Cancer Stem Cells: Targeting the Root Causes of Cancer

Growing evidence suggests cancer stem cells are behind tumor growth and relapse. New therapies that target this subpopulation are needed, especially for the deadliest cancers.

by Robert Hariri

Therapies currently in development are not targeting the root cause of prostate cancer, according to a study recently published in the journal Cell Death & Differentiation. The origin, according to the authors of the study, resides in cancer stem cells.

Targeting cancer stem cells is being explored as a potential avenue to improve treatment for the most deadly forms of cancers such as pancreatic cancer.

Cancer stem cells are a subpopulation of cells within a tumor that researchers believe are the main suspect in the development of new solid tumors in a variety of cancers. These cells have two defining characteristics that are typically associated with stem cells. First, they can divide indefinitely, and second, they can differentiate—or transform into—a number of other cancer cell types. Those qualities make these cells particularly dangerous.

To make matters worse, many cancer therapies have a limited effect on cancer stem cells. These treatments target the general population of tumor cells but aren’t equipped to tackle this particularly stubborn subpopulation. So while current cancer therapies are often able to shrink the majority of the tumor, they leave behind the cancer stem cells that were responsible for forming the tumor in the first place.

Cancer stem cells may thus be one of the reasons cancers come back—or relapse—following otherwise successful treatment like surgery or chemotherapy. It’s similar to cutting off the top of a weed without removing the roots; in the end, the roots allow the weed to grow again.

While scientists still don’t fully understand the exact mechanisms behind cancer stem cells, most believe that these cells do play a vital role in the disease. “I’m a firm believer that the microenvironment, the stem cell ‘niche,’ is every bit as important as the cell itself,” Dr. Barbara Vonderhaar, a researcher at the National Cancer Institute’s (NCI) Center for Cancer Research, said to the NCI Cancer Bulletin. “I don’t know if just any cell can become [a cancer stem cell], but there is a hierarchy of cells, and some may be able to function in a stem cell-like manner, and others may not.”



Targeting cancer stem cells is being explored as a potential avenue to improve treatment for the most deadly forms of cancers such as pancreatic cancer. In a paper published in the journal Cancer Stem Cells in 2009, researchers reported the identification of pancreatic cancer stem cells in a population of pancreatic cancer cells.

Building off this work, a group of researchers at the University of Pennsylvania School of Medicine recently reverted a sample of human pancreatic cancer cells back to a stem-cell-like state to find a way to detect pancreatic cancer earlier. When placed inside a mouse model, these cells began forming early-stage tumors. In a paper published last year in the journal Cell Reports, the researchers reported the identification of cell signals that they believe could be used to detect or predict the early progression of the pancreatic cancer.

Meanwhile, biopharmaceutical companies are developing new therapies that target cancer stem cells. OncoMed, one of Celgene’s partners, is one such biotech company looking for more effective treatments for a variety of cancers, including pancreatic cancer and non-small cell lung cancer. This partnership demonstrates Celgene’s continued commitment to target the causes, not just the symptoms, of cancer.

Robert Hariri is the founder, chairman and chief science officer at Celgene Cellular Therapeutics.