Abstract 684: DT-9045, a novel PAR2 inhibitor with best-in-class properties that reduces resistance to both EGFR-targeting therapies and immunotherapy in oncology models
Authors: Brugat Thibaut , Kadiri Maleck , Aouad Samya , Blayo Anne-Laure , Rugeri Baptiste , Mousson Antoine , Janvier Aurélie , Steinberg Edith , Baron Luc , Recolet Mandy , Wirth Xavier , Garcia-Leon Maria Jesus , Ruet Quentin , Semache Meriem , Sabbagh Laurent , Blanchard Orphée , Franchet Christel , Mayer Stanislas , Stagg John , Lenne Nathalie , Schann Stephan 
Published: March 2024

Abstract
Protease-activated receptor 2 (PAR2) is a promising therapeutic target in oncology and immuno-oncology. It is upregulated and associated with poor prognosis in several cancer types. A pan-cancer meta-analysis showed that PAR2 is one of the genes most significantly associated with resistance to immune checkpoint blockade (ICB) and T cells dysfunction in cancer patients. Mechanistically, being expressed by various cells of the tumor microenvironment, PAR2 promotes both survival and proliferation of cancer cells and dampens the anti-cancer immune response. Domain Therapeutics has developed a novel PAR2 inhibitor, DT-9045, with best-in-class properties. Indeed, compared to its most advanced competitors, DT-9045 is a small molecule, orally bioavailable, insurmountable, biased, and active in tumor-like conditions (i.e. acidic pH and high level of activating proteases). This compound is also highly potent and selective on PAR2. Pharmacokinetic properties are suitable with a once-a-day oral administration. In vitro, DT-9045 completely prevented PAR2-mediated resistance to EGFR-targeting drugs. In vivo, its combination with anti-PD1 therapy showed a significant increase in efficacy over monotherapies in preclinical syngeneic mouse cancer models. This result was similar to the one observed in PAR2 knockout mice, indicating that oral administration of DT-9045 induces a complete inhibition of the receptor. We have further demonstrated that treatment with a PAR2 inhibitor enhances dendritic cell-mediated T cell activation and intratumoral infiltration of CD4+ and CD8+ T cells as well as a decrease in M2 macrophage infiltration. In conclusion, Domain Therapeutic has identified a novel PAR2 inhibitor, DT-9045, with clear competitive advantages. This preclinical candidate has shown strong potency in alleviating the resistance to both EGFR-targeting therapies and immunotherapy in preclinical cancer models. IND-enabling studies are currently ongoing to bring this new hope for cancer patients to the clinic.
Citation Format: Thibaut Brugat, Maleck Kadiri, Samya Aouad, Anne-Laure Blayo, Baptiste Rugeri, Antoine Mousson, Aurélie Janvier, Edith Steinberg, Luc Baron, Mandy Recolet, Xavier Wirth, Maria Jesus Garcia-Leon, Quentin Ruet, Meriem Semache, Laurent Sabbagh, Orphée Blanchard, Christel Franchet, Stanislas Mayer, John Stagg, Nathalie Lenne, Stephan Schann. DT-9045, a novel PAR2 inhibitor with best-in-class properties that reduces resistance to both EGFR-targeting therapies and immunotherapy in oncology models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 684.