title: In vivo structural activity and optimization studies of folate-tubulysin conjugates.
abstract: Herein we report on the potencies of 4 related folate-conjugated tubulysins constructed with either tubulysin B hydrazide (EC0305), tubulysin A hydrazide (EC0510), the N,O-acetal derivative of natural tubulysins (EC0317) or a tubulysin B ester (EC0302). Our results confirmed that EC0305 is the most favorable conjugate of the group due to its potent antitumor activity [100% cures at 1 micromol/kg, three times a week (TIW) for 2 weeks] and its favorably low toxicity profile. In contrast, the natural tubulysin B drug proved to be inactive against a human nasopharyngeal tumor model when administered at doses near to or greater than the maximum tolerated dose (MTD). When tested against more chemoresistant folate receptor expressing M109 and 4T1-cl2 tumors, EC0305 displayed superior antitumor activity over a previously disclosed folate conjugate of desacetylvinblastine monohydrazide (EC145). These studies demonstrate that EC0305 has significant antiproliferative activity against FR expressing tumors, including those which are generally more chemoresistant, and that EC0305 should be considered for development as a candidate for the treatment of advanced FR-expressing human cancers.
authors.affiliation: Endocyte, Inc., 3000 Kent Avenue, Suite A1-100, West Lafayette, Indiana 47906, USA.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Reddy
authors.forename: Ryan
authors.initials: R
authors.lastname: Dorton
authors.forename: Alicia
authors.initials: A
authors.lastname: Dawson
authors.forename: Marilynn
authors.initials: M
authors.lastname: Vetzel
authors.forename: Nikki
authors.initials: N
authors.lastname: Parker
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Nicoson
authors.forename: Elaine
authors.initials: E
authors.lastname: Westrick
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Klein
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.forename: Iontcho R
authors.initials: IR
authors.lastname: Vlahov
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Leamon
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry* / Q000494:pharmacology* / Q000633:toxicity; D001798:Blood Proteins / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002417:Cattle; D045744:Cell Line, Tumor; D004285:Dogs; D005260:Female; D058973:Folate Receptors, GPI-Anchored; D005492:Folic Acid / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009842:Oligopeptides / Q000737:chemistry* / Q000494:pharmacology* / Q000633:toxicity; D011485:Protein Binding; D011817:Rabbits; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D000970:Antineoplastic Agents; D001798:Blood Proteins; D002352:Carrier Proteins; D058973:Folate Receptors, GPI-Anchored; D009842:Oligopeptides; D011956:Receptors, Cell Surface; C510756:tubulysin A; D005492:Folic Acid