In the United States, Orphan Drug designation is granted to drugs or biologics intended to treat, prevent, or diagnose rare diseases or conditions. A rare disease is one affecting under 200,000 Americans. This designation comes with a variety of benefits for the drug developer, including fee waivers, tax credits, increased regulatory assistance, and seven years of market exclusivity upon approval. In a news release from May 12, 2022, biopharmaceutical company Neurocrine Biosciences, Inc. (“Neurocrine”) shared that its product valbenazine, designed to treat Huntington’s disease-associated chorea, earned Orphan Drug designation from the FDA. 

What is Valbenazine?

To begin, let’s take a look at what valbenazine is. According to Medline Plus, valbenazine is:

in a class of medications called vesicular monoamine transporter 2 (VMAT2) inhibitors. It works by changing the activity of certain natural substances in the brain.

Currently, valbenazine is approved to treat tardive dyskinesia (TD), a disorder involving involuntary movements. This medication is taken orally. 

Since chorea also represents uncontrolled and involuntary movements, Neurocrine sought to understand whether valbenazine could be a potential therapeutic option. In the Phase 3 KINECT-HD clinical trials, researchers found valbenazine to be safe, effective, and relatively well-tolerated. Moving forward, Neurocrine will continue to evaluate the therapy in the open-label KINECT-HD2 study. 

About Huntington’s Disease (HD)

HTT gene mutations cause Huntington’s disease, or Huntington’s chorea, a progressive neurological disease which causes a loss of physical and mental functions. An estimated 3-7 out of every 100,000 individuals will have Huntington’s disease. The gene mutations cause abnormally long and toxic chains of huntingtin (a protein) to accumulate. As this chain breaks apart, it binds to – and causes the death of – neurons. Most individuals with Huntington’s disease are diagnosed between their 30s-40s. However, some individuals are diagnosed younger. Symptoms of Huntington’s disease can include:

• Chorea
• Changes in behavior and personality
• Difficulty learning or retaining information
• Mood swings and mood difficulties such as anxiety, irritability, impulsivity, and depression
• Problems with balance and coordination
• Difficulty swallowing or speaking
• Twitching, shrugging, head jerks, or other subtle movement changes
• Forgetfulness