What Is Krystexxa?
Krystexxa is a treatment option for patients unable to take conventional gout treatments (or who were not helped by conventional treatments). In technical terms, Krystexxa (generic name pegloticase), is a PEGylated recombinant mammalian urate oxidase (enzyme). It was formerly known as Puricase.
How Does Krystexxa Work?
Krystexxa is a biologic drug. It works by breaking down uric acid, the substance that causes gout. It is used in gout patients who either:
- have failed to normalize serum uric acid and whose signs and symptoms of gout are not well-controlled with urate-lowering medications at maximum allowable dosages
- for patients who should not take conventional urate-lowering medications (e.g., allopurinol.)
How Is Krystexxa Given?
Krystexxa is not given orally. It is administered intravenously (IV) every 2 weeks.
How Has Kystexxa Performed in Clinical Trials?
In clinical trials, Krystexxa administered every 2 weeks produced clinically significant improvements compared to placebo. Treatment resulted in:
- reduction or resolution of gout tophi (deposits of uric acid under the skin)
- decrease in number of tender or swollen joints
- reduction of flares (an escalation of gout symptoms) in terms of frequency and number of incidences after 4 to 6 months of treatment
- improvements in pain and in health-related quality of life after 6 months of treatment compared to placebo.
What Side Effects and Warnings Have Been Associated With Krystexxa?
The drug's sponsor, Savient Pharmaceuticals, Inc., had reported adverse reactions, including gout flares and infusion reactions. The risk-versus-benefit is still under review by the FDA.
Is Krystexxa FDA-Approved and Available?
On June 16, 2009, an Arthritis Advisory Committee to the FDA recommended approval of Krystexxa by a 14-1 vote. Though the FDA is not bound by the recommendation, it does usually follow it. Savient Pharmaceuticals reports that an FDA decision is expected around August 1, 2009.
UPDATE: On August 2, 2009, Savient Pharmaceuticals announced that it received a complete response letter from the FDA which stated approval of Krystexxa could not be granted at this time. In part, the FDA stated concerns over a proposed change in the manufacturing process for commerical use of Krystexxa and offered guidance for a Risk Evaluation and Mitigation Strategy (a medication guide and communication plan). The drugmaker will work with the FDA towards the goal of resubmission for approval -- perhaps in early 2010.
UPDATE: On September 14, 2010, the FDA approved Krystexxa (pegloticase) for gout in adults who do not respond to or tolerate conventional treatment. Read more.
Sources:
FDA Appointed Arthritis Advisory Committee Recommends U.S. Food and Drug Administration Approval for KRYSTEXXA(TM) for Refractory Chronic Gout. June 16, 2009.
Savient Provides Update on Pegloticase BLA. February 12, 2009.
http://investor.savient.com/ReleaseDetail.cfm?ReleaseID=365090
