Inclusion Criteria:

• Histologically confirmed diagnosis of relapsed/refractory MCL or hematologically/bone marrow confirmed relapsed/refractory CLL that is not amenable to cure by surgery or other means and has failed at least 1 prior systemic therapy;
• Subjects may have been treated with up to 6 prior systemic therapies for relapsed/refractory disease or have become intolerant to a systemic therapy
• For MCL, must have measurable disease
• At least 4 weeks since the last systemic therapy, including RT, for the treatment of MCL/CLL;
• At least 4 weeks since taking any corticosteroids prior to the first dose of MDX-1411
• ECOG Performance Status 0 to 2;
• No known positivity for human immunodeficiency virus (HIV) and no active infection with Hepatitis B or Hepatitis C;

Exclusion Criteria:

• History of severe hypersensitivity reactions to other monoclonal antibodies;
• Use of other investigational drugs within 30 days before study drug administration
• Prior treatment with any other anti-CD70 antibody;
• Active infection requiring i.v. systemic therapy within 4 weeks of receiving the first dose of MDX-1411;
• Evidence of bleeding diathesis or coagulopathy;
• Active autoimmune disease requiring immunosuppressive therapy;
• Known current drug or alcohol abuse;
• Underlying medical conditions that will make the administration of MDX-1411 hazardous