Evaluating a gene therapy approach to treating PKU


(BPT) - By now, you have likely seen the term “gene therapy” used somewhere. While it may seem like something out of a sci-fi movie, gene therapy approaches are already being used to treat people living with rare genetic diseases today. Still, you might be wondering, “What is gene therapy?”

Gene therapy and PKU

Gene therapy is a type of genetic medicine that is designed to introduce a functional copy of a gene, or an “instruction manual” that tells the body how to make a specific protein, into a person’s cells where there is a missing or mutated (nonworking) gene that is causing a disease. The goal of gene therapy is for the functional copy of the gene to begin working as it should and thereby address the genetic disorder. Gene therapies can be made in different ways and are most commonly delivered using an adeno-associated virus (AAV) vector, which is a virus that will not cause disease.

A unique characteristic of gene therapy is that it is designed to be given to a patient just one time but to have long-term effects, especially for cells of the body that are not dividing rapidly, such as an adult liver. There are FDA-approved gene therapies that are being used to treat patients with rare genetic disorders and many more that are being developed and tested in human clinical research studies. One disease that could potentially be addressed with a gene therapy approach is phenylketonuria, or PKU, a rare, genetic metabolic disorder that affects nearly 16,500 people in the U.S.

PKU is caused by mutations in the PAH gene and results in a loss of function of the enzyme phenylalanine hydroxylase, or PAH, which is responsible for the metabolism of phenylalanine, or Phe, an amino acid that a person gets exclusively from their diet. If left untreated, toxic levels of Phe can accumulate in the blood. Currently, there are no treatment options that target the underlying genetic cause of PKU, and the vast majority of patients are required to follow a life-long, difficult diet that is incredibly low in protein and requires use of medical foods.

pheNIX: A clinical trial for adults with PKU

A clinical trial called pheNIX is evaluating an investigational gene therapy for adults with PKU. This gene therapy is designed to be given to the patient through a single intravenous, or I.V., administration, with follow-up appointments with a physician to monitor the patient’s health.

The pheNIX trial is enrolling adults with PKU at clinical sites throughout the U.S. Candidates for pheNIX include PKU patients who are:

  • Aged 18-55 years
  • Willing and able to maintain their existing diet
  • Willing to commit to required study visits and tests for the duration of the trial

There are additional requirements to participate, which your doctor can explain. Does this sound like something you or someone you know would be interested in? If so, talk to your doctor or take this short questionnaire to see if you are a candidate for pheNIX.