What is the most expensive infusion drug?

October 10, 2025 •

4 min read

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.

Quick Summary

Lenmeldy for metachromatic leukodystrophy is the most expensive infusion drug, priced at $4.25 million, surpassing previous record-holders Hemgenix and Zolgensma. The high cost reflects complex gene therapy development for rare diseases, manufacturing challenges, and the perceived long-term value of a potential cure.

Key Points

Current Most Expensive Drug: The gene therapy Lenmeldy (atidarsagene autotemcel), used to treat metachromatic leukodystrophy (MLD), is currently the most expensive infusion drug, priced at $4.25 million for a single dose.
Historical Context: The record for the most expensive drug has been broken several times recently by other gene therapies, including Hemgenix for hemophilia B ($3.5M) and Zolgensma for spinal muscular atrophy ($2.125M).
Root Cause Treatment: High-cost gene therapies work by targeting and correcting the genetic root cause of a disease, potentially offering a one-time cure rather than repeated, lifelong treatments.
High Development Costs: The astronomical prices are attributed to the immense investment in research, development, and complex manufacturing processes for these highly specialized treatments.
Economic Model for Rare Diseases: Because these treatments address ultra-rare or 'orphan' diseases with very small patient populations, the cost must be spread over a limited number of individuals, necessitating a higher price per dose.
Complex Financial Burden: The high cost creates significant challenges for insurance companies and the healthcare system, leading to complex reimbursement discussions and innovative payment models like outcome-based pricing to manage financial risk.

The Current Record Holder: Lenmeldy (Atidarsagene Autotemcel)

Kyowa Kirin's gene therapy, Lenmeldy, officially became the most expensive infusion drug following its U.S. approval in 2024 for metachromatic leukodystrophy (MLD). MLD is a rare and devastating genetic disorder that causes progressive damage to the nervous system. The one-time, bone marrow-based infusion delivers a functional copy of the ARSA gene to correct the underlying cause of the disease in children who have not yet shown symptoms. The price is justified by the manufacturer based on the drug's potential to provide a long-term, and in some cases curative, effect that avoids a lifetime of high-cost supportive care and management of severe disability.

A History of High-Priced Gene Therapies

Before Lenmeldy, other gene therapies captured headlines for their unprecedented price tags, each one briefly holding the record for the most expensive drug in the world:

Hemgenix (Etranacogene Dezaparvovec): Approved by the FDA in November 2022 for adults with hemophilia B, Hemgenix is a one-time gene therapy priced at $3.5 million. It was considered a cost-effective solution compared to the long-term, continuous costs of managing the lifelong bleeding disorder, which could exceed $20 million per patient.
Zolgensma (Onasemnogene Abeparvovec): In 2019, Zolgensma, a gene therapy for children under two with spinal muscular atrophy (SMA), was approved and priced at $2.125 million. The single intravenous infusion replaced a defective gene, offering a one-time treatment that was hailed as a medical miracle and drastically reduced death rates from the disease.
Skysona (Elivaldogene Autotemcel): Also from bluebird bio, Skysona was briefly the most expensive drug at $3.0 million for cerebral adrenoleukodystrophy (CALD), shortly after Zynteglo.
Zynteglo (Betibeglogene Autotemcel): Priced at $2.8 million in 2022, Zynteglo from bluebird bio is a one-time infusion for beta-thalassemia that became the most expensive treatment at the time of its approval.
Luxturna (Voretigene Neparvovec): As one of the early gene therapies approved in 2017, Luxturna for inherited retinal disease was priced at $850,000 per patient, representing an early milestone in high-cost gene therapy.

Why Are Infusion Drugs So Expensive?

The price of these infusions, particularly gene therapies, is driven by a unique set of factors that differ from traditional pharmaceuticals.

Addressing the Genetic Root Cause

Instead of managing symptoms, gene therapies aim to correct the underlying genetic error. This is a paradigm shift in treatment, offering a potential cure. The high upfront cost is positioned as a replacement for a lifetime of recurring, and often very expensive, treatments, hospital visits, and palliative care. For example, the one-time $3.5 million Hemgenix infusion is seen as cost-effective compared to the decades of regular factor infusions required for hemophilia B management.

Investment in Research and Development

Bringing a new drug to market, especially a novel gene therapy, is incredibly expensive. The research and development process is long, complex, and high-risk, with many candidates failing before reaching approval. Furthermore, the specialized manufacturing processes for gene therapies are extremely complex and costly to scale. The significant investment must be recouped from the limited sales to the small patient populations these drugs target.

Orphan Drug Status and Niche Markets

Most of these record-breaking treatments are for rare, or "orphan," diseases. A small patient population means that the manufacturer cannot rely on high sales volumes to offset R&D costs. To make the development of such niche drugs economically viable, companies set very high prices per dose. This business model is based on serving a critical, unmet need, but it places a significant financial burden on the healthcare system.

