Cancer cells adapt cunning ways to evade death. In a new instance, researchers have found yet another hiding place: the bone marrow
. There, breast cancer cells stow away and become immune to chemotherapy and other anticancer therapies. Thus remission is short-lived as, inevitably, these cancer cells emerge and deal another blow to the patients.
But, because researchers now know where the cancer cells hide, they can begin to target drugs that block cancer’s entry into the bone marrow. Another tactic is to flush the cancer cells from its secret hideout, so that conventional therapies will have a chance to kill these cells.
This year, an estimated 246,660 women in the US will be diagnosed with breast cancer – a disease that currently ranks as one of the most common causes of cancer deaths in American women. Because of public exposure and aggressive research, screening and treatment options have improved the outcome for breast cancer patients. Still, some breast cancer patients experience relapse despite being declared cancer-free. Where does the cancer hide only to reemerge?
As it turns out, some types of breast cancer cells have a special receptor – a “key” – on their surfaces. This key is specific for molecules called E-selectin, which are found in the blood vessels of the bone marrow. With the key, the breast cancer cells silently slip into the protection of the bone marrow, escaping the effects of chemotherapy and radiation treatments.
In bone biopsies taken from breast cancer patients, doctors find evidence of the migration of these cells into the breast cancer. They term these events “micrometastases.” Once safe, the cancer can reactivate and cause unexpected relapse events.
Knowing how the breast cancer cells get inside bone marrow has given researchers two new routes of action. The first is to force the hidden cancer cells back out into the open where they’re sensitive to anticancer treatments. Indeed, they found the cancer cells could be flushed out of hiding with a drug known as Plerixafor, which is used in bone marrow donation for this exact function.
The second line of treatment from this discovery is blocking cancer cell’s access to the bone marrow, either by destroying the key or altering E-selectin’s recognition to the cancer cells. One molecule under investigation is GMI-1271, which showed promising results in mice. The full extent of this drug is being investigated in human clinical trials.
"We are hopeful that by understanding how these breast cancer cells migrate through the body and what their life cycle is, we can discover ways to make them more vulnerable and treatable," said Dorothy Sipkins, professor at Duke University, and senior study author.
Additional source: Duke University press release