Abstract C123: Discovery and characterization of novel pre|CISION® technology compounds delivering complementary dual warheads to the tumor microenvironment following FAP cleavage

Abstract The proprietary pre|CISION® technology incorporates a peptidic substrate that is specifically cleaved by Fibroblast Activation Protein α (FAP). FAP is a post-proline protease that is overexpressed on the surface of cancer associated fibroblasts (CAFs) in many solid tumors, and facilitates delivery of pre|CISION® medicines specifically to the tumor microenvironment (TME). Previously we have presented AVA6103, a pre|CISION® -enabled exatecan candidate in IND-enabling studies. AVA6103 consists of exatecan, a potent Topoisomerase I inhibitor, covalently linked to a dipeptide containing a cleaving sequence (D-Ala-L-Pro), which is susceptible to hydrolysis by FAP but is resistant to hydrolysis by other mammalian proteases. Exatecan has been investigated both as a single agent and as a warhead in ADC therapeutics in the clinic. However, clinical utility of this family of warheads is limited by dose-limiting toxicities, including severe neutropenia. The exquisite selectivity of the pre|CISION® substrate for FAP results in release of exatecan warhead in the TME, greatly increasing the therapeutic window and hence reducing systemic exposure and associated toxicities. Drug combinations are commonly used in cancer therapy to improve outcomes and overcome resistance, therefore we hypothesized that incorporating two complimentary warheads into a single pre|CISION® molecule may offer similar benefits whilst minimizing systemic toxicity. To create dual warhead pre|CISION® PDCs, a series of compounds have been engineered with modifications in the capping-group and linker portions. Using structure-based drug design, clear structure-activity relationships have been established for affinity to, and susceptibility of linker cleavage by FAP and subsequent warhead release. We now demonstrate how the use of the precision technology platform has been widened to selectively control the release of multiple warheads from a single molecular species via a FAP cleavable linker. Selective release has been demonstrated through the use of kinetics showing the ability to tune the individual release of each warhead and in cellular studies showing potent cytotoxicity and bystander activity in cell-based assays including tumor cell-fibroblast 3D co-culture models. Induction of downstream pharmacodynamic markers for each warhead have also been evaluated. We show the potential of the technology to deliver a therapeutically relevant combination of warheads specifically to the TME while reducing systemic dose-limiting toxicities. This broadens the utility of the pre|CISION® platform in the delivery of novel medicines. Citation Format: Tom Clough, Alexa Kennedy, Ellen Watts, Iva Zlatareva, Folake Orafidiya, Hanna Buist, Victoria Juskaite, David Jones, Dave Liebowitz, Michelle Morrow, Francis Wilson. Discovery and characterization of novel pre|CISION® technology compounds delivering complementary dual warheads to the tumor microenvironment following FAP cleavage [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2025 Oct 22-26; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2025;24(10 Suppl):Abstract nr C123.