The US Food and Drug Administration (FDA) has approved Genentech’s Kadcyla (ado-trastuzumab emtansine or T-DM1) for the treatment of HER2-positive metastatic breast cancer (mBC).

Kadcyla, an antibody-drug conjugate (ADC), has been developed by joining trastuzumab antibody with a chemotherapy drug DM1 using a stable linker.

The FDA approval was based on the positive results from the international, randomised, open-label Phase III EMILIA (TDM4370g/BO21977) study, which compared Kadcyla alone to lapatinib in combination with Xeloda (capecitabine) in 991 patients.

The study enrolled patients with HER2-positive locally advanced breast cancer and who had previously been treated with Herceptin (trastuzumab) and a taxane chemotherapy.

The results showed that patients treated with Kadcyla had a median progression-free survival of 9.6 months compared to 6.4 months in patients treated with lapatinib plus capecitabine, and median overall survival of 30.9 months in the Kadcyla group compared to 25.1 months.

The study also demonstrated that patients taking Kadcyla experienced a 32% reduction in the risk of dying compared patients receiving lapatinib and Xeloda (HR=0.68; p=0.0006).

The company has also submitted a marketing authorisation application for Kadcyla, which is currently under review by the European Medicines Agency (EMA).

Genentech, which has licensed the technology for Kadcyla under an agreement with ImmunoGen, expects the drug to be available in the US within two weeks.

As part of the approval, Genentech plans to initiate patient assistance programmes for people taking Kadcyla through Genentech Access Solutions.

Image: Building 32, part of Genentech headquarters in San Francisco, US. Photo: Courtesy of Coolcaesar.