Background: The NLRP3 (NOD-, LRR- and pyrin domain-containing protein 3) inflammasome is a critical component of the innate immune system and a promising therapeutic target for inflammation-driven diseases. Dysregulation or excessive activation of the NLRP3 inflammasome is implicated in chronic inflammation and related pathologies through the release of IL-1β and other inflammatory cytokines [1]. NIMA-related kinase 7 (NEK7) [2], a key regulator of NLRP3 inflammasome activation, is a novel therapeutic target, as its degradation can suppress inflammasome signaling. MRT-8102 is a highly selective, oral molecular glue degrader (MGD) that promotes NEK7 degradation via the E3 ubiquitin ligase cereblon (CRBN), leading to proteasomal clearance. This mechanism represents an innovative approach to target NLRP3 signaling with broad potential to treat various inflammatory diseases, including gout.

Objectives: To assess the potential therapeutic activity of MGD-mediated degradation of NEK7 in a model of MSU-driven gouty arthritis in rabbits and to test the impact of NEK7 degradation in various in vitro and ex vivo models of NLRP3 inflammasome activation.

Methods: Gouty arthritis was modeled in rabbits via intra-articular injection of monosodium urate (MSU) crystals and monitored over a 7-day period. Key outcomes of disease progression included measurements of joint swelling and scoring of synovial pathology using musculoskeletal ultrasound and joint histopathology scored by an independent blinded pathologist. Whole blood from non-human primates (NHP) previously dosed orally with MRT-8102 was stimulated ex vivo with LPS and nigericin. For in vitro experiments, the NLRP3 inflammasome was activated by treating human monocyte-derived macrophages or whole blood with LPS followed by nigericin. ASC speck formation in human peripheral blood was assessed using flow cytometry.

Results: To assess efficacy in an in vivo inflammatory disease model, NEK7-targeting MGDs, MRT-8046 and MRT-8102, were tested in a rabbit model of gout induced by intra-articular MSU injection. Both prophylactic and therapeutic oral administration of a NEK7 MGD improved clinical outcomes, including reductions in joint swelling, synovial inflammatory cell infiltration, cartilage lesion score, and overall pathological findings. Ultrasound musculoskeletal assessments confirmed improvements in joint pathology. Importantly, prophylactic and therapeutic administration of a NEK7 MGD reduced plasma IL-1β levels at least three-fold, a response that was comparable to the prophylactic administration of prednisolone used as a positive control. To further evaluate the in vivo effects of MRT-8102-mediated NEK7 degradation, healthy NHPs were orally administered MRT-8102 once a day for 5 days. NEK7 levels in PBMCs were reduced to 44% of pre-dose levels on day 1 (24 h post-dose) and further declined to 15% by day 5. Upon cessation of MRT-8102 administration, NEK7 protein recovered to baseline by day 15. IL-1β production was also inhibited. Ex vivo whole blood stimulation assays showed IL-1β release was reduced to less than 3% of pre-dose levels in blood harvested 6 hours after the first dose of MRT-8102, and IL-1β was undetectable after stimulation on day 5. In an ex vivo assay of gout patient-derived whole blood stimulated with LPS and nigericin, NEK7 MGD incubation reduced levels of IL-1β release. MRT-8102 also inhibited IL-1β release in both healthy human and NHP whole blood following LPS and nigericin stimulation, with improved potency compared to a NLRP3 inhibitor. MRT-8102 resulted in 20-fold reduction of ASC speck formation in human CD14+ monocytes from whole blood stimulation, suggestive of reduced inflammasome activation. Similarly, MRT-8102 reduced IL-1β, IL-1α, IL-18 and caspase-1 activity in stimulated human monocyte-derived macrophages, along with reductions in SYTOX Green staining indicating prevention of pyroptosis-mediated cell death [3]. Lastly, using x-ray crystallography, we confirmed that MRT-8102 forms a ternary complex with NEK7 and the E3 ligase CRBN. Additionally, tandem mass tag proteomics and western blot analysis confirmed that MRT-8102 is highly selective for NEK7 over commonly degraded neosubstrate proteins [4] and the broader proteome in a cereblon-dependent manner.

Conclusion: MRT-8102 is a potent and highly selective NEK7 MGD that effectively suppresses NLRP3-driven inflammation. Our findings demonstrate robust inhibition of IL-1β, pyroptosis and ASC speck formation across in vitro models, complete IL-1β suppression in an ex vivo inflammation model in NHPs, and therapeutic efficacy in a functional rabbit model of gout. These results highlight the potential of NEK7-targeting MGDs as a promising therapeutic approach for NLRP3-mediated inflammatory diseases, including gout.

REFERENCES: [1] Ramachandran R, Manan A, Kim J, Choi S. NLRP3 inflammasome; a key player in the pathogenesis of life-style disorders. Exp Mol Med. 2024 Jul;56(7):1488-1500.

[2] Sharif H, Wang L, Wang WL, et al. Structural mechanism for NEK7-licensed activation of NLRP3 inflammasome. Nature. 2019 Jun;570(7761):338-343.

[3] Devant P, Kagan JC. Molecular mechanisms of gasdermin D pore-forming activity. Nat Immunol. 2023 Jul;24(7):1064-1075.

[4] Wu W, Nelson G, Koch R, et al. Overcoming IMiD resistance in T-cell lymphomas through potent degradation of ZFP91 and IKZF1. Blood. 2022;139(13):2024-2037.

Acknowledgements: The authors would like to thank Marisa Peluso, the PRT, and the entire Monte Rosa Therapeutics team for their contributions to this work.

Disclosure of Interests: Daric Wible Monte Rosa Therapeutics, Qian Chen Monte Rosa Therapeutics, Sophia Nguyen Monte Rosa Therapeutics, Martin Schillo Monte Rosa Therapeutics, Vanessa Verdine Monte Rosa Therapeutics, Keerthana Gosala Monte Rosa Therapeutics, Alexandra Trouilloud Monte Rosa Therapeutics, Hervé Farine Monte Rosa Therapeutics, Vaik Strande Monte Rosa Therapeutics, Debora Bonenfant Monte Rosa Therapeutics, Chris King Monte Rosa Therapeutics, Kris Meier Monte Rosa Therapeutics, Coleman Komishane Monte Rosa Therapeutics, Maciej Cabanski Monte Rosa Therapeutics, Anna Kostikova Monte Rosa Therapeutics, Laura McAllister Monte Rosa Therapeutics, Eswar Krishnan Monte Rosa Therapeutics, Filip Janku Monte Rosa Therapeutics, Magnus Walter Monte Rosa Therapeutics, Elisa Liardo Monte Rosa Therapeutics, Alison Paterson Monte Rosa Therapeutics, Arvin Iracheta-Vellve Monte Rosa Therapeutics.

© The Authors 2025. This abstract is an open access article published in Annals of Rheumatic Diseases under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ). Neither EULAR nor the publisher make any representation as to the accuracy of the content. The authors are solely responsible for the content in their abstract including accuracy of the facts, statements, results, conclusion, citing resources etc.