OBJECTIVES : To examine use of pegloticase for patients in US clinical care and identify variables associated with longer time on therapy.

METHODS : Study population: 110 gout-diagnosed patients who initiated their last pegloticase course between Jul 2015 and Oct 2019 with >180 days follow-up from pegloticase initiation (index). Chart reviews were conducted for all study patients to determine treatment status (ongoing vs. discontinued) and reasons for discontinuation. Statistical analyses included t-test (continuous variables), chi-square or Fischer’s exact tests (categorical variables), and Kaplan-Meier and log-rank or Wilcoxon tests (time to event). Assessments of serum uric acid (sUA) were limited to patients with 2+ measures.

RESULTS : At time of assessment, 84% (95) had discontinued treatment; 19% (18/95) discontinued as intended upon meeting treatment goals, 39% (37/95) lack or loss of efficacy, 16% (15/95) adverse events, 8% (8/95) lost to follow up, 2% (2/95) each for cost or payer denial and unrelated health issues. Of the 15 patients who discontinued therapy due to adverse events, 80% (12) cited infusion and/or allergic reactions. Median times to discontinuation were 20 weeks overall and 22 weeks for non-planned discontinuation. Controlled sUA (<2 sUA ≥6 mg/dL) and concurrent use of immune-modulating therapies (predominantly methotrexate) were associated with a significantly longer pegloticase duration. Variables NOT associated with unplanned discontinuation were race, gender, age, payer type, kidney disease, osteoarthritis or osteoporosis, baseline sUA, and pegloticase infusion schedule. None of the 12 patients who discontinued due to infusion or allergic reactions received concurrent immune-modulating therapies.

CONCLUSIONS : These observations suggest that treatment with pegloticase may be lengthened with concomitant use of immune-modulating therapies; however, a larger scale prospective study should be done to confirm to further elucidate the benefits of immunomodulation beyond durability of treatment, including safety benefits such as minimal to no infusion reactions.