Random Drug Levels and Anti-Drug Antibodies Predict Rheumatoid Outcomes Save

Researchers from Manchester, UK have reported the results of their BRAGGSS study showing that certolizumab (CZP) random drug levels and anti-drug antibody (ADAbs) levels can predict optimal outcomes in CZP treated rheumatoid arthritis patients. 

Monoclonal antibody based therapies are known to result in ADAbs that may impair responses or contribute to adverse events.  Interestingly, assays for both ADAbs and drug trough levels have become increasingly popular in inflammatory bowel disease patients, where it is thought to be predictive.  Amongst rheumatologists their use has not gained traction, with most rheumatologists claiming that their management success has been high without such expensive and not readily obtained assays.

BRAGGSS (Biologics in Rheumatoid Arthritis Genetics and Genomics Study Syndicate) is a CZP prospective cohort study involving 60 centers in the UK.

Their prospective cross-sectional analysis of 115 RA patients treated with CZP, blood samples involved the collections at 3, 6 and 12 months. Randomly obtained, serum samples were assayed for CZP drug levels and ADAbs by ELISA and radioimmunoassay.

ADAbs were detected in 37% at 12 months and were significantly associated with lower drug levels over 12 months.

Drug level was associated with 12 months EULAR response (p=0.042). In the multivariate model, ADAb level and adherence to drug were significantly associated with drug concentrations.

This study demonstrates that practical assessments with random drug levels may be clinically useful. In their study, higher CZP drug levels were associated with better clinical responses at 12 months. Moreover, the development of ADAbs were predictably correlated with low drug levels and lesser clinical responses.