title: CD20 up-regulation in pediatric B-cell precursor acute lymphoblastic leukemia during induction treatment: setting the stage for anti-CD20 directed immunotherapy.
abstract: CD20 is expressed in approximately one- half of pediatric acute lymphoblastic leukemia (ALL) cases with B-cell precursor (BCP) origin. We observed that it is occasionally up-regulated during treatment. To understand the impact of this on the potential effectiveness of anti-CD20 immunotherapy, we studied 237 CD10(+) pediatric BCP-ALL patients with Berlin-Frankfurt-Munster (BFM)-type therapy. We analyzed CD20 expression changes from diagnosis to end-induction, focusing on sample pairs with more than or equal to 0.1% residual leukemic blasts, and assessed complement-induced cytotoxicity by CD20-targeting with rituximab in vitro. CD20-positivity significantly increased from 45% in initial samples to 81% at end-induction (day 15, 71%). The levels of expression also increased; 52% of cases at end-induction had at least 90% CD20(pos) leukemic cells, as opposed to 5% at diagnosis (day 15, 20%). CD20 up-regulation was frequent in high-risk patients, patients with high minimal residual disease at end-induction, and patients who suffered later from relapse, but not in TEL/AML1 cases. Notably, up-regulation occurred in viable cells sustaining chemotherapy. In vitro, CD20 up-regulation significantly enhanced rituximab cytotoxicity and could be elicited on prednisolone incubation. In conclusion, CD20 up-regulation is frequently induced in BCP-ALL during induction, and this translates into an acquired state of higher sensitivity to rituximab. This study was registered at http://www.clinicaltrials.gov as #NCT00430118.
authors.affiliation: Children's Cancer Research Institute, Vienna, Austria.
authors.forename: Michael N
authors.initials: MN
authors.lastname: Dworzak
authors.forename: Angela
authors.initials: A
authors.lastname: Schumich
authors.forename: Dieter
authors.initials: D
authors.lastname: Printz
authors.forename: Ulrike
authors.initials: U
authors.lastname: Pötschger
authors.forename: Zvenyslava
authors.initials: Z
authors.lastname: Husak
authors.forename: Andishe
authors.initials: A
authors.lastname: Attarbaschi
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Basso
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Gaipa
authors.forename: Richard
authors.initials: R
authors.lastname: Ratei
authors.forename: Georg
authors.initials: G
authors.lastname: Mann
authors.forename: Helmut
authors.initials: H
authors.lastname: Gadner
mesh_terms: D000293:Adolescent; D000911:Antibodies, Monoclonal / Q000008:administration & dosage*; D058846:Antibodies, Monoclonal, Murine-Derived; D018951:Antigens, CD20 / Q000096:biosynthesis*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage*; D001215:Asparaginase / Q000008:administration & dosage; D002648:Child; D002675:Child, Preschool; D003630:Daunorubicin / Q000008:administration & dosage; D005260:Female; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects*; D006801:Humans; D007223:Infant; D008297:Male; D018365:Neoplasm, Residual; D015452:Precursor B-Cell Lymphoblastic Leukemia-Lymphoma / Q000188:drug therapy* / Q000378:metabolism*; D011241:Prednisone / Q000008:administration & dosage; D012008:Recurrence; D000069283:Rituximab; D015854:Up-Regulation / Q000187:drug effects; D014750:Vincristine / Q000008:administration & dosage
chemical_list: D000911:Antibodies, Monoclonal; D058846:Antibodies, Monoclonal, Murine-Derived; D018951:Antigens, CD20; D000069283:Rituximab; D014750:Vincristine; D001215:Asparaginase; D011241:Prednisone; D003630:Daunorubicin
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