Seven-year-old Josh Hardy, who was critically ill at St. Jude Children’s Research Hospital in Memphis, was set to become the first patient in a clinical trial of the experimental antiviral drug brincidofovir. Drugmaker Chimerix announced the decision after working with the Food and Drug Administration to expedite the trial, which would initially make the drug available to 20 patients.

Josh, a first-grader from Fredericksburg, Virginia, had survived several cancers since being diagnosed with a rare kidney cancer at nine months old. A bone marrow transplant left his immune system severely weakened, and he developed a widespread adenovirus infection. He was in intensive care with heart and kidney failure.

Chimerix initially declined the family’s request for the drug through the FDA’s compassionate-use process. The company said that providing it individually to Josh and other patients could slow efforts to bring it to market. Its president and CEO, Kenneth Moch, said the company had received more than 80 similar requests over two years and had been working with the FDA on a way to help more patients.

Josh’s family and supporters drew national attention to his case through television appearances, social media, petitions and calls to the company. The “Save Josh” Facebook page attracted more than 15,000 supporters, while local businesses and charities organized additional support. Moch said the campaign also brought death threats against him and other Chimerix employees.

Josh’s parents expressed relief and gratitude after learning of the decision, and supporters thanked Chimerix and the people who had joined the campaign. St. Jude cautioned that the drug’s safety and effectiveness in children had not been established and that Josh’s condition remained critical and complex.