Our laboratory studies cancer stem cells. I have blogged about these cells before. Cancer stem cells are thought to be a small population of cells within a tumor that are resistant to chemotherapy and are capable of regenerating a new tumor. Thus, these cells are thought to be responsible for local relapses and for metastatic disease. Because they are resistant to chemotherapy, our usual treatments don’t get rid of them, so finding ways to kill these cells is critical to the further advancement of cancer treatment.
There are many theories to explain the resistance of cancer stem cells to chemotherapy. One of these is that there are important metabolic differences between cancer stem cells and most other cancer cells. One such difference might involve a signaling pathway called mTOR. mTOR stands for “mammalian target of rapamycin.” Rapamycin is a drug that is used primarily to prevent the rejection of transplanted organs. It turns out that rapamycin works by interfering with the function of a specific enzyme that was given the name mTOR.
For a variety of reasons, inhibiting mTOR activity has been predicted to make cells more sensitive to chemotherapy. In collaboration with another researcher at Johns Hopkins, Jonathan Powell, our laboratory has done some experiments that seem to show that inhibiting mTOR increases the sensitivity of cancer stem cells to chemotherapy.
Last winter, we responded to a call from the National Comprehensive Cancer Network for research proposals utilizing an mTOR inhibitor for the treatment of cancer. Based on our laboratory data, we proposed a clinical trial that would treat patients with a combination of a chemotherapy drug (liposomal doxorubicin, or Doxil) and an mTOR inhibitor (in this case temsirolimus, or Torisel).
In March we learned that our proposal would be funded.
On Monday, I signed the contract that will allow our clinical trial, now approved by the Institutional Review Board, the Food and Drug Administration, and the Johns Hopkins Clinical Research Committee, to begin to enroll patients. We hope to treat our first patients in late August.
I can’t wait to see whether we are able to help the patients willing to enroll in this trial! How gratifying it would be to know that work in our lab led to a new way to treat cancer patients. That, after all, is why we do this.