The U.S. Food and Drug Administration (FDA) has granted approval for the use of Rezdiffra (resmetirom) in the treatment of noncirrhotic non-alcoholic steatohepatitis (NASH) in adults with moderate to advanced liver scarring (fibrosis). This marks a significant milestone as it offers a medication specifically targeting liver damage in patients with NASH, in addition to diet and exercise.

NASH is a condition that occurs as a result of the progression of nonalcoholic fatty liver disease. Over time, liver inflammation can lead to liver scarring and dysfunction, often accompanied by other health issues such as high blood pressure and type 2 diabetes. It is estimated that around 6-8 million people in the U.S. have NASH with moderate to advanced liver scarring, and this number is expected to rise.

Rezdiffra is a partial activator of a thyroid hormone receptor, and its activation in the liver helps reduce the accumulation of liver fat. The safety and effectiveness of Rezdiffra were evaluated based on a surrogate endpoint, analyzing liver inflammation and scarring, in a 54-month randomized, double-blind placebo-controlled trial. The sponsor of the drug is currently conducting a postapproval study to confirm Rezdiffra's clinical benefits.

In the trial, a total of 888 subjects with NASH and liver scarring were enrolled and randomly assigned to receive either placebo or different doses of Rezdiffra along with standard care for NASH, including counseling for a healthy diet and exercise. After 12 months, the liver biopsies showed that a higher percentage of subjects treated with Rezdiffra experienced resolution of NASH or an improvement in liver scarring compared to those who received the placebo.

The most common side effects observed with Rezdiffra treatment were diarrhea and nausea. However, the drug comes with specific warnings and precautions, such as the potential for drug-induced liver toxicity and gallbladder-related side effects. It should be avoided in patients with decompensated cirrhosis, and if signs or symptoms of worsening liver function occur during treatment, it should be discontinued.

Healthcare providers should be aware that combining Rezdiffra with certain other drugs, particularly statins for lowering cholesterol, may lead to significant drug interactions. Further details on recommended dosage, administration modifications, and potential drug interactions can be found in the full prescribing information.

Rezdiffra has been approved by the FDA under the accelerated approval pathway, which fast-tracks drugs for serious conditions that address unmet medical needs. The ongoing 54-month study will assess the clinical benefits of Rezdiffra after an extended treatment period. The drug has received Breakthrough Therapy, Fast Track, and Priority Review designations for this indication.

The approval of Rezdiffra has been granted to Madrigal Pharmaceuticals, and it represents a crucial step forward in providing a treatment option for patients with NASH and moderate to advanced liver scarring.