Cancer patients opt for unapproved drug
Internet trade pre-empts clinical trial.
Helen Pearson
An
experimental cancer drug shrinks tumours in rats with no apparent side
effects. The scientists behind the study plan to do a clinical trial in
humans, but it could take years to complete. Meanwhile, dying patients
begin taking the unapproved drug and collect their results on the web.
Both groups desperately want to save lives: but which is the right
route to follow?
This
scenario has been playing out in recent weeks for a compound called
dichloroacetate (DCA). It taps into long-running issues about whether
terminally ill patients should be able to get access to drugs that have
not yet had formal approval. Researchers fear that those taking the
drug could suffer unanticipated side effects; patients argue they don't
have the luxury of waiting for clinical trials to find out.
In
January this year, Evangelos Michelakis at the University of Alberta in
Edmonton, Canada, and his colleagues reported that DCA has seemingly
remarkable anticancer properties (S. Bonnet et al. Cancer Cell 11,
37-51; 2007). DCA is a small molecule that blocks an enzyme in
mitochondria - the energy-production centres in cells - causing more
glucose to be metabolized in the mitochondria rather than by a
different pathway in the cytoplasm. The compound has been in clinical
trials for years as a treatment for certain mitochondrial diseases, but
it has not yet been approved.
Mitochondria
also control cell suicide, and Michelakis wondered whether cancer cells
were suppressing these cellular structures to prevent the cells from
dying - and so thought DCA might reactivate them. When his team gave
DCA to rats that were growing human lung tumours, the tumours stopped
growing within a week, and three months later were half the size of
those in untreated animals. Other experimental drugs have had similar
effects. But DCA stands out because it seems to leave healthy cells
untouched, has been relatively safe in human trials, can be taken by
mouth and easily penetrates tissues. "If there were a magic bullet,"
wrote Newsweek about the discovery, "it might be something like dichloroacetate."