title: Efficient elimination of B-lineage lymphomas by anti-CD20-auristatin conjugates.
abstract: The anti-CD20 antibody rituximab is useful in the treatment of certain B-cell malignancies, most notably non-Hodgkin's lymphoma. Its efficacy has been increased when used in combination with chemotherapy, yet anti-CD20 monoclonal antibodies (mAbs) directly conjugated with drugs such as doxorubicin (Dox) have failed to deliver drug or to demonstrate antitumor activity. We have produced anti-CD20 antibody-drug conjugates that possess potent antitumor activity by using the anti-mitotic agent, monomethyl auristatin E (MMAE), linked via the lysosomally cleavable dipeptide, valine-citrulline (vc). Two anti-CD20 conjugates, rituximab-vcMMAE and 1F5-vcMMAE, were selectively cytotoxic against CD20(+) B-lymphoma cell lines, with IC(50) values ranging from 50 ng/mL to 1 microg/mL. Unlike rituximab, which showed diffuse surface localization, rituximab-vcMMAE capped and was internalized within 4 hours after binding to CD20(+) B cells. Internalization of rituximab-vcMMAE was followed by rapid G(2)-M phase arrest and onset of apoptosis. Anti-CD20 antibody-drug conjugates prepared with Dox were internalized and localized as with rituximab-vcMMAE, yet these were not effective for drug delivery (IC(50) > 50 microg/mL). Consistent with in vitro activity, rituximab-vcMMAE showed antitumor efficacy in xenograft models of CD20-positive lymphoma at doses where rituximab or rituximab-Dox conjugates were ineffective. These data indicate that anti-CD20-based antibody-drug conjugates are effective antitumor agents when prepared with a stable, enzyme-cleavable peptide linkage to highly potent cytotoxic agents such as MMAE.
authors.affiliation: Seattle Genetics, Inc., 21823-30th Drive Southeast, Bothell, WA 98021, USA.
authors.forename: Che-Leung
authors.initials: CL
authors.lastname: Law
authors.forename: Charles G
authors.initials: CG
authors.lastname: Cerveny
authors.forename: Kristine A
authors.initials: KA
authors.lastname: Gordon
authors.forename: Kerry
authors.initials: K
authors.lastname: Klussman
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Mixan
authors.forename: Dana F
authors.initials: DF
authors.lastname: Chace
authors.forename: Damon L
authors.initials: DL
authors.lastname: Meyer
authors.forename: Svetlana O
authors.initials: SO
authors.lastname: Doronina
authors.forename: Clay B
authors.initials: CB
authors.lastname: Siegall
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Francisco
authors.forename: Peter D
authors.initials: PD
authors.lastname: Senter
authors.forename: Alan F
authors.initials: AF
authors.lastname: Wahl
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism / Q000494:pharmacology*; D058846:Antibodies, Monoclonal, Murine-Derived; D018951:Antigens, CD20 / Q000276:immunology*; D000970:Antineoplastic Agents / Q000378:metabolism / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D004317:Doxorubicin / Q000494:pharmacology; D016503:Drug Delivery Systems; D016195:G2 Phase / Q000187:drug effects; D006801:Humans; D016393:Lymphoma, B-Cell / Q000188:drug therapy / Q000276:immunology; D051379:Mice; D009842:Oligopeptides / Q000009:adverse effects / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D000069283:Rituximab; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
chemical_list: D000911:Antibodies, Monoclonal; D058846:Antibodies, Monoclonal, Murine-Derived; D018951:Antigens, CD20; D000970:Antineoplastic Agents; D009842:Oligopeptides; D000069283:Rituximab; D004317:Doxorubicin; C495575:monomethyl auristatin E