Abatacept may benefit ACPA-negative undifferentiated arthritis, which generally has a poor prognosis and for which there is no proven therapy currently available, according to a report published in Rheumatology.

A 1-year course of abatacept (Orencia) reduced disease activity and an ultrasound measure of synovial inflammation in a manufacturer-funded, open-label, proof-of-concept study. However, it did not achieve the primary composite endpoint of remission on the DAS44 (44-joint Disease Activity Score), a maximum of one swollen joint for at least 3 consecutive months, and no radiographic progression after 6 months of treatment.

“These data justify evaluation in a larger, controlled cohort” of poor-prognosis patients in this “important but understudied” population, said Maya H. Buch, PhD, professor of rheumatology at the Leeds (England) Institute of Rheumatic and Musculoskeletal Medicine and her associates.

They assessed 20 adults with undifferentiated arthritis that had lasted 12 weeks to 18 months who showed definite, active synovitis in at least 1 of 20 scanned joints and had no previous disease-modifying antirheumatic drug (DMARD) therapy; these study subjects were considered likely to progress to rheumatoid arthritis. They received 14 doses of IV abatacept for 1 year.

Two patients withdrew from the study at 6 months and 12 months because of adverse events, and another three were lost to follow-up. Only 2 of the 20 patients (10%) achieved the composite primary endpoint. The majority of patients met two of the individual components – 15 patients showed no radiographic progression and 12 had a maximum of one swollen joint – but only 6 achieved DAS44 remission, the investigators said ( Rheumatology [Oxford]. 2016 Oct 22. doi: 10.1093/rheumatology/kew357 ).

The treatment appeared to suppress C-reactive protein levels immediately, from a median of 9 mg/L at baseline to 0 mg/L at 3 and 6 months. This implies a clear biologic effect. The median number of swollen joints also decreased from a median of 2 at baseline to 0 at 6 and 12 months. There were small reductions in median scores on a disability index and a small decrease in patient-reported visual analog scale disease activity from a median of 52 at baseline to 28 at 6 months and 24 at 12 months. Median ultrasound scores of synovitis decreased from 10 at baseline to 3 at both 6 and 12 months.

Most of these benefits persisted for 1 year after abatacept therapy was stopped, but approximately half of patients required a synthetic DMARD to maintain the benefits. “Overall, these data suggest that in the vast majority of patients (18 of 20), abatacept therapy prevented further progression of disease, but on cessation, additional therapy was indicated to maintain this,” Dr. Buch and her associates said.

There were no serious adverse events during treatment, including no infections and no abnormal liver function tests. A total of 131 nonserious adverse events were reported.

This study was supported by a research grant from Bristol-Myers Squibb and by institution-level grants from Arthritis UK and the U.K. National Institute for Health Research. Dr. Buch reported ties to Bristol-Myers Squibb, AbbVie, AstraZeneca, Pfizer, and Roche-Chugai; her associates reported ties to numerous industry sources.