New Cancer Drug Shrinks Tumors

annnie, Flickr
annnie, Flickr

Gotta love a new breast cancer breakthrough. This one just in: “A new targeted cancer drug has been shown to shrink tumors in women with metastatic breast cancer after an average of seven other drugs, including Herceptin, failed,” says Charlene Laino for WebMD.

The new drug is called T-DM1. The T stands for trastuzumab (that’s scientific for Herceptin), and the DM1 comes from an old chemotherapy drug called maytansine that was abandoned several decades ago after it was found to be too toxic for patients, according to Dr. Ian Krop of the Dana-Farber Cancer Institute in Boston.

Well, isn’t it still too toxic? Nope, because Herceptin only zeroes in on cancer cells that express HER2, says Krop, and DM1 is delivered only to those cells. “The cytotoxic drug goes right to the cancer cells, so it’s not floating around and causing other problems,” he says.  “And Herceptin still does all the things that Herceptin does.”

Herceptin is a drug used to fight HER2-positive cancers — tumors that have too much of a type of protein called HER2. Herceptin, a man-made antibody, binds to and blocks the HER2 receptor that appears on the surface of some breast cancer cells. It was one of my drugs, and it seems to be working — I’m alive five years after my diagnosis. But metastatic breast cancer (the kind that has spread to other organs) can become resistant to Herceptin, which is why researchers have been searching for new drugs to attack HER2.

With this new drug, tumors shrank in one-third of women studied (they all had breast tumors for an average of three years). In another 12 percent, tumors stopped growing for at least six months. The women had previously been treated with therapies including Herceptin, Tykerb and Xeloda, and each had failed.

“This is the first study looking at women who have failed so many other treatments,” reports Krop. He thinks the results (presented at the San Antonio Breast Cancer Symposium December 9-13) are as good as he’s ever seen in such a sick population. And researchers expect T-DM1 will perform even better in women with earlier-stage cancer.