Abstract LB174: Inducing complete and long-lasting tumor eradications at safe and well tolerated doses of a nectin-4 ADC generated with novel peptide linkers for payload conjugation
Authors: Attinger-Toller Isabella , Probst Philipp , Bertrand Romain , Stark Ramona , Santimaria Roger , Grabulovski Dragan , Schlereth Bernd , Spycher Philipp 
Published: June 2022

Abstract
The Araris’ site-specific and one-step linker conjugation technology aims at generating stable, safe and highly potent ADCs without the need for antibody engineering prior to payload conjugation. Here, we generated an anti-Nectin-4 ADC that shows superior activity to enfortumab-vedotin (Padcev®, EV) in head-to-head in vitro and in vivo studies. Based on enfortumab as the targeting antibody and monomethyl auristatin E (MMAE) as payload, we generated within 24 hours highly homogeneous and pure ADCs with a drug-to antibody-ratio (DAR) of approximately 2 and above 98% monomeric content. In in vitro assays on target positive cell-lines, the Araris ADC demonstrated potent cell-cytotoxicity in the low nM-range similar to the approved enfortumab-vedotin which has a DAR of 4. Moreover, our ADC showed excellent stability in mouse, cynomolgus and human sera exemplified by the absence of payload deconjugation or linker cleavage while EV showed significant payload deconjugation during the 14d incubation period. Interestingly, despite the improved stability, the kinetics for MMAE release was comparable to EV in human Cathepsin B or human liver-lysosome (HLL) enzyme cleavage assays. Most importantly, the ADC was extremely stable in circulation as shown in pharmacokinetic studies in rodents, demonstrating an exposure profile comparable to the unmodified enfortumab parent antibody. There was no loss of payload during the 3 week study duration and the calculated half-life of the Araris ADC was approximately 10 days, which is more than 2-fold the half-life of EV. In efficacy studies using a SUM-190PT breast cancer model, a single injection at a dose of 10µg/kg normalized payload induced a complete tumor regression that lasted throughout the whole study duration of more than 100 days. EV administered at the same payload dose showed only a short and transient tumor regression with no animal (0/6) reaching a complete response with some tumor growth retardation until day 20. Our data impressively show that the Araris ADC has superior efficacy even at least 3x lower payload dose compared to EV which are normally needed to achieve complete tumor remission. The very high efficacy even at low dose levels combined with the high plasma stability offer the opportunity to develop an ADC having potentially lower dose-limiting toxicities such as peripheral neuropathy, skin toxicity or neutropenia.
Citation Format: Isabella Attinger-Toller, Philipp Probst, Romain Bertrand, Ramona Stark, Roger Santimaria, Dragan Grabulovski, Bernd Schlereth, Philipp Spycher. Inducing complete and long-lasting tumor eradications at safe and well tolerated doses of a nectin-4 ADC generated with novel peptide linkers for payload conjugation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB174.