April 02, 2024
By Highpoint Digest News Staff
Washington, DC – (Highpoint Digest) – On March 14, 2024, the U.S. Food and Drug Administration (FDA) approved Rezdiffra (resmetirom) for the treatment of adults with noncirrhotic non-alcoholic steatohepatitis (NASH) with moderate to advanced liver scarring (fibrosis), to be used along with diet and exercise.
“Previously, patients with NASH who also have notable liver scarring did not have a medication that could directly address their liver damage,” said Nikolay Nikolov, M.D., acting director of the Office of Immunology and Inflammation in the FDA’s Center for Drug Evaluation and Research. “Today’s approval of Rezdiffra will, for the first time, provide a treatment option for these patients, in addition to diet and exercise.”
NASH is a result of the progression of nonalcoholic fatty liver disease where liver inflammation, over time, can lead to liver scarring and liver dysfunction. NASH is often associated with other health problems such as high blood pressure and type 2 diabetes. By at least one estimate, approximately 6-8 million people in the U.S. have NASH with moderate to advanced liver scarring, with that number expected to increase. Rezdiffra is a partial activator of a thyroid hormone receptor; activation of this receptor by Rezdiffra in the liver reduces liver fat accumulation.
The safety and efficacy of Rezdiffra was evaluated based on an analysis of a surrogate endpoint at month 12 in a 54-month, randomized, double-blind placebo-controlled trial. The surrogate endpoint measured the extent of liver inflammation and scarring. The sponsor is required to conduct a postapproval study to verify and describe Rezdiffra’s clinical benefit, which will be done through completing the same 54-month study, which is still ongoing. To enroll in the trial, patients needed to have a liver biopsy showing inflammation due to NASH with moderate or advanced liver scarring. In the trial, 888 subjects were randomly assigned to receive one of the following: placebo (294 subjects); 80 milligrams of Rezdiffra (298 subjects); or 100 milligrams of Rezdiffra (296 subjects); once daily, in addition to standard care for NASH, which includes counseling for healthy diet and exercise.
At 12 months, liver biopsies showed that a greater proportion of subjects who were treated with Rezdiffra achieved NASH resolution or an improvement in liver scarring as compared with those who received the placebo. A total of 26% to 27% of subjects who received 80 milligrams of Rezdiffra and 24% to 36% of subjects who received 100 milligrams of Rezdiffra experienced NASH resolution and no worsening of liver scarring, compared to 9% to 13% of those who received placebo and counseling on diet and exercise. The range of responses reflects different pathologists’ readings. In addition, a total of 23% of subjects who received 80 milligrams of Rezdiffra and 24% to 28% of subjects who received 100 milligrams of Rezdiffra experienced an improvement in liver scarring and no worsening of NASH, compared to 13% to 15% of those who received placebo, depending on each pathologist’s readings. Demonstration of these changes in a proportion of patients after just one year of treatment is notable, as the disease typically progresses slowly with a majority of patients taking years or even decades to show progression.
The most common side effects of Rezdiffra included diarrhea and nausea. Rezdiffra comes with certain warnings and precautions, such as drug-induced liver toxicity and gallbladder-related side effects.
Use of Rezdiffra should be avoided in patients with decompensated cirrhosis. Patients should stop using Rezdiffra if they develop signs or symptoms of worsening liver function while on Rezdiffra treatment.
Using Rezdiffra at the same time as certain other drugs, in particular statins for lowering cholesterol, may result in potentially significant drug interactions. Health care providers should refer to the full prescribing information for additional information on these potentially significant drug interactions with Rezdiffra, recommended dosage and administration modifications.
The FDA approved Rezdiffra under the accelerated approval pathway, which allows for earlier approval of drugs that treat serious conditions and address an unmet medical need, based on a surrogate or intermediate clinical endpoint that is reasonably likely to predict clinical benefit. The required aforementioned 54-month study, which is ongoing, will assess clinical benefit after 54 months of Rezdiffra treatment.
Rezdiffra received Breakthrough Therapy, Fast Track and Priority Review designations for this indication.
The FDA granted the approval of Rezdiffra to Madrigal Pharmaceuticals.
About the accelerated approval pathway
Accelerated Approval
When studying a new drug, it can sometimes take many years to learn whether a drug actually provides a real effect on how a patient survives, feels, or functions. A positive therapeutic effect that is clinically meaningful in the context of a given disease is known as “clinical benefit”. Mindful of the fact that it may take an extended period of time to measure a drug’s intended clinical benefit, in 1992 FDA instituted the Accelerated Approval regulations. These regulations allowed drugs for serious conditions that filled an unmet medical need to be approved based on a surrogate endpoint. Using a surrogate endpoint enabled the FDA to approve these drugs faster.
In 2012, Congress passed the Food and Drug Administration Safety Innovations Act (FDASIA). Section 901 of FDASIA amends the Federal Food, Drug, and Cosmetic Act (FD&C Act) to allow the FDA to base accelerated approval for drugs for serious conditions that fill an unmet medical need on whether the drug has an effect on a surrogate or an intermediate clinical endpoint.
A surrogate endpoint used for accelerated approval is a marker – a laboratory measurement, radiographic image, physical sign or other measure that is thought to predict clinical benefit, but is not itself a measure of clinical benefit. Likewise, an intermediate clinical endpoint is a measure of a therapeutic effect that is considered reasonably likely to predict the clinical benefit of a drug, such as an effect on irreversible morbidity and mortality (IMM).
The FDA bases its decision on whether to accept the proposed surrogate or intermediate clinical endpoint on the scientific support for that endpoint. Studies that demonstrate a drug’s effect on a surrogate or intermediate clinical endpoint must be “adequate and well controlled” as required by the FD&C Act.
Using surrogate or intermediate clinical endpoints can save valuable time in the drug approval process. For example, instead of having to wait to learn if a drug actually extends survival for cancer patients, the FDA may approve a drug based on evidence that the drug shrinks tumors, because tumor shrinkage is considered reasonably likely to predict a real clinical benefit. In this example, an approval based upon tumor shrinkage can occur far sooner than waiting to learn whether patients actually lived longer. The drug company will still need to conduct studies to confirm that tumor shrinkage actually predicts that patients will live longer.
Where confirmatory trials verify clinical benefit, FDA will generally terminate the requirement. Approval of a drug may be withdrawn or the labeled indication of the drug changed if trials fail to verify clinical benefit or do not demonstrate sufficient clinical benefit to justify the risks associated with the drug (e.g., show a significantly smaller magnitude or duration of benefit than was anticipated based on the observed effect on the surrogate).
Source: FDA
Photo courtesy of Amber Specialty Drug
