title: Comparison of CD20 expression in B-cell lymphoma between newly diagnosed, untreated cases and those after rituximab treatment.
abstract: Few studies have statistically investigated reduced CD20 expression in B-cell lymphoma after rituximab therapy and genomic mutation of CD20 associated with reduction. We examined CD20-positive rate in follicular lymphoma (FL) and diffuse large B-cell lymphoma (DLBCL) by flow cytometry (FCM) and immunohistochemical staining (IHS), comparing 138 cases after rituximab therapy with 360 initial, not yet treated cases. Sequence analysis of exons 3 to 8 of CD20 was performed on 22 cases with low CD20-positive rate after rituximab treatment. The results showed a statistical correlation between CD20-positive rate in FCM and IHS. By FCM, the CD20-positive rate among post-rituximab cases was significantly lower than among initial cases in DLBCL, non-germinal center origin B-cell type (average values [avg] 57.8 and 87.9, respectively) (P < 0.0001), FL2 (avg, 93.9; 103.2) (P = 0.0083), and FL3A (avg, 90.6; 100.7) (P = 0.033). Stratified analyses of post-rituximab cases showed significantly lower CD20-positive rate in cases that were resistant at the start of the treatment and cases with progressive disease during rituximab therapy before biopsy. Sequence analysis showed silent mutation of exon 4 (632 C/T) in seven cases, although this number was not statistically significant. These results suggest the influence of B-lymphoma subtype and a therapeutic effect before biopsy on CD20 expression at relapse and contribute to a better therapeutic approach for relapse cases after rituximab therapy.
authors.affiliation: Department of Pathology, School of Medicine, Kurume University, Kurume, Japan. miyoshi_hiroaki@med.kurume-u.ac.jp
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Miyoshi
authors.forename: Fumiko
authors.initials: F
authors.lastname: Arakawa
authors.forename: Kensaku
authors.initials: K
authors.lastname: Sato
authors.forename: Yoshizo
authors.initials: Y
authors.lastname: Kimura
authors.forename: Junichi
authors.initials: J
authors.lastname: Kiyasu
authors.forename: Masanori
authors.initials: M
authors.lastname: Takeuchi
authors.forename: Maki
authors.initials: M
authors.lastname: Yoshida
authors.forename: Ayako
authors.initials: A
authors.lastname: Ichikawa
authors.forename: Yukinao
authors.initials: Y
authors.lastname: Ishibashi
authors.forename: Yukihiko
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Shinji
authors.initials: S
authors.lastname: Nakashima
authors.forename: Daisuke
authors.initials: D
authors.lastname: Niino
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Sugita
authors.forename: Koichi
authors.initials: K
authors.lastname: Ohshima
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D058846:Antibodies, Monoclonal, Murine-Derived / Q000627:therapeutic use*; D018951:Antigens, CD20 / Q000235:genetics / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D005260:Female; D005434:Flow Cytometry; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D008224:Lymphoma, Follicular / Q000188:drug therapy / Q000378:metabolism*; D016403:Lymphoma, Large B-Cell, Diffuse / Q000188:drug therapy / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D000069283:Rituximab; D017421:Sequence Analysis; D055815:Young Adult
chemical_list: D058846:Antibodies, Monoclonal, Murine-Derived; D018951:Antigens, CD20; D000970:Antineoplastic Agents; D000069283:Rituximab