What a vaccine does

The breast cancer vaccine tells the body how to distinguish between normal cells and tumor cells, and prompts T-cells to seek out and kill cancer cells

Darby Steadman, 38, Severna Park. Enrolled in Emens' second trial in April. She is scheduled for a fourth and final round of vaccine this month. The mother of two young children and the daughter of a breast cancer survivor, Steadman took the most aggressive approach to her breast cancer diagnosis: double mastectomy. She was told there was a less than 1 percent chance of recurrence, but the cancer came back.

Susan Marangi, 60, Parkville. Enrolled in Emens' first trial in December 2006, getting her last vaccination more than a year ago. It has been nearly 20 years since her first breast cancer diagnosis. She was cancer free for 11 years before she was told two years ago that her cancer had spread to her hip. Marangi is the unofficial leader of a loose-knit group of women in the trials who compare notes.

The reporting

Reporter Stephanie Desmon and photographer Chiaki Kawajiri spent the past six months following the lives of four women enrolled in a trial of an experimental breast cancer vaccine, and the Johns Hopkins oncologist who oversees it. They witnessed virtually all of the scenes, and have first-hand accounts of the others. Desmon spent many hours interviewing Dr. Leisha Emens over multiple occasions, as well as visiting her lab, watching her give talks about her research and accompanying her to a gym to prepare for a mountain-climbing trip. Other events were reconstructed through interviews with patients, co-workers, family members and experts in the field of cancer immunology.