In December 2012, just before her fifth birthday, Allison Schablein was diagnosed with seven brain tumors. She had surgery and chemotherapy — and for two months her tumors responded to treatment. Then they stopped responding.

Her doctors dove deeper into Allison's genetic profile. They found that her cancer was driven by a mutation also found in some forms of adult melanoma skin cancer. A new drug was available to target this mutation in adults, and Dr. Mark Kieran, Allison's oncologist at Dana-Farber/Boston Children's Cancer and Blood Disorders Center, suggested she try it.

So the New Hampshire girl became a pioneer in precision medicine. Allison became the first pediatric brain-tumor patient in the world to receive the treatment.

It worked.

Four years later, Allison is still tumor free and enjoying acrobatic dancing, jewelry and hip hop. Kieran says, "We are now on the hunt for different mutations in other types of brain tumors, and the drugs that can target them."