In breast cancer treatment the approach has always been to try and kill all of the cancer cells. But what if you instead tried to place metastatic cells in a state of dormancy, keeping them inactive and unable to give rise to new tumors?
That’s the focus of a new study and it opens the door to a potential new approach to treating fast evolving cancer cells.
“Most cancer therapy is targeted with the idea that we want to kill all of the cancer cells. Rid the body of cancer,” says Michael Wendt, as assistant professor at Purdue University in West Lafayette, Indiana.
Therein lies the problem. That’s not realistic. “There are lots of studies that suggest we’re never going to be able to do that,” Wendt added. “Cancer cells evolve so fast that they will always find a way to overcome any type of therapy.”
That led Wendt and a team of scientists from Purdue and other academic institutions to experiment with a different approach — contain the cancer and block it from developing and spreading, but leave it in place.
“An emerging concept in cancer treatment is that maybe we shouldn’t try to kill all of the cancer cells, but try to keep them in a low state that doesn’t generate any kind of symptoms. A sort of dormancy, if you will,” Wendt explained.
For this study, the researchers used the drug fostamatinib to keep cancer cells in a dormant state. Their findings appear in the journal Cancer Research. Fostamatinib is currently approved by the FDA for the treatment of immune thrombocytopenia, an autoimmune disease characterized by a low platelet count in the blood.
In this study, the drug was used in mice to test its effect on metastatic cancer cells (cancer cells that will spread cancer to other areas from the original tumor). Their research showed that fostamatinib was able to contain metastatic cancer cells and stop them from developing into full tumors.
This could be important because breast cancer can fool doctors. It can seem to be fully eradicated in a patient, when in reality cancer cells have spread to other parts of the body and have entered a latent state for many years. This escapes detection, and then suddenly the cancer blooms in different locations and the patient is now at far greater risk. Once these cells awaken, they tend to give rise to new and sometimes more aggressive and less treatable tumors.
“After you have breast cancer, you always get this dissemination of cancer cells,” writes Aparna Shinde, Ph.D., lead author of the Purdue study. “Breast cancer is no longer considered a curable disease — it is now considered a chronic disease because 10 or 20 year later, you can get secondary tumors because of the metastasizing cells.”
That’s why the study sought to see if containing metastatic cells and blocking their development would be more effective than trying to destroy every cancerous cell. Basically this approach would keep cancer cells in a dormant state.
The researchers in this study used fostamatinib because they knew that the drug inhibits the activity of spleen tyrosine kinase, a protein present in latent metastatic cancer cells. In the study, when they treated metastatic cancer cells with fostamatinib, those cells remained contained and did not give rise to new tumors.
“This is great because this a drug with low toxicity. It’s designed for people with chronic disease so that they can take it for a long time. So we think fostamatinib is a perfect candidate for this kind of years-long lock-‘n’-block type of approach,” Shinde writes in the study.
The problem with rolling into a full clinical trial to further explore the findings of this study is that, technically, the patients are in remission and disease-free. These patients probably have dormant cancer cells disseminating through their bodies, but there isn’t any way of detecting those right now. So, it would be virtually impossible to set up a clinical trial at this point.
Still, the promise of this approach of keeping metastatic cancer cells dormant rather than the futile approach of trying to kill every last cell merits extensive additional research.