Smart Bomb for HER2+ Breast Cancer

HER2 breast cancer responds well to experimental drug TDM 1

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) HER2-positive breast cancer is one of the most aggressive forms of the disease. It tends to grow and spread rapidly. An experimental drug may halt this beast and offer a gentler ride for women living with it .

An investigational drug works like a smart bomb zeroing in on the HER2 targets in the tumor cells and delivering the added payload of chemotherapy.

And with all this power, the drug is less toxic than standard treatments.

"Ask about medications being tested in clinical trials."

A phase III clinical trial has found that the drug called trastuzumab emtansine, or T-DM1, slows the progression of HER2+ breast cancer, prolongs the lives of women living with it and does its work without the expected chemo side effects, including hair loss.

Kimberly Blackwell, MD, of the Duke Cancer Institute, led the three-year international study called EMILIA, which involved nearly 1,000 people with advanced HER2+ breast cancer.

HER2 stands for human epidermal growth factor receptor 2. It's a cell protein that encourages cancer cells to grow. It plays a role in about 20 percent of invasive breast cancers.

"This drug is significantly better than the current approved combination in keeping the cancer under control," said Dr. Blackwell, who is the director of the Breast Cancer Clinical Program at Duke and principal investigator of the international study.

"This is a drug that brings us another step closer to treating cancer without the side effects of chemotherapy. It's going to be a good option for patients faced with HER-2 positive tumors," she said.

Current therapies involve an antibody called Herceptin (trastuzumab) that latches onto the HER2 protein and messes with its ability to drive tumor growth.

Herceptin has been the gold standard for treating HER2 breast cancers. It's used alone or in combination with chemotherapies.

T-DM1 works with Herceptin, linking it directly with chemotherapy drugs.

Steven Libutti, MD, vice chairman of surgery and director of the Montefiore Einstein Center for Cancer Care, tells dailyRx, "The whole strategy of smart bombs or targeting the therapies directly to the tumor I think is a very rational one."

The investigational drug slowed progression by just over three months. Patients who received T-DM1 had no tumor growth for 9.6 months, compared to 6.4 months for those receiving the standard drug therapy.

"These are significant and clinically meaningful improvements against comparative drugs that are highly effective for this group of patients," Dr. Blackwell said.

After two years of treatment with T-DM1, 65.4 percent of patients were still living, compared with 47.5 percent of patients receiving the standard therapy.

While encouraging, the survival trend didn't meet the study's design goal. Overall survival rates will be analyzed later.

The drug also caused fewer side effects. While some patients suffered liver injury and a drop in blood platelets, most didn't experience hair loss, nausea, rashes and diarrhea, all of which are common with traditional chemotherapies.

Dr. Blackwell explained, "It delivers the drug directly to the cancer cells, while avoiding cells that don't really need to receive chemotherapy, which keeps patients from getting sick."

"As a clinician who takes care of breast cancer patients, it's important to have a treatment that is both effective and well tolerated," Blackwell said.

She concluded her remarks by saying simply, "This drug works."

Results from this trial were presented June 3, 2012 at the 48th American Society of Clinical Oncology annual meeting in Chicago

Based on these findings, Genentech, the drug's manufacturer, will seek marketing approval from the U.S. Food and Drug Administration.

Genentech and its parent company, Roche, funded the clinical trial.

Nine of the 14 authors (excluding Dr. Blackwell) disclosed financial relationships (consultancy, stock ownership, advisory roles) with a number of pharmaceutical companies, including Roche/Genentech, the manufacturer of T-DM1.

Reviewed by: 
Review Date: 
June 4, 2012
Last Updated:
September 13, 2012