Yttrium Y 90 Anti-CD19 Antibody BU-12 in Patients With Advanced Relapsed or Refractory Acute Lymphoblastic Leukemia or Chronic Lymphocytic Leukemia

Inclusion Criteria: * Histologically confirmed CD19-positive (\> 25% by flow cytometry evaluation of bone marrow blasts) disease of 1 of the following types: * Primary refractory or relapsed acute lymphoblastic leukemia (ALL) defined as persistent disease following a minimum of two different standard effective chemotherapy induction attempts at time of diagnosis or at relapse * Chronic Lymphocytic leukemia (CLL) following blast crisis (≥15% bone marrow blasts following a minimum of one standard effective chemotherapy induction attempt) * Human anti-mouse antibody (HAMA) must be negative * Patients who have relapsed ≥ 60 days following an autologous or allogeneic transplant are eligible if all other eligibility criteria are met * No active central nervous system (CNS) disease * ECOG performance status (PS) 0-2 or Karnofsky PS 60-100% * Life expectancy \> 8 weeks * Total bilirubin ≤ 2.5 times upper limit of normal (ULN) * AST and ALT ≤ 2.5 times ULN * Creatinine normal OR creatinine clearance ≥ 60 mL/min * LVEF ≥ 45% by MUGA/ECHO * Oxygen saturation on room air \> 92% and no oxygen requirement * Not pregnant or nursing * Negative pregnancy test * Fertile patients mus use effective contraception Exclusion criteria: * History of allergic reactions attributed to compounds of similar chemical or biologic composition to of yttrium Y 90 anti-CD19 antibody BU-12 or other agents used in study * Uncontrolled illness including, but not limited to, any of the following: * Ongoing or active infection * Symptomatic congestive heart failure * Unstable angina pectoris * Cardiac arrhythmia * Psychiatric illness/social situations that would limit compliance with study requirements * HIV-positive * Active graft-vs-host disease * Less than 4 weeks since prior agents and recovered * Less than 7 days since prior therapy with any biologic agent, defined as a growth factor or cytokine * Less than 3 months since prior antibody or biologic anticancer therapy (e.g., alemtuzumab or epratuzumab) * Other concurrent investigational agents * Patients with peripheral blasts \> 5,000/uL may receive concurrent hydroxyurea