Sprifermin more beneficial in Patients at Risk of Rapid Knee OA Progression: Study

Sprifermin is a recombinant human fibroblast growth factor 18 investigated as a possible anabolic intra-articular (i.a.) DMOAD.

"Recent literature supports selection of patients with moderate-high Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores and low joint space width to improve detection of a pain response while enriching for structural progression," the authors wrote. "Such patients display greater cartilage loss than those without joint space narrowing and low pain frequency. Insights from the FORWARD trial suggest a floor effect due to the relatively high proportion of patients with low pain (32% with WOMAC pain sub-scale score <40/100) and relatively high minimum joint space width (mJSW; 50% >3.7 mm) at baseline."

Dr HansGuehring and his team conducted a post-hoc analysis to assess the pain outcomes and cartilage thickness change in a subgroup at risk (SAR) of further progression in the FORWARD trial of knee osteoarthritis patients treated with sprifermin. They randomized the patients to receive: sprifermin 100 µg every 6 months (q6mo), 100 µg q12mo, 30 µg q6mo, 30 µg q12mo, or placebo for 18 months. They determined SAR as baseline medial or lateral minimum joint-space width (mJSW) 1.5–3.5 mm and WOMAC pain score 40–90 units. Researchers also included the follow-up data of 3 years for analysis. They evaluated the treatment benefit by repeated measures, linear dose-effect trends by timepoint.

Key findings of the study were:

• Among 549 patients the researchers identified 161 (29%) SAR patients.
• Among participants in the at-risk subgroup, the researchers noted that the mean difference in WOMAC pain at year 3 in those who received 100 µg every 6 months, compared with placebo, was –8.75, vs 0.97 for the intent-to-treat population.
• They found that participants in the at-risk subgroup who received placebo lost more cartilage over 2 years than those in the placebo group in the modified intent-to-treat population, with a mean change from baseline of –0.05 mm compared with –0.02.
• They further noted that net total femorotibial joint thickness gains in participants who received sprifermin 100 µg every 6 months were similar in the at-risk subgroup and the modified intent-to-treat population, at 0.06 compared with 0.05.

The authors concluded, "Selection for low mJSW and moderate-to-high pain at baseline resulted in more rapid disease progression and demonstrated translation of structure modification (with maintained net benefit on total cartilage thickness) into the symptomatic benefit. This subgroup may represent a target population for future trials."

For further information:

https://doi.org/10.1016/j.semarthrit.2021.03.005