New drug causes cancer to "melt away" in patients with advanced leukaemia

It worked in 79% of patients.

A new drug has been shown to significantly reduce cancer cells in almost 80 percent of patients with an advanced form of leukaemia in a four-year clinical trial. In 20 percent of patients, it caused complete remission of the disease.

The new drug, Venetoclax, is taken in tablet form, and was given in varying doses to 116 patients in Australia and the US over a four-year period. The patients tested had advanced cases of chronic lymphocytic leukaemia (CLL) that all other conventional treatment options had failed to improve.

Despite their bleak prognosis at the beginning of the trial, 79 percent of the patients had their cancer cells reduced by at least half. Impressively, 20 percent went into remission, and had such a profound response that the most sensitive tests couldn't detect any remaining leukaemia cells in their bodies.

Based on the results, which have been published in The New England Journal of Medicine, Venetoclax has now been given Priority Review status by the US Federal Drug Agency (FDA) for treating certain cases of CLL. That status is only given to medications that the FDA deems as having the potential to provide significant improvements in the diagnosis, treatment, or prevention of a disease.

The drug achieved such impressive results by targeting a protein called BCL-2, which was shown in the 1980s to promote cancer cell survival. Venetoclax is the first class of drug that's been developed specifically to block the action of BCL-2.

In a field where many of the most promising treatments in the lab often end up failing in clinical trials, it's an incredibly exciting result. But the drug isn't perfect, which is why it's only being ear-marked for patients who have run out of other options.

Side effects experienced by some patients during the trials included nausea, pneumonia, diarrhoea, respiratory tract infections, anaemia, and prostate cancer. Some patients reported no side effects at all.

That doesn't sound great, but when all other treatments have failed, it's something patients might be willing to risk in order to greatly reduce their leukaemia cells.

CLL is one of the most common forms of leukaemia, with more than 14,000 people being diagnosed with the disease in the US in 2015, and more than 4,000 being killed by it.