Methods and kits for predicting infusion reaction risk and antibody-mediated loss of response by monitoring serum uric acid during PEGylated uricase therapy

1. A method of treating a patient suffering from gout having a serum uric acid (SUA) level of 6 mg/dl or less and reducing the incidence of infusion reaction in the patient during PEGylated uricase therapy without measuring anti-PEGylated uricase and anti-PEG antibody titers, comprising the steps of:

intravenously administering to said patient a therapeutically effective amount of PEGylated uricase every two weeks;

obtaining a biological sample from said patient after a period of at least 2 weeks, wherein said biological sample is selected from the group consisting of blood, serum, and plasma;

measuring a uric acid level in said biological sample; and

indicating that the uric acid level is associated with a lower likelihood of antibody-mediated PEGylated uricase clearance when said uric acid level is maintained at less than 6 mg/dl or indicating that said uric acid level is associated with a higher likelihood of antibody-mediated PEGylated uricase clearance at a time point when said uric acid level is measured at least 6 mg/dl;

if said uric acid level is less than 6 mg/dl then continuing said administration of PEGylated uricase every two weeks; or

if said uric acid level is above 6 mg/dl then discontinuing said administration of PEGylated uricase every two weeks, thereby reducing the incidence of infusion reaction in said patient;

wherein said patient previously received ineffective allopurinol therapy or has a medical history in which allopurinol therapy is contraindicated.

2. The method of claim 1 , wherein said gout is refractory.

3. The method of claim 1 , wherein said gout is chronic or tophaceous.

4. The method of claim 1 , wherein the patient is administered one or more of fexofenadine, hydrocortisone, or acetaminophen, prior to each administration of PEGylated uricase.

5. The method of claim 1 , wherein the infusion reaction comprises one or more of dyspnea, hypotension, hypertension, swelling, bronchospasm, chest pain, nausea, vomiting, or abdominal pain.

6. The method of claim 1 , wherein the infusion reaction occurs within 2 hours of said intravenous administration of the PEGylated uricase.

7. The method of claim 1 , wherein the PEGylated uricase comprises a mammalian uricase amino acid sequence truncated at the amino terminus or the carboxy terminus, or both the amino and the carboxy termini, by 1 to 13 amino acids, and further comprising an amino acid substitution at position 46, said truncation and amino acid substitution being relative to the native mammalian uricase amino acid sequence.

8. The method of claim 7 , wherein the amino terminal amino acid is alanine, glycine, proline, serine, or threonine.

9. The method of claim 1 , wherein the PEGylated uricase is pegloticase.