From biopsy bottlenecks to biomarker breakthroughs - how non-invasive tools are reshaping MASH trials

A transformative phase in MASH development

Metabolic dysfunction-associated steatohepatitis (MASH), formerly NASH, represents the progressive and fibrotic form of metabolic dysfunction-associated steatotic liver disease (MASLD). Affecting an estimated one-third of adults worldwide (~25–38%), MASLD continues to rise in parallel with obesity and type 2 diabetes, with a significant proportion progressing to MASH. This condition carries a markedly increased risk of cirrhosis, liver failure, and hepatocellular carcinoma, making early detection and intervention critical.

Historically, liver biopsy has served as the diagnostic gold standard and gatekeeper for clinical trial enrolment. Yet its reliance introduces significant burden on patients and trial operations. High screen failure rates, logistical complexity, and limited suitability for repeated monitoring have created a development bottleneck. As non-invasive tests (NITs) gain traction among clinicians, sponsors, and regulators, their role in clinical development is expanding. They offer potential to improve trial efficiency and patient experience, while supporting scalable global programmes.

This article explores the evolving NIT landscape, emerging regulatory perspectives, and strategic opportunities to optimise MASH trial design and execution. With the right approach, NIT-led strategies have the potential to reshape the future of MASH clinical development.

The biopsy bottleneck – a barrier to precision and scale

Sponsors and CROs face the dual challenge of accurately identifying eligible participants and demonstrating treatment benefit within a heterogeneous disease population. Reliance on liver biopsy complicates both objectives. Biopsy is inherently invasive and associated with risks such as bleeding, infection, and post-procedural pain, which can deter participation and negatively impact retention. It samples a tiny fraction of the liver (<1/50,000), contributing to staging variability and inter-reader disagreement in histopathological assessment. Many screened patients also fail to meet histological criteria for “at-risk” MASH, resulting in high screen failure rates. Repeat biopsies are also ethically and operationally constrained, limiting feasibility for longitudinal disease monitoring.

Collectively, these issues prolong recruitment and increase trial costs, particularly in Phase IIb and III trials where enrichment for populations with advanced fibrosis is critical. Such pressures have accelerated interest in alternative, non-invasive strategies.

Non-invasive tests are expanding the diagnostic toolbox

Recent advances in NITs are redefining how liver disease is characterised in both clinical practice and research. These tools support a range of objectives, including screening for advanced fibrosis, identifying “at-risk” MASH (NAS ≥4 with ≥F2 fibrosis), monitoring disease progression or resolution, and differentiating MASLD from both MASH and healthy individuals.

Serum biomarkers and scoring systems are becoming key tools in non-invasive assessment. The ELF test demonstrates strong performance for advanced fibrosis and holds both EU CE-IVD and US FDA De Novo authorisation. Widely used scores such as FIB-4 and NFS offer practical, low-cost options despite limitations in intermediate ranges. Emerging biomarkers, including Pro-C3, NIS2+™, and FNI are showing promise for identifying fibrotic or at-risk MASH, with potential utility as rule-in/rule-out tools depending on their predictive characteristics.

Imaging-based approaches, including elastography and magnetic resonance techniques, provide non-invasive characterisation of liver fibrosis and steatosis with strong diagnostic performance. Transient elastography using FibroScan® offers a rapid and widely accessible ultrasound-based measure of liver stiffness, with the controlled attenuation parameter (CAP) available to estimate steatosis in many settings. Magnetic resonance elastography (MRE) and MRI–proton density fat fraction (MRI-PDFF) are recognised for their precision and reproducibility, and their combined use supports detailed liver phenotyping.

Increasingly, composite algorithms that integrate biomarkers with imaging parameters, such as FAST, MEFIB, and MAST, are demonstrating superior performance compared with single-modality testing. Emerging multi-omics approaches are also advancing the field, therefore making selection of the most appropriate combination a strategic consideration in modern trial design.

Regulatory and clinical guidance are evolving

Regulatory agencies, including the FDA and EMA, have acknowledged the potential for NITs to support trial enrichment, dose selection, and mechanistic insights, particularly in earlier-phase development. Although liver biopsy remains the definitive standard for pivotal Phase III trials. Clinical society guidance echoes this direction. The AASLD recommends¹ FIB-4, NFS, and FibroScan as frontline tools, reserving biopsy for ambiguous or advanced cases. Similarly, the joint EASL–EASD–EASO advocate a stepwise approach². Initial risk stratification using simple serum scores, escalation to ELF or imaging when indicated, and application of validated cut-offs to guide diagnosis and trial inclusion. Collectively, these developments signal a move toward more pragmatic and patient-centred diagnostic strategies.

