The future success of new RA drugs or novel strategies will hinge upon more stringent selection of trial participants, better patient stratification and improved outcome measures, experts say.
Analysing recent Phase 3 RA trial failures, Professors René Westhovens and Patrick Verschueren, Katholieke Universiteit Leuven, Belgium, argued that many patients in contemporary RA trials are not truly refractory, and disease control could be improved by incorporating new strategies and approaches (such as treat to target) with existing medicines, better streamlining the pool of patients for clinical trials of novel approaches.
“From our point of view, the ideal candidate for advanced therapy both in clinical practice as in clinical trials would be a patient not responding sufficiently to such an intensive initial strategy,” they wrote in an editorial published in the Annals of the Rheumatic Diseases.
“Today, unfortunately, the treatment history of patients included in clinical trials can be very heterogeneous, with some having previously received delayed or inappropriate treatment. This has an important effect on placebo responses and a priori responsiveness to any kind of new drug.”
Lessons from contRAst trials
Their comments follow a critical analysis of the contRAst programme assessing otilimab, the first investigational therapy to target granulocyte-macrophage colony-stimulating factor (GM-CSF) to enter late-stage development.
In the Phase III contRAst 3 trial, a weekly subcutaneous dose of 150 mg otilimab failed to show a significant benefit or non-inferiority to the active comparator sarilumab in patients with RA refractory to conventional synthetic (cs) DMARDs and advanced therapies such as biologic or targeted synthetic DMARDs.
In the Phase III contRAst 1 and contRAst 2 trials, otilimab had outperformed placebo in patients who failed to respond to csDMARDs or bDMARDs but was less effective than tofacitinib. This followed positive data from preclinical and Phase II studies backing the rationale of targeting GM-CSF in RA.
According to Professors Westhovens and Verschueren, fundamental issues might have contributed to otilimab’s late-stage failure, which should be kept in mind for other future clinical studies in rheumatology.
Phase II trials included DAS28 remission as the primary outcome, previously linked with an increased efficacy mismatch between Phase II and III outcomes.