Roche has announced that the phase III EMILIA study of trastuzumab emtansine (T-DM1) met its co-primary endpoint, of a significant improvement in the time patients with HER2-positive metastatic breast cancer (mBC) lived without their disease getting worse (progression-free survival; PFS). The study showed that the risk of disease worsening or death was reduced by 35 per cent for people who received trastuzumab emtansine compared to those who received lapatinib plus Xeloda (capecitabine) chemotherapy (HR=0.65, p-value <.0001).

The EMILIA study is the first randomised phase III trial of trastuzumab emtansine in patients with HER2-positive mBC who had previously received Herceptin (trastuzumab) and a taxane chemotherapy.

There was also a trend for patients who received trastuzumab emtansine to live longer (overall survival, or OS, the other co-primary endpoint of the study) than those who received lapatinib plus Xeloda, but these data are currently not mature. The safety profile of trastuzumab emtansine was consistent with that seen in previous studies, with fewer patients who received trastuzumab emtansine experiencing Grade 3 or higher (severe) adverse events (AEs) than those who received lapatinib plus Xeloda (40.8 per cent compared to 57 per cent).

The EMILIA data was presented in the plenary session at the 48th Annual Meeting of the American Society of Clinical Oncology (ASCO) in Chicago on June 3 by Kim Blackwell, MD, Duke University School of Medicine.

“The encouraging efficacy, safety profile and quality of life results from the EMILIA study support our belief that trastuzumab emtansine may have an important role for patients with HER2-positive metastatic breast cancer,” said Hal Barron, MD, chief medical officer and Head, Global Product Development. “We are working with global regulatory authorities to submit these data as quickly as possible and hope that trastuzumab emtansine will soon be available to patients with this aggressive type of breast cancer.”

Based on the EMILIA findings, Roche and Genentech plan to submit applications for trastuzumab emtansine in HER2-positive mBC this year to the European Medicines Agency (EMA) and US Food and Drug Administration (FDA).

Trastuzumab emtansine is an investigational medicine known as an antibody-drug conjugate (ADC). It is comprised of the antibody trastuzumab and the chemotherapy DM1 attached together using a stable linker. Trastuzumab emtansine is designed to target and inhibit HER2 signalling and deliver the chemotherapy directly inside HER2-positive cancer cells.

EMILIA (TDM4370g/BO21977) is an international, phase III, randomised, open-label study comparing trastuzumab emtansine alone to lapatinib in combination with Xeloda in 991 patients with HER2-positive locally advanced or metastatic breast cancer whose disease progressed after initial treatment with Herceptin and a taxane-based chemotherapy.

The co-primary efficacy endpoints of the study are PFS (as assessed by an independent review committee) and OS. Safety is also a primary endpoint of the study. Other study endpoints include and one-year and two-year survival rates, safety profile, PFS as assessed by investigator, objective response rate, duration of response and quality of life.

Trastuzumab emtansine is an ADC being studied in HER2-positive cancers. It is comprised of the antibody trastuzumab and the chemotherapy agent DM1 attached together using a stable linker. Trastuzumab emtansine is designed to target and inhibit HER2 signalling and deliver the chemotherapy agent DM1 directly inside HER2-positive cancer cells. Trastuzumab emtansine binds to the HER2-positive cancer cells, and is thought to block out-of-control signals that make the cancer grow while also calling on the body's immune system to attack the cancer cells. Once trastuzumab emtansine is absorbed into those cancer cells, it is designed to destroy them by releasing the DM1.

In addition to EMILIA, there are two ongoing Phase III studies of trastuzumab emtansine:

MARIANNE is comparing three different regimens (trastuzumab emtansine alone, trastuzumab emtansine plus pertuzumab, and Herceptin plus a taxane chemotherapy) in patients with HER2-positive mBC who have not been previously treated for their metastatic disease.

TH3RESA is comparing trastuzumab emtansine to physician's choice of treatment in people with HER2-positive mBC who have already received both Herceptin and lapatinib.

Genentech, a member of the Roche Group, licenses technology for trastuzumab emtansine under an agreement with ImmunoGen, Inc.