A new class of medication stops cancer in its tracks by by putting cancer cells to sleep, preventing them from dividing and proliferating.
The discovery by Melbourne scientists, believed to be a world first, treats cancer without the harmful side effects caused by conventional cancer therapies and without damaging the cells’ DNA.
The new class of drugs could provide an exciting alternative for people with cancer and has already shown great promise in halting cancer progression in models of blood and liver cancers, as well as in delaying cancer relapse.
Research led by Associate Professor Tim Thomas and Associate Professor Anne Voss from the Walter and Eliza Hall Institute, Professor Jonathan Baell from the Monash Institute of Pharmaceutical Sciences and Dr Brendon Monahan from Cancers Therapeutics CRC investigated whether inhibiting KAT6A and KAT6B could be a new approach to treating cancer.
A/Prof Thomas said the new class of drugs was the first to target KAT6A and KAT6B proteins. Both are known to play an important role in driving cancer. KAT6A sits at number 12 on the list of genes most commonly amplified in cancers.
“Early on, we discovered that genetically depleting KAT6A quadrupled the life expectancy in animal models of blood cancers called lymphoma. Armed with the knowledge that KAT6A is an important driver of cancer, we began to look for ways of inhibiting the protein to treat cancer,” A/Prof Thomas said.
The compounds had already shown great promise in preclinical testing, he said.
“This new class of anticancer drugs was effective in preventing cancer progression in our preclinical cancer models. We are extremely excited about the potential that they hold as an entirely new weapon for fighting cancer.
“The compound was well tolerated in our preclinical models and is very potent against tumour cells, while appearing not to adversely affect healthy cells,” A/Prof Thomas said.
No more DNA damage
There is a critical difference between this new class of drugs and standard cancer therapies.
Chemotherapy and radiotherapy work by causing irreversible DNA damage. Cancer cells are unable to repair this damage, and they die. The downside is that the therapies cannot be targeted only to cancer cells, and cause significant damage to healthy cells as well. This causes well-known short-term side effects, such as nausea, fatigue, hair loss and susceptibility to infection, as well as long-term effects such as infertility and increased risk of other cancers developing.
“Rather than causing potentially dangerous DNA damage, as chemotherapy and radiotherapy do, this new class of anticancer drugs simply puts cancer cells into a permanent sleep,” A/Prof Voss said.
“This new class of compounds stops cancer cells dividing by switching off their ability to ‘trigger’ the start of the cell cycle,” she said. “The technical term is cell senescence. 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.”
A/Prof Voss said the team believed the drugs might be effective in delaying cancer recurrence.
“There is still a lot of work to be done to get to a point where this drug class could be investigated in human cancer patients,” she said. “However, our discovery suggests these drugs could be particularly effective as a type of consolidation therapy that delays or prevents relapse after initial treatment.
“The possibility of giving clinicians another tool that they could use to substantially delay cancer recurrence could have a big impact for patients,” A/Prof Voss said.
The research, almost a decade in the making, required strong collaboration between experts in cancer research, medicinal chemistry and drug discovery. The study has been published in the journal Nature.