Sprifermin

In 2020, Merck reported 5-year follow-up data from the Phase 2 clinical trial for knee osteoarthritis (OA). The placebo controlled, multi-center study demonstrated that sprifermin was able to promote statistically significant improvement in cartilage thickness relative to control in a dose-dependent manner, meeting the primary endpoint of the study. The findings suggested the ability of FGF18 to arrest progression to joint replacement, with 0% of patients in the high dose group progressing to Total Knee Replacement (TKR) surgery over the 5 year study period; in contrast, nearly 1 in 10 patients of the high risk subgroup progressed to TKR when treated with the placebo. These findings suggest significant potential of FGF18 as a disease modifying drug for the treatment of OA (DMOAD) and warrant further clinical evaluation.

Sprifermin was well tolerated with no severe adverse events associated with the treatment. Long-term follow up showed that continual injections (up to 12 per year of bilateral treatment) may need to be sustained over a period of multiple years to prevent recurrence of cartilage loss. Improvement in WOMAC, a secondary endpoint, was met for the Subgroup at Risk. Subsequent analysis further demonstrated that a clinically meaningful reduction in the rate of symptomatic progression (WOMAC) was demonstrated in the full trial population and Subgroup at Risk by the high treatment dose.