Pharmacological reviews

Obesity and metabolic dysfunction-associated steatotic liver disease (MASLD) are estimated to affect 13% and one-third of adults worldwide, respectively. The novel antiobesity medications achieve marked bodyweight loss and improve associated metabolic conditions, including MASLD. This review summarizes the development and mode of action and available published data on the effectiveness of approved and potential (off-label) antiobesity products in the management of adult and pediatric obesity and MASLD. Additionally, their safety is highlighted. The most effective antiobesity drugs evaluated in double-blind, randomized controlled trials include semaglutide, tirzepatide, and retatrutide with up to 10.8%, 17.8%, and 22.1% placebo-subtracted bodyweight loss, respectively, in adults after 48-72 weeks. Semaglutide also reduces placebo-subtracted body mass index mean by up to 16.7% in adolescents with obesity after 68 weeks. Moreover, these novel drugs are highly effective in treating adults with MASLD. Semaglutide and tirzepatide resolve metabolic dysfunction-associated steatohepatitis (MASH) without worsening of fibrosis placebo-subtracted in 41% and 53% of patients, respectively, after 52-72 weeks. Semaglutide, tirzepatide, and retatrutide reduce hepatic fat on magnetic resonance imaging-proton density fat fraction placebo-subtracted by 41%, 47%, and 81%, respectively, after 48-72 weeks. Tirzepatide also decreases fibrosis without worsening of MASH placebo-subtracted in up to 25% of patients. However, no pediatric trials have been conducted to study these novel drugs in biopsy-proven MASLD. In conclusion, the novel antiobesity drugs are highly effective in obesity and MASLD. However, more biopsy-based clinical trials are required to determine the effectiveness of these medications in adult metabolic dysfunction-associated steatohepatitis-associated fibrosis and pediatric MASLD. SIGNIFICANCE STATEMENT: This work reviews the current antiobesity medications, their structure, mode of action, and effectiveness. These medications are revolutionizing the management of metabolic dysfunction-associated steatotic liver disease by significantly reducing hepatic steatosis, disease activity, and even liver fibrosis.

The history of antiobesity pharmacotherapies is marked by disappointments, often entangled with societal pressure promoting weight loss and the prevailing conviction that excess body weight signifies a lack of willpower. However, categories of emerging pharmacotherapies generate hope to reduce obesity rates. This systematic review of phase 2 and phase 3 trials in adults with overweight/obesity investigates the effect of novel weight loss pharmacotherapies, compared to placebo/control or US Food and Drug Administration-approved weight loss medication, through searching Medline, Embase, and ClinicalTrials.gov (2012-2024). We identified 53 phase 3 and phase 2 trials, with 36 emerging antiobesity drugs or combinations thereof and 4 withdrawn or terminated trials. Oral semaglutide 50 mg is the only medication that has completed a phase 3 trial. There are 14 ongoing phase 3 trials on glucagon-like peptide-1 (GLP-1) receptor agonists (RAs) (ecnoglutide, orforglipron, and TG103), GLP-1 RA/amylin agonist (CagriSema), GLP-1/glucagon RAs (mazdutide and survodutide), GLP-1/glucose-dependent insulinotropic polypeptide and glucagon RA (retatrutide), dapagliflozin, and the combination sibutramine/topiramate. Completed phase 2 trials on incretin-based therapies showed a mean percent weight loss of 7.4% to 24.2%. Almost half of the drugs undergoing phase 2 trials are incretin analogs. The obesity drug pipeline is expanding rapidly, with the most promising results reported with incretin analogs. Data on mortality and obesity-related complications, such as cardio-renal-metabolic events, are needed. Moreover, long-term follow-up data on the safety and efficacy of weight maintenance with novel obesity pharmacotherapies, along with studies focused on underrepresented populations, cost-effectiveness assessments, and drug availability, are needed to bridge the care gap for patients with obesity. SIGNIFICANCE STATEMENT: Obesity is the epidemic of the 21st century. Except for the newer injectable medications, drugs with suboptimal efficacy have been available in the clinician's armamentarium for weight management. However, emerging alternatives of novel agents and combinations populate the current obesity therapeutic pipeline. This systematic review identifies the state and mechanism of action of emerging pharmacotherapies undergoing or having completed phase 2 and phase 3 clinical trials. The information provided herein furthers the understanding of obesity management, implying direct clinical implications and stimulating research initiatives.