title: Enhanced activity of monomethylauristatin F through monoclonal antibody delivery: effects of linker technology on efficacy and toxicity.
abstract: We have previously shown that antibody-drug conjugates (ADCs) consisting of cAC10 (anti-CD30) linked to the antimitotic agent monomethylauristatin E (MMAE) lead to potent in vitro and in vivo activities against antigen positive tumor models. MMAF is a new antimitotic auristatin derivative with a charged C-terminal phenylalanine residue that attenuates its cytotoxic activity compared to its uncharged counterpart, MMAE, most likely due to impaired intracellular access. In vitro cytotoxicity studies indicated that mAb-maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl-MMAF (mAb-L1-MMAF) conjugates were >2200-fold more potent than free MMAF on a large panel of CD30 positive hematologic cell lines. As with cAC10-L1-MMAE, the corresponding MMAF ADC induced cures and regressions of established xenograft tumors at well tolerated doses. To further optimize the ADC, several new linkers were generated in which various components within the L1 linker were either altered or deleted. One of the most promising linkers contained a noncleavable maleimidocaproyl (L4) spacer between the drug and the mAb. cAC10-L4-MMAF was approximately as potent in vitro as cAC10-L1-MMAF against a large panel of cell lines and was equally potent in vivo. Importantly, cAC10-L4-MMAF was tolerated at >3 times the MTD of cAC10-L1-MMAF. LCMS studies indicated that drug released from cAC10-L4-MMAF was the cysteine-L4-MMAF adduct, which likely arises from mAb degradation within the lysosomes of target cells. This new linker technology appears to be ideally suited for drugs that are both relatively cell-impermeable and tolerant of substitution with amino acids. Thus, alterations of the linker have pronounced impacts on toxicity and lead to new ADCs with greatly improved therapeutic indices.
authors.affiliation: Seattle Genetics, Inc., 21823 30th Drive SE, Bothell, Washington 98021, USA. sdoronina@seagen.com
authors.forename: Svetlana O
authors.initials: SO
authors.lastname: Doronina
authors.forename: Brian A
authors.initials: BA
authors.lastname: Mendelsohn
authors.forename: Tim D
authors.initials: TD
authors.lastname: Bovee
authors.forename: Charles G
authors.initials: CG
authors.lastname: Cerveny
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Alley
authors.forename: Damon L
authors.initials: DL
authors.lastname: Meyer
authors.forename: Ezogelin
authors.initials: E
authors.lastname: Oflazoglu
authors.forename: Brian E
authors.initials: BE
authors.lastname: Toki
authors.forename: Russell J
authors.initials: RJ
authors.lastname: Sanderson
authors.forename: Roger F
authors.initials: RF
authors.lastname: Zabinski
authors.forename: Alan F
authors.initials: AF
authors.lastname: Wahl
authors.forename: Peter D
authors.initials: PD
authors.lastname: Senter
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage / Q000737:chemistry / Q000627:therapeutic use*; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000138:chemical synthesis / Q000627:therapeutic use*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D016503:Drug Delivery Systems; D018796:Immunoconjugates / Q000008:administration & dosage / Q000737:chemistry / Q000627:therapeutic use*; D020128:Inhibitory Concentration 50; D016403:Lymphoma, Large B-Cell, Diffuse / Q000188:drug therapy* / Q000473:pathology; D020714:Maximum Tolerated Dose; D051379:Mice; D016513:Mice, SCID; D009842:Oligopeptides / Q000008:administration & dosage / Q000138:chemical synthesis / Q000627:therapeutic use*; D016896:Treatment Outcome; D047368:Tumor Burden; D023041:Xenograft Model Antitumor Assays
chemical_list: D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D018796:Immunoconjugates; D009842:Oligopeptides; C513576:monomethylauristatin F