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.
A novel approach
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 hope the drugs might 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 it was too early to say how the drugs could be used in clinical settings, but researchers were excited about several 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 just growth generally.”
Big pharma had tried and failed
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.
“We started this 10 years ago and screened nearly a quarter of a million different compounds.
“It took several years to develop a highly specific compound which just targeted the process we are interested in, and then it took a number of years to demonstrate this really did work in laboratory models.
“It’s taken about a decade to get to this point … and 52 people have been involved.”
Dr Thomas said the next step was to seek industry partnerships to take the new drug concept into human trials.
“It’s very important that we make sure the treatment is safe, and so we need to do a lot of safety and efficacy studies before we can say that this is ready to be rolled out in clinics,” Dr Thomas said.
A ‘major step forward’, experts say
Cancer biologist Darren Saunders from the University of NSW said the research was particularly significant because there are many genes involved in cancer growth that are “very difficult to make drugs against”.
“[This research] covers the full spectrum of understanding the basic biology of a disease, to going and finding a compound, and then designing a drug based on that, and testing it in animal models,” Dr Saunders said.
“It’s still a bit of step to get from where they are into an actual drug in humans, but this is a really important proof of concept that says this strategy works.”
Professor Greg Goodall from the Centre for Cancer Biology agreed and said it was a major step forward for cancer research.
“It really is a very large body of work with considerable importance and prospect for translation into human use,” Professor Goodall said.
“One would really be hoping for a pretty smooth sailing through those clinical tests and into clinical use for humans.”
The research was a long-running collaboration between the Walter and Eliza Hall Institute of Medical Research, Monash University, Cancer Therapeutics CRC, The University of Melbourne, Peter MacCallum Cancer Centre, and CSIRO.