Experimental drug shrinks lung cancer tumours in mice
Tumours formed from lung cancer cells completely disappeared in mice treated with an experimental drug, US scientists say.
"The profound effect on tumour growth in mice shows that switching off TOPK could be a promising approach for treating some cancers in the future" - Professor Peter Parker, Cancer Research UK
Researchers from the University of Chicago also found that certain side-effects linked to the drug, called OTS964, could be avoided when the treatment was delivered using a particular method.
The drug switches off the TOPK protein, which is thought to promote tumour growth in a number of human cancers, including lung and breast.
Study author Professor Yusuke Nakamura said TOPK appears to play an important role in the growth of cancer cells.
"Without TOPK the cells can't seem to divide,” he said.
“Instead they remain tethered by a tiny bridge. When that finally breaks apart, they can't close the membrane. Everything within the cells spills out, they suffer and then die."
In attempt to find a potential new drug to block TOPK, the researchers looked at 300,000 chemicals, producing over 1,000 of the most promising compounds – one of which was developed into OTS964.
Following encouraging results in cancer cells grown in the laboratory, the researchers assessed how effective the experimental treatment was in mice carrying tumours made up of human lung cancer cells.
They administered the drug intravenously to six mice, twice a week for three weeks. And according to their findings published in the journal Science Translation Medicine, the team observed rapid tumour shrinkage, which continued even after treatment stopped. In five of the six mice, the tumours completely disappeared.
But when the scientists initially administered the drug it was found to disrupt the processes that control how blood cells are made, causing side-effects that included anaemia and increased risk of infection.
To combat this, the drug was placed in tiny bubbles made out of the same material as a cell membrane, and administered using an injection.
These bubbles, known as liposomes, were found to work just as well as the initial injections of the drug with none of the blood-related side-effects.
Experts welcomed the promising findings of the study, but cautioned that more research will be needed before its effectiveness as a treatment for cancer in humans can be fully assessed.
Professor Peter Parker, a Cancer Research UK expert in cell signalling, said: “The findings of this early stage study are interesting, and the profound effect on tumour growth in mice shows that switching off TOPK could be a promising approach for treating some cancers in the future. But so far the results have only been shown in cells grown in the lab and in mice, leaving a number of questions unanswered.
“Piecing together the finer details of how TOPK controls cell division, and the consequences of switching it off, will be crucial before this potential new drug can be taken further into clinical trials.”
While this study primarily involved lung cancers, genetic analyses have linked the TOPK gene to breast, brain, liver, bladder and other solid tumours as well as certain types of leukaemia. Researchers have therefore speculated that the protein may also be a good drug target for these additional types of cancer.
The team behind this latest study are now working with oncologists at the university to begin a phase-1 clinical trial of OTS964 by the autumn of 2015.