in the initial 2-year results of the ongoing FORWARD trial.
“Sprifermin appears to be the first investigational medicinal product to show dose-dependent prevention of cartilage loss and an increase in cartilage thickness, not only in the total tibiofemoral joint [TFJ] but also in both the medial and lateral compartments, including the central medial femorotibial region,” said Marc H. Hochberg, MD, primary investigator in the trial and division head of rheumatology and clinical immunology at the University of Maryland, Baltimore. “The recommendation is that these findings should be further evaluated in phase 3 clinical trials.”
Dr. Marc Hochberg
He and his colleagues randomized 549 osteoarthritis (OA) patients to double-blind treatment with one of four different dosing regimens of sprifermin or placebo. These patients were aged 40-85 with symptomatic radiographic primary femorotibial knee OA measuring grade 2 or 3 on the Kellgren-Lawrence scale and a medial minimum joint space width (mJSW) 2.5 mm or greater.
At 2 years, researchers observed a significant dose-dependent relationship between the amount of sprifermin given and the increase in total TFJ cartilage thickness. Patients who received three 100-mcg intra-articular injections of sprifermin every 6 months (group 1) showed a gain in TFJ cartilage thickness of 0.03 mm as seen on MRI, while those who received three 100-mcg injections of sprifermin every 12 months (group 2) had a gain of 0.02 mm, Dr. Hochberg said during a late-breaking abstract session at the annual meeting of the American College of Rheumatology. By contrast, those who received placebo had a loss in TFJ cartilage thickness of 0.02 mm (P less than .001). The other two groups received 30 mcg of sprifermin in three weekly injections every 6 months (group 3) or every 12 months (group 4), and these had TFJ cartilage thickness losses of about 0.01 mm or less.
Similar dose-dependent relationships were observed for some of the secondary endpoints, which included changes in cartilage thickness seen in the medial and lateral compartments, changes in cartilage thickness in the compartments’ subregions, and changes in mJSW. Significant differences in cartilage thickness were observed between sprifermin treatment groups and placebo in the medial (group 1, gain of 0.02 mm vs. loss of 0.03 mm; P less than .001) and lateral (groups 1 and 2, gain of 0.04 mm vs. loss of 0.01 mm; P less than .001) TFJ compartments, and in central medial and lateral TFJ subregions.
Changes in mJSW as seen on x-ray between those in group 1 and those on placebo were significant for the lateral compartment, with an increase in mJSW at the higher doses and a decline in the placebo group, but not for the medial compartment.
There were no significant differences in Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores among the treatment groups. Dr. Hochberg noted that patients were permitted to take pain medications during the study, which could have affected this result.
The most frequently reported adverse events were musculoskeletal and connective tissue disorders, specifically arthralgias and back pain, Dr. Hochberg said. The incidence of acute inflammatory reactions was higher with sprifermin, compared with placebo, but the increase was only significant after the first injection cycle, he said.
Merck KGaA and the EMD Serono Research Institute funded the study. Dr. Hochberg reported receiving consulting fees from numerous companies that market or are developing OA drugs, including EMD Serono.