The lesson from last week's FDA Arthritis Advisory Committee meeting to review Pfizer Inc.'s tofacitinib is that companies working in the crowded RA space may need enriched - and larger - placebo groups to show an effect on progression using radiographic endpoints.

The gold standard for measuring efficacy in rheumatoid arthritis is ACR20, a measure of inflammatory disease activity. But rheumatologist Robert Landewe told BioCentury that even when inflammation is decreased, "there is still an ongoing process of cartilage and bone destruction."