GSK dumps major pipeline prospect otilimab on lackluster phase 3 data in rheumatoid arthritis

GSK has dumped one of its top pipeline prospects. While two of the three phase 3 trials of otilimab hit their primary endpoints, the Big Pharma concluded the efficacy fell short of the level needed to take the anti-GM-CSF antibody forward in rheumatoid arthritis (RA). 

Last year, GSK identified otilimab as a potential blockbuster that formed part of a late-stage pipeline with potential peak sales in excess of 20 billion pounds sterling ($23 billion). The company moved into phase 3 and forecast blockbuster sales despite a phase 2 clinical trial of the candidate missing its primary endpoint and other developers of anti-GM-CSF antibodies stopping work in RA.

Now, GSK has joined its peers in walking away from the opportunity. The company called time on its plan to seek approval for otilimab after reviewing the results from three late-phase clinical trials that tested two doses of the antibody against placebo, Pfizer’s Xeljanz, and Sanofi and Regeneron’s Kevzara.

Two of the clinical trials hit their primary endpoints, with significantly more patients on otilimab than placebo having a 20% or greater improvement in symptoms. However, otilimab performed no better than placebo on the 20% measure in the third clinical trial.

GSK is yet to share data from the studies or discuss how otilimab compared to the two active controls used in the trials but did speak qualitatively about the findings, stating that the “efficacy demonstrated is unlikely to transform patient care for this difficult-to-treat patient population.” 

While GSK is still analyzing the data, it has concluded that the “limited efficacy demonstrated does not support a suitable benefit/risk profile for otilimab as a potential treatment for RA.” The conclusion led GSK to drop plans to file for approval of the antibody. The company will share full results from the phase 3 program next year.

GSK's decision comes days after the Big Pharma announced it was axing its NY-ESO-1 T-cell receptor pact with Lyell Immunopharma, with Adaptimmune then revealing it is taking over the reins of the program.