Study of AMD3100 (Plerixafor) and Rituximab in Patients With Chronic Lymphocytic Leukemia or Small Lymphocytic Lymphoma

Inclusion Criteria:

* Females of child bearing potential must agree to abstain from sexual activity or to use a medically approved contraceptive measure/regimen during and for 3 months after the treatment period or be surgically sterile. Males must agree to abstain from sexual activity or agree to utilize a medically approved contraception method during treatment and for 3 months after the treatment period or be surgically sterile.
* Diagnosis of CLL or SLL, relapsed from at least one prior therapy.
* CLL/SLL cells expressing CD20 documented during screening.
* Eastern Cooperative Oncology Group (ECOG) performance status of ≤2.
* Life expectancy of at least 12 weeks.
* Serum creatinine ≤2.0 mg/dL.
* Total bilirubin ≤2.0 mg/dL.
* ALT (alanine aminotransferase) and AST (aspartate aminotransaminase) ≤2 times the upper limit of normal (ULN); for patients with liver involvement of CLL/SLL disease, this limit is increased to ≤5 times the ULN.
* At the time of enrollment, patients must be \>4 weeks since major surgery, radiotherapy, chemotherapy (\>6 weeks for some chemotherapies), immunotherapy, biotherapy/targeted or investigational therapies and recovered from the toxicity of prior treatment to ≤ grade 1.

Exclusion Criteria:

* White Blood Cells (WBC) \>250 x 10\^9 cells/L.
* Disease refractory to rituximab therapy- defined as a failure to respond to prior rituximab-containing regimen.
* Women who are breastfeeding.
* Active viral hepatitis.
* Active infection or treatment with antimicrobial or antiviral therapy within 1 week of enrollment with the exception of prophylactic therapy.
* History of prior allergic reaction to plerixafor or rituximab.
* Significant lung disease.
* Serious cardiac disease such as a history of sustained ventricular arrhythmia, uncontrolled and serious congestive heart failure (CHF), angina, acute coronary syndrome, or myocardial infarction within 6 months of enrollment or other significant medical or psychosocial conditions that warrants exclusion.