Strict rules govern how firms test new treatments but withdrawing a drug can have adverse effects for patients trialing them, writes Dominic Coyle
Clinical trials are always a risk, both for patients and for the companies trying to prove the efficacy of their products.
From the company's perspective, trials can throw up all sorts of unexpected results despite the best research and preparation. Adverse results can be catastrophic for businesses whose shareholders and other financial backers invest largely on the basis of drug pipelines and the prospects of future sales success.
For the patient, the situation is even more critical. Most are seriously unwell in the first place, sick enough to take the risk of being dosed with an experimental drug that may prove beneficial but, then again, might not.
Ann (not her real name) has been battling with multiple sclerosis (MS) since her early 30s. As the condition progressed, she found her declining mobility made her more dependent on her husband and family. Worse still, for a woman who worked with her hands, she found herself suffering from diminishing sensation in her hands and feet.
When Elan Pharmaceuticals and Biogen Idec began clinical trials for Tysabri, then called Antegren, her neurologist put her name forward. Apart from the MS, Ann was young, healthy and had a clean medical history in that she had not been taking a series of medicines that might contaminate the trial.
"I enrolled in trials because I thought it mattered a lot, I thought, maybe, one person might not have to wake up every day, lying very still, taking mental inventory of fingers and toes before daring to move as a result of the decisions of myself and others to take part in the trial and that would have made it all worthwhile."
Ann was lucky initially. The experimental drug was designed to slow down the progression of her disease, not reverse its physical symptoms.
"I certainly did not expect to find a miracle, just a small step to help those walking behind me would have been enough. I'd have been happy with that. But it was a miracle, from my point of view, I was so alive. I was healthy and strong and so happy."
From a position where her mobility was borderline, Ann had almost fully recovered from the physical symptoms of her condition.
Ann spent three years on the trials and, as a result of her positive experience and that of the trial patients in general, Tysabri won fast-track approval from the US regulator, the Food and Drug Administration (FDA), for sale on the open market late last year.
Then, in February, disaster struck. Follow-up studies indicated that two people in a trial of the drug along with an existing Biogen MS treatment, Avonex, had contracted a rare and potentially fatal brain disease, progressive multifocal leukoencephalopathy (PML). One died.
The drug was withdrawn and one subsequent case of PML emerged in a trawl of existing patient data.
All three cases of PML involved people who had been taking a range of other drugs including immunosuppressants and steroids.
"I was gutted," says Ann, who was on the trial using Antegren/Tysabri on its own. No one on that MS trial has shown signs of PML. "Going into the trials, the most important thing for me was to never compromise them in any way, not even a sip of beer. That's why I am so disappointed that so many very sick people were in trials and that spelled a horrible verdict for a very good drug."
Six months down the line, Ann is now confined to a wheelchair and losing her sight. She is angry at losing the gains she had made and desperate to see Tysabri back on the market.
"I understand the importance of safety and the need for the companies and the regulator to be careful. But the fact is that the one thing that was allowing me to live with dignity has been taken away from me.
"I would sign any consent form to enable me to access Tysabri again. People need to understand how important trials are to those of us who find ourselves in this position," says Ann.
Elan and Biogen are currently talking to the FDA about bringing Tysabri back to market.