Rasburicase in gout

Question: Rasburicase is an IV medication that is a recombinant urate oxidase found in many organisms but NOT humans. There is a clear role for rasburicase in tumor lysis syndrome especially in the setting of hematological malignancy/chemotherapy and urate nephropathy, but what is the role of rasburicase in an acute gout flare, which is also characterized by high serum uric acid levels? I found one study that dealt with this, as well as a few case reports that shared their experiences using rasburicase for severe gout flares.

Study:

Rasburicase for tophaceous gout not treatable with allopurinol: an exploratory study.

Richette P, Brière C, Hoenen-Clavert V, Loeuille D, Bardin T.

J Rheumatol. 2007 Oct;34(10):2093-8. 

Summary of results:  10 patients with gout that did not improve with allopurinol therapy were selected for this study. These patients received rasburicase 0.2 mg/kg 1) in 6 monthly infusions (Group 1, N=5) and 2) in 5 daily infusions (Group 2, N=5). It was reported that Group 1 had statistically significant lowered serum uric acid levels after 6 months. In Group 2, serum uric acid levels decreased in the acute setting of treatment, but were not significantly lowered from baseline at 1 or 2 months. Reportedly, 2/5 patients in Group 1 (versus 0/5 in Group two) also had decreased tophus sizes. However, 2/5 patients in Group 1 and 4/5 patients in Group 2 had gout flares, despite colchicine treatment. (Richette et al., 2007)

Other papers to note: On a case report level, rasburicase has been shown to be useful in cases of severe gout. This is NOT an exhaustive list, just a few examples from the literature:

1) Rasburicase treatment in severe tophaceous gout: a novel therapeutic option.

Moolenburgh JD, Reinders MK, Jansen TL.

Clin Rheumatol. 2006 Sep;25(5):749-52. 

• This case reports the use of rasburicase in a severe case of gout that persisted despite standard therapy. Rasburicase helped improve the burden of tophaceous gout in this patient.

2) Successful treatment with rasburicase of a tophaceous gout in a patient allergic to allopurinol.

Richette P, Bardin T.

Nat Clin Pract Rheumatol. 2006 Jun;2(6):338-42; quiz 343.

• This case reports the use of rasburicase in a severe of gout in a patient who could not tolerate allopurinol. This patient also had some renal insufficiency likely secondary to urate nephropathy. The rasburicase helped to lower uric acid levels in this patient. 

3) Urate oxidase (rasburicase) for treatment of severe tophaceous gout.

Vogt B.

Nephrol Dial Transplant. 2005 Feb;20(2):431-3

• This case reports the use of rasburicase in a patient with severe gout and allopurinol allergy. Use of rasburicase was reported to lower serum uric acid levels, improve gouty arthritis symptoms and decrease tophaceous burden.

Thoughts: The current data supporting use of rasburicase in gout remains on the case series or report level. Undoubtedly, rasburicase lowers uric acid levels and may thereby possibly help with gout symptoms in some patients as reported by multiple authors, but I have not been convinced by current data that rasburicase effectively and consistently treats gout flares. It makes sense to use rasburicase in a gout flare when there is concurrent urate nephropathy or TLS - but the main indication would be for urate nephropathy  or TLS, and not the gout per se.