Cycling has led the sports pack in terms of performance-enhancing drugs like erythropoietin (EPO). [© V.RUMI - Fotolia.com]
Cyclists aren’t riding at quite the same fast clip, suggesting that doping among champion bike riders is slowing down as well. As riders cruised into Paris last month at the end of this year’s Tour de France, after racing 2,131 miles over 23 days, it appeared that doping may not have played the dominant role it once did in this highly competitive sport.
Cycling has led the sports pack with a legendary bad record for doping, rivaling only baseball in its use of performance-enhancing drugs, most notably erythropoietin (EPO). The finishing climbs in the 2010 and 2011 Tours de France were slower than those of the 1990s and the 2000s, some by many minutes. The fastest riders on three of the last climbs in the Tour were three minutes slower than many of the fastest riders on the same climbs during the 1990s and 2000s, according to The New York Times.
This June, the Biotechnology Industry Organization (BIO) said it had endorsed the “joint declaration on cooperation in the fight against doping in sport” between the World Anti-Doping Agency (WADA) and the International Federation of Pharmaceutical Manufacturers and Associations (IFPMA).
The declaration between WADA and the IFPMA outlines cooperative efforts to identify medical compounds with doping potential and facilitate development of detection methods in the context of the fight against doping sport.
Drugs used in bike doping have included EPO, blood doping (infusions of packed red blood cells), human growth hormone, stimulants, and diuretics. EPO was pretty much the drug of choice in cycling, working by stimulating the production of red blood cells to increase the blood’s oxygen-carrying capacity, consequently increasing the amount of oxygen that can be carried from the lungs to the muscles.
Cyclists typically inject EPO prior to a big training block out of competition to ensure that by the time of the competition all traces of the synthetic EPO will have disappeared. EPO enables athletes to train harder and longer.
Users can also micro dope to stay under the testing detection limits. Until a urine detection test became available in 2000, use and abuse of EPO was more the rule than the exception among professional bike racers.
On June 1, 1989, FDA approved Amgen’s EPO Aranesp, a recombinant version of a naturally ocurring hormone produced in the kidneys, as a treatment for anemia in kidney dialysis patients. The next day Amgen shipped its first batch of the drug to UCLA Medical Center. By the end of June, it had sold nearly $17 million worth of the drug, its first product after nine years in business.
EPO variations also become used for doping almost as soon as they hit the market. Roche received sanction from the FDA in January 2008 to market a continuous erythropoiesis receptor activator (CERA), under the trade name Mircera (methoxy polyethylene glycol-epoetin beta), for the treatment of anemia in patients with chronic kidney disease. Mircera is a third-generation erythropoiesis-stimulating agent administered either once every two weeks to correct anemia or once per month to maintain hemoglobin levels.
Mircera made its appearance as a doping agent in endurance sport as professional cyclist Riccardo Ricco tested positive in a urine sample test in the 2008 Tour de France and was dismissed from the race by his team and arrested by the French police. Later that year samples from about 30 tour riders were re-tested using a new, more effective blood-based test for CERA. In October 2008, three champion cyclists tested positive for the drug.
Companies producing therapeutics hardly imagined that their medications would become the drugs of choice for enhancing competitive athletic performances. Steve Elliott, Ph.D., a scientific executive director of Amgen, who was involved in the development of Aranesp, told GEN that with regard to the potential risks of using EPO and similar drugs, “the purpose of clinical trials is to define an optimal risk-benefit profile for using EPO. If you use it as prescribed, you do well.”
What an athlete does, he explained, is completely different. “A patient treated with EPO is anemic, with low hemoglobin, and they are being brought up to near-normal. An athlete is already at normal and is trying to go to super-normal. No clinical trial has taught us how to do that safely; there’s no understanding of it, and any attempt to do it is foolish.”
As companies help sports stay ahead of doping, secrecy surrounds new test development. Dr. Elliott noted, “A lot of what happens is not made public. I attended a meeting that was organized to discuss EPO testing for the 2002 winter Olympic games, all behind the scenes.
“We discussed what a test might look like in the fall of 2001. The games were March of 2002. A lot of drama and espionage went into the development and implementation of the test by the doping lab, and we were involved. The test strategies aren’t revealed in advance because athletes could potentially use the information and do something different in order to still cheat.
“We need two classes of tests,” Dr. Elliott said. “The ideal is the direct test to determine whether you have the drug on board. The other is an indirect test, looking at the effects of doping, for example sudden changes in red blood cell concentration.”
To detect doping with EPO, urine samples collected from athletes are tested by WADA-accredited laboratories. In recent years, however, the test’s reliability has been seriously and credibly questioned by scientists from the Copenhagen Muscle Research Center in Denmark in a 2008 article published in the Journal of Applied Physiology.
The researchers injected eight males who were recreational athletes with EPO and collected urine samples before the injections on eight more occasions. They then sent two identical sets of samples to two separate, WADA-approved testing labs. The results proved widely divergent, with one lab detecting numerous positive results and the other detecting no positive results.
Drug companies that produce EPO have helped antidoping laboratories develop direct tests based on minute differences between the recombinant molecules and the natural form. But, as athletes increasingly obtain knock-offs produced in China and India with subtle biochemical differences, testers have trouble staying ahead in the race. To date, only costly and time-consuming isoelectric focusing techniques can distinguish among glycosylation patterns on these molecules and distinguish among recombinant and endogenous forms of EPO.
Martial Saugy, Ph.D., the director of the Swiss Laboratory for Doping Analyses, and his team have developed another testing technique. Instead of looking for drugs or minute traces of their breakdown products in blood and urine, they pioneered the “biologial passport,” which builds up a profile of an individual over time, trying to detect biochemical changes that indicate doping.
Since 2008, Dr. Saugy’s laboratory and the International Cycling Union (UCI), cycling’s international federation based in Aigle, Switzerland, have created biological passports for hundreds of professional cyclists, some containing data from dozens of blood draws.
Rather than ordinary spot-testing approaches that look for unnatural ratios between biological constituents in a single sample or for direct chemical evidence of known doping agents, the passport allows investigators to find deviations from the rider’s test-established norm that might result from doping, even if the specific drug or tactic remains unknown.
For example, the test will look at reticulocyte formation (level of immature blood cells) to determine whether accelerated or decellerated reticulocyte production is occuring. According to Michael Ashenden, Ph.D., a sports scientist and a member of the independent board UCI has assembled to evaluate the profiles, each member of the group can examine whatever markers he or she chooses in blood profiles.
“I tend to scrutinize reticulocyte [immature red blood cell] values,” Dr. Ashenden said, “to see if there are any signs of accelerated or decelerated reticulocyte production.” An acceleration, he says, might point to use of EPO to increase red blood cell production, while a decrease indicates that the athlete just stopped using EPO or recently took a transfusion of stored red blood cells, the process for which the term “blood doping” was coined.
The main benefit of the passport, Dr. Elliott remarked, is that it serves as a warning to athletes that, behind the scenes, they are being watched. As doping practices continue to become more sophisticated, WADA says it will further develop and refine this passport strategy to monitor a selection of an athlete’s biological parameters over a period of time, ideally throughout his or her career, to detect abnormal variations.
Dr. Elliott noted that a critical element to managing the risk that a drug will be used for sports doping remains the development of detection assays even before a drug is launched. And while this year’s relatively longer race times in the Tour may signal diminished use of doping, the ultimate disincentive may prove to be a real fear of getting caught by newer, better testing.