Sprifermin (INN) (developmental code name AS-902330),[1] is a recombinant human fibroblast growth factor 18 (rhFGF18) analog,[2] which is under development by TrialSpark for the treatment of osteoarthritis.[3] FGF18 and sprifermin act via the Fibroblast Growth Factor Receptor (FGFR) family, with preferential activity via FGFR3c.[4]
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.[5] 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.[6] 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.[5] 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.[5] Improvement in WOMAC, a secondary endpoint, was met for the Subgroup at Risk.[5] 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.[7]