Phase I/II Study of CAMPATH in Patients With Relapsing or Refractory Non-Hodgkin's Lymphoma

Inclusion Criteria: Patients must have: * Pathologically confirmed diagnosis of relapsing or refractory non-Hodgkin's lymphoma that has failed conventional therapy. * Measurable disease (lesions that can be accurately measured by CT scan and a greatest transverse diameter larger or equal to 1 cm or palpable lesions that both diameters larger or equal to 2 cm). * Life expectancy of at least 12 weeks. - World Health Organization (WHO) performance status (PS) of 0, 1, or 2. * Adequate marrow and organ function (details are listed in the protocol). * Female patients with childbearing potential must have a negative serum pregnancy test within 2 weeks prior to enrollment. Male and female patients must agree to use an effective contraceptive method while on study treatment, if appropriate, and for a minimum of 6 months following study therapy. * Signed, written informed consent. Exclusion Criteria: Patients must not have: * Prior autologous bone marrow or stem cell transplant within 6 months of study entry. * A history of prior allogeneic bone marrow transplant or organ transplant. * Previously untreated non-Hodgkin's lymphoma. * Previously treated with CAMPATH. * Patients with bulky disease, ie any single mass \> 7.5cm. * Prior radiotherapy to the only site of measurable disease. * Medical condition requiring chronic use of oral, high-dose corticosteroids. * Autoimmune thrombocytopenia. * Use of investigational agents within previous 30 days or any anti-cancer therapy within the previous 3 weeks. Patients must have recovered from all acute toxicities of any prior therapy. * Past history of anaphylaxis following exposure to humanized monoclonal antibodies. * Active, uncontrolled infection, including human immunodeficiency virus (HIV) positive. * Active secondary malignancy. * Active central nervous system (CNS) involvement with NHL. * Pregnant or lactating women. Male or female patients who do not agree to use effective contraceptive method(s) during the study. * Any significant concurrent disease or illness that would, in the opinion of the investigator, compromise patient safety or compliance, or interfere with the interpretation of study results.