A phase 2 trial of hydroxychloroquine in individuals at risk for rheumatoid arthritis

Individuals with serum elevations of anti-cyclic citrullinated peptide (anti-CCP) antibodies are at increased risk for future rheumatoid arthritis (RA). No pharmacologic interventions have been approved for the prevention of RA in such 'at-risk' individuals. However, hydroxychloroquine (HCQ) is used without supporting clinical trial evidence. In this phase 2 randomized trial, individuals at-risk for RA with anti-CCP ≥2 times the upper limit of normal (ULN) were assigned to receive HCQ or placebo for 12 months, with up to 24 months of post-drug follow-up. The primary outcome was the development of clinical RA, as defined in the protocol, at 36 months. Secondary outcomes included safety, development of inflammatory arthritis (IA), and participant-reported joint symptoms. Of 144 randomized participants, 71 were assigned to HCQ and 73 to placebo. In the modified intent-to-treat population, clinical RA occurred in 21 of 69 (30.4%) participants in the HCQ group and 24 of 73 (32.9%) in the placebo group. The risk of clinical RA at 36 months was 0.336 with HCQ and 0.394 with placebo (difference -0.058; 95% confidence interval -0.336 to 0.220; P=0.52). Results for IA were similar. The occurrence and severity of joint symptoms were not observed to differ between groups. Adverse event incidence was similar between groups. In this trial involving individuals with anti-CCP levels ≥2 times the ULN, 12 months of HCQ did not prevent the development of clinical RA at 36 months. (Funded by the National Institute of Allergy and Infectious Diseases; ClinicalTrials.gov number, NCT02603146.).