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DynEPO: A new form of EPO undetectable by the UCI's urine test
In the ongoing battle against doping in sport, it seems there's always a new substance on the horizon that the detection bodies don't know about or can't detect. The imminent release of DynEPO, a new version of the commonly-used EPO will require another round of modifications to the current testing regime, as Anthony Tan writes.
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A leading sports scientist has claimed that DynEPO - the latest drug approved by the European Union to fight kidney disease - poses a very serious threat to the cycling community. Although not wishing to be named for political reasons, the potential danger to endurance athletes, particularly within the sport of cycling, is clearly apparent:
"DynEPO is now much closer to the real thing - it looks just like normal human EPO, which means that even though it is produced via recombinant DNA techniques, the final product would not be detected by the urine test."
As the name implies, DynEPO (epoetin delta) is a variant of human erythropoietin - a hormone that stimulates "erythropoiesis", the natural production of red blood cells in the body. DynEPO has been designed for the treatment of anaemia related to chronic renal (kidney) disease - specifically for patients receiving or about to undergo dialysis, to elevate and maintain their red blood cell production.
"In theory, it would be undectectable by the urine test"
The claim that DynEPO will be undectable by the urine test developed by the French national doping laboratories in Châtenay-Malabry is of considerable concern, as the urine test has been the standard protocol for detection of EPO and its variants (such as NESP) since April 1 last year.
The good news is that the UCI is already aware of DynEPO. When Cyclingnews questioned Dr Mario Zorzoli, the high-profile Chief Medical Officer for the UCI, his response was:
"If you're talking about DynEPO, we're already on this one."
The bad news is that the UCI confirmed the urine test's inability to detect DynEPO:
"From what we have heard, DynEPO is produced naturally by human cells, not animal cells, so in theory, it would be undectectable by the urine test."
Legal wrangling delays global releaseOn March 26, 2002, the European Commission granted Transkaryotic Therapies (TKT), the biopharmaceutical company that has developed DynEPO, marketing authorisation for the fifteen countries of the European Union. In a collaborative agreement, Transkaryotic Therapies will engage the services of Aventis Pharma, the pharmaceutical company of Aventis Worldwide, to propagate and market DynEPO for full-scale commercial production. However TKT and Aventis are currently involved in litigation with both Amgen Inc and Kirin-Amgen Inc relating to the commercial production and sale of DynEPO. California based Amgen is the world's largest biotechnology company, and are the proprietary owners for Epogen (Epoetin Alfa) - a substance much the same as Erythropoietin (EPO) - and Aranesp (NESP). Amgen developed EPO, Epogen and NESP to enable cancer and kidney disease patients to fight anemia. Last year, the U.S. District Court for the District of Massachusetts concluded that DynEPO infringed several claims of patents asserted by Amgen, and the High Court of Justice in the United Kingdom ruled that DynEPO infringed one claim of a patent asserted by Kirin-Amgen. In both the U.S. and U.K., TKT and Aventis have filed appeals with decisions expected by 2003. With appeals pending in both the U.S. and U.K., a launch of DynEPO has not yet been planned. |
What is the difference between normal EPO and DynEPO?
EPO is a peptide hormone, which means it is composed of a relatively short sequence of amino acids, the building blocks of proteins - produced in the body to stimulate the production of red blood cells. Commercially-produced EPO is made using recombinant DNA techniques, and such is known as r-HuEPO (recombinant human EPO).
When human EPO is produced in this way using non-human cell lines (the most common being hamster ovary cells), it ends up with slightly different characteristics than the EPO produced by human cells. It still has the same effect, but the amount of sugars attached to the hormone vary.
As a result, r-HuEPO has a slightly different charge and weight than EPO produced naturally within the body. The urine test can detect these differences in charge and weight, and can therefore determine if someone has recently injected EPO (within two to four days).
In contrast, DynEPO, although commerically-produced using similar DNA techniques as r-HuEPO, is now sufficiently similar to the "real thing". The similarity being that DynEPO, like human erythropoietin, is produced using human cell lines, not via animal cells. This similarity will, in theory, make DynEPO indistinguishable from naturally produced EPO using the current urine test.
What about blood testing for EPO?
The blood testing procedure that was used in conjunction with the urine test at the Sydney Olympics and more recently, at the 2002 Winter Olympic Games in Salt Lake City, does not directly detect EPO use, but instead evaluates abnormalities based on the effects of EPO use over time.
And according to the UCI, this blood test could still detect DynEPO. This more extensive, more costly test differs from the current blood test used by the UCI, which is used as a "health check" that only enables a rider's haematological profile to be evaluated - which include one's haematocrit level and level of reticulocytes (young red blood cells).
Because all forms of EPO cause abnormally fast RBC production rates, the enhanced time-based blood test would still identify that something fishy was going on if DynEPO was the substance being used.
The UCI is aware of the limitations of the current blood test and recognises that its best chance of detecting EPO will be during the longer stage races. For the major one day races, the UCI's strategy consists of more frequent blood and urine test in the weeks preceding the race.
Urine test only partially effective, DynEPO or no DynEPO
Urine tests can only detect EPO use two to four days after injection. EPO is usually administered three to six weeks prior to competition (so that new red blood cells can have enough time to grow and mature); so urine testing alone, although accurate, is only partially effective.
Furthermore, current blood testing procedures are limited to a portion of the participants based on the available resources. For example, in a UCI-sanctioned one day race, blood tests are conducted on approximately 60 riders as part of the mandatory health checks. Assuming there are 180 participants and a particular athlete is using EPO, there is roughly a two in three chance of not being blood tested.
