Starving cancer cells shows potential

SAN FRANCISCO — Stanford University researchers have found a way to target and kill certain kinds of cancer cells by starving them to death, instead of blasting them with toxic chemotherapy drugs that can harm normal, healthy cells.

The discovery was studied in a common type of kidney cancer cell, but it could apply to tumors in other parts of the body as well. The therapy would work by turning off the cancer cells' ability to absorb glucose, which is often the primary source of energy in rapidly growing tumors.

So far scientists have found two possible drugs that could be used to starve the cancer cells, although neither has been tested in humans. If the drugs work, they may give doctors their first opportunity to kill off cells in the most common type of kidney cancer. And the drugs could offer an alternative to chemotherapy for many other types of cancer, researchers said.

“This discovery deviates from the traditional chemotherapy concept where you're given a cytotoxic agent, which is highly effective in killing tumor cells but also harms normal tissue,” said Amato Giaccia, director of radiation oncology at Stanford and an author of the study, which was published in Science Translational Medicine.

Targeted drug therapy is a major field of study in cancer treatment, and scientists around the world are focusing their research on finding new drugs that will attack and kill cancer cells and leave healthy tissue alone.

Kidney cancer is an especially active field for such research because treatments are very limited for the disease. The most common type of kidney cancer, renal cell carcinoma, isn't easily treated with radiation or chemotherapy. The main treatment is usually removal of the tumor or the affected kidney, along with drug therapy to stop the cancer from spreading.

Renal cell carcinomas are able to spread more quickly than normal tissues because of a specific genetic mutation that turns off the cancer cells' innate ability to suppress growth. In turn, that mutation makes the rapidly growing cancer cells especially reliant on glucose for energy.

The Stanford scientists looked for drugs that would target cells with that genetic mutation, then attack the cells' ability to use glucose. They screened 64,000 possible drugs and found five that seemed to do the job.

Two of those five have been studied thoroughly, and someday all of the drugs, plus others that have not yet been found, may be used together to attack cancer cells in humans, scientists said.

“I don't think we're going to have one magic bullet. It's going to be the combination of therapies that will work,” said Denise Chan, an author of the study.

Oncologists not affiliated with the study said they would be thrilled if the new drugs proved effective after further study in animals and, eventually, humans.

Treatment of renal cell carcinomas has improved dramatically in the past five years, but it's still one of the most difficult cancers to fight, and almost no one is cured of it, said Dr. Lauren Harshman, an oncologist at Stanford.

“The improvements in quality of life and potentially survival could be really dramatic,” Harshman said. “But again, this needs a lot more study.”