Genascence Announces Positive 12-Month Safety and Biomarker Data for GNSC-001 Gene Therapy in Knee Osteoarthritis Trial

PALO ALTO, Calif. – May 12, 2025 – Genascence Corporation, a clinical-stage biotechnology company focused on gene therapy for musculoskeletal diseases, today announced positive 12-month safety and biomarker results from its Phase 1b DONATELLO clinical trial evaluating GNSC-001 for knee osteoarthritis (OA). GNSC-001 is a potential first-in-class gene therapy designed to block interleukin 1 (IL-1), a key driver of OA.

The 12-month analysis demonstrated that the study met its primary endpoint, showing continued safety and tolerability across all tested doses. It also met a key secondary endpoint, revealing sustained expression of IL-1 receptor antagonist (IL-1Ra) in the synovial fluid, building upon previously reported six-month data.

GNSC-001 is a genetic medicine that utilizes an adeno-associated viral vector to express an optimized human IL-1Ra, a naturally occurring protein that inhibits IL-1 signaling. By delivering this therapy directly into the affected joint via a single intra-articular injection, GNSC-001 aims to provide long-term IL-1 inhibition.

The FDA granted GNSC-001 Fast Track designation in Q4 2024, and Genascence recently had a successful meeting with the FDA regarding the design of its Phase 2b/3 clinical trial focused on efficacy, which is planned to initiate in 2026.

Genascence CEO, Thomas Chalberg, Ph.D., emphasized the debilitating nature of OA and the limitations of current treatments, stating that the 12-month data supports the potential of GNSC-001 to transform the OA treatment paradigm.

CSO Annahita Keravala, Ph.D., highlighted that GNSC-001 is the first IL-1 inhibitor to demonstrate sustained therapeutic levels of IL-1Ra following a single administration, suggesting a potentially disease-modifying benefit for knee OA, a condition lacking disease-modifying treatments.

Lisa Kadyk, Ph.D., CIRM Fellow at the California Institute for Regenerative Medicine (CIRM), which supported the trial, lauded the innovative approach of GNSC-001 and its potential to offer a more effective, long-term treatment for knee OA.

About the DONATELLO Clinical Trial: This Phase 1b study (NCT05835895) was a double-blind, placebo-controlled, dose-ranging trial evaluating the safety, tolerability, and pharmacodynamics of a single intra-articular injection of GNSC-001 in 67 participants with knee OA across 10 U.S. centers.

Data and Safety Summary: Through 12 months, GNSC-001 was well-tolerated with no treatment-related deaths, serious adverse events (SAEs), or AE-related withdrawals. Common target knee AEs included arthralgia, joint swelling, and joint effusion. The study showed that mean IL-1Ra expression reached and remained above target therapeutic levels in multiple arms throughout the 12-month follow-up, with immune-conditioning generally supporting higher and more prolonged expression.

About Osteoarthritis (OA) of the Knee: OA is a progressive joint disease affecting over 30 million Americans, leading to cartilage destruction, pain, and loss of function. Current treatments primarily manage pain, and there are no therapies to alter or slow its progression.

The positive 12-month data from the DONATELLO trial represents a significant step forward in the development of a potential disease-modifying gene therapy for knee osteoarthritis.