A multicentre, efficacy and safety study of methotrexate to increase response rates in patients with uncontrolled gout receiving pegloticase (MIRROR): 12-month efficacy, safety, immunogenicity, and pharmacokinetic findings during long-term extension of an open-label study

Table 4 Summary of adverse events and serious adverse events

	MTX run-in (4 weeks), ITT population (N = 15)	Pegloticase + MTX treatment (up to 52 weeks), mITT population (N = 14)
Any AE, n (%)	10 (66.7%)	14 (100%)
Any SAE, n (%)	0 (0.0%)	1 (7.1%)^a
AEs occurring in > 1 patient in either period, n (%)
Gout flare	5 (33.3%)	13 (92.9%)
Diarrhea	1 (6.7%)	3 (21.4%)
Nasopharyngitis	1 (6.7%)	3 (21.4%)
Upper respiratory tract infection	0 (0.0%)	3 (21.4%)
Muscle strain	0 (0.0%)	3 (21.4%)
Arthralgia	0 (0.0%)	3 (21.4%)
Sinusitis	0 (0.0%)	2 (14.3%)
Hypertension	0 (0.0%)	2 (14.3%)
Liver function test values increased	0 (0.0%)	2 (14.3%)^b
Nausea	2 (13.3%)	1 (7.1%)
Abdominal discomfort	2 (13.3%)	0 (0.0%)
AEs of special interest, n (%)
Infusion reactions	–	1 (7.1%)^c
Anaphylaxis	–	0 (0.0%)
Cardiovascular events	0 (0.0%)	0 (0.0%)
Gout flare (patients with ≥ 1 flare)	5 (33.3%)	13 (92.9%)
Number of flares, mean ± SD [range]	1.2 ± 0.5 [1, 2]	6.5 ± 5.8 [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]
Number of flares, median	1	5

MTX Methotrexate, ITT Intent-to-treat (any patient exposed to MTX during the run-in period), mITT Modified intent-to-treat (any patient exposed to pegloticase during the pegloticase + MTX treatment period)
^a Bacterial sepsis unrelated to the study treatment; patient remained in the study on treatment
^b One patient had a grade 1 ALT increase (82 U/L), and 1 patient had a grade 1 increase in both ALT (80 U/L) and AST (53 U/L); both patients had AE resolution following a methotrexate dose reduction to 10 mg/week
^c Mild cough after infusion 5; patient remained on therapy, completed the study at week 24, and was a treatment responder during month 6

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