Comparative preclinical activity of the folate-targeted Vinca alkaloid conjugates EC140 and EC145.
EC140 is a water soluble folate conjugate of desacetylvinblastine monohydrazide (DAVLBH), which is constructed with an endosome-cleavable acyl hydrazone bond. This agent has proven to be active and specific against well established, subcutaneous folate receptor (FR)-positive tumors in multiple animal models. Recent structure-activity and optimization studies have yielded a disulfide bond-containing counterpart to EC140, herein referred to as EC145. This new conjugate was found to retain high affinity for FR-positive cells, and it produced specific, dose-responsive activity in vitro. Comparative in vivo efficacy tests confirmed that, like EC140, EC145 displays activity against both syngeneic and xenograft tumor models. However, EC145 was found to be more active and better tolerated than EC140; hence, more durable complete responses were consistently observed in EC145-treated tumor-bearing animals. Furthermore, EC145 was not found to be active against a FR-negative tumor model. Additional preclinical studies are therefore warranted to better understand EC145's breadth of activity against FR-positive tumors.
Leamon
Christopher P
CP
Endocyte, Inc., 3000 Kent Ave., West Lafayette, IN 47906, USA. chrisleamon@endocyte.com
Reddy
Joseph A
JA
Vlahov
Iontcho R
IR
Westrick
Elaine
E
Parker
Nikki
N
Nicoson
Jeffrey S
JS
Vetzel
Marilynn
M
D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control; D000818:Animals; D001667:Binding, Competitive; D001798:Blood Proteins / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004354:Drug Screening Assays, Antitumor / Q000379:methods; D058973:Folate Receptors, GPI-Anchored; D005492:Folic Acid / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D015394:Molecular Structure; D009374:Neoplasms, Experimental / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D011485:Protein Binding; D011622:Pterins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D011956:Receptors, Cell Surface / Q000378:metabolism; D013997:Time Factors; D047368:Tumor Burden; D014748:Vinca Alkaloids / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D023041:Xenograft Model Antitumor Assays
D001798:Blood Proteins; D002352:Carrier Proteins; C519604:EC140 compound; C520389:EC145; D058973:Folate Receptors, GPI-Anchored; D011622:Pterins; D011956:Receptors, Cell Surface; D014748:Vinca Alkaloids; D005492:Folic Acid