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ZIDOVUDINE, the only drug licensed for the treatment of AIDS, causes
cancer in animals. Studies carried out by the manufacturer in the US, Burroughs
Wellcome of North Carolina, have shown that the drug can give rise to tumours
when given in high doses, by mouth, to mice and rats.

A letter sent out to doctors from the company says that the findings
‘must be balanced against the known risk of untreated HIV infection’. Commenting
on the studies, Ian Weller, of the Middlesex Hospital in London, said that
the news was not altogether surprising as zidovudine interferes with the
synthesis of DNA.

Researchers at Burroughs Wellcome found that vaginal tumours occurred
mainly in a group of mice given the highest of three doses of zidovudine.
The tumours tended to occur towards the ends of the animals’ lives.

Weller said that the liver removes the drug from the blood and converts
it into an inactive form much more efficiently in humans than in rodents.
The rats and mice in the studies, therefore, had much higher levels of zidovudine
in their blood than is usual in human patients.

Patients with AIDS and their doctors would still feel happy about taking
and prescribing zidovudine, even in the light of these results, Weller predicted.
But he added that the finding emphasised the need to retain a group of patients
taking placebos in studies such as the British Concorde trial, which is
designed to determine whether zidovudine can delay the onset of AIDS in
people infected with HIV.

Burroughs Wellcome points out that the results in rodents do not necessarily
mean that the drug can cause cancer in humans. The company is continuing
with work to determine the mechanism of the drug’s ability to cause tumours.

Experts on the AIDS epidemic in the US have attacked the Government
for being ‘unresponsive’ to the needs of people infected with the virus.

In a startling move, the President’s Commission on AIDS, scheduled to
report on the epidemic by August 1990, decided to speak now ‘because of
the urgency’ of the problem, the commission said last week. Its first report
states that ‘a series of problems have resulted in a health-care system
singularly unresponsive to the needs of HIV-infected people’. The pattern
of infection is ‘reaching’ crisis proportions among the young, the poor,
women and many minority communities’, the commission warned.