VIENNA – Resolution of nonalcoholic steatohepatitis (NASH), and reduction of fibrosis on liver biopsy were achieved with the oral, thyroid hormone receptor beta-selective agonist resmetirom (Madrigal Pharmaceuticals) in patients with NASH and associated cirrhosis in a pivotal phase 3 clinical trial. The primary results of the MAESTRO-NASH (NCT03900429) trial were reported at the European Association for the Study of the Liver Congress 2023.
Both doses of resmetirom – 80 mg and 100 mg – met the primary endpoints of NASH resolution and no worsening of fibrosis on liver biopsy. The key secondary endpoint of LDL cholesterol lowering was also achieved with statistical significance. Likewise, improvement was seen in liver enzymes, and liver and spleen volumes.
In the intent-to-treat population, NASH resolution was achieved in 26% (P < .0001) in the 80-mg resmetirom group, 30% (P < .0001) in the 100-mg group, and 10% in those taking placebo. And ≥ 1-stage improvement in fibrosis with no worsening of the nonalcoholic fatty liver disease activity score (NAS) was achieved by 24% (P < .0002), 26% (P < .0001), and 14% in these groups respectively.
The investigational, liver-directed agent, designed to improve NASH by increasing hepatic fat metabolism and reducing lipotoxicity, was well tolerated overall with a favorable safety profile.
“This is an exciting time for NASH because we are at the forefront of having a drug to treat these patients, and the benefit to patients promises to be huge,” asserted Stephen Harrison, MD, principal investigator of the MAESTRO studies, gastroenterologist and hepatologist, and founder of Pinnacle Clinical Research, San Antonio, in reporting 52-week results.
“This is the first treatment to achieve meaningful effects on both primary liver biopsy endpoints – disease activity and fibrosis – which is absolutely critical because fibrosis pertains to a worse prognosis. [These results] are reasonably likely to predict clinical benefit in a phase 3 trial in patients with NASH,” he added.
FDA-chosen endpoints likely to predict clinical outcomes
The ongoing 54-month, phase 3, registrational, double-blind, placebo-controlled trial involved taking liver biopsies from 966 patients at around 200 global sites. Biopsy readings were taken by two pathologists that were then combined into a single treatment effect.
Patients had biopsy-proven NASH with fibrosis stages F1B, F2, or F3, the presence of three or more metabolic risk factors, a FibroScan vibration-controlled transient elastography (VCTE) score of 8.5 kPa or more, baseline MRI proton density fat fraction (MRI-PDFF) of 8% or more, and a NAS score of 4 or more with at least 1 in each NAS component. Around 65% of participants had type 2 diabetes, between 13% and 16% were taking glucagonlike peptide-1 (GLP-1) receptor agonists, and 46%-51% were taking statins.
Patients were randomized 1:1:1 to once-daily resmetirom 80 mg or 100 mg orally or to placebo and treated for 52 weeks.
Both liver histological improvement primary endpoints at week-52 were proposed by the U.S. Food and Drug Administration as reasonably likely to predict clinical benefit and as such support accelerated approval for the treatment of NASH with liver fibrosis. These primary endpoints were NASH resolution (ballooning 0, inflammation 0/1) with ≥ 2-point improvement in NAS with no worsening of fibrosis, and ≥ 1-stage reduction in fibrosis with no worsening of NAS.
Patients on resmetirom showed improvement in NAS components and fibrosis, and less worsening of NAS and fibrosis, compared with placebo. Percentage improvement was seen in 31%, 33%, and 15% of patients on 80 mg resmetirom, 100 mg resmetirom, and placebo respectively; no change was seen in 51%, 48%, and 51% respectively; and worsening was seen in 18%, 19%, and 34% respectively.
The key secondary endpoint of LDL cholesterol lowering was also met. “There was a significant effect of resmetirom 80 and 100 mg on multiple atherogenic lipids/lipoproteins at both week 24 and 52,” reported Dr. Harrison. The 52-week percentage change from baseline in LDL cholesterol was –14%, –20%, and 0% for the 80-mg resmetirom group, the 100-mg group, and the placebo group respectively.
“We also saw a significant reduction in liver enzymes [alanine transaminase, aspartate transaminase, and gamma-glutamyl transferase (GGT)] relative to placebo both in terms of percentage and absolute measures,” Dr. Harrison added. “[And] the change in liver enzymes was associated with the neutral biomarker that increases with resmetirom target engagement.”
Resmetirom at both doses also resulted in a significant effect on MRI-PDFF and Fibroscan CAP. At week 52, 80 mg resmetirom, 100 mg, and placebo led to –42.1%, –51.4% and –10.4% change from baseline in MRI-PDFF, while Fibroscan CAP changed by –39.6%, –41.3%, and –14.5% respectively, reported Dr. Harrison. Liver volume dropped by –21.6% in the 80-mg group and –25.8% in the 100-mg group, compared with –1.0% in the placebo group. Spleen volume changed by –5.9%, –6.1%, and +3.2% respectively.
Liver stiffness, as measured by Fibroscan VCTE at week 52, changed from –3.7 KPa (F1B) to –2.0 KPa (F3) at 80 mg, and from –3.7 KPa (F1B) to –2.5 KPa (F2) and –3.3 KPa (F3) at the 100-mg dose.
Further analysis showed that improvements in fibrosis and NASH resolution were seen across all key subgroups, including baseline fibrosis stage (F2 or F3), NAS (< 6, ≥ 6), type 2 diabetes status, age (< 65 years, ≥ 65 years), and sex.