When chemotherapy alone is used to treat cancer, some dormant cells may survive and become resistant to additional treatment; but, when combined with immunotherapy, the majority of these cells may be destroyed, according to recent data.
While immunotherapies have burst onto the scene as a new, game-changing treatment strategy for various cancer types, physicians and health care professionals have struggled at times with discerning how and when these treatments should be administered.
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In a study published in the Journal of Leukocyte Biology, researchers led by Masoud H Manjili, PhD, Virginia Commonwealth University (Richmond, VA), treated breast cancer tumor samples with a common chemotherapy agent to see how cells would respond. They observed that the majority of cancerous cells died as a result, but that a residual population of tumor cells survived and became dormant. Populations of these cells were both indolent and quiescent, and were refractory to additional doses of chemotherapy or radiation therapy. In patients, these circumstances could lead to disease recurrence.
However, researchers also noticed that the indolent cells expressed low levels of Ki67 while the quiescent cells were Ki67-negative. When they treated the dormant cells with a product of the immune system, they found that both were highly susceptible to immunotherapy, although only the quiescent cells were unable to escape from treatment.
The results of this study suggest that administration of immunotherapy in a setting of advanced stage prophylaxis, ie, after the completion of conventional cancer therapies, when tumor dormancy is established but before distant recurrence of the disease, could effectively target dormant tumor cells and prevent advanced stage disease,” authors of the study concluded. “The challenge is to develop combinatorial therapies, ie, AIT, following the administration of epigenetic modulators or small molecules that could induce cell-cycle arrest and establish a quiescent type of tumor dormancy so as to render dormant tumor cells resistant to immunoediting and escape from immunotherapy.”
