A NEW drug could save the lives of many children with leukaemia who have not responded to other treatments.
Children who were expected to have only weeks to live have shown improvements after treatment with clofarabine, a drug being developed by Bioenvision, a company with headquarters in Edinburgh.
Some of the children are still alive one to two years after the treatment, strongly suggesting that it will prove a valuable new weapon in treating what is still the commonest fatal illness in children.
Treatment of cancer in children has been one of the greatest success stories in medicine in the past 30 years. In the late Sixties, 850 children under the age of 14 died of cancer every year in Britain. Today the figure is 300.
The most marked improvements have been in treating leukaemia, the commonest childhood cancer. In 1960, a diagnosis with acute lymphoblastic leukaemia (ALL) or acute myeloid leukaemia (AML) amounted to a death sentence. Survival was measured in months. By the late 1990s, survival from ALL — defined as being alive five years after diagnosis — exceeded 80 per cent. Survival from AML was better than 50 per cent.
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The success has been achieved by the use of drugs to control the cancer, and bone marrow transplants to repopulate the body with healthy cells. But there are still about 100 children a year who do not benefit from existing drugs.
For them, clofarabine offers new hope of reducing the cancer sufficiently to allow a bone marrow transplant to succeed.
At a meeting in Oslo on Sunday the latest results of US trials involving this group of children were reported by Pamela Kearns, a specialist in childhood cancers from Bristol. The results showed that 15 out of 49 children with ALL showed a complete or partial response when treated with clofarabine, and the same was true for nine out of 35 children with AML. “A complete response means that leukaemia cells have almost completely disappeared from the bone marrow,” Dr Kearns said.
“A partial response means there has been a significant reduction in such cells. It’s still early days, but the length of time they are surviving is impressive.”
The trial in the US was led by Dr Sima Jeha, of St Jude’s Children’s Research Hospital in Memphis, Tennessee, who was unable to be in Oslo to present the results. She said: “The remissions are durable, allowing patients to go on to bone marrow transplants.”
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This will give them a good chance of a complete cure. Bone marrow transplants do not work unless the number of leukaemia cells can be reduced by drugs first.
A trial has been started at 11 centres across Britain to try to duplicate the US results. The plan is to recruit 60 patients, all of whom have failed to respond to existing drugs.
“There are not many such cases, so it would probably take us until the middle of next year to recruit all 60,” Dr Kearns said. “It’s exciting to have the opportunity to do these trials.”
The drug is also in a trial in adult patients with AML at a dozen hospitals in Britain. This was started last month, sooner than expected, because the results of a preliminary trial had been so successful. The first patient was treated in Edinburgh in August, and the plan is to treat another 64. Many adult patients are elderly, very unwell and cannot tolerate intensive courses of chemotherapy. The hope is that clofarabine will offer them a suitable treatment.
Dr Chris Wood, chief executive officer of Bioenvision, said when the trial got under way: “The fact that investigators chose to close the preceding study earler than planned because of its better-thanexpected results is testimony to physician confidence in clofarabine and the encouraging results obtained.”
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Clofarabine belongs to the nucleoside analogue class of drugs, designed to damage the DNA of cancer cells and kill them. Developed at the Southern Research Institute in Birmingham, Alabama, clofarabine was designed to combine the good features of two existing drugs in the same class, fludarabine and cladribine.
So far, clofarabine is not licensed for use in either the US or Britain, but applications for licences have been made. If all continues to go well it could be licensed in the US by the end of the year and in Europe by the middle of next year, according to Hugh Griffith, chief operating officer of Bioenvision.
The company also hopes that the drug may be effective against tumours of the pancreas and prostate.