Abstract 5942: Discovery of WRN inhibitors as targeted therapy in the treatment of microsatellite unstable (MSI-H) tumors

Abstract The synthetic lethality resulting from the inhibition of the WRN helicase protein has been observed in tumors characterized by high levels of microsatellite instability (MSI-H). This instability stems from a deficiency in the DNA mismatch repair (MMR) mechanisms, leading to the accumulation of DNA damage. This phenomenon is notably prevalent in 10-30% of colorectal, gastric, endometrial, and ovarian cancers. Specifically, the inhibition of WRN helicase activity induces DNA damage leading to cell cycle arrest and apoptosis exclusively in MSI-H cell lines. This selectivity underscores the therapeutic potential of WRN inhibitors, as they demonstrate efficacy against MSI-H cells while remaining non-toxic to microsatellite stable (MSS) cell lines. Ryvu is developing a chemical series of potent, selective WRN helicase inhibitors. Structure-based optimization facilitated the rapid expansion and delivery of a compound library with novel intellectual property (IP), demonstrating target engagement in cells and selective potency over other RecQ family members. The correlation between the cellular effect and selectivity upon treatment with these ligands was confirmed in the clonogenic assay, specifically in responder, microsatellite instable cell lines only, thereby leaving a substantial safety margin (100x) relative to non-responder, microsatellite stable lines. Target engagement has been confirmed by dose dependent DNA damage pathway activation concomitant with WRN degradation in in vitro assays. The pharmacokinetic properties of these compounds are favorable for progressing to in vivo studies. The correlation between compound exposure and on-target effect was confirmed in PK/PD and efficacy studies in xenograft MSI-H cancer models. These data provide pharmacological proof-of-concept for the synthetic lethal effect of our inhibitors and support WRN inhibition as a new oncological therapy. Citation Format: Wojciech Schönemann, Agnieszka Ludwig-Słomczyńska, Łukasz Dudek, Marcin Król, Marco Farinone, Urszula Kulesza, Wojciech Jasnosz, Izabela Mac, Karol Zuchowicz, Katarzyna Wierzbicka, Aleksandra Buchcic-Szychowska, Andrzej Gondela, Anna Zagórska, Oliwia Matuszewska, Marta Sowińska, Marcin Nowogródzki, Marianna Girardi, Szymon Paluch, Svitlana Sukhomlinova, Agata Chłopek, Iana Levenets, Kamila Kozłowska-Tomczyk, Katarzyna Łagosz-Ćwik, Mateusz Stoszko, Szymon Woroszyło, Maciej Mikulski, Justyna Jabłońska, Magdalena Wiśniewska, Katarzyna Palus-Chramiec, Paulina Podkalicka-Gołda, Anita Janiga, Sylwia Sudoł-Tałaj, Magdalena Sieprawska-Lupa, Magdalena Miodek, Jacek Faber, Róża Starczak, Bozena Winnik, Agnieszka Świrska, Anna Kowal-Chwast, Dawid Gogola, Sanja Novak Ratajczak, Agata Dudek, Nilesh Gaud, Grzegorz Satała, Agata Stachowicz, Martin Swarbrick, Krzysztof Brzózka, Magdalena I. Zawadzka. Discovery of WRN inhibitors as targeted therapy in the treatment of microsatellite unstable (MSI-H) tumors 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 (6Suppl): Abstract nr 5942.