Alemtuzumab and Clofarabine for Relapsed or Refractory Acute Lymphoblastic Leukemia

Inclusion Criteria:

1. Provide signed written informed consent. If a patient is under the 18 years of age the parent or the guardian will also need to provide written informed consent.
2. Diagnosis of ALL (B or T lineage) who have received therapy with at least 1 but not more than 3 prior different induction regimens and have been deemed to have relapse or refractory disease. The phase II component of the study enrollment will be limited to 2 different prior induction regimens if patients are older than 30 years.
3. ALL lymphoblasts with CD52 expression on at least 10% on lymphoblasts.
4. Age \>= 16 years of age.
5. ECOG PS 0-2.
6. Have adequate renal and hepatic functions.
7. Subject or their patient or guardian is capable of understanding the investigational nature, potential risks and benefits of the study, and able to provide valid informed consent.
8. Female patients of childbearing potential must have a negative serum pregnancy test within 2 weeks prior to enrollment.
9. Male and female patients must use an effective contraceptive method during the study and for a minimum of 6 months after study treatment. Subjects 16 and 17 years old must also adhere to effective contraception methods or abstinence during the study and for a minimum of 6 months after study and the nature of contraception or abstinence must be documented.
10. CMV PCR negative prior to enrollment

Exclusion Criteria:

1. Current concomitant chemotherapy, radiation therapy, or immunotherapy other than as specified in the protocol.
2. Use of investigational agents within 30 days or any anticancer therapy within 2 weeks before study entry with the exception of hydroxyurea, CNS treatment or prophylaxis, or tyrosine kinase inhibitors for individuals with Philadelphia chromosome positive ALL. The patient must have recovered from all acute toxicities from any previous therapy.
3. Lack of bone marrow or blood involvement by leukemia such as a documented CNS or testicular only relapse.
4. Have any other severe concurrent disease, or have a history of serious organ dysfunction or disease involving the heart, kidney, liver, or other organ system that may place the patient at undue risk to undergo treatment.
5. Patients with any known or suspected Hepatitis B, C and HIV infections.
6. Patients with a systemic fungal, bacterial, viral, or other infection not controlled (defined as exhibiting ongoing signs/symptoms related to the infection and without improvement, despite appropriate antibiotics or other treatment).
7. Pregnant or lactating patients.
8. Any significant concurrent disease, illness, or psychiatric disorder that would compromise patient safety or compliance, interfere with consent, study participation, follow up, or interpretation of study results.