In October 2017, just after Ronnie Dogan’s first birthday, his doctors made a desperate, last-ditch phone call. Ronnie was born with a rare genetic disease, IPEX syndrome, that caused his immune system to wage widespread attacks on his body’s healthy tissues.
The name is an acronym of the syndrome’s main features: immunodysregulation polyendocrinopathy enteropathy X-linked.
Hospitalized for all but a few days of his life, Ronnie suffered severe gastrointestinal problems that required surgical removal of large portions of his small intestine.
No matching donor was available for a stem cell transplant — the only potential cure — and Ronnie was so fragile it was unclear if he could even survive a transplant. More than once during his first year of life, his family was encouraged to take him home to pass away.
But Ronnie’s mother and grandmother pushed to keep him hospitalized. By his first birthday, the little boy was in limbo, alive but lacking a path to health. He was in his fourth hospital, the University of California-Davis Medical Center in Sacramento, to be near his family in Stockton, California, when his physicians reached out for help.
“They called Stanford and asked, ‘What do we do now? He’s 1,’” said Rosemary Anama, Ronnie’s grandmother and legal guardian. She appreciated the phone call but didn’t expect much to come of it. “That’s where Dr. Alice came in. She came and said, ‘Hey, we can transplant him.’”
Family finally has hope
Bacchetta, an associate professor of pediatrics, is an expert in IPEX syndrome. Bertaina, also an associate professor of pediatrics, had recently moved from the largest children’s hospital in Europe, where she developed a way to give stem cell transplants to patients who lack a well-matched donor.
Bacchetta and Bertaina were recruited to Stanford during the university’s push to build its Center for Definitive and Curative Medicine, which is designed to bridge the gap between basic scientific discoveries and cures, particularly for gene therapy and stem cell transplants. Global efforts on these fronts are beginning to pay off.
After decades of research, gene therapy techniques are producing viable therapies: For example, the gene therapy treatment strimvelis treats a form of severe combined immunodeficiency, or “bubble boy disease.” And several Stanford scientists are improving stem cell transplants, in which a patient’s diseased bone marrow is replaced with that from a healthy donor. Previously restricted to treatment for blood cancers, the transplants are helping a widening circle of patients.
So, in spite of the dismal prognosis others had given Ronnie, the Stanford experts had reason for optimism. They had options no other hospital in the United States could provide.
“I found Ronnie better than I had expected,” Bertaina said. “I had already transplanted IPEX patients much sicker than him with good results.” Bacchetta had been performing stem cell transplants in IPEX patients since 2003, shortly after the gene responsible for the disorder was identified. She, too, felt that Ronnie could be a transplant candidate.
Ronnie’s family was skeptical. They’d recently been told there was no hope.
The physicians weren’t surprised by this reaction.
“Before we met them, they went through so much, so many different therapies, and nothing was enough to cure the disease or to really overcome the clinical manifestations,” Bacchetta said. “Usually it’s very, very traumatic for a family to see their child so sick, to have a disease which is basically incurable or curable only with a very steep pathway, an invasive treatment.”
Bacchetta and Bertaina explained how their proposed plan differed from a standard stem cell transplant: They could use bone marrow from a partially matched donor, Ronnie’s father, plus a gentler drug-conditioning regimen to prepare for the procedure.
Once the news sank in, Anama felt celebratory.
“I was extremely excited to know that my baby had a second chance at life,” Anama said. “I don’t even have the words for it — I was past happy and excited.”
Acute autoimmune disease
IPEX syndrome intrigues scientists because it provides a worst-case scenario of rampant autoimmunity.
“It’s one disease that recapitulates all the different autoimmune diseases you can find in adults later on,” Bacchetta said. Patients can have early Type 1 diabetes and severe intestinal disease. Their intestinal and skin problems resemble ramped-up versions of celiac disease and eczema.
These autoimmune diseases, which are becoming increasingly common, arise from a combination of genetic susceptibility and environmental influences, including immune events such as infections.
The complex interactions between these factors are hard to study. IPEX syndrome is simple by comparison: It shows up soon after birth, caused by a single, recessive gene mutation and most patients are male.
