T-DM1 and Her-2 positive breast cancer
About 20 per cent of breast cancers diagnosed are HER2-positive. In some cases it can be particularly aggressive, and tends to strike women at younger ages. Worse it is often diagnosed at a late stage.
In its time Herceptin (trastzumab), a conjugated monoclonal antibody, was dubbed a ’wonder drug’ for HER-2 positive breast cancer patients. While there is no doubt Herceptin has helped, it doesn’t always work and in some cases where it works, its effects only last a year or so. A new drug pertuzumab has arrived which helps stop Herceptin being blocked in some cases. But the real question is - what’s a woman with stage 3 or 4 metastatic HER-2 positive breast cancer to do with few options remaining?
T-DM1
The solution could be yet another ‘wonder drug’ T-DM1, an experimental drug that’s been in several clinical trials. Often referred to as ‘super Herceptin’ by trial patients, T-DMI was developed in a joint venture between Herceptin’s owners, Genentech, and ImmunoGen, who prepared the cancer killing agent used. The idea is that Herceptin locks onto the cancer cells for the DM1 agent to do its job.
In one trial (the EMILIA study - a randomized phase III trial from February 2009 through October 2011 at 213 centers in 26 countries; New England Journal of Medicine, online), T-DM1 increases median overall survival for women with HER -2 positive metastatic breast cancer by 5.8 months compared to those who were treated with lapatinib (Tykerb) plus capecitabine (Xeloda). T-DM1 had fewer Grade 3 or higher adverse side effects.
In a phase II Clinical Trial presented at the Breast Cancer Symposium in San Antonio, Texas in 2012, 45 per cent of recipients had a positive response (defined essentially as a halt to tumour growth); and in a third of patients the tumours actually shrank. The FDA will probably insist that women treated with the drug become part of a large phase III clinical trial. Women currently taking the drug will be allowed to continue so that long-term usage and side-effects can be monitored.
See our Overview on Breast Cancer (HERE)
See our Review of Drugs (HERE)