title: Loss of CD20 expression following treatment with rituximab (chimaeric monoclonal anti-CD20): a retrospective cohort analysis.
abstract: A retrospective analysis of CD20 expression following rituximab for B-cell non-Hodgkin's lymphoma demonstrated a significant change in immunophenotype in 6/25 (24%) patients with persistent bone marrow (BM) infiltration. In three out of six patients, the B cells were uniformly CD20-/CD79alpha+, consistent with frank loss of CD20 expression. In the remaining three cases, the BM infiltrate was predominantly (> 80%) CD20-/CD79alpha+. Two of the former but none of the latter three cases achieved a clinical response. In three further cases, the post-treatment BM infiltrate was composed entirely of benign or reactive CD3+ T cells. Frank loss of CD20 was not seen in 25 post-treatment lymph node biopsies. Immunophenotyping is therefore an important adjunct in the diagnosis of BM infiltration following rituximab.
authors.affiliation: Imperial Cancer Research Fund Medical Oncology Unit, St. Bartholomew's Hospital, London, UK. jforan@unmc.edu
authors.forename: J M
authors.initials: JM
authors.lastname: Foran
authors.forename: A J
authors.initials: AJ
authors.lastname: Norton
authors.forename: I N
authors.initials: IN
authors.lastname: Micallef
authors.forename: D C
authors.initials: DC
authors.lastname: Taussig
authors.forename: J A
authors.initials: JA
authors.lastname: Amess
authors.forename: A Z
authors.initials: AZ
authors.lastname: Rohatiner
authors.forename: T A
authors.initials: TA
authors.lastname: Lister
mesh_terms: D000911:Antibodies, Monoclonal / Q000009:adverse effects*; D058846:Antibodies, Monoclonal, Murine-Derived; D015703:Antigens, CD / Q000276:immunology; D018951:Antigens, CD20 / Q000276:immunology*; D000970:Antineoplastic Agents / Q000009:adverse effects*; D001402:B-Lymphocytes / Q000276:immunology; D001854:Bone Marrow Cells / Q000276:immunology; D017252:CD3 Complex / Q000276:immunology; D051925:CD79 Antigens; D006801:Humans; D016130:Immunophenotyping; D007167:Immunotherapy; D017254:Leukemic Infiltration; D016393:Lymphoma, B-Cell / Q000276:immunology* / Q000628:therapy; D011947:Receptors, Antigen, B-Cell / Q000276:immunology; D012189:Retrospective Studies; D000069283:Rituximab; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D058846:Antibodies, Monoclonal, Murine-Derived; D015703:Antigens, CD; D018951:Antigens, CD20; D000970:Antineoplastic Agents; D017252:CD3 Complex; D051925:CD79 Antigens; C497881:CD79A protein, human; D011947:Receptors, Antigen, B-Cell; D000069283:Rituximab