It is important to remember that the only riders who are tested for EPO use by the urine test are those that have haematocrit levels above the set limit or display anomalies considered unusual based on previous blood tests (as well as the race winner and two random draws). Therefore if some riders were using DynEPO a few days before a race and kept their haematocrit levels under the UCI limit, they would not be caught out, even if subjected to the urine test.
However Dr Mario Zorzoli, Chief Medical Officer at the UCI, has not altogether dismissed the urine test's inability to pick up DynEPO just yet:
"Some medical experts have told us that DynEPO, although produced naturally via human cells, is not produced by the kidney cells - which is where natural human EPO is produced. So based on this distinction, we may still be able to pick up use of DynEPO via the urine test."
Is it money stopping the UCI introducing more blood testing?
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Presently the UCI conducts blood tests before races only as a method of selection for the urine test, so does it come down to a question of money?
Although it has been criticised for a lack of spending in the past, the UCI claims that it now invests nearly 10 percent of own annual budget (equal to 4.5 million euros in 2001) in the fight against doping. In addition, the various national federations contribute around 1.8 million euros each year to combat doping.
Enrico Carpani, Press Officer for the UCI, gave a somewhat vague answer when asked if the adoption of more blood tests would be worthwhile:
"We use blood tests throughout many other UCI races, but for us, it is not compulsory. The urine test is enough to detect EPO and NESP. Like Mr Verbruggen says, it is partly to do with money, but it also has something to do with logistics."
Logistics is definitely an issue: Bo Hamburger, the first rider to be tested positive for EPO use from the urine test was tested during an out-of-competition urine test, the day he competed in Fleche Wallonne on April 18, 2001.
Dr Mario Zorzoli supported his colleague Carpani on this issue:
"In fact, we conduct blood testing more often than most people think - riders are subject to both blood and urine testing at nearly all major UCI races.
"By the end of each Grand Tour, we manage to test all riders at least once and many twice. Before the Giro d'Italia, the UCI had already conducted around 2,300 blood tests."
So is it a question of reliability?
A blood test developed by the scientists at the Australian Institute of Sport has been used during the last two Olympic Games, and was instrumental in detecting the use of NESP (novel erythropoiesis stimulating protein or darbepoietin alpha, another synthetic form of EPO) by several cross-country skiers at Salt Lake City. However a quirk in the IOC rules meant they were allowed to keep their medals before subsequent testing, and were only stripped of medals won after the urine tests were also confirmed positive.
Capacity has been cited as an issue on a number of occasions. Only 10 to 15 athletes underwent the blood test for NESP at the Winter Olympics, because (according to the IOC) of the limited capacity of the laboratories - for example, over 30 hours of lab time were required to perform tests on the blood of Spanish cross-country skier Johann Muehlegg before he was declared positive.
"Too complicated, too hard, too expensive"
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In November 2000, UCI President Hein Verbruggen was questioned over the events surrounding the Festina doping scandal. He said that the UCI "did not feel responsible if a rider is doping, or a soigneur gives them drugs."
"I am convinced that there is a small group of hardened cheaters, a much larger group that feels it's OK to take things not in excess, a group that takes legal drugs and finally, a few who do not take anything," he added. "The rider has the choice – nobody decides for him."
And just a few weeks later, Verbruggen was equally frank about the introduction of blood testing during major tours: "To use a (compulsory) blood and urine test for a cycle race such as the Tour de France would be too complicated, too hard, and too expensive."
Why create a new EPO?If standard EPO is an effective therapy, why are pharmacological companies creating new forms? Once again, it's a question of money – not a lack of it, but everyone wanting a slice of the protein therapeutics pie that's worth over US$20 billion and growing. Standard EPO has been in use since the 1970s to treat chronic renal failure, and the biotechnology firms that produce EPO have sought and obtained patent protection covering many of the genetic engineering techniques they use. Given the size of the market for protein therapeutics, those companies with a patent in place effectively raise the barriers of entry and at the same time, substantially increase their wealth. A lesser reason is that conventional genetic engineering techniques for protein production may face technical limitations arising from the need to first clone the gene of interest. For certain proteins, this step adds to development times, increases costs and is technically challenging. Technical difficulties may also arise from the use of non-human production cell lines, which may result in the production of proteins that have therapeutically significant differences from those naturally produced by the cells of the human body. Furthermore, production processes based on conventional genetic engineering may not have incorporated recent advances compared to processes originally developed over a decade ago. In an effort to overcome these commercial barriers and technical limitations, Transkaryotic Therapies (TKT) has developed "gene activation" technology for the production of therapeutic proteins that does not rely on the manipulation of cloned genes. Using its proprietary technology, TKT has succeeded in producing therapeutic proteins in human cells by bypassing regulatory DNA sequences set in the "off position" with regulatory DNA sequences set in the "on position" in order to activate the gene of interest (click here for a diagrammatic explanation). Gene targeting is a technology by which DNA fragments can be "cut and pasted" precisely at pre-selected locations within the cell's genome. Gene targeting can be thought of as molecular surgery, with the surgical tools literally functioning at the molecular level. Via gene targeting, cells have the capacity to align two homologous DNA sequences (two sequences that are quite similar) and exchange one with the other - allowing the cell to exchange the new active sequences in place of the old inactive ones. The new sequences must be introduced precisely in order to allow the proper initiation of gene expression. The ability to detect use of these cloned cells will be the next challenge for the detection agencies. |
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