FDA Moves Forward With Its Guidance Framework for Rare Disease Trials: 2026
Reporter: Stephen J. Williams, Ph,D.
In 2025, the Trump Administration had determined it wants to streamline the FDA and clinical trials in order to expedite much needed drugs for various terminal diseases such as cancer and rare childhood diseases. In 2026, under the guidance of the new FDA commissioner, Dr. Makary, the FDA initiated guidance for the proposed changes in February and available for comments at that time. This has been a growing discussion aver the years and the FDA wanted, for many years, to figure out they could speed bringing new therapies to market, especially for terminally ill patients. Given the progress of biomarkers development early in the drug discovery process and new computational technologies, the time seems to be ready for such changes in trial design and even for the long drug development process. In addition the FDA up to this point was focused on other matters so it wasn’t really at the forefront of their to do list.
FDA Launches Framework for Accelerating Development of Individualized Therapies for Ultra-Rare Diseases
- For Immediate Release:
The U.S. Food and Drug Administration today issued draft guidance for sponsors seeking approval for targeted individualized therapies by generating substantial evidence of effectiveness and safety when randomized controlled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.
The draft guidance, issued by the Center for Biologics Evaluation and Research and Center for Drug Evaluation and Research, specifically discusses genome editing and RNA-based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.
“President Trump promised to accelerate cures for American families — and we are delivering, especially for children with ultra-rare diseases who cannot afford to wait,” said Health and Human Services Secretary Robert F. Kennedy, Jr. “We are cutting unnecessary red tape, aligning regulation with modern biology, and clearing a path for breakthrough treatments to reach the patients who need them most.”
“This guidance is a critical step the FDA is taking to tailor our regulatory approach to patients with ultra-rare conditions,” said FDA Commissioner Marty Makary, MD, MPH. “It is our priority to remove barriers and exercise regulatory flexibility to encourage scientific advances and deliver more cures and meaningful treatments for patients suffering from rare diseases.”
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.
- 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.
“Designing treatments unique to individual patients has always been the promised goal of personalized medicine,” said Chief Medical and Scientific Officer and Center for Biologics Evaluation and Research Director Vinay Prasad, MD, MPH. “After 25 years the FDA has, for the first time, outlined a framework to facilitate these approvals. The Plausible Mechanism Framework is a revolutionary advance in regulatory science.”
“The Plausible Mechanism draft guidance creates a novel framework through which cutting-edge treatments tailor-made for patients with ultra-rare diseases can be used as a basis for FDA approval,” said Center for Drug Evaluation and Research Acting Director Tracy Beth Høeg, MD, Ph.D. “We anticipate our Plausible Mechanism draft guidance will inspire industry to place increased focus on individualized therapies, thereby driving innovation, improving safety, lowering costs and offering more patients with ultra-rare diseases a unique shot at a life-saving treatment.”
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. 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 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.
In June of 2026, the FDA formalized their discussion into guidelines for discussion so it appears the following are not set into register of regulations as of yet.
From https://www.fda.gov/drugs/guidances-drugs/guidance-documents-rare-disease-drug-development
Guidance Documents for Rare Disease Drug Development
In general, FDA’s guidance documents do not establish legally enforceable responsibilities. Instead, guidances describe the agency’s current thinking on a topic and should be viewed only as recommendations, unless specific regulatory or statutory requirements are cited. The use of the word should in agency guidances means that something is suggested or recommended, but not required.
Below are selected guidances that are relevant to rare disease drug development, organized by topic. This list does not include all FDA guidances on or relevant to rare disease drug development but represents our most commonly used guidances. This list may be updated periodically.
I have kept the original text in order for reference and to provide the background for these changes “in their words”.
However there are a few themes in these guideline changes and discussions including:
- definitions of rare diseases
- reduction of complexities and simplification of trial design and requirements (the FDA wants to go to a more ONE trial with very well designed controls than the two trial design for INDs (I will discuss this further in a near future post)
- accelerated approval which will entail streamlining both the submission and approval process for rare conditions
- heavy reliance on biomarkers during drug development and clinical trials (which is already in frequent use in pharma)
- early communication with the FDA
- more reliance on plausible mechanism of action to reduce number of studies needed
Rare Disease
Considerations for the use of the Plausible Mechanism Framework to Develop Individualized Therapies that Target Specific Genetic Conditions with Known Biological Cause
The purpose of this guidance is to describe considerations for generating substantial evidence of effectiveness and evidence of safety for individualized therapies based on a plausible mechanism framework.
Rare Diseases: Considerations for the Development of Drugs and Biological Products
This guidance clarifies FDA’s thinking on important considerations in rare disease drug development to ultimately assist rare disease drug and biologic product developers in conducting successful drug development programs.
