Researchers develop new drug that puts cancer cells to 'sleep' in mice

Australian scientists have taken a "major step forward" in the world of cancer research with the discovery of a new type of drug that can put cancer cells in animals into a permanent state of sleep. The drugs, which have been nearly a decade in the making, are the first of their kind: they stop cancer cells from reproducing without the harmful side effects caused by conventional cancer therapies.

"We are extremely excited about the potential that they hold as an entirely new weapon for fighting cancer," said Associate Professor Tim Thomas from Walter and Eliza Hall Institute of Medical Research, who co-led the study.

The research, published today in the journal Nature, found the drugs were effective in halting the progression of blood and liver cancers in mice, as well as in delaying cancer relapse. "The drugs were well tolerated in our preclinical models and are very potent against tumour cells, while appearing not to adversely affect healthy cells," Dr Thomas said.

Conventional drug treatments cause irreversible DNA damage to cancer cells, but also damage healthy cells; this is where the side-effects of chemotherapy come from. The new drugs were designed to stop the production of specific proteins that drive cancer growth. "This class of compounds stops cancer cells dividing by switching off their ability to 'trigger' the start of the cell cycle," said co-author Associate Professor Anne Voss. "The cells are not dead, but they can no longer divide and proliferate. Without this ability, the cancer cells are effectively stopped in their tracks." The researchers now hope the drugs may be effective in halting the progression of cancer or delaying its recurrence in humans. "The drug we've developed is a proof of concept … the next step is to develop more suitable compounds that work in the same way but that can be used in cancer patients," Dr Thomas said.

He added that it was too early to say how the drugs could be used in clinical settings, but researchers were excited about a number of different applications. "We can imagine there would be certain cancers where this mechanism we are targeting is really the driver of cancer, and then in other situations it may be more useful as a therapy to prevent relapse," he said.

"But we don't think every cancer under every circumstance will be susceptible, and this is because we're targeting a specific mechanism, rather than growth generally."

According to Dr Thomas, a number of large pharmaceutical companies had tried in the past, and failed, to develop drugs that inhibit the cell mechanism at the centre of this research. "This was a particularly difficult class of proteins to target … It was considered to be perhaps even undruggable," he said. "It took several years to develop a highly specific compound which targeted the pro- cess we are interested in, and then it took a number of years to demonstrate this really did work in laboratory models." Dr Thomas said the next step was to seek industry partnerships to take the new drug concept into human trials. (Courtesy ABC News)