Menu Back to Poster-Presentations-Details

P324: Glutamate Dehydrogenase (GLDH) as a Safety Biomarker: Applying a Regulatory Science Framework for Drug Development Tools

Poster Presenter

Anna-Marika Bauer

Regulatory Specialist II
Critical Path Institute
United States

Objectives

To demonstrate the implementation of a Regulatory Science Framework for Drug Development Tools through the qualification of glutamate dehydrogenase (GLDH) as a safety biomarker intended to improve the interpretation of drug-induced liver injury in clinical trials involving muscle injury.

Method

Drug development tools developed through public–private partnerships informed the creation of the Framework, which outlines unmet need identification, context-of-use definition, evidence generation, and regulatory strategy. This 1-year update presents GLDH as an application of the Framework.

Results

Public–private partnerships (PPPs) have produced regulatory-ready Drug Development Tools (DDTs) that improve drug development resulting in safer and more effective treatments for patients. These efforts informed a Regulatory Science Framework and decision tree that describe how unmet needs are defined, contexts of use are specified, evidence is generated, and regulatory strategies are executed. Drug-induced liver injury (DILI) is a major cause of clinical trial termination and postmarketing withdrawal. Standard biomarkers such as alanine aminotransferase (ALT) lack liver specificity and may rise with skeletal muscle injury, creating uncertainty in trials enrolling patients with muscle disease. Early FDA discussions confirmed the need for a complementary biomarker to distinguish hepatocellular injury from muscle-derived transaminase elevations. GLDH, a mitochondrial enzyme abundant in hepatocytes and minimal in skeletal muscle, was identified as a biologically plausible safety biomarker. The Predictive Safety Testing Consortium’s Hepatotoxicity Working Group coordinated data sharing and aggregation, assay evaluation, and regulatory engagement to advance GLDH as a safety biomarker. Analytical validation of the GLDH assay demonstrated acceptable precision, specificity, stability, and reproducibility. Clinical data showed GLDH increases in hepatocellular injury but not in isolated muscle injury, supporting liver specificity. Although less sensitive than ALT in some contexts, GLDH provided value when ALT elevations were confounded. Nonclinical data supported biological relevance. Through iterative review under FDA Section 507 of the 21st Century Cures Act, the context of use was refined to a narrowly defined safety application in clinical trials, where muscle injury may confound interpretation of transaminase results. Following the FDA Biomarker Qualification Program, GLDH was formally qualified in November 2025 for this defined context of use.

Conclusion

The GLDH qualification illustrates how a structured Regulatory Science Framework de-risks biomarker development by aligning unmet need, evidentiary strength, and regulatory strategy. The process began with a clear articulation of a specific regulatory gap: uncertainty in interpreting liver safety signals in trials enrolling patients with muscle injury. Rather than pursuing replacement of ALT or a standalone DILI diagnosis, stakeholders aligned on a focused safety context where GLDH provides incremental interpretive value. Early and sustained engagement with the FDA shaped evidentiary expectations and scope. The Context of Use statement was intentionally narrow to match available data, ensuring analytical validation, clinical datasets, and translational evidence supported the proposed application. Transparent acknowledgment of limitations, including lack of qualification in pre-existing liver disease and requirement for concomitant biomarkers, strengthened regulatory confidence. The development program exemplified key Framework principles: • Multi-stakeholder collaborations within a public–private partnership • Data sharing, aggregation and harmonization across studies • Analytical and clinical validation tailored to intended use • Iterative regulatory engagement to manage uncertainty • Transparent documentation of limitations and out-of-scope populations The outcome is a qualified safety biomarker that improves interpretation of hepatic safety signals in defined clinical trial populations, reducing ambiguity in benefit–risk assessment and supporting informed regulatory decisions. More broadly, the GLDH case exemplifies how application of a regulatory science framework transforms scientific insight into regulatory-ready solutions that accelerate drug development while maintaining patient safety.