FDA approval for Krystexxa – what you go through to reach the promised land

This page - FDA approval for Krystexxa (pegloticase) - was last reviewed, or updated, on 29 June 2018. 

N.B. Krystexxa™ is its brand name. Pegloticase is its generic name.

The FDA approves Krystexxa (pegloticase) – but who gets it??

Who gets this new medicine for gout depends on whether all other drugs for gout have failed and if you have chronic gout. Anyone with an existing heart condition of any kind will be very carefully considered (see below). Krystexxa (pegloticase) is a biologic – it’s an intravenous infusion. You’re being given a form of uricase (the name used is a PEGylated uric acid specific enzyme) to convert uric acid mainly to allantoin, which is well excreted by the kidneys.

How long do you take it?

The trial results showed that on average it took 3 – 6 months for 59% of remaining patients to end gout flares, and 65% removed at least one tophi, in those who responded well. But in the OLE extension trial (which lasted 2 years) more patients reduced uric acid to its target and removed tophi or some of their tophi. After five months of the OLE, patients taking Krystexxa every 2 weeks no longer had gout flares. Many patients have safely taken this drug for a year, and some even for 2 to 2 ½ years. So if 6 months doesn’t work, perhaps an extension might do the trick for you. 

The huge factors will be whether you have immune or adverse reactions to it; what other conditions you have and how they behave; how well you feel you are progressing and whether you see it through. Others include: did your uric acid level fall to below 6.0 mg/dL and remain below this level?; has a measured tophus or tophi shrunk?; what do the treatment professionals think of your case?

Krystexxa Safety 

There were nine deaths in the whole development program (programme), but it has to be said many trial patients had serious medical conditions when they began treatment. Three of these were in those receiving placebo (a dummy drug). All deaths were of course investigated but it was not considered by investigators that Krystexxa (pegloticase) caused them. 

A big concern has been about those with heart conditions, and you should note that Krystexxa has not been specifically studied in patients with congestive heart failure.

There is some uncertainty about its safety in patients with cardiac diseases. Most study patients had pre-existing heart diseases before the phase 3 trials began. Some patients in the trials experienced heart irritation and annoyance. If you have a heart condition, get advice from doctors, especially a rheumatologist and cardiologist. Those administering the course will want to know too, and they will make a judgement.

Adverse events 

Almost all participants suffered at least one adverse event, in the phase 3 trials and in the OLE extension trial. Across four Krystexxa-taking groups, in each of these trials 19% - 25% withdrew because of adverse events, serious and otherwise. The most usual reasons for dropping out were infusion reactions and gout flares. 

Serious adverse events  

23%-32% in each of the four groups taking Krystexxa in the phase 3 and OLE trials suffered serious adverse events. These included infusion reactions, (because of this drug’s immunogenicity – it generated an antibody response to varying degrees in almost 90% of 

patients), allergic reactions (anaphylaxis - mainly caused by infusion reactions), infections, cardiovascular (heart) events, (4% - 5% in each of the pegloticase groups - many patients had pre-existing risk factors for these) and gout flares (an average of 3% across each of the pegloticase groups).

Infusion reactions reached their height at dose 3 or 4, and declined thereafter.

Remember when uric acid is reduced, especially as fast as this new medicine for gout does, gout flares are triggered, sometimes despite the preventative medicine taken. No surprise that this happened. If you can take the gout flares, if you get them, you have a better chance of reaching the promised land, and in any case you will get gout attacks again if you withdraw. The most common infusion reactions symptoms were urticaria (itchy skin), dyspnea, (shortage of breath) erythema (a skin redness rash) and flushing.

Other adverse events  

Common ones included nausea, headaches, back pains, chest pains and chest discomfort, constipation, colds and sore throats, fever, elevated blood pressure, vomiting and others similarly weighty.

Will you be able to stay off Krystexxa if the course has ended well for you?

This is a huge question. When you've done it you will be a dealing with gout pioneer. Someone who has valuable gout therapy experience to pass on. Needless to say, this website will be delighted to hear of patient's experiences.

