Roche has been boosted by the news that the US Food and Drug Administration has granted a priority review to its eagerly-anticipated antibody drug conjugate T-DM1 for breast cancer.

The agency has now confirmed the action date of February 26 for T-DM1, which combines the Swiss major's blockbuster Herceptin (trastuzumab) with partner ImmunoGen's chemotherapy DM1 (emtansine). The  proposed indication is for the treatment of people with HER2-positive, unresectable locally advanced or metastatic breast cancer  who have received prior treatment with Herceptin and a taxane chemotherapy.

There has been much positive late-stage data on T-DM1, such as the Phase III study known as Emilia, which showed that the ADC significantly extended the lives of people with HER2-positive metastatic breast cancer compared to the combination of GlaxoSmithKline's Tykerb/Tyverb (lapatinib) and Roche's own chemotherapy Xeloda (capecitabine).

Roche chief medical officer Hal Barron said the firm is very pleased to get the priority review, "as we know people with HER2-positive metastatic breast cancer still need new treatment options". The company also disclosed that its marketing authorisation application for T-DM1 has also been accepted for review by the European Medicines Agency.

Analysts like the look of the drug and Cowen & Co's Simos Simeonidis and Yatin Suneja issued a research note saying "we continue to believe that T-DM1 will be approved and on the market in early 2013".