What this means for sponsors and CROs

For sponsors and CROs, the growing adoption of NITs represents both a challenge and an opportunity. When thoughtfully integrated into study protocols, NITs can support more efficient recruitment and enrich study populations, with potential to lower screen failure rates. Advantages that are particularly relevant for large, global, multi-site trials.

A tiered “rule-in/rule-out” framework is emerging as best practice:

• Tier 1: Community-level rule-out using low-cost serum-based tools such as FIB-4 or ELF to exclude low-risk individuals early.
• Tier 2: Rule-in of probable candidates using imaging-based NITs or composite scores, such as MRE or FAST, to confirm elevated risk and justify further assessment.
• Tier 3: Selective use of confirmatory liver biopsy when definitive histological data are required for regulatory submission or primary endpoint validation.

Beyond recruitment efficiency, the repeatability and scalability of NITs facilitate broader site participation, including in under-represented regions, strengthening diversity efforts. Their suitability for repeated assessment also enables interim analyses and longitudinal endpoint tracking, aligning well with contemporary adaptive trial designs.

Real-world proof of feasibility

The landmark approval of resmetirom (Rezdiffra) in 2024 marked a turning point in MASH therapeutics³. As the first drug approved by the FDA for non-cirrhotic MASH, its development programme illustrated the value of integrating NITs into trial design. The MAESTRO trials incorporated MRI-PDFF, serum biomarkers (including TIMP-1, CK-18, adiponectin, and Pro-C3), and ELF scoring alongside biopsy-based endpoints⁴. Observed concordance between changes in NIT measures and histological improvement supported their utility as complementary indicators of treatment response. The success of resmetirom demonstrates that biomarker-first approaches, when underpinned by robust validation and sound methodology, can meaningfully contribute to regulatory success.

Remaining challenges and the road ahead

Despite significant progress, challenges remain. Many current NITs perform best in advanced fibrosis (F3–F4), limiting sensitivity in earlier disease stages. Encouragingly, the FDA recently accepted a letter of intent to qualify liver stiffness measurement by vibration-controlled transient elastography (VCTE) as a “reasonably likely” surrogate endpoint for registrational trials in adults with non-cirrhotic MASH and moderate-to-advanced fibrosis. Marking an important step toward recognising NITs as practical tools for both clinical decision-making and patient care. Platform variability, inconsistent thresholds, and uneven global access continue to pose challenges, potentially affecting trial equity and comparability. Collaborative initiatives such as NIMBLE, LITMUS, and GRIPonMASH, are addressing these gaps by driving standardisation, multi-ethnic clinical validation, and regulatory alignment.

Reducing reliance on liver biopsy represents a strategic shift toward more efficient and accessible MASH trials. Non-invasive tools offer a pathway to accelerate recruitment, enhance diagnostic precision, and support flexible trial designs while improving participant experience. As validation expands and regulatory frameworks continue to evolve, now is the time to embrace biomarker-first strategies. Importantly, the impact of NITs can extend beyond trial completion. Once aligned with regulatory expectations, these technologies have potential applications in post-marketing settings, including real-world evidence generation, health economics analyses, and label expansion strategies, helping to maximise the long-term value of therapeutic innovation.

References

[1] Rinella ME, Neuschwander-Tetri BA, Siddiqui MS, Abdelmalek MF, Caldwell S, Barb D, Kleiner DE, Loomba R. AASLD Practice Guidance on the clinical assessment and management of nonalcoholic fatty liver disease. Hepatology. 2023 May 1;77(5):1797-1835. doi: 10.1097/HEP.0000000000000323. PMID: 36727674.

[2] European Association for the Study of the Liver (EASL); European Association for the Study of Diabetes (EASD); European Association for the Study of Obesity (EASO). EASL-EASD-EASO Clinical Practice Guidelines on the Management of Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD). Obes Facts. 2024;17(4):374-444. doi: 10.1159/000539371. doi: 10.1159/000541386. PMID: 38852583.

[3] FDA Approves First Treatment for Patients with Liver Scarring Due to Fatty Liver Disease | FDA. https://www.fda.gov/news-events/press-announcements/fda-approves-first-treatment-patients-liver-scarring-due-fatty-liver-disease.

[4] Harrison SA, Bedossa P, Guy CD, Schattenberg JM, Loomba R, Taub R, Labriola D, et al.; MAESTRO‑NASH Investigators. A Phase 3, Randomized, Controlled Trial of Resmetirom in NASH with Liver Fibrosis. N Engl J Med. 2024 Feb 7;390(6):497–509. doi:10.1056/NEJMoa2309000. PMID: 38324483.