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Trial to Evaluate ALN-CIDEB in Adults With Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD)
A Trial to Learn if ALN-PNP is Safe and Well Tolerated in Healthy Adults and Adult Participants With Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD)
What is NASH (MASH)?
NASH stands for nonalcoholic steatohepatitis. In 2023, liver experts renamed it MASH, metabolic dysfunction associated steatohepatitis, because it is driven by things like excess weight, type 2 diabetes, high blood pressure, and high cholesterol. It is the same disease, and many doctors and studies still use both names. It starts as fatty liver disease, where extra fat builds up in liver cells. In some people the fat causes inflammation and damage, and that is MASH. The damage can slowly turn into scarring, called fibrosis, and in some people into cirrhosis.
It is a common problem. Yale Medicine estimates that 6 to 8 million Americans have NASH with moderate to advanced liver scarring. And most of them do not know it, because the disease usually causes no symptoms until the liver is badly damaged. The first medicine approved for it, Rezdiffra (resmetirom), arrived in March 2024. The second, Wegovy (semaglutide), was approved for MASH in August 2025. Both got accelerated approval, which means larger studies are still checking whether they prevent cirrhosis and other serious problems over time.
Our guide to fatty liver treatment options explains more.
The stages of liver scarring in NASH (MASH)
Doctors grade the scarring from F0 to F4. Most NASH and MASH trials use these stages to decide who can join, so knowing your stage helps you see which studies fit you.
- F0: No scarring.
- F1: Mild scarring.
- F2: Moderate scarring. Many treatment trials start here.
- F3: Advanced scarring. Many treatment trials include F2 and F3 together.
- F4: Cirrhosis. Some trials are only for people with compensated cirrhosis, which means the liver still works well enough and there are no major complications yet.
The stage is usually measured with a FibroScan or other non-invasive test, and some trials also use a liver biopsy. Our guide explains what FibroScan results mean.
Types of NASH (MASH) clinical trials
Treatment trials for F2 and F3 fibrosis. New medicines that aim to clear the inflammation and reverse some of the scarring. Many are added on top of standard care.
Cirrhosis trials. Studies for people with compensated cirrhosis due to MASH, the group with no approved medicine yet.
Weight and metabolic trials. Medicines and procedures that treat weight, blood sugar, and the liver at the same time; see obesity clinical trials and type 2 diabetes clinical trials.
Diagnostic and imaging studies. New ways to measure liver fat and scarring without a biopsy. Some of these are simple visits with a scan.
Observational studies. Studies that follow people over time to learn how the disease progresses. No new treatment is given.
Interested in learning more about fatty liver disease? Read our guide: Can fatty liver disease be reversed?
Who can participate in NASH (MASH) clinical trials?
Most treatment trials enroll adults with MASH and stage F2 or F3 fibrosis. Some are only for people with compensated cirrhosis (F4). The stage is usually confirmed by FibroScan, blood tests, imaging, and in some trials a liver biopsy. Many studies also look for people who have type 2 diabetes, excess weight, high blood pressure, or high cholesterol, because these conditions drive the disease. People who drink a lot of alcohol, or who have other liver diseases such as hepatitis B or C, are usually not eligible. Most studies keep your current medicines and add the study treatment on top. Eligibility always varies by study.
Do NASH (MASH) trial participants get paid?
Some studies offer compensation for time and travel, and study related care is typically provided at no cost to participants. Compensation varies by trial and is always described during the informed consent process before you agree to anything.
Curious whether clinical trials pay participants? Here's how compensation actually works.
How to enroll in a NASH (MASH) clinical trial
Identify your trial. Use the filters to search by condition and location. Look for studies that match your fibrosis stage.
Explore study details. Click "Learn more" to see the stage required, the tests involved, and whether a biopsy is needed.
Complete the health profile. Click "See if you qualify" to begin the 5-step application. Have ready your FibroScan or biopsy results, your liver blood tests, and the medicines you take.
Submit the application. A clinical trial coordinator reviews it and contacts you. Nothing is decided until informed consent, and participation is voluntary at every step.