For Bridget Spence, graduation from college was a short-lived joy. Just one week after receiving her degree, a medical diagnosis sent her reeling.

"I was diagnosed with stage 4 breast cancer in 2005. Cancer was in my lymph nodes, liver and breast at the time of my diagnosis," she told ABC News.

She had HER2-positive breast cancer, a particularly aggressive form of the disease. For four years, her cancer progressed, and a combination of drugs kept it stable for a while.

But about a year ago, her cancer started growing again, and she wasn't sure what she would do. That's when her doctors told her about a trial of an experimental drug, called T-DM1, designed to target and attack cancer cells in HER2-positive breast cancer patients.

While other drugs couldn't shrink Spence's cancer, she said T-DM1 did, and kept it at bay for nine months.