Hormone–based therapy has revolutionized the treatment of breast cancer, but when these therapies fail, patients often have few other options.

Dr. Mark Clemons and colleagues played an important role in an international clinical trial that has opened the door for a new kind of drug for these patients.

Published in The Lancet Oncology journal, the trial tested a drug that targets a protein called PI3K. Patients who received the drug survived an additional two months without disease progression, and a certain subset survived an additional four months without progression. Although side effects were a concern, the trial showed for the first time that PI3K could be a promising target for advanced breast cancer.

The Ottawa Hospital was one of the top enrolling sites in this trial, which included more than 1,000 patients in 29 countries.