STEP 9 Study Design
No pre-study dietary intervention was required in the STEP 9 trial, although a reduced-calorie diet and increased physical exercise were used alongside both semaglutide and placebo treatment.
STEP 9 was a multicenter, multinational phase 3 clinical trial that enrolled people if they had a body mass index (BMI) of > 30, had a clinical diagnosis of knee OA with moderate radiographic changes (Kellgren-Lawrence grade of 2-3), and were experiencing knee pain.
In addition to a baseline WOMAC pain score of at least 40 points (where 0 represents no and 100 the worst pain), the participants had to have a WOMAC numerical rating scale (NRS) score of ≥ 3.1.
A total of 407 participants were recruited and randomly allocated, 2:1, to receive once-weekly subcutaneous injections of either semaglutide 2.4 mg or placebo for a total of 68 weeks.
Dr. Bliddal presented demographic information only for the study population as a whole, showing that the mean was 56 years, 81.6% were women, 60.9% were White, 11.8% Native American, 7.6% Black, and 19.7% of other ethnic origin.
Moreover, the mean bodyweight at baseline was 108.6 kg, and the mean baseline BMI was 40.3, with 75% of participants having a BMI ≥ 35. The mean waist circumference was 118.7 cm. The mean baseline WOMAC pain score was 70.9.
Other Findings
In addition to the reductions seen in the coprimary endpoints of weight loss and knee pain, the WOMAC physical function score was also reduced from baseline to week 68 to a greater degree in the semaglutide than placebo arm, by a respective 41.5 vs 26.7 points, with a significant estimated treatment difference of -14.9 points.
“The use of pain medication went down as well; you can see the drop was faster in the semaglutide group than the placebo group, and it was maintained throughout the study,” Dr. Bliddal said during his presentation. He noted that patients had to temporarily stop taking pain relievers such as acetaminophen 3 days before their pain was assessed.
Additional findings reported in the abstract, but not presented at the meeting, were a significant estimated treatment difference of -1.0 in NRS pain intensity, more people treated with semaglutide than placebo achieving ≥ 5% (87.0% vs 29.2%) or ≥ 10% (70.4% vs 9.2%) weight loss.
“Safety and tolerability with semaglutide were consistent with the global STEP program and the GLP-1 receptor agonist class in general,” Dr. Bliddal reported.
Serious adverse events occurred in a respective 10.0% and 8.1% of participants, and adverse events leading to discontinuation were recorded in 6.7% and 3%. Around one third (2.2%) of those leading to discontinuation in the semaglutide arm were gastrointestinal adverse events.
The STEP 9 study was funded by Novo Nordisk. Henning is a principal investigator for the trial and acknowledged that research grants were received from Novo Nordisk to his institution, as well as consulting fees and honoraria. He has also received congress and travel support from Contura. Dr. Vincent was not involved in the study and had no relevant conflicts of interest to disclose.
A version of this article appeared on Medscape.com.