Abstract 2974: Targeting cadherin-6 (CDH6) with an antibody-drug conjugate for the treatment of ovarian and renal cancer
Authors: Collins Scott D. , Saxena Parmita , Li Xiao Y. , Shim Yeonju , Ostrom Lance , Yoder Nicholas C. , Catcott Kalli C. , McShea Molly A. , Sun Xiuxia , Bilic Sanela , Tschantz William R. , Flaherty Meghan , Mansfield Keith , Hu Tiancen , Capka Vladimir , Kurz Markus , Liric Rajlic Ivana , Serdakowski London Anne , Nguyen Duc , Mosher Rebecca , Meyer Matthew J. , Bourret Aaron , Saeh Jamal , Cameron Scott , Lees Emma , Bialucha Carl U. 
Published: July 2016

In an attempt to mine tumor versus normal mRNA expression datasets for novel tumor antigens, we identified the Cadherin-6 (CDH6) gene as frequently overexpressed in ovarian and renal cancers, while featuring a lineage-restricted normal tissue expression pattern. CDH6, also known as K-(kidney)-cadherin, is a member of the cadherin superfamily of calcium-dependent cell-cell adhesion molecules. We hypothesized that based on the combined observation of frequent overexpression of CDH6 in cancer and a restricted normal tissue expression, CDH6 might be an ideal tumor antigen for targeting using an antibody-drug conjugate (ADC) approach.

CDH6-ADC is a fully-human anti-CDH6 IgG1, linked via sulfo-SPDB to the maytansinoid payload DM4. The antibody component of CDH6-ADC was selected from a panel of anti-CDH6 antibodies based on a multi-factorial lead selection campaign incorporating readouts of internalization propensity, in vitro cytotoxicity, as well as in vivo PK and efficacy across multiple linker-payload formats. CDH6-ADC features potent, target-dependent in vivo activity consistent with the mechanism of the anti-mitotic, tubulin-targeting sulfo-SPDB-DM4 linker-payload combination used. Specifically, treatment of CDH6-expressing ovarian cancer xenograft models with CDH6-ADC results in the time-dependent generation of intra-tumoral ADC catabolites and concomitant induction of phospho-histone H3 and cleaved caspase-3 - markers of G2/M arrest and apoptosis, respectively. CDH6-ADC induces durable tumor regressions at clinically relevant exposures in multiple human patient-derived tumor xenografts (PDX) across both ovarian and renal cancer lineages.

To gain a more thorough understanding of CDH6-ADC activity in pre-clinical models of human ovarian cancer and identify potential molecular correlates for patient stratification, we profiled CDH6-ADC in a PDX clinical trial or PCT comprising 31 individual PDX models. In this unselected population, treatment with CDH6-ADC resulted in robust anti-tumor activity. Integration of PDX response data with CDH6 target expression in both the PDX models and human clinical samples indicate CDH6 expression patterns consistent with in vivo activity are found in a substantial fraction of ovarian, renal and cholangiocarcinoma patients. Together, the encouraging pre-clinical efficacy and tolerability data support the clinical evaluation of CDH6-ADC.

Citation Format: Scott D. Collins, Parmita Saxena, Xiao Y. Li, Yeonju Shim, Lance Ostrom, Nicholas C. Yoder, Kalli C. Catcott, Molly A. McShea, Xiuxia Sun, Sanela Bilic, William R. Tschantz, Meghan Flaherty, Keith Mansfield, Tiancen Hu, Vladimir Capka, Markus Kurz, Ivana Liric Rajlic, Anne Serdakowski London, Duc Nguyen, Rebecca Mosher, Matthew J. Meyer, Aaron Bourret, Jamal Saeh, Scott Cameron, Emma Lees, Carl U. Bialucha. Targeting cadherin-6 (CDH6) with an antibody-drug conjugate for the treatment of ovarian and renal cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2974.