Rheumatoid arthritis (RA) patients treated with 4 mg baricitinib treatment had rapid response with a lower baseline Clinical Disease Activity Index (CDAI) score and had a gradual or limited response with a higher one, according to new findings.

Baracitinib is a popular oral agent used for treating moderate-to-severe RA and while it has proven effective, treatment responses have varied widely between patients.

Four phase 3 clinical trials were conducted to analyze baracitinib response patterns and predictors of such patterns.

The study was led by Peter C. Taylor, PhD, from the Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences at the University of Oxford.

“The main objective of these analyses was to describe response patterns during baricitinib treatment; however, identifying predictors of each trajectory group would be of interest,” Taylor and colleagues wrote. “As part of the present analyses, attempts to assess predictors of response patterns were made using machining learning approaches (classification and regression tree or random forest) evaluating all potential baselines as well as early responses.”

Background

The investigators of each of the studies analyzed patients 18 years of age or older with moderate-to-severe RA, which they defined as generally 6 or more out of 68 tender joints and 6 or more of 66 joints with swelling.

The studies were titled RA-BEGIN, RA-BEAM, RA-BUILD, and RA-BEACON, with each using a growth mixture model—a new method of latent class mixed model—being used to classify patients into various subgroups with CDAI response trajectories.

Both RA-BEGIN or RA-BEAM involved collecting data up to rescue from week 0 through week 52. They added that data up to rescue for weeks 0 through 24 were collected for RA-BUILD and RA-BEACON.

The investigators noted that data were assessed individually, and analyses for each one were done through R software.

Findings

The research team concluded that, among the other points of interest, RA patients showed rapid responses with a lower baseline CDAI and but those with a limited or slower response had higher baseline CDAI.

They stated that for each individual study, there were 3 total response trajectories that they identified.

The researchers noted that in 3 studies—in which patients were naïve to biological disease-modifying anti-rheumatic drugs (bDMARDs)—there was higher disease activity on average when assessed through CDAI.

Within the 3 studies, rapid responders to the treatments—which was about 65 to 71% of participants—reported lowest CDAI rankings at baseline. The same group was shown after 16 weeks to have and achieved mean CDAI ≤ 10.

The 10 to 17% of study participants who were gradual responders showed higher CDAI scores at baseline by had lower disease activity after 24 weeks.

The investigators added that the 18 to 22% of study participants found to be partial responders showed higher baseline CDAI scores and could not reach a mean CDAI of ≤ 10.

They additionally noted that for patients found to be bDMARD-experienced, their subgroups were shown to be the following:

• Rapid responders having a mean CDAI of ≤ 10, making up about 42% of patients
• Partial responders having a mean CDAI decrease of around 15 points from baseline, making up about 42% of patients
• Limited responders, making up about 15% of participants

“In patients receiving baricitinib 4-mg, lower baseline CDAI was generally associated with rapid response, while higher baseline CDAI scores were generally seen for patients who either reached treatment targets more gradually, or who had a partial or limited response,” they wrote. “Maintenance of response was observed with continued baricitinib treatment in all response groups and generally included maintenance of mTSS.”

The study, “Patient Disease Trajectories in Rheumatoid Arthritis Patients Treated with Baricitinib 4-mg in Four Phase 3 Clinical Studies,” was published online in Rheumatology and Therapy.