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

OBJECTIVE: 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' treatment history. We examined RA treatment sequences and biologic/JAK inhibitor (JAKi) initiation overall and by line of therapy (LoT) to estimate the size of the eligible RA patient population in the United States for a new predictive treatment response test using a population-based RA inception cohort. METHODS: We used an augmented health plan claims database to create an inception cohort of patients with RA and estimated the rate of advanced treatment (biologic or JAKi) addition or switch. Results were stratified by advanced treatment-naïve versus treatment-experienced status and also described specific RA treatment sequences and combinations over time. RESULTS: Among 37,656 patients with RA, 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 (py) (22.7/100 py in biologic-naïve patients and >30/100 py in treatment-experienced patients). Rates varied substantially between prescribers, with an observed add/switch rate in the practices of prescribers in the highest decile (53.8/100 py) more than four-fold greater than rates in the practice of prescribers in the lowest decile (12.1/100 py). CONCLUSION: These findings highlight the size and characteristics of the eligible RA population in the United States 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.