Her son was dying, but his rare cancer made it difficult to get the right drug

Eighteen months after his initial diagnosis, chemotherapy hadn't slowed 21-year-old Mason Henderson's rare brain tumor, which had spread to his spinal fluid. So he left his home in southeastern Texas to spend three weeks in a clinical trial in New York City.But that failed, too, leaving a murky path for Henderson, whose cancer was so rare the World Health Organization had only given it a name in 2021. So early this year, Henderson's doctors, evaluating his tumor's deep genetic language, turned to a drug made by Merck and AstraZeneca called Lynparza. It was not the standard of care for Henderson's condition — there wasn't really any standard, which is not unusual for rare cancers.