Nimbus Therapeutics Announces Initiation of First-in-Human Clinical Trial with NDI-219216, Novel WRN Inhibitor for MSI-H Tumors

Nimbus Therapeutics, LLC ("Nimbus Therapeutics" or "Nimbus"), a biotechnology company that designs and develops breakthrough medicines through its powerful computational drug discovery engine, today announced that its Phase 1/2 clinical trial of NDI-219216, the company's investigational non-covalent Werner syndrome helicase (WRN) inhibitor, is actively enrolling and dosing patients with advanced solid tumors.

"The initiation of this clinical trial marks an important milestone in advancing our novel WRN inhibitor program," said Anita Scheuber, M.D., Ph.D., Senior Vice President, Therapeutic Head, Oncology at Nimbus. "We are excited to be evaluating NDI-219216 in patients with advanced disease, who currently have limited treatment options when they experience disease progression on standard of care therapies. The trial is actively enrolling across multiple clinical sites, and we look forward to generating important additional safety and efficacy data as we advance this promising candidate through clinical development."

The Phase 1/2 clinical trial (NCT06898450) is an open-label, dose escalation and dose expansion study designed to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary antitumor activity of NDI-219216 in patients with advanced cancer. The study will be conducted in three parts: Part A (dose escalation), Part B (dose optimization), and Part C (dose expansion).

Nimbus presented promising preclinical data on NDI-219216 (previously NTX-452) at the 36th EORTC-NCI-AACR Symposium on Molecular Targets and Cancer Therapeutics in October 2024. The data demonstrate that NDI-219216 is a potent and selective WRN inhibitor with significant tumor regression and sustained complete responses observed at low doses in MSI-H tumor models refractory to immunotherapy and chemotherapy.

The company will present new findings comparing covalent versus non-covalent WRN inhibition mechanisms and demonstrating NDI-219216's superior efficacy across multiple preclinical MSI-H tumor models compared with other clinical-stage WRN inhibitors in a poster presentation at the American Association for Cancer Research (AACR) Annual Meeting being held April 25-30, 2025 in Chicago. The poster entitled "NDI-219216: a non-covalent, potent, selective and highly efficacious WRN inhibitor with best-in-class potential for the treatment of MSI-H tumors" highlights key preclinical findings related to NDI-219216, including:

• Demonstration of activity against a potential resistance mutation at Cysteine 727 that could significantly reduce the efficacy of covalent WRN inhibitors
• Robust tumor regression across multiple MSI-H tumor models, including those that are refractory to existing standard of care agents
• Superior efficacy at lower doses and in less responsive MSI-H tumor models compared to other clinical-stage WRN inhibitors

"The data we are presenting at AACR 2025 highlight several important features of our non-covalent WRN inhibitor," said Peter J. Tummino, Ph.D., President of Research and Development at Nimbus. "NDI-219216 has the potential for more durable target engagement than covalent inhibitors and maintains potency against potential resistance mutations. Its superior efficacy across multiple MSI-H tumor models, including those less sensitive to other WRN inhibitors and those refractory to current therapies, reinforces our belief that NDI-219216 represents a best-in-class opportunity with broad potential across multiple MSI-H tumor types with significant unmet need."

About NDI-219216

NDI-219216 is a highly potent and selective non-covalent investigational inhibitor of Werner syndrome helicase (WRN) activity being developed for the treatment of MSI-H tumors. WRN is a DNA helicase required for DNA replication and DNA repair and is a validated synthetic lethal target for tumors with microsatellite instability (MSI). MSI is a phenotypic consequence of deficient mismatch repair (dMMR) and occurs in various tumor types, including colorectal, gastric, and endometrial cancers. In preclinical studies, treatment with NDI-219216 exhibited robust antitumor activity across multiple cell line-derived xenograft (CDX) and patient-derived xenograft (PDX) MSI-H tumor models, including models for colorectal, gastric, and endometrial cancers.

About Nimbus Therapeutics

Nimbus Therapeutics is a clinical-stage, structure-based drug discovery company developing novel small molecule medicines designed to act against well-validated but difficult-to-drug targets implicated in multiple human diseases. The company advances promising research based on a unique strategy that combines leading-edge computational technologies with a tailored array of machine learning-based predictive modeling approaches. Nimbus' pipeline includes a WRN inhibitor in Phase 1/2 clinical development (NCT06898450) and a diverse portfolio of preclinical programs across oncology, immunology, and metabolism, including a SIK inhibitor program and other undisclosed metabolic targets. The company is headquartered in Boston, Mass. To learn more about Nimbus, please visit www.nimbustx.com.

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