Cancer therapy’s ‘next big wave’: radiation drugs that track and kill cancer cells

Doctors are reporting improved survival in men with advanced prostate cancer who were given an experimental drug that delivers radiation directly to tumor cells.

Few such drugs are approved now, but the approach could become a way to also treat people with other hard-to-reach or inoperable cancers.

“You can treat tumors that you cannot see,” said Dr. Frank Lin, who wasn’t involved in the study but heads a division at the National Cancer Institute that helps develop such medicine. “Anywhere the drug can go, the drug can reach tumor cells.”

The new study results were released by the American Society of Clinical Oncology ahead of its annual meeting this weekend.

The research, which was funded by Novartis, the drug’s maker, which plans to seek approvals in the United States and Europe later this year — tested an emerging class of medicine called radiopharmaceuticals, drugs that deliver radiation directly to cancer cells. The drug tested is a molecule that contains a tracker and a cancer-killing payload.

Trillions of these molecules hunt down cancer cells, latching onto protein receptors on the cell membrane. The payload emits radiation, which hits tumor cells within its range.

When cancer is confined to the prostate, radiation can be beamed onto the body or implanted in pellets. But those methods don’t work well in more advanced prostate cancer. About 43,000 men in the United States each year are diagnosed with prostate cancer that has spread and no longer responds to hormone-blocking treatment.

To get radiation treatment to such patients, the study involved 831 men with advanced prostate cancer. Two-thirds were given the radiation drug, the rest a comparison group. Patients got the drug through an IV every six weeks, up to six times.

After about two years, those who got the drug did better, on average. The cancer was kept at bay for nearly nine months versus about three months for the others. Survival was better, too — about 15 months versus 11 months.

That might not seem like much, but “these patients don’t have many options,” said ASCO president Dr. Lori Pierce, a cancer radiation specialist at the University of Michigan.

In the coming decade, such drugs “will be a major thrust of cancer research,” said Dr. Charles Kunos, who worked on standards for radiopharmaceutical research at the National Cancer Institute before leaving to join University of Kentucky’s Markey Cancer Center. “It will be the next big wave of therapeutic development.”

“There’s great potential” with drugs being tested for melanoma and breast, pancreatic and other cancers, said Dr. Mary-Ellen Taplin of Dana-Farber Cancer Institute in Boston, who had no role in the study but reviewed the data.