The mutated gene codes for a key immune-regulating protein called FOXP3. Normally, this protein interacts with a vast network of targets, acting as the conductor in a complicated symphony whose instruments are regulatory T cells. The cells maintain “self” tolerance. In IPEX syndrome, without functional regulatory T cells, other immune cells freely attack the body’s healthy tissues.
When Ronnie was born, he seemed fine. Immune protection passed from his mother kept him free of symptoms. But after about a week at home, he stopped eating, ran a fever and developed green diarrhea. “He made this groaning [sound], like he was in agony, in intense pain,” Anama said.
Anama and her daughter, Ronnie’s mother, Tiffany Pigg, took the baby to a community medical center in Stockton. His electrolytes were off balance and he was badly dehydrated. He was transferred to a local hospital, then a larger regional center.
His medical team stabilized him, but it took months to figure out what was wrong. Given that IPEX syndrome is very rare, the slow diagnosis wasn’t surprising. Most doctors never see a case.
Once Ronnie’s disease was identified through genetic testing, his physicians gave him immune-suppressing drugs and tried to prepare him for a stem cell transplant. But the medications made him sicker.
“The T cells they were trying to kill came back more aggressively,” Anama said. “They told us, ‘We can’t give him the transplant. He won’t make it through.’”
Ronnie’s medical team encouraged the family to take him home and keep him comfortable until he passed away. Ronnie’s mother refused, asking that he remain hospitalized. Not long afterward, when Ronnie was about 7 months old, his mother signed guardianship of her son over to Anama. “She said ‘Mom, I can’t do it,’” Anama said.
Ronnie’s baby brother is born
After the Stanford physicians met Ronnie, the little boy’s health worsened again. It took five months to stabilize him enough for him to be transferred to Lucile Packard Children’s Hospital Stanford.
During the wait, in March 2018, Ronnie’s little brother was born. A few days later, it became apparent that baby Levi also had IPEX syndrome.
“Fortunately for Levi, thank God, they caught it early,” Anama said. Levi arrived at Packard Children’s when he was 3 weeks old. “He was started on a lot of medications that helped save his organs,” his grandmother said.
Importantly, Levi did not suffer the severe intestinal disease that required so many surgeries for Ronnie. After his diagnosis, Anama also became Levi’s guardian.
The Stanford team decided they would use the same transplant approach for both brothers. There were two challenges: First, the boys’ blood stem cells needed to be killed to make room for transplanted cells to grow in their bone marrow.
Bertaina proposed using a drug called treosulfan that was available only in Europe; it had fewer side effects for the liver than similar medications. She asked the U.S. Food and Drug Administration for expanded access, also known as a compassionate-use exemption, to allow the brothers to receive it.
The bigger problem was that Ronnie and Levi didn’t have a matched stem cell donor. Typically, physicians match a patient to a healthy bone marrow donor who shares all the same subtypes of the body’s 10 HLA antigens, immune identity markers that project from cell surfaces.
Using a closely matched donor reduces the risk of a potentially fatal transplant complication called graft-versus- host disease, in which the donated immune cells attack the recipient’s tissues.
People inherit half their HLA antigens from each parent. An ideal transplant scenario is to use stem cells donated by a healthy sibling with a 10-for-10 antigen match. Ronnie and Levi didn’t have other siblings. A second-best option is to find a match using a donor registry. But patients from ethnic minority populations are less likely than white patients to match to a registered donor, and none were a fit for Ronnie or Levi, who are black.
The technique Bertaina pioneered in Italy takes a different approach. Technicians process stem cells from the donor to eliminate alpha-beta T cells, immune cells that instigate graft-versus-host disease. As a result, patients can be safely transplanted using stem cells from a donor with only 5 of 10 matching HLA antigens — such as a parent.
The boys’ father, who was not affected by IPEX syndrome, was the obvious choice, and he agreed to donate bone marrow.
“Alpha-beta T cell depletion is becoming our backbone platform for every type of transplant,” Bertaina said. The team is now offering it to most children who need stem cell transplants.
Parallel search for treatments
While the physicians helped Ronnie and Levi, Bacchetta was also busy in the lab. Her team is developing gene-therapy approaches to IPEX syndrome, work funded largely by the Bonnie Uytengsu and Family Endowed Fund for Genetic Immune Diseases. Although a stem cell transplant gives a patient functional new genes — from the donor — methods of delivering these genes directly in the patient’s own cells might be better.
