Chemotherapy can save lives, but it comes with some unpleasant side effects. The drugs target rapidly dividing cells, which allows them to home in on tumors, but they also kill normal cells such as those in hair follicles. Although the resulting hair loss is not life-threatening, it can be extremely distressful to patients. Now a team reports that they can prevent chemotherapy-induced hair loss in rats by first rubbing the animals' skin with a newly developed drug.
The new drug targets an enzyme called cyclin-dependent kinase 2 (CDK2), which drives a key step in the cell division cycle. Many researchers in both industry and academe are looking for CDK inhibitors, mainly in hope of developing agents to block the growth of cancer cells. But William Kaelin of the Dana-Farber Cancer Institute in Boston, who is among those doing this work, points out that CDK inhibitors offer two possibilities. They can be used, he says, to find "either smarter ways to kill cancer cells or smarter ways to protect normal cells."
Focusing on the latter goal, a team led by Stephen Davis of Glaxo Wellcome Research and Development in Research Triangle Park, North Carolina, developed a potent CDK2 inhibitor suitable for topical application. The researchers tested the drug in two animal models. In one, the researchers transplanted human scalp hair onto mice. When they applied the CDK2 inhibitor to the actively growing hair transplants, the researchers report in the 5 January issue of Science, it temporarily inhibited hair follicle cell division. In a second model, they rubbed the drug into the hair of newborn rats and then gave them a chemotherapeutic agent. The drug prevented hair loss in half the animals and reduced it in another 20%. It wasn't as effective against a combination of two chemo drugs, protecting only 33% of the animals from hair loss. Davis also says that his team didn't detect any interference with the ability of the chemotherapeutic drugs to kill cancer cells in animal tumor models.
Oncologist David Fisher of Dana-Farber describes the work so far as an "enormous advance." He speculates that it might also be possible to design inhibitors to protect other normal tissues that are damaged by chemotherapeutic drugs. The lining of the gut--where damage causes nausea and vomiting--is one possibility, if a nonabsorbable version can be produced.