GSK, J&J’s RA drug pulls off clean sweep of major endpoints in PhIII trial

(By Maxwell Hamilton - Flickr: The Glaxo Smith Kline Offices in Brentford with Olympic Logo, CC BY 2.0,

A rheumatoid arthritis drug in development at GlaxoSmithKline ($GSK) and Johnson & Johnson ($JNJ) has hit both co-primary endpoints in a Phase III trial. The data readout positions the partners to push ahead with plans to file for approval of a drug that appears to improve outcomes in people for whom existing rheumatoid arthritis drugs have proven ineffective.

GSK and J&J limited enrollment in the 1,670-person study to patients with moderate to severe forms of the condition who had taken synthetic disease-modifying anti-rheumatic drugs (DMARDs) without success. Participants were randomized to one of the arms and given either a placebo or one of two dosing regimens of the drug, sirukumab, an injectable monoclonal antibody that blocks a protein called interleukin-6. After one year of treatment, patients enrolled in both of the treatment arms showed fewer signs of joint damage than those who received the placebo.

Both treatment arms also met the other co-primary endpoint. That endpoint looked at the number of participants achieving ACR20 after 16 weeks. ACR20, a tool the American College of Rheumatology designed to show when a person’s condition has improved by 20%, was achieved after 16 weeks by more than 50% of participants in the treatment arms. A little more than one-quarter of participants in the placebo arm achieved ACR20 over that time frame. Similar differences between the treatment and placebo arms were seen in four major secondary endpoints assessed in the trial.

The clean sweep of primary and major secondary endpoints in the trial in a population that has been failed by existing treatments suggests there is at least one area of the congested rheumatoid arthritis market where sirukumab could carve out a niche. “Treatments that may allow rheumatologists to limit the progression of the disease from causing permanent joint damage are valuable in the management of a chronic inflammatory condition like rheumatoid arthritis,” Tsutomu Takeuchi, a professor of medicine and lead researcher in the trial, said in a statement.

GSK has previously said the plan is to file for approval of sirukumab this year. Another IL-6-targeting antibody, Regeneron ($RGEN) and Sanofi’s ($SNY) sarilumab, is already in front of FDA. The PDUFA date for sarilumab, which bested AbbVie’s ($ABBV) Humira in a Phase III trial, is scheduled for the end of October. If approved, both drugs will face competition from incumbents such as Humira, an incoming wave of biosimilars and, potentially in the future, JAK1 inhibitors and other next-generation products from the likes of AbbVie and Gilead ($GILD).

Despite this level of competition, J&J has singled out sirukumab as one of its pipeline prospects that is capable of racking up blockbuster sales.

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- and Reuterstake