ACN00177 Granted Rare Pediatric Disease Designation for Homocystinuria 

In early December, biotechnology company Aeglea BioTherapeutics, Inc. (“Aeglea”) announced that its therapy ACN00177 received Rare Pediatric Disease designation from the FDA for the treatment of homocystinuria. Should this drug eventually make it to market, it offers a significant improvement in the realm of treatment options for patients with this condition.


Developed by Aeglea, ACN00177 is described as a:

novel recombinant human enzyme, which degrades the amino acid homocysteine and its related homocystine dimer.

Patients with homocystinuria often have too much homocysteine build-up in their blood. Because of the gene mutations which cause this condition, homocysteine is not correctly metabolized. In mice models of homocystinuria, ACN00177 significantly improved survival rates, reduced symptoms, and lowered homocysteine levels. Thus far, ACN00177 was given Orphan Drug status in both America and Europe. Moving forward, Aeglea will evaluate the safety, efficacy, and tolerability of ACN00177 in a Phase 1/2 clinical trial.

The therapy was given Rare Pediatric Disease designation. This status is granted to drugs designed to treat pediatric patients (those under 18) with rare diseases. Overall, a rare disease is one which impacts less than 200,000 Americans. This status also gives Aeglea the chance to receive Priority Review on their application.


Also known as cystathionine beta synthase deficiency, homocystinuria is a rare metabolic disorder which prevents the body from properly metabolizing certain amino acids. Because homocystinuria is inherited in an autosomal recessive pattern, a patient must receive one defective gene from each parent. Typically, homocystinuria affects patients in Qatar, Germany, Ireland, and Norway at a much higher rate than the rest of the globe.

In many cases, symptoms will appear within the first year of life. However, in milder cases, symptoms may not appear until adolescence or early adulthood. Symptoms and characteristics include:

  • Intellectual and developmental delays
  • Epilepsy
  • Nearsightedness
  • Failure to thrive
  • Osteoporosis
  • Long limbs and a tall, thin build
  • Lens dislocation
  • Megaloblastic anemia
  • Abnormal blood clotting

Learn more about homocystinuria.

Jessica Lynn

Jessica Lynn

Jessica Lynn has an educational background in writing and marketing. She firmly believes in the power of writing in amplifying voices, and looks forward to doing so for the rare disease community.

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