Potent anticarcinoma activity of the humanized anti-CD70 antibody h1F6 conjugated to the tubulin inhibitor auristatin via an uncleavable linker.
OBJECTIVE
The antitubulin agent monomethyl auristatin F (MMAF) induces potent antitumor effects when conjugated via protease cleavable linkers to antibodies targeting internalizing, tumor-specific cell surface antigens. Humanized 1F6 (h1F6) is a humanized monoclonal antibody targeting CD70, a member of the tumor necrosis factor family that is expressed on hematologic malignancies and carcinomas. Here, we tested h1F6-maleimidocaproyl (mc) MMAF conjugates, consisting of an uncleavable mc linker, for their ability to interfere with the growth of CD70-positive carcinomas.


METHODS
To evaluate the optimal drug per antibody ratio, we conjugated either four or eight MMAF molecules to the cysteines that comprise the interchain disulfides of h1F6 and determined antitumor activities in vitro and in xenografted mice. The tumor types tested included glioblastoma, patient-derived renal cell carcinoma (RCC) cell isolates, and standard RCC tumor cell lines.


RESULTS
All h1F6-mcMMAF conjugates potently interfered with the growth of all carcinomas in vitro and resulted in complete responses of RCC tumors implanted orthotopically or s.c. in mice. In vitro, h1F6-mcMMAF(8) was generally more potent than h1F6-mcMMAF(4). However, h1F6-mcMMAF(4) displayed equal or better efficacy than h1F6-mcMMAF(8) when administered to tumor-bearing mice.


CONCLUSIONS
We showed that h1F6-mcMMAF conjugates inhibited the growth of human carcinomas and that increased drug loading, while improving potency in vitro, did not substantially affect the pharmacodynamic and pharmacokinetic properties in vivo. Based on these findings, h1F6-mcMMAF(4), designated SGN-75, has been identified as a potential antibody-drug conjugate for clinical development.
Oflazoglu
Ezogelin
E
Department of Preclinical Therapeutics, Seattle Genetics Inc., 21823 30th Drive Southeast, Bothell, WA 98021, USA.
Stone
Ivan J
IJ
Gordon
Kristine
K
Wood
Christopher G
CG
Repasky
Elizabeth A
EA
Grewal
Iqbal S
IS
Law
Che-Leung
CL
Gerber
Hans-Peter
HP
D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry*; D061067:Antibodies, Monoclonal, Humanized / Q000737:chemistry / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D053282:CD27 Ligand / Q000737:chemistry* / Q000276:immunology*; D002292:Carcinoma, Renal Cell / Q000188:drug therapy / Q000473:pathology; D045744:Cell Line, Tumor; D004220:Disulfides / Q000737:chemistry; D005909:Glioblastoma / Q000188:drug therapy / Q000473:pathology; D006801:Humans; D020128:Inhibitory Concentration 50; D007680:Kidney Neoplasms / Q000188:drug therapy / Q000473:pathology; D051379:Mice; D009368:Neoplasm Transplantation; D009842:Oligopeptides / Q000737:chemistry / Q000494:pharmacology*; D014404:Tubulin / Q000737:chemistry; D050257:Tubulin Modulators / Q000737:chemistry
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D053282:CD27 Ligand; D004220:Disulfides; D009842:Oligopeptides; C000599296:SGN-75 antibody-drug conjugate; D014404:Tubulin; D050257:Tubulin Modulators; C513576:monomethylauristatin F