An experimental ‘armed antibody’ drug from Roche will ensure longer survival times for women with an aggressive type of advanced breast cancer, including preventing their disease from worsening.

Trastuzumab emtansine (T-DM1), the new combination drug has shown a 41% improvement in HER2-positive breast cancer patients taking T-DM1, and which showed no worsening of their breast cancer, in comparison with those given trastuzumab or Herceptin, along with chemotherapy, according to data from a mid-stage clinical trial.

Study lead Sara Hurvitz, said since far fewer T-DM1 patients stopped treatment during the phase II trial, there was significant reduction in side effects in the T-DM1 group, of particular importance and meaningful clinically.

These study results have given a boost to medicine, Roche has been developing with ImmunoGen to succeed blockbuster Herceptin, with over $5 billion in sales in 2010.

Hurvitz, Director of the Breast Oncology Programme at University of California, Los Angeles, said the study data showed first-line T-DM1 treatment ensured longer survival times without cancer progression and fewer side effects, in comparison with standard chemotherapy and trastuzuma.

The 137 patients involved in the study, who had not undergone any chemotherapy or HER2-targeted therapy, lived 14.2 months when given T-DM1 without any worsening of the disease, in comparison to 9.2 months for those being given a combination of Herceptin and chemotherapy.

T-DM1 combines trastuzumab, an antibody and the active ingredient in Herceptin with agent DM1, derived from an extremely powerful type of chemotherapy called maytansine, delivers its toxic payload to cancer cells.