Eli Lilly and partner Incyte reported new data on their JAK inhibitor baricitinib that reinforce its potential as a new therapy for rheumatoid arthritis (RA).
Top-line results from two phase III studies were reported late last year, but the data were presented in full at the ongoing EULAR meeting in Rome and show the drug can achieve impressive responses in RA patients who have not responded well to established therapies.
The results suggest that the companies remain on course to file for the drug later this year and could pose a significant challenge to Pfizer’s Xeljanz (tofacitinib), currently the only JAK inhibitor approved for use in RA.
Cowen & Co analyst Eric Schmidt said the data show that baricitinib “is an incrementally improved JAK inhibitor for refractory RA,” and could achieve peak annual sales as high as $1.5bn in that indication.
The results of the RA-BUILD trial showed that almost two thirds (62%) of patients with active RA and an inadequate response to disease-modifying anti-rheumatic drugs (DMARDS) such as methotrexate achieved a 20% improvement in symptoms within three months of starting treatment with baricitinib. With placebo, that level of improvement was seen in 40% of patients at that time point.
A sizeable proportion of patients were showing a benefit as early as a week after starting treatment with Lilly and Incyte’s drug and – after six months – 34% of them achieved a 50% improvement in symptoms and 18% were reporting a 70% benefit.
Similarly, in the RA-BEACON study involving patients unresponsive to biologic therapy with anti-tumour necrosis factor (TNF) drugs, a 20% improvement in symptoms was achieved in 55% of the baricitinib group and 27% of the placebo group.
After six months, 50% improvements were achieved in 29% of patients on baricitinib, and the 70% improvement in scores was seen in 17% of the group.
Schmidt said the data indicates that baricitinib is approval in refractory RA and so would allow it to compete with Xeljanz, sales of which grew 78% in the first quarter of the year to reach $89m.
Cowen & Co expect the JAK inhibitors to grab around 15% of the $20bn market for RA and psoriatic arthritis drugs.