title: Improved therapeutic results by pretargeted radioimmunotherapy of non-Hodgkin's lymphoma with a new recombinant, trivalent, anti-CD20, bispecific antibody.
abstract: We examined whether a pretargeting method using a new recombinant anti-CD20 bispecific antibody (bsMAb) followed by (90)Y-1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid ((90)Y-DOTA)-peptide could reduce hematologic toxicity yet improve therapeutic responses compared with conventional (90)Y-anti-CD20 IgG and a chemically conjugated bsMAb. TF4, a humanized, tri-Fab bsMAb with two Fabs binding CD20 and one Fab binding histamine-succinyl-glycine (HSG), developed by the dock and lock (DNL) method, was tested in nude mice with Ramos B-cell lymphomas. Optimal pretargeting required a 29-h interval between TF4 and (90)Y-DOTA-HSG, and 20-fold more moles of TF4. TF4 cleared more rapidly from the blood than anti-CD20 IgG, with early processing in the liver, spleen, and kidney. At 24 h, TF4 improved tumor uptake of (111)In-HSG-peptide 2.6-fold [13% versus 5% injected dose per gram (ID/g)] and enhanced tumor to blood ratios >45-fold (770 versus 17), compared with an anti-CD20 Fab x anti-HSG Fab chemical conjugate, and by 1.6-fold (9.0% versus 5.6% ID/g) and 1,600-fold (522 versus 0.32), respectively, compared with radiolabeled anti-CD20 IgG. A severe (>or=90%) and prolonged reduction of WBCs was observed at the maximum dose of (90)Y-anti-CD20 IgG, whereas pretargeting resulted in a <or=60% transient drop. TF4 pretargeting resulted in highly significant improvement in survival, curing 33% to 90% of the animals, even at relatively low doses, whereas most tumors progressed quickly without cures with (90)Y-anti-CD20 IgG. These results indicate an improved therapeutic index with pretargeted radioimmunotherapy (RAIT) using a DNL-constructed tri-Fab, bsMAb, compared with conventional therapy with directly radiolabeled antibody or with a chemically conjugated bsMAb. These encouraging results prompt testing these constructs for pretargeting RAIT in patients.
authors.affiliation: Garden State Cancer Center, Center for Molecular Medicine and Immunology, Belleville, New Jersey 07109, USA. rmsharkey@gscancer.org
authors.forename: Robert M
authors.initials: RM
authors.lastname: Sharkey
authors.forename: Habibe
authors.initials: H
authors.lastname: Karacay
authors.forename: Samuel
authors.initials: S
authors.lastname: Litwin
authors.forename: Edmund A
authors.initials: EA
authors.lastname: Rossi
authors.forename: William J
authors.initials: WJ
authors.lastname: McBride
authors.forename: Chien-Hsing
authors.initials: CH
authors.lastname: Chang
authors.forename: David M
authors.initials: DM
authors.lastname: Goldenberg
mesh_terms: D000818:Animals; D018033:Antibodies, Bispecific / Q000737:chemistry / Q000493:pharmacokinetics / Q000627:therapeutic use*; D018951:Antigens, CD20 / Q000276:immunology*; D001682:Biological Availability; D016503:Drug Delivery Systems / Q000379:methods; D005260:Female; D006801:Humans; D018796:Immunoconjugates / Q000737:chemistry / Q000493:pharmacokinetics / Q000627:therapeutic use; D008228:Lymphoma, Non-Hodgkin / Q000532:radiotherapy*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008954:Models, Biological; D016499:Radioimmunotherapy / Q000379:methods*; D011993:Recombinant Fusion Proteins / Q000493:pharmacokinetics / Q000627:therapeutic use; D014018:Tissue Distribution; D016896:Treatment Outcome; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
chemical_list: D018033:Antibodies, Bispecific; D018951:Antigens, CD20; D018796:Immunoconjugates; D011993:Recombinant Fusion Proteins