Although the cancer stem cell hypothesis for new cancer therapeutics is really no more of a gamble than any other current basis for cancer drug discovery, this article provides a timely, excellent perspective on its historical context and current nuances. The quoted stem cell scientists criticize with extreme requirements for “proof,” whereas the cancer physicians very appropriately demur to the bottom line: Will it lead to better cancer treatments, even if only in small additive improvements to existing therapies. Even if intrinsically active, cancer stem cell drugs must also deal with well-known generic barriers to effective delivery to cancer cell targets; but the effort would find advantages by deploying Asymmetrex’s technologies for counting both normal tissue stem cells and cancer stem cells.
15 January 2015 Article by Jocelyn Kaiser in Science Online
>60—Ongoing or planned cancer stem cell clinical trials200 million—Dollars invested so far in Verastem
THE CANCER STEM CELL model emerged in the mid-1990s, when stem cell biologist John Dick of the University of Toronto reported that his team had isolated rare cells in the blood of people with leukemia that seemed to play a key role in the cancer. Although such patients’ blood teems with aberrant white blood cells, only a few of them were capable of growing into a new leukemia when injected into mice. Those cells appeared to be misguided versions of the normal adult blood stem cells that differentiate into mature blood cells. Like normal stem cells, the cancer stem cells carried distinctive surface proteins and were self-renewing: They could divide to produce both a regular cancer cell and a new stem cell.
Verastem’s strategy is to screen approved drugs and other chemicals for their ability to block focal adhesion kinase (FAK), an enzyme that helps tumor cells stick to each other and also helps cancer stem cells survive. In the body, Weinberg believes, blocking FAK kills cancer stem cells directly and also makes it harder for these rare cells within a primary tumor to travel through the bloodstream and seed metastases.