title: CD33 target validation and sustained depletion of AML blasts in long-term cultures by the bispecific T-cell-engaging antibody AMG 330.
abstract: Antibody-based immunotherapy represents a promising strategy to target and eliminate chemoresistant leukemic cells. Here, we evaluated the CD33/CD3-bispecific T cell engaging (BiTE) antibody (AMG 330) for its suitability as a therapeutic agent in acute myeloid leukemia (AML). We first assessed CD33 expression levels by flow cytometry and found expression in >99% of patient samples (n = 621). CD33 was highest expressed in AMLs with NPM1 mutations (P < .001) and lower in AMLs with complex karyotypes and t(8;21) translocations (P < .001). Furthermore, leukemic stem cells within the CD34(+)/CD38(-) compartment displayed CD33 at higher levels than healthy donor stem cells (P = .047). In MS-5 feeder cell-based long-term cultures that supported the growth of primary AML blasts for up to 36 days, AMG 330 efficiently recruited and expanded residual CD3(+)/CD45RA(-)/CCR7(+) memory T cells within the patient sample. Even at low effector to target ratios, the recruited T cells lysed autologous blasts completely in the majority of samples and substantially in the remaining samples in a time-dependent manner. This study provides the first correlation of CD33 expression levels with AML genotype in a comprehensive analysis of adult patients. Targeting CD33 ex vivo using AMG 330 in primary AML samples led to T cell recruitment and expansion and remarkable antibody-mediated cytotoxicity, suggesting efficient therapeutic potential in vivo.
authors.affiliation: Department of Internal Medicine III, Klinikum der Universität München, Munich, Germany;
authors.forename: Christina
authors.initials: C
authors.lastname: Krupka
authors.forename: Peter
authors.initials: P
authors.lastname: Kufer
authors.forename: Roman
authors.initials: R
authors.lastname: Kischel
authors.forename: Gerhard
authors.initials: G
authors.lastname: Zugmaier
authors.forename: Jan
authors.initials: J
authors.lastname: Bögeholz
authors.forename: Thomas
authors.initials: T
authors.lastname: Köhnke
authors.forename: Felix S
authors.initials: FS
authors.lastname: Lichtenegger
authors.forename: Stephanie
authors.initials: S
authors.lastname: Schneider
authors.forename: Klaus H
authors.initials: KH
authors.lastname: Metzeler
authors.forename: Michael
authors.initials: M
authors.lastname: Fiegl
authors.forename: Karsten
authors.initials: K
authors.lastname: Spiekermann
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Baeuerle
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Hiddemann
authors.forename: Gert
authors.initials: G
authors.lastname: Riethmüller
authors.forename: Marion
authors.initials: M
authors.lastname: Subklewe
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018033:Antibodies, Bispecific / Q000276:immunology* / Q000627:therapeutic use; D018929:Cell Culture Techniques; D018920:Coculture Techniques; D005260:Female; D005434:Flow Cytometry; D005838:Genotype; D006801:Humans; D007167:Immunotherapy / Q000379:methods*; D007621:Karyotyping; D015470:Leukemia, Myeloid, Acute / Q000276:immunology* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D000090243:Nucleophosmin; D063268:Sialic Acid Binding Ig-like Lectin 3 / Q000378:metabolism*; D013601:T-Lymphocytes / Q000276:immunology*; D013997:Time Factors
chemical_list: D018033:Antibodies, Bispecific; C000716967:NPM1 protein, human; D063268:Sialic Acid Binding Ig-like Lectin 3; D000090243:Nucleophosmin