Treatment Sequencing and Line of Therapy for Biologics and JAK inhibitors in Rheumatoid Arthritis Patients: Implications for Design and Uptake of New Drugs and Predictive Biomarker Diagnostics

Background The opportunity for new biomarker‐based tests to predict treatment response and the appropriate use of emerging rheumatoid arthritis (RA) therapies may depend on patients’ prior treatment history. We examined rheumatoid arthritis (RA) treatment sequences and biologic/JAKi initiation overall and by line of therapy (LoT) to estimate the size of the eligible RA patient population in the U.S. for a new predictive treatment response test using a population‐based RA inception cohort. Methods We utilized an augmented health plan claims database to create an inception cohort of RA patients and estimated the rate of advanced treatment (biologic or JAKi) addition or switch. Results were stratified by advanced treatment naïve vs. treatment‐experienced status and also described specific RA treatment sequences and combinations over time. Results Among 37,656 RA patients, 59,557 new RA treatment initiations were identified. Most patients (85.2%) initiated biologics; the remainder initiated JAKi. Of these, 40.2% used biologics/JAKi as monotherapy. The overall biologic/JAKi addition/switch rate was 25.7 per 100 patient‐years (22.7/100py in biologic‐naïve patients, and >30/100py in treatment‐experienced patients). Rates varied substantially between prescribers, with an observed add/switch rate in the practices of prescribers in the highest decile (53.8/100py) more than 4‐fold greater than rates in the practice of prescribers in the lowest decile (12.1/100py). Conclusions These findings highlight the size and characteristics of the eligible RA population in the U.S. initiating a new RA biologic or JAKi treatment each year, thus providing valuable insights for stakeholders developing or marketing new RA therapies or biomarker‐based diagnostic tests to predict future treatment response.