Roche’s Kadcyla was significantly better than Herceptin at reducing the risk of breast cancer recurrence in certain patients with residual disease after surgery, according to new study findings presented at the San Antonio Breast Cancer Symposium.

Data from the Phase III KATHERINE study show that Kadcyla (trastuzumab emtansine) as a single agent significantly reduced the risk of disease recurrence or death by 50% compared to Herceptin (trastuzumab) as an adjuvant (after surgery) treatment in people with HER2-positive early breast cancer (eBC) who have residual disease following neoadjuvant therapy.

At three years, 88.3% of people treated with Kadcyla did not have their breast cancer return compared to 77.0% treated with Herceptin, marking an 11.3% improvement.

“The KATHERINE results demonstrate a significant reduction in the risk of recurrence of HER2-positive early breast cancer in people with residual disease after neoadjuvant therapy, and we look forward to submitting these data to health authorities as soon as possible,” said Sandra Horning, Roche’s chief medical officer and head of Global Product Development.

Kadcyla is an antibody-drug conjugate (ADC) engineered to deliver potent chemotherapy directly to HER2-positive cancer cells, potentially limiting damage to healthy tissues.

The drug is the only ADC approved as a single agent for the treatment of people with HER2-positive metastatic breast cancer who have previously received Herceptin and taxane chemotherapy, separately or in combination.

It is hoped that results from the KATHERINE trial will pave the way for the drug’s use earlier in the breast cancer treatment pathway.