title: Heterogeneous CD52 expression among hematologic neoplasms: implications for the use of alemtuzumab (CAMPATH-1H).
abstract: OBJECTIVE
  CD52 is a GPI-linked glycoprotein expressed by B cells, T cells, monocytes, and macrophages. The humanized monoclonal antibody alemtuzumab (CAMPATH-1H) is specific for CD52 and is Food and Drug Administration - approved for the treatment of relapsed or refractory chronic lymphocytic leukemia (CLL). The utility of CAMPATH in the treatment of other hematologic neoplasms has been explored; however, a comprehensive survey of CD52 expression among a broad spectrum of WHO-defined tumor types has not been completed.
  
  
  METHODS
  We evaluated 294 hematologic neoplasms for the presence of CD52 using standard immunohistochemical techniques on paraffin-embedded biopsy specimens fixed with formalin, B-Plus, Zenker's acetic acid, or B5-formalin.
  
  
  RESULTS
  The vast majority of low-grade B cell lymphoproliferative disorders (CLL/small lymphocytic leukemia, follicular lymphoma, lymphoplasmacytic lymphoma, hairy cell leukemia, and mucosa-associated lymphoid tissue lymphomas) express CD52. In addition, we found that the majority of precursor B cell acute lymphoblastic leukemia/lymphomas express this antigen. In contrast, there is surprising heterogeneity in CD52 expression among more aggressive B cell lymphomas, with 25% of cases of diffuse large B cell lymphoma and Burkitt lymphoma demonstrating no detectable CD52. In addition, the majority of neoplasms of the T cell lineage are negative for the antigen, including most cases of precursor T cell acute lymphoblastic leukemia/lymphoma, anaplastic large cell lymphoma, and peripheral T cell lymphoma, not otherwise specified. Finally, the vast majority of cases of acute myeloid leukemia, Hodgkin lymphoma, and multiple myeloma are negative for CD52 expression.
  
  
  CONCLUSIONS
  In contrast with CLL, the variable expression of CD52 among other hematologic malignancies suggests that target validation on a case-by-case basis will likely be necessary to guide the rational analysis of CAMPATH therapy.
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Rodig
authors.forename: Jeremy S
authors.initials: JS
authors.lastname: Abramson
authors.forename: Geraldine S
authors.initials: GS
authors.lastname: Pinkus
authors.forename: Steven P
authors.initials: SP
authors.lastname: Treon
authors.forename: David M
authors.initials: DM
authors.lastname: Dorfman
authors.forename: Henry Y
authors.initials: HY
authors.lastname: Dong
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Shipp
authors.forename: Jeffery L
authors.initials: JL
authors.lastname: Kutok
mesh_terms: D000208:Acute Disease; D000074323:Alemtuzumab; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D000912:Antibodies, Neoplasm / Q000627:therapeutic use*; D015703:Antigens, CD / Q000096:biosynthesis* / Q000187:drug effects; D000951:Antigens, Neoplasm / Q000096:biosynthesis* / Q000187:drug effects; D000074301:CD52 Antigen; D006023:Glycoproteins / Q000096:biosynthesis* / Q000187:drug effects; D006801:Humans; D007150:Immunohistochemistry; D007951:Leukemia, Myeloid / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D016393:Lymphoma, B-Cell / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D016399:Lymphoma, T-Cell / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D008232:Lymphoproliferative Disorders / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D016896:Treatment Outcome
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000912:Antibodies, Neoplasm; D015703:Antigens, CD; D000951:Antigens, Neoplasm; D000074301:CD52 Antigen; C000613862:CD52 protein, human; D006023:Glycoproteins; D000074323:Alemtuzumab