Value-Based Pricing Models

Manufacturers are increasingly using a value-based pricing strategy, tying the drug's price to the long-term benefits it provides to patients and the healthcare system. The argument is that if a treatment cures a disease or significantly improves a patient's quality of life over decades, the high upfront cost is a worthwhile investment. Some manufacturers offer payment models, such as installments over several years or rebates if the treatment fails, to help payers manage the financial risk.

The Financial Impact on the Healthcare System

The emergence of multimillion-dollar gene therapies presents significant financial challenges for payers, including private insurers and government programs like Medicare and Medicaid. The high cost can lead to:

Restricted Access: Insurers may establish strict criteria for coverage, limiting access to only the most severe cases or youngest patients. This can result in heartbreaking delays or denials for eligible patients.
Payment Models: Innovative financing schemes, such as outcomes-based agreements, where payments are tied to treatment success, are becoming more common. These arrangements attempt to mitigate risk for payers and ensure the drug provides its promised value.
Budget Strain: A single patient's treatment can exhaust a small insurer's annual budget. The potential for multiple patients needing these therapies within a single year creates significant budget uncertainty for hospitals and payers.

Comparing High-Cost Infusion Therapies


Drug Name	Indication	Active Ingredient	Price (List)	Key Feature
Lenmeldy	Metachromatic Leukodystrophy (MLD)	Atidarsagene Autotemcel	$4.25 Million	One-time hematopoietic stem cell-based gene therapy
Hemgenix	Hemophilia B	Etranacogene Dezaparvovec	$3.5 Million	One-time intravenous infusion for adults
Zolgensma	Spinal Muscular Atrophy (SMA)	Onasemnogene Abeparvovec	$2.125 Million	One-time intravenous infusion for children under 2
Skysona	Cerebral Adrenoleukodystrophy (CALD)	Elivaldogene Autotemcel	$3.0 Million	One-time hematopoietic stem cell-based gene therapy
Zynteglo	Beta-Thalassemia	Betibeglogene Autotemcel	$2.8 Million	One-time hematopoietic stem cell-based gene therapy

Conclusion: The Evolving Landscape of Costly Treatments

Lenmeldy currently holds the title for the most expensive infusion drug, but the history of recent years suggests that this record is likely to be broken again as new gene therapies for rare diseases come to market. These revolutionary treatments offer hope for long-term cures for conditions that were once fatal or debilitating, presenting an unprecedented challenge to the healthcare system. The high price tag is a complex issue, reflecting massive development costs, small patient populations, and innovative value-based pricing models. As more of these groundbreaking therapies are approved, stakeholders will need to continue developing innovative payment and reimbursement strategies to ensure patient access to these potentially life-saving or curative treatments.

Visit the Institute for Clinical and Economic Review for more on drug cost-effectiveness and impact.

Frequently Asked Questions

The gene therapy Lenmeldy (atidarsagene autotemcel) is currently the most expensive infusion drug, with a list price of $4.25 million for a single, one-time dose. It is used to treat metachromatic leukodystrophy (MLD), a rare and fatal genetic disorder.

MLD is a rare, inherited genetic disorder caused by a defective gene. This defect leads to the accumulation of fatty substances in cells, particularly in the brain, spinal cord, and peripheral nerves, which causes progressive neurological damage.

The high price of gene therapies is due to several factors, including the enormous investment in research and development, the complex and expensive manufacturing process, and the small patient populations they treat. The high, one-time cost is also viewed as a value proposition, potentially offering a cure that prevents a lifetime of more costly treatments.

Patients rarely pay the full list price out-of-pocket. Instead, payment is typically covered by insurance, which negotiates the final cost. Manufacturers, payers, and patient support programs often collaborate to find solutions, such as innovative payment plans or installment options, to make these treatments accessible.

To address the financial risk for payers, some manufacturers have entered into outcomes-based payment agreements. Under these arrangements, the manufacturer may provide a rebate or refund part of the treatment cost if the patient does not achieve the promised therapeutic outcome.

While Hemgenix ($3.5 million for Hemophilia B) and Zolgensma ($2.125 million for SMA) previously held the title of most expensive drug, Lenmeldy's price of $4.25 million for MLD now surpasses them. All three are one-time, high-cost gene therapies for rare genetic diseases, but their specific indications and prices differ based on the condition treated and market dynamics.

The trend of increasingly high-priced gene therapies is likely to continue as more groundbreaking treatments are approved for rare diseases. Future pricing will likely remain a topic of intense discussion among pharmaceutical companies, insurers, patient advocates, and regulatory bodies.