At the Bedside: Patient with rare genetic metabolic disorder can eat regular food, thanks to new drug tested in clinical trial at UTHealth Houston

For the first time in her 37 years, Andrea Price is eating any food she wants.

When she was just 9 days old, Andrea was diagnosed with a genetic disorder called phenylketonuria (PKU), in which the body cannot break down the amino acid phenylalanine, which is found in most foods but is very high in meat, egg, fish, and soy products. The resulting buildup of phenylalanine in the blood can cause severe neurodevelopmental issues, abnormal brain function, and damage to the brain’s white matter.

At the time Andrea was born, there was only one treatment: an extreme protein-restricted diet and a medical formula that supplied the amino acids her body needed to live.

“I grew up with great family structure. My mom knew what she needed to do to help me thrive and succeed through diet management,” Andrea said. “But you are bullied in school because your food looks different, or you are teased because the formula smells awful.”

When she was 10 and her family was living in Corpus Christi, Texas, Andrea began seeing PKU clinical expert and researcher Hope Northrup, MD, professor and director of the Division of Medical Genetics in the Department of Pediatrics with McGovern Medical School at UTHealth Houston.

“There was no clinic in Corpus Christi that treated PKU,” Andrea said. “You are bound to have to travel to see someone unless you live in a large metroplex. I had an annual PKU checkup in Houston, and the team there was in constant contact with us. They are a huge support system for families, teaching them how to navigate and really go through life. I don’t want to know what I would do without them.”

Andrea’s life continued to change for the better at Camp PHEver, an annual summer camp for children with PKU that the Division of Medical Genetics hosts each year. She built lifetime friendships with other PKU patients who attended her wedding and toasted her with raised cups of formula.

“It was the first time I got to meet other kids with PKU. You don’t realize how important it is until you meet others, and you realize you are not alone,” said Andrea, who attended the camp every year from the time she was 10 and eventually became a camp counselor. “I remember who bullied me back in elementary school. Those words impact you and affect how you try to hide PKU. Having a huge support system to stay on the diet, maintaining those resources — they are lifelines.”

Northrup, Memorial Hermann Chair at McGovern Medical School, has spent her career looking for therapies for patients with metabolic disorders like PKU.

“When I started, we had one or two options for medical formula. Now we have 50,” Northrup said. “We expanded the horizons on medical food and now have enzyme substitution therapy that we helped test here. We have several more projects in the works, including trials for gene therapy, a small-molecule therapy, and mRNA therapy.”

Northrup’s team was a top enroller nationwide for a Phase III trial for pegvaliase, the enzyme substitution therapy. The drawback of pegvaliase, Northrup said, is that because it is a foreign protein, the body’s immune system tries to reject it. The medication has to be started slowly over time and in low doses. It can take months to work, and the average response time is a year. There are also side effects: injection site reactions, joint pain, hypersensitivity reactions, and, in extreme cases, anaphylaxis.

But for the first time, Northrup had patients who no longer had to rely on the strict diet.

“One of my patients told me that this medication was life-changing. I sat at my desk and cried,” Northrup said. “I had patients in the trial who I followed all their lives. They had normal levels of phenylalanine, and I thought I would never see that.”

Andrea was enrolled in the clinical trial, but she left when she and her husband decided to have children. After two successful pregnancies, in which she had to be especially rigid on her diet, she resumed the medication, which had been approved by the Food and Drug Administration in 2018. Her second child was born in March 2022, and she began taking the medication again in September of that year. She travels annually from her home in Fredericksburg, Texas, to see Northrup and her team.

“My goal was to have family dinners and not have to prepare a separate meal,” Andrea said. “With PKU, you have to plan out your foods and weigh, measure, and journal. It can be taxing. As humans, we love to socialize around food with outings and celebrations. Having PKU takes the joy out of it.”

She just recently began responding to the medication fully, allowing her to eat normally for the first time in her life. She stopped suffering from what she called “brain fog” when levels of phenylalanine rose in her bloodstream.

“Right now, I am eating liberally,” Andrea said. “I can go on Boy Scout campouts with my family and eat the same food. I feel like the world is my oyster — and I can eat oysters!”

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