Tag: Rare diseases

Affecting an estimated one in ten Americans, there are more than 7,000 rare diseases, and for these patients, an orphan drug provides a critical, often life-saving, treatment option. Historically, the small patient populations for these conditions made drug development financially unviable, leading to a significant gap in treatment options.

In 2024, the global orphan drug market reached an estimated revenue of nearly $190 billion, illustrating the significant financial impact of these medications. This success raises the question: **What is the highest grossing orphan drug?** The answer is more complex than it appears, as many top sellers have expanded indications far beyond their initial orphan status.

Over 7,000 rare diseases collectively affect more than 30 million Americans, yet historically, most have had no approved treatment. Orphan drugs are specialized medications developed to treat, prevent, or diagnose these rare conditions, addressing a critical, unmet medical need.

As of late 2024 and into 2025, the one-time gene therapy Lenmeldy (atidarsagene autotemcel) for metachromatic leukodystrophy holds the title of the most expensive infusion drug, with a staggering list price of $4.25 million. This represents a new peak in the rapidly evolving landscape of ultra-high-cost pharmaceuticals, dominated by groundbreaking gene therapies for rare genetic diseases.

Affecting approximately 1 to 5 people per million, Kleine-Levin Syndrome (KLS) is a rare and disabling neurological disorder. The recurrent episodes of excessive sleepiness, cognitive impairment, and behavioral changes make treatment challenging, with no single definitive answer to the question, 'What is the drug of choice for Kleine-Levin syndrome?'.

Affecting approximately 1 in 40,000 to 60,000 births, Gaucher disease is the most common lysosomal storage disorder, caused by a deficiency of the enzyme glucocerebrosidase (GCase). Understanding the specific therapeutic strategies for this genetic condition is essential for managing symptoms and improving quality of life, which is precisely how you treat glucocerebrosidase deficiency.

Priced at $4.25 million for a single infusion, Kyowa Kirin's Lenmeldy is currently the most expensive drug substance in the world. This one-time gene therapy is a groundbreaking treatment for the ultra-rare genetic disorder metachromatic leukodystrophy (MLD), highlighting the high costs associated with advanced therapeutic innovation.

According to a 2020 study, 108 branded drugs approved between 1983 and 2017 in the U.S. had multiple orphan indications, demonstrating that a drug can have multiple orphan drug designations. This practice of pursuing multiple indications for the same drug has significant implications for patients, pharmaceutical companies, and the broader healthcare system.

As of 2025, the most expensive medication in the U.S. is Lenmeldy, a gene therapy priced at $4.25 million per dose [1.2.7]. This article answers **what is the most expensive medication in the US?** and explores the groundbreaking science and complex economics behind these costly treatments.

Accounting for a significant portion of prescription drug spending, specialty drugs are defined by their high cost and complexity. To better understand these life-changing therapies, here are concrete examples illustrating the range of **what are examples of specialty drugs?**