New Study Results for T-DM1: Treatment for Her2+ Breast Cancer

By Joyce Bichler, Deputy Director

We’re pleased report new data about trastuzumab emtansine (T-DM1) for treatment of HER2-positive metastatic breast cancer. As always, Breast Cancer Action works to make sure that all new drugs approved for breast cancer treatments provide benefit to patients (not just the companies that manufacture them). We evaluate treatments on whether they extend life, improve quality of life, or cost less than drugs currently on the market. Up until this week Genentech’s T-DM1 met this standard only because data showed it had less side effects than the current treatment. We are now pleased to report that the latest data, published in the current online issue of the New England Journal of Medicine, shows that T-DM1 also increases median overall survival (OS) for women with HER2-positive metastatic breast cancer by 5.8 months compared to those who were treated with lapatinib (Tykerb) plus capecitabine (Xeloda). This statistically significant result along with data that shows that T-DM1 had fewer Grade 3 or higher adverse side effects makes it a treatment that provides meaningful benefits to women with metastatic Her2-positive disease.

HER2-positive breast cancer, which accounts for less than a third of breast cancer diagnoses, produces an excessive amount of the protein human epidermal growth factor receptor 2. This protein expression allows for researchers to develop drugs that can specifically target these cells. T-DM1 enables targeted delivery of the chemotherapy DM1 to HER2+ cancer cells by linking it to the antibody trastuzumab (Herceptin).

The current results come from the EMILIA study which is a randomized phase 3 trial which enrolled 991 patients from February 2009 through October 2011 at 213 centers in 26 countries. Although other data from the study have been released earlier, this is the first report on overall survival. The data shows that T-DM1 significantly increased median OS to 30.9 months vs. 25.1 months for the control group, an increase of 5.8 months. In addition, overall serious side effects were lower in the T-DM1 group, 15.5% vs. 18% in the control group. The incidence of adverse effects Grade 3 or higher were also lower for those taking T-DM1, 40.8% for the T-DM1 group vs. 57% for the control group. The most common Grade 3 or higher adverse effects for the T-DM1 patients were a decrease of blood platelets and higher enzymes that can indicate kidney, heart or liver problems. The good news is not only that fewer women in the T-DM1 group had severe side effects but that the nature of the adverse effects women had were tolerable.

Because of the positive results of the EMILIA study, women who were in the control groups will now be offered the option to receive T-DM1. In addition, we are glad to see Genentech has opened an Expanded Access Program to provide T-DM1 to eligible patients while the company seeks FDA approval. Genentech has submitted an application to the FDA for use of T-DM1 in people with HER2-positve locally advanced or metastatic breast cancer who have received prior treatment with Herceptin and a taxane chemotherapy. Genentech has requested an expedited review of their application.

The cost of T-DM1 has not yet been reported yet we know this drug will have a high price tag. For example, Herceptin alone currently costs approximately $54,000 for a 12 month course of treatment. We hope that T-DM1 can get to the women who can benefit from this treatment and not be put out of reach for those who cannot afford it.

Breast Cancer Action has been following the progress of T-DM1 for some time now. We maintained a cautionary approach until there was data to show that this drug actually does make a difference in overall survival for women with metastatic cancer. We are pleased to see that it does. Increasing survival by almost 6 months is invaluable to those who have metastatic breast cancer as well as those who care about them. We will now push to be sure all who need and want this treatment will be able to have access to it, without the barriers of cost. And while we applaud Genentech for this addition to metastatic treatment options, we will continue to call for research and treatment options that go beyond these small increments in extending life. We need to address the root causes of breast cancer and stopping it before it starts and we need to have treatments that allow women to live long lives beyond their diagnosis of this disease.

This entry was posted in BCA News.