FDA Issues Draft Guidance to Accelerate Individualized Therapies for Ultra-Rare Diseases

The U.S. Food and Drug Administration issued draft guidance for sponsors seeking approval for targeted individualized therapies by generating substantial evidence of effectiveness and safety when randomized controlled trials are not feasible due to small patient populations. Called the plausible mechanism framework, the draft guidelines establish a new approval process for individualized therapies for rare disorders.

In the United States, there are over 10,000 rare diseases that affect more than 30 million Americans, according to the National Organization for Rare Disorders, which maintains a database of conditions. Because randomized controlled trials typically take years, cost millions of dollars and involve large numbers of patients, and because rare disorders can affect only a small handful of people, treatments for rare conditions can take years to approve if they're approved at all.

The draft guidance, issued by the Center for Biologics Evaluation and Research and Center for Drug Evaluation and Research, specifically discusses genome editing and RNA-based therapies such as antisense oligonucleotides but leaves open the potential that this framework may apply to additional tailored therapeutics provided they directly address the underlying specific cause of the disease.

The draft guidance focuses on therapies that target a specific genetic, cellular or molecular abnormality and are designed to correct or modify the underlying cause of disease. Key criteria include identifying the disease-causing abnormality, demonstrating the therapy targets the root cause or proximate biological pathway, relying on well-characterized natural history data in untreated patients, and confirming successful target drugging or editing. For traditional approval, therapies should demonstrate improvement in clinical outcomes, disease course, or biomarkers if they are established to predict clinical benefit.

Because genome editing technologies are designed to be highly specific to unique DNA sequences, a product targeting different mutations in a single gene could be included in a single product application and potentially evaluated through the use of master protocols that evaluate these product variations in a single trial. Under the new framework, a disease with 100 mutations of the same gene would no longer require 100 clinical trials. A highly supported "plausible" mechanism of action may then be used to support the addition of other such genome editing product variants, intended to treat patients with mutations that were not included in the clinical trial used to support the original approval.

The FDA's Center for Drug Evaluation and Research will conduct the reviews of so-called investigational new drugs, clustering treatments that work with similar mechanisms, such as gene editing, into a single clinical trial. The FDA recognizes that an adequate and well-controlled clinical investigation in this context will include a small sample size, therefore, investigation results should be sufficiently robust to exclude chance findings. When determining effectiveness, the FDA considers the specific disease, the strength of the evidence and the challenges of conducting clinical investigations for individualized therapies.

The guidelines require long-term safety monitoring. The draft guidance, Considerations for the Use of the Plausible Mechanism Framework to Develop Individualized Therapies that Target Specific Genetic Conditions with Known Biological Cause, is available for public comment. Comments must be submitted within 60 days of publication in the Federal Register.

The new approval guidelines for rare disease treatments is the latest FDA effort during President Donald Trump's second term to accelerate timelines and reduce regulatory oversight for medications — moves that have drawn praise but also raised concerns about safety standards.