Please use the Contact Us form. 

The simple answer is you must keep your uric acid level down to that you will learn, ended your attacks, and maybe removed all or some of your tophi. The difficult answer is more questions. Can you keep it down, and if not, what medicines will you take? It’s not known if allopurinol at 300 mg daily, or the other drugs for gout, will work on ex treatment failure chronic gout patients for whom allopurinol didn’t work before at 800 mg daily. What natural remedies and diets will you use, and will you be able to stay on diets that keep purine intake down and encourage its excretion? Will you make other lifestyle changes that may be necessary such as adequate exercise? 

Hardly anything has been said about this in respect of Krystexxa, although more will be learnt when more academic journal articles are published and information is released.  And of course, over the next few years, when more experience of Krystexxa has been acquired. 

As far as going back onto Krystexxa is concerned, there is no study data on its safety and ability for patients who went off it for longer than four weeks. Of course its developers say such patients should be monitored very carefully.

Savient Pharmaceuticals, its developers, have promised the FDA they will continue post marketing studies of Krystexxa, and report on their findings.

What will this new medicine for gout cost? 

This isn't a cheap tablet or capsule.  In fact a full course may cost a patient's payer around US$60,000 – a premium price despite the slow growth-with-high-unemployment-and-indebtedness economic climate in which it is prescribed. 

Later, when it reaches approval stage in countries with large social medicine sectors, these countries will have to decide whether they can afford it, and for whom, in an economic climate which will probably remain dull. Health budgets will remain under severe pressures for extra spending, unless the economic climate improves. 

That day is coming soon, because in early January 2013 Krystexxa was approved by the European Medicines Agency for the EU.(See below).

Glucose-6-phosphate dehydrogenase (G6PD) deficiency (Favism).

This is a risk for hemolysis (red blood cells are broken down) and methemoglobinemia (reduced ability of the blood to carry oxygen). Patients of African or Mediterranean ancestry should be screened for this before starting the course because they have a higher risk of it. 

Dealing with gout with this new gout therapy - what you must go through.  

So, let’s say you’ve had gout for 15 years, have tophi in more than one joint, get a painful gout attack every 6 weeks plus you have hypertension or other conditions associated with gout. Neither existing drugs, nor any of the natural remedies have helped. This treatment means you will be regularly taking NSAIDs or colchicine to hopefully prevent gout flares on the Krystexxa course, plus antihistamines and corticosteroids before each intravenous infusion of Krystexxa to help deal with allergic reactions.

Colchicine, corticosteroids, and pegloticase are heavy duty drugs. You are at your wits’ end but all this, I am afraid, is what has to be taken to hopefully end gout flares and remove tophi if you have chronic gout. Then there are the adverse events that most will go through. And the trial statistics, as you have read, show there is no guarantee of success.

On the other hand over 25% of happy trialists have been on it for 2 to 2½ years and nearly 50% of those who started, have remained on it for 18 months. They were able to deal with all the safety issues and the reactions. Many have achieved excellent results.

Read it up in detail if you think you want it.

Whether you can take this course depends of the judgement of your doctor(s) and your own. To help you decide, you can read more about Krystexxa

There's FDA approval for Krystexxa, but it has been withdrawn in the EU 

On 10 January 2013 Krystexxa (generic name: pegloticase) was E.U. approved (called marketing authorisation) by the European Medicines Agency, for adults with chronic tophaceous gout. But in June 2016 it was withdrawn  from EU markets.

Read more about Krystexxa's E.U. approval in the October 2012 issue of our gout newsletter.

You can read more about Krystexxa in the November 2010 edition of our free monthly newsletter, the Gout Dugout.



Make sure you read the prescribing information and patient medication guide. This website says it's intended for U.S. audiences only.

Related pages 

Go to our first page about FDA approval for Krystexxa

Read about a new gout drug under development that may become the most successful at clearing up tophi.                 

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