World-first gene therapy begins rebuilding Melbourne man's immune system

Rozek was born without a functional immune system and spent the first few years largely inside a Melbourne hospital. The condition is widely known as "bubble boy disease" because of David Vetter, a Texan boy who lived inside a sterile plastic chamber for almost all of his 12 years. The standard long-term treatment is a bone marrow transplant from a matched donor, which can carry serious risks including graft failure and death. Rozek had a transplant as a toddler, but it gradually failed, leaving him with minimal immunity. By adulthood, his health had deteriorated.

In Australia, every newborn is now tested for SCID through the heel prick test, with about six new cases diagnosed each year. One of Rozek's clinicians at the Royal Melbourne Hospital, Dr Samantha Chan, contacted Dr Suk See DeRavin at the US National Institutes of Health about an upcoming experimental gene therapy trial. For three years, the two doctors shipped samples of Rozek's blood to the US on dry ice to test his eligibility.

Rozek flew to Maryland last August to receive the treatment. After three weeks of medical tests, he underwent apheresis to harvest his stem cells through a line in his neck. Scientists genetically edited the cells in a laboratory over the next month. He then received chemotherapy to make room in his bone marrow for a 30-millilitre infusion of the repaired cells. "It's just crazy that I still am alive," Rozek said. "I just don't know how the body can function without the immune system."

Dr Chan said Rozek would have died without access to the trial. "There's no doubt it's been a huge success," she said. "It offers hope at a normal life." Rozek is already seeing benefits: for the first time, he is properly absorbing nutrients, having gained 10 kilograms, and his immune system is improving on blood tests. He has come off medications. However, the treatment will not reverse decades of damage. A childhood infection left him with about 70 per cent lung capacity, and he has ongoing bone issues from malnutrition. "It won't fully cure everything," Rozek said. "But it was the easiest decision I've ever had to make."

Back in Melbourne, a research team at the Walter and Eliza Hall Institute led by Professor Shalin Naik is working to bring similar treatments to Australia. With a $5 million Medical Research Future Fund grant, Naik's team is developing a method to package gene-editing machinery into microscopic mRNA droplets, similar to those used in COVID-19 vaccines, which could allow doctors to repair stem cells with a simple injection in the arm. Naik estimated his team is two to three years away from clinical trials.