ASCO: T-DM1 Extends Progression-Free Survival in Women with HER2-Positive Metastatic Breast CancerWednesday, June 6th, 2012
An abstract presented at the 2012 Annual Meeting of the American Society of Clinical Oncology (ASCO) has announced the results from the trastuzumab emtansine (T-DM1) phase III EMILIA trial. The trial compares T-DM1 as monotherapy to lapatinib (TykerbÂ®) plus capecitabine (XelodaÂ®; [L+C]) for the treatment of HER2-positive metastatic breast cancer that has progressed after treatment with trastuzumab (HerceptinÂ®) and a taxane in any setting (early or metastatic disease) in 991 women. T-DM1 is an example of an antibody-drug conjugate, combining trastuzumab with the cytotoxin DM1, via a linker. The conjugate is 100 times more potent than paclitaxel.
Among the study findings reported:
- Treatment with T-DM1 significantly improved progression-free survival (PFS) compared with treatment with L+C. Median PFS was 9.6 months compared with 6.4 months, respectively. T-DM1 reduced the risk of cancer progression by 35% (hazard ratio [HR], 0.65; P<0.0001).
- Data for overall survival (OS), a co-primary endpoint of EMILIA, are not mature at this time. A longer follow-up is required.
- For patients treated with T-DM1, the estimated 1- and 2-year survival rates were 84.7% and 65.4%, respectively. For the patients receiving L+C, the estimated 1- and 2-year survival rates were 77.0 % and 47.5%, respectively.
- Patients treated with T-DM1 experienced more severe adverse events (AEs) than those treated with lapatinib plus capecitabine (40.8% versus 57%, respectively). The most common AEs were low platelet count, increased enzymes released by the liver/other organs, and anemia. These findings are consistent with previous studies.
The only subgroup where the drug did not deliver an advantage over the comparator arm was in women older than 65 years of age, who comprised only a small fraction of the trial. But according to the National Cancer Institute (NCI), the median age of breast cancer diagnosis is 61 years of age, and roughly 40% of all women are diagnosed at 65 years of age or older.
In addition to the EMILIA trial, T-DM1 is in phase III testing for treatment of HER2-positive metastatic breast cancer in the MARIANNE and TH3RESA trials.
- Blackwell KL, Miles D, Gianni L, et al. Primary results from EMILIA, a phase II study of trastuzumab emtansine (T-DM1) versus capecitabine (X) and lapitinib (L) in HER2-positive locally advanced or metastatic breast cancer (MBC) previously treated with trastuzumab and a taxane [abstract LBA1]. ASCO Annual Meeting, Chicago, IL. June 1-5, 2012. Available at: http://abstract.asco.org/AbstView_114_98675.html. Accessed June 6, 2012.