Exanta Withdrawn After Liver Damage to Patient
by Richard Irving
It was once touted as a $3 billion wonder drug
to replace an ancient medicine commonly used as a rat poison. Yesterday,
however, Britain's second-biggest pharmaceuticals maker finally pulled
the plug on Exanta, developed at a cost of several hundred million pounds,
after a patient testing the treatment suffered severe liver damage.
Shares in AstraZeneca fell after the Anglo-Swedish group said that it would pull the drug from sale and halt all further development work.
The drugs giant once had high hopes that Exanta would replace warfarin as a blockbuster medicine to treat thrombosis. Regulators in about a dozen countries had approved the drug as a blood-thinner for patients who had undergone hip or knee replacements.
However, AstraZeneca suffered a crucial blow in September 2004 when the US Food and Drug Administration refused to approve the treatment, citing concerns that it might cause liver damage if used over a long period.
The move shocked analysts and doctors, who had expected regulators to embrace any improvement to warfarin. Sir Tom McKillop, then the company's chief executive, was so incensed that he threatened legal action.
Yesterday AstraZeneca said that new trials of the drug had unearthed new safety concerns after a patient using Exanta over a longer period had suffered liver damage. A company spokesman declined to give further details, except to say that the problem had not resulted in death and that the patient was now receiving appropriate care.
About 400 people in Europe, Brazil and Argentina were taking the drug. A further 600 patients were testing Exanta for other indications in clinical trials that were halted last night. The drug generated just $575,000 (£330,000) in sales in 2005.
Analysts argued last night that AstraZeneca was unlikely to face a raft of class action lawsuits similar to those that swamped Merck when the American drugs maker unexpectedly pulled Vioxx from the market, emphasising that the company had not experienced safety problems with the treatment before.
David Brennan, who took over from Sir Tom last month, described the withdrawal as a precautionary measure to preserve patient safety.
Mr Brennan added that AstraZeneca was determined to find a replacement for warfarin, insisting that work on a follow-up compound to Exanta, so far known only by the codename AZD0837, would continue. However, the new compound, which works in the same way as Exanta but has a different chemical make-up, is at least five years away from pharmacy shelves.
News of Exanta's demise is not entirely unexpected. In an interview with The Times this month Mr Brennan admitted that the drug would never be commercially available in the United States. Shares in AstraZeneca fell 6p to £26.16.
Drug's Decline
· July 2003: Exanta trials reveal signs of potential liver damage,
unnerving shareholders
· October 2003: AstraZeneca says development is on track and pledges
to file for approval in the US by the end of the year
· December 2003: Exanta bounces back when French regulators approve
treatment
· July 2004: first suggestions that the US Food and Drug Administration
might be concerned at Exanta's links to possible liver damage
· September 2004: FDA declines to approve Exanta. Sir Tom McKillop,
chief executive, says the FDA is misguided
· October 2004: Sir Tom insists company is dedicated to Exanta
· December 2004: regulators in France review safety of Exanta
· February 2005: Shareholders file lawsuit alleging that handling
of Exanta launch was botched
· February 2006: David Brennan, new chief executive, admits Exanta
is commercially doomed in US. Company pulls drug from market
The Times, 15th February 2006
