Frank, Jirik, molecular, biologist,
Jirik: Treating tumors spread to the bone with new drugs at the Alberta Cancer Board
Technology provides shortcut to answers
So much of science is about exploring in the dark and making the best guesses you can to find a path towards the light. Sometimes, though, technology provides a shortcut—giving researchers a fresh set of eyes to peer into what was previously impenetrable. A breast cancer research project being led by University of Calgary molecular biologist Frank Jirik is a good case in point.
Jirik’s three-year project involves testing new drugs that might be used to treat tumours that have spread to the bone. Over time, these metastatic tumours trigger severe bone loss which leads to pain, limb fractures or even the collapse of spinal column vertebrale.
Current treatment methods are aimed at reducing tumour growth through radiation, chemotherapy or the use of a drug (bisphosphonates) to try to inhibit the ability of certain bone-destroying cells, known as osteoclasts. Since these treatments are only partially effective, and sometimes involve serious side-effects, there’s an urgent need to find better ways to arrest bone destruction—and to prevent the spread of the cancer in the first place.
Traditional animal studies investigating how metastatic tumours behave were limited by the researchers’ inability to peer into the bone structure, and left researchers guessing at when a particular drug started having an effect. Also, these types of studies were unable to detect subtle effects that a drug might have on the cancer—for example, an ability to reduce a tumour by 15–20 per cent rather than a 50–75 per cent change, which is the only kind you could see post-mortem.
“Everyone wants the magic bullet,” says Jirik. “You know, administer the drug and eliminate the tumour or kill it by 90 per cent. But if it has only a 15 per cent effect, that doesn’t make it useless. Maybe it can be used in combination with another drug, right? But unless you can detect that smaller difference, you might throw away a perfectly good drug.”
Enter a new technological innovation: the micro-computed tomography (micro-CT) scanner. With this device, the entire mouse can be put inside and imaged, much as a person would be in a normal CT scanner. Images can be taken on a regular basis and the mouse kept alive throughout the process. With the proper computer software, this technology is able to provide precise 3-D images of the bone, allowing for measurements down to the width of a single red blood cell.
Jirik and his colleagues are taking advantage of another recent technological advance. Using an enzyme found in fireflies, they inject mice with a chemical that, when it’s broken down, emits light. In this way, the cancer tumours are illuminated, allowing researchers to see how many there are, where they exist and to follow their growth in real time. It also lets them know exactly where to go with the micro-CT scanner to image what’s happening with the bone.
The ultimate goal, of course, is to benefit patients who may have only a few years left to live. “Once cancer comes back and spreads to the bone, it’s very hard to get rid of,” says Jirik. “So anything you can do to help the person live with the disease is going to improve their quality of life.”
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