Cyclophosphamide and Alemtuzumab In Lymphoma

Inclusion Criteria: * Participants must have histologically confirmed non-Hodgkin lymphoma and be considered ineligible for standard curative therapeutic options, including high dose chemotherapy with autologous stem cell rescue. * Participants with the following subtypes of CD52 positive non-Hodgkin lymphoma (defined as ≥ 50% positive staining by immunohistochemical staining or flow cytometry by local lab) will be considered eligible: * High-grade B-cell lymphoma, with MYC and BCL2 and/or BCL6 rearrangements (DHL) * DLBCL or high-grade B-cell lymphoma NOS or B-cell lymphoma unclassifiable with features intermediate between Burkitt lymphoma and diffuse large B-cell lymphoma with MYC and BCL2 protein over-expression by immunohistochemical (IHC) staining as defined by MYC expression in ≥ 40% of cells and BCL2 positivity ≥ 50% (DOL) * Transformed lymphoma with MYC rearrangement by FISH or over-expression by IHC, as above * CD52 positive mature T-cell lymphoproliferative disorder * There is no limit to the prior number of chemotherapy regimens. Patients with prior autologous or allogeneic stem cell transplantation, as well as prior therapy with cyclophosphamide or alemtuzumab, are eligible. * Age ≥ 18 and ≤75 * ECOG performance status ≤2 (Karnofsky ≥60%, see Appendix A) * Participants must have normal organ and marrow function as defined by peripheral blood values below: * leukocytes ≥1,000/mcL * absolute neutrophil count ≥500/mcL * platelets ≥25,000/mcL * total bilirub…