULN for patients with liver involvement); c.) Serum creatinine > 2 x ULN and/or creatinine clearance < 60 mL/min
11) Pregnant or breast-feeding women (sexually active females of childbearing potential must have a negative serum or urine pregnancy test).
12) Refused to use effective birth control methods if applicable. Women that can have children must use a medically acceptable method of birth control while participating in the study (birth control pill, intrauterine device or injection of Depo-Provera) and for at least 30 days after the last dose of study medication. |