Roche's Perjeta has moved a significant step closer to becoming the first drug to be approved in the US for use in breast cancer patients before they receive surgery. 

The US Food and Drug Administration has granted a Perjeta (pertuzumab) regimen a priority review as a neoadjuvant (before surgery) treatment in patients with HER2-positive early-stage breast cancer, which means it could be approved by October 31 this year.

The idea behind the therapy is to reduce the tumour's size (before it has spread to other parts of the body), in order to make it easier to remove surgically or enable breast-conserving surgery, potentially giving patients a better change of treatment success.

Perjeta, in combination with Herceptin and chemotherapy, has already been given a green light in the US (and Europe and Japan) for use in HER2-positive cancer that has spread, and if regulators approve its earlier use the drug could become the first cleared for both the pre- and post-surgery setting. 

The treatment is a humanised monoclonal antibody administered intravenously that is designed specifically to prevent the HER2 receptor from pairing with other HER receptors on the surface of cells, a process believed to play a role in tumour growth and survival. 

Sales forecasts for Perjeta seem to vary wildly, ranging from $600 million to $2.5 billion and up to a stellar $8.5 billion if multiple indications are approved, FiercePharma has reported.