Roche has submitted T-DM1, which combines its blockbuster Herceptin with partner ImmunoGen's chemotherapy drug DM1, with US regulators.

Specifically, the Swiss firm has submitted a Biologics Licence Application to the US Food and Drug Administration for T-DM1, an antibody-drug conjugate (ADC) combining Herceptin (trastuzumab) and DM1, in people with advanced HER2-positive breast cancer who have previously received multiple HER2-targeted medicines and chemotherapies. The submission is based on the results of a 110-women Phase II study which showed T-DM1 shrank tumours in 33% of women who had received on average seven prior medicines for advanced HER2-positive breast cancer.

Hal Barron, Roche’s chief medical officer, noted that “while we've made great strides in treating HER2-positive breast cancer, there is a group of people whose breast cancer will come back after many treatments, leaving them with very limited options”. He added that the data have shown that T-DM1 shrank tumours in these people, “so we are excited to have submitted this application to the FDA”.

It is pretty unusual for Phase II data to be the basis of a filing to the FDA but Roche noted that one Phase III trial is ongoing and another late-stage study is planned of T-DM1, alone or in combination with other medicines. The Basel-headquartered group has some 50 ADCs in early stages of R&D for multiple tumour types but this is the first to be submitted.

Analysts believe the combo could bring in $300 million for HER2-positive breast cancer and top more than $2 billion if approved for additional indications.