“The main, huge difference is that with gene therapy we correct the patient’s cells,” Bacchetta said. “We will not have to face all the problems of compatibility between the donor and patient.”
Her team is pursuing two approaches: In one method, they collect lymphocytes — white blood cells — from the patient’s body and transfer a normal copy of the FOXP3 gene to the T cells. “This transforms them into regulatory T cells, which can be given back to the patient,” Bacchetta said. “The cells integrate normal FOXP3 into their DNA and acquire the function that is missing.”
Bacchetta’s team is preparing to move this method, which has been extensively tested in animals, to human clinical trials. Because the scientists are transferring the functional gene to T cells, which do not live indefinitely, the approach will not cure IPEX syndrome — but it could stop the disease for a time. And it would have fewer side effects than immune-suppressing drugs now used for patients who can’t have stem cell transplants.
“What we know from the first studies with gene therapy in T cells is that although they do not provide a cure, they can live for many years in the patient and help to correct the genetic defect,” Bacchetta said.
In humans, the researchers plan to explore whether gene-converted regulatory T cells could treat a variety of autoimmune diseases — not just IPEX syndrome — and allow patients to reduce their use of immune suppressive drugs.
Bacchetta’s team is also investigating the use of CRISPR-Cas9 technology, which allows precise gene editing, to insert a functional FOXP3 gene into stem cells from IPEX patients. Patients would receive a stem cell transplant with their own corrected cells. If it works, it would be a permanent cure.
“We’re very excited about the gene-therapy methods that Dr. Bacchetta and our other investigators are developing at the Center for Definitive and Curative Medicine because they give hope to many patients,” said the center’s director, Maria Grazia Roncarolo, MD, professor of pediatrics and of medicine. “This work is providing curative treatments and the chance for a normal life not just for people with rare diseases but also for people with common inherited disorders like sickle cell anemia and thalassemia.”
Boys’ personalities shine through
Ronnie arrived at Packard Children’s on April 7, 2018, and received his stem cell transplant May 2. Levi arrived the day after his brother, and his transplant was Aug. 9. Then, the family had to wait several months to see if the new cells would take hold and grow in the boys’ bone marrow.
After his transplant, Ronnie continued to struggle with gastrointestinal complications from his long illness. For most of his life, he’s received all his nutrients intravenously. He’s had two intestinal surgeries and may need others. His body’s constant struggle for nutrition has delayed his growth and development.
Levi, spared the severe autoimmune attacks his brother endured, did better in most respects, and with the medical team’s encouragement, Anama took him home to Stockton in January. He contracted an infection and had to be hospitalized again 10 days later.
A recent endoscopy showed that Levi is free of IPEX symptoms; Anama took him home again on April 29.
There have been other bright spots, too. The boys have upbeat personalities and have bonded with their caregivers at Packard Children’s, particularly nurses Sonja Munoz and Jarleen Vallejo.
“Bringing Levi home — enjoying getting out, playing, feeding him, cuddling him — and then realizing, ‘I have to take him back’ was extremely hard,” Anama said.
Anama works full time in Stockton and mostly visits the hospital on weekends, so the nurses provide much more than just basic medical care. For instance, “Sonja is there with Ronnie, teaching him how to count or say his ABCs, or she’s taking his socks to the sink and washing them out because she knows Ronnie needs socks and grandma won’t be here for a few days,” Anama said. “They have been really awesome the whole way.”
Anama is grateful her grandsons are alive. She loves seeing the boys show who they are, such as when they’re dancing to the “Baby Shark” song that exploded on social media over the last year. “Ronnie sways side to side and Levi goes back and forth,” she said with a chuckle.
“Levi is so resilient; he just operates like nothing ever was wrong,” she added. “He crawls over me like I’m a tree. He’s playful and so loving.”
And since his successful transplant has allowed him to start healing, Ronnie’s development has advanced tremendously.
“It might not be a big accomplishment to anyone else, but when he started rolling, trying to pull himself up, those milestones were big for me,” Anama said. “I remember when he couldn’t do any of that.”