British patients are among thousands around the world who may have been harmed by a new drug withdrawn from trials by Pfizer, the world’s biggest pharmaceutical company. Pfizer confirmed yesterday that it had abandoned development of torcetrapib after evidence from a trial involving 15,000 patients showed that it increased death rates from heart attacks and stroke.

The drug was designed to raise the levels of “good” cholesterol in the bloodstream. Its withdrawal is a blow to Pfizer, which was counting on it becoming a big seller. It was close to being submitted for a licence, a manufacturing plant had been built and preliminary data suggested that it had the potential to save millions of lives. It was was “both surprising and disappointing”, said, Jeffrey Kindler, Pfizer’s chief executive officer.

The decision to pull the plug came when data from a trial called Illuminate were analysed by the safety board, the only people allowed to see the data. The board found that in 7,500 people taking a combination of torcetrapib and atorvastatin (Lipitor) there had been 82 deaths from heart attack and stroke, whereas in a similar number taking atorvastatin alone there had been 51 deaths. Philip Barter, an Australian specialist who chaired the study’s steering committee, said: “We believed that the study was coming along as expected, and this new information was totally unexpected and disappointing, given the potential benefits of this drug.”

Pfizer had no choice but to abandon the trial, the drug and the $800 million (£400 million) it has spent developing it over the past 15 years. They told clinical investigators over the weekend to tell those taking the torcetrapib/atorvastatin combination to stop. The US Food and Drug Administration said in a statement that it supported the company’s decision.

Pfizer was unable to say yesterday how many British patients were taking the drug, but it was being provided as part of the trial at 22 sites, including London, Birmingham, Dundee, Bath, Cardiff, Edinburgh, Exeter, Glasgow, Romford and Warwick. If each site had recruited 60 partipants — the average across the study — about 1,300 patients in Britain would have been involved, half taking the combination drug and half Lipitor. But the numbers could have been greater or smaller than these. Pfizer was also unable to say if any of the deaths were in Britain.

There had been warning signs about torcetrapib. In earlier trials it had showed signs of raising blood pressure slightly, and elevated blood pressure is a risk factor for both heart disease and stroke.

Statins have achieved great success by lowering cholesterol levels. But the ideal is to lower the levels of “bad” LDL cholesterol and to raise levels of “good” HDL cholesterol. The combination being tried by Pfizer was designed to achieve this.

Torcetrapib works by inhibiting a protein in the liver that transports cholesterol. In a small trial reported in 2004, torcetrapib combined with a statin raised levels of HDL cholesterol by 61 per cent, a big change that ought to have translated into big benefits.

Pfizer, which has been hit by the expiry of patents on many of its drugs, had undertaken what it said was the “largest and most comprehensive clinical trial programme ever” to prove the benefits of the drug. Two days ago Pfizer said that it hoped to file an application with the Food and Drug Administration for approval of torcetrapib by the second half of next year.

Trial failure

1990 evidence published that raising HDL cholesterol would cut heart risks

1993 Pfizer develops a chemical that might be able to do it

1995 the chemical, called CP-529, shows that it works in test-tubes

1999 first human trials show how CP-529 works in the body

2003 $800 million phase III trials begin to test safety and efficacy

2004 15,000 patients sign up for a trial

2006 development of torcetrapib abandoned

Times Recommends

• Time-worn Freddie gives up Test matches
• Brighton company 'involved in cyber attack'
• The art of survival: it’s all in the mind