Background: Acute gout flares are a known result of urate-lowering in gout patients ¹ and are the most common adverse event in patients treated with pegloticase. ² Fortunately, the proportion of pegloticase-treated patients who experience flares and the number of flares/patient decrease over time. ³ Though well-studied in the clinical trial setting, little has been published on the rate of acute gout flares during pegloticase therapy in a real-world, rheumatology setting. This retrospective study examined one community practice’s findings on gout flares in uncontrolled gout patients co-treated with pegloticase and methotrexate.

Objectives: This retrospective chart review examined acute gout flare occurrence and characteristics in patients undergoing pegloticase-methotrexate co-therapy. Patients with and without gout flares were also compared to investigate potential factors that may have influenced gout flare.

Methods: All patients who underwent pegloticase plus methotrexate co-therapy between January 2017 and March 2021 at a community rheumatology practice were included. Patient, treatment, and flare characteristics were extracted from the medical record and compiled into a de-identified data set.

Results: 29 patients treated with pegloticase and methotrexate (28 subcutaneous, 1 oral) were included. Mean patient age was 59.9±17.0 years and 79% were male. Gout duration was 11.7±10.8 years, pre-therapy serum uric acid (sUA) averaged 9.4±1.8 mg/dL, and 97% had visible tophi. Patients had received 12.8±14.3 pegloticase infusions over 25.1±9.7 weeks, with pre-infusion sUA<6 mg/dL in 27/29 patients (93%) at last pegloticase dosing. 23 gout flares were noted in 12 patients (41%, 1.9±1.8 flares/patient), 59% of which were noted as severe and 50% involved a single joint. Acute gout flare was most common in the first 4 weeks of therapy, with first flare occurring a mean of 3.4±2.1 weeks after first pegloticase infusion. Demographic and treatment characteristics were similar between flaring and non-flaring patients. However, patients with ≥1 flare were older (65.8±15.4 years vs. 55.6±17.8 years), more often obese (83% vs. 47%), and had an overall higher comorbidity burden.

Conclusion: This retrospective study of real-world pegloticase use suggests that gout flare rates may be lower in a real-world setting (41%) than that reported in clinical trials (76─86% ^2,3 ), which have different gout flare criteria. Consistent with clinical trials, ^2,3 flare rate was highest during the first 4 weeks of pegloticase treatment, progressively decreasing over time. Interestingly, these data suggest that patients who experience gout flares on pegloticase may have more obesity and a higher comorbidity burden than those who do not experience flares. Further examination of gout flares during real-world pegloticase use is warranted.

REFERENCES:

[1]Pillinger MH, Mandell BF. Semin Arthritis Rheum 2020;50:S24-30.

[2]Sundy JS, et al. JAMA 2011;306:711-20.

[3]Botson JK, et al. J Rheumatol 2021;48:767-74.

Disclosure of Interests: John Albert Speakers bureau: Horizon Therapeutics, Consultant of: Horizon Therapeutics, Lissa Padnick-Silver Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics, Brian LaMoreaux Shareholder of: Horizon Therapeutics, Employee of: Horizon Therapeutics