(CBS NEWS) -- A 7-year-old boy who has beaten cancer four times but whose weakened immune system is being threatened by a rare virus will start receiving an experimental treatment within 48 hours after the drug's manufacturer reached an agreement with federal officials for a pilot trial to begin immediately.
The boy, Josh Hardy, will be the first patient to be enrolled Wednesday in the new study of the drug, brincidofovir, the Durham, N.C.-based company, Chimerix, announced late Tuesday.
Earlier the company had said it could not release the drug to Josh outside of clinical trials. The boy's family had been pleading with the company to change its mind.
The U.S. Food and Drug Administration agreed to the pilot trial of brincidofovir for the treatment of adenovirus infections in immune-compromised patients, the company said in a statement late Tuesday. The FDA will work expeditiously with Chimerix to design a Phase 3 study that would be a continuation of the pilot trial, the company said.
"Josh Hardy's story brought to public attention the often-devastating impact of adenovirus infection, and helped accelerate a discussion between the FDA and Chimerix regarding the need for additional clinical development to assess brincidofovir's potential in adenovirus infection," Kenneth I. Moch, Chimerix's president and CEO, said in a statement.
Chimerix had said earlier that it could not comply with a compassionate-use request for several reasons, including the fact that many other sick children had filed such requests.
Moch had also said that prescribing the drug outside of Phase 3 clinical trials underway to determine its safety and efficacy might derail that process.
While it is not certain that the drug will help Josh, his family and St. Jude Children's Research Hospital in Memphis have said it might be the boy's only hope.
"This virus has really done a number on his little body, he's bleeding internally and he's in a lot of pain," his grandmother Mae Staton told the CBS affiliate WTVR in Richmond, Va.
St. Jude Children's Research Hospital said it had been notified by Chimerix that it would receive brincidofovir within the next 48 hours to treat Josh's adenovirus.
"This drug is experimental and has not yet been approved by the FDA and the safety and effectiveness of the medication has not yet been established for use in children," the hospital said in a statement.
The drug will be administered under a new treatment protocol as approved by a committee charged with compliance to federal and institutional regulations for clinical research, it said.
"It is also important to understand that this remains a critical and complex medical situation," it said.
Josh, who is from Fredericksburg, Va., was diagnosed with cancer in his kidneys while he was 9 months old, said Staton, and he has defeated it three more times since.
Last November, doctors determined he needed a bone marrow transplant due to secondary myelodysplastic syndrome. It is a tough-to-treat disease of the blood and bone marrow that occurs following chemotherapy or radiation that prevents blood stem cells from maturing into healthy cells, according to the Cleveland Clinic.
The bone marrow transplant took place in January at St. Jude Children's Research Hospital.
Josh was in a coma for 16 days after, his grandmother said, and once he came out of it, he developed a gastrointestinal adenovirus, which is a family of viruses that can cause infections ranging from respiratory infections to fever, diarrhea, pink eye, bladder infections and rashes, according to the Centers for Disease Control and Prevention.
People with weakened immune system are at higher risk from getting sick from an adenovirus infection.
According to a March 5 letter from Dr. Victor Santana, associate director for clinical research at St. Jude -- which was posted on the "SaveJosh" Facebook page -- conventional treatments have not fought off the virus, and the boy's life is in danger.
He wrote that St. Jude approached Chimerix on Feb. 12 with a compassionate-use application for brincidofovir, but the request was denied. Afterwards, the hospital tried standard treatment but it led to kidney failure and Josh needed dialysis.
Santana expressed concern that after having fought childhood cancer for so long, Josh might succumb to the virus that was increasing in his body.
In the statement issued late Tuesday, Moch said: "This 20-patient open-label study underscores Chimerix's mission to develop innovative antiviral therapies in areas of high unmet need - for everyone. Being unable to fulfill requests for compassionate use is excruciating, and not a decision any one of us ever wants to have to make."