Rare Diseases: Natural History Studies for Drug Development: Draft Guidance for Industry
FDA is publishing this draft guidance to help inform the design and implementation of natural history studies that can be used to support the development of safe and effective drugs and biological products for rare diseases. A natural history study collects information about the natural history of a disease in the absence of an intervention, from the disease’s onset until either its resolution or the individual’s death. Although knowledge of a disease’s natural history can benefit drug development for many disorders and conditions, natural history information is usually not available or is incomplete for most rare diseases; therefore, natural history information is particularly needed for these diseases.
Rare Pediatric Disease Priority Review Vouchers
This guidance provides information on the implementation of section 908 of the Food and Drug Administration Safety and Innovation Act (FDASIA), which added section 529 to the Federal Food, Drug, and Cosmetic Act (the FD&C Act). Under section 529, FDA will award priority review vouchers to sponsors of certain rare pediatric disease product applications that meet the criteria specified in that section.
Rare Diseases: Early Drug Development and the Role of Pre-IND Meetings : Draft Guidance for Industry
The purpose of this draft guidance is to assist sponsors of drug and biological products for the treatment of rare diseases in planning and conducting more efficient and productive pre-investigational new drug application (pre-IND) meetings. Drug development for rare diseases has many challenges related to the nature of these diseases. This draft guidance is intended to advance and facilitate the development of drugs and biological products for the treatment of rare diseases.
Slowly Progressive, Low-Prevalence Rare Diseases with Substrate Deposition That Results from Single Enzyme Defects: Providing Evidence of Effectiveness for Replacement or Corrective Therapies : Guidance for Industry
This document provides guidance to sponsors on the evidence necessary to demonstrate the effectiveness of investigational new drugs or new drug uses intended for slowly progressive, low-prevalence rare diseases that are associated with substrate deposition and are caused by single enzyme defects. This guidance applies only to those low-prevalence rare diseases with well-characterized pathophysiology, and in which changes in substrate deposition can be readily measured in relevant tissue or tissues.
Pediatric Rare Diseases–A Collaborative Approach for Drug Development Using Gaucher Disease as a Model : Draft Guidance for Industry
The purpose of this guidance is to facilitate drug development in pediatric rare diseases. In particular, it discusses a new possible approach to enhance the efficiency of drug development in pediatric rare diseases using Gaucher disease as an example.
Inborn Errors of Metabolism That Use Dietary Management: Considerations for Optimizing and Standardizing Diet in Clinical Trials for Drug Product Development: Guidance for Industry
This guidance describes the Food and Drug Administration’s (FDA’s) current recommendations regarding how to optimize and standardize dietary management in clinical trials for the development of drugs that treat inborn errors of metabolism (IEM) for which dietary management is a key component of patients’ metabolic control. Optimizing dietary management in these patients before entry into and during clinical trials is essential to providing an accurate evaluation of the efficacy of new drug products.
Accelerated Approval
Accelerated Approval and Considerations for Determining Whether a Confirmatory Trial is Underway
For drugs granted accelerated approval, sponsors have been required to conduct confirmatory studies postapproval to verify and describe the anticipated effect on irreversible morbidity or mortality or other clinical benefit. In the Consolidated Appropriations Act, 2023 (CAA), Congress amended section 506(c) of the FD&C Act (21 U.S.C. 356(c)), to provide additional authorities to help ensure timely completion of such trials, including that FDA “may require, as appropriate, a study or studies to be underway prior to approval, or within a specified time period after the date of approval, of the applicable product.” This draft guidance, when finalized, will describe FDA’s interpretation of the term “underway” and policies for implementing this requirement, including factors FDA intends to consider when determining whether a confirmatory trial is underway prior to an accelerated approval action.
Accelerated Approval – Expedited Program for Serious Conditions
Accelerated approval is one of FDA’s expedited programs intended to facilitate and expedite development and review of new drugs to address an unmet medical need in the treatment of a serious or life-threatening condition. The purpose of this guidance is to provide information on FDA’s policies and procedures for accelerated approval as well as threshold criteria generally applicable to concluding that a drug is a candidate for accelerated approval. This guidance also describes the procedures for expedited withdrawal of approval of a product approved under accelerated approval and the revisions Congress made through the Consolidated Appropriations Act, 2023 (Public Law 117-328). Additional programs to expedite product development and review are covered in other guidances.
Benefit-Risk
Benefit-Risk Assessment for New Drug and Biological Products
The intent of this guidance is to clarify for drug sponsors and other stakeholders how considerations about a drug’s benefits, risks, and risk management options factor into certain premarket and postmarket regulatory decisions that the Food and Drug Administration (FDA or Agency) makes about new drug applications (NDAs) submitted under section 505(c) of the Federal Food, Drug, and Cosmetic Act (FD&C Act) as well as biologics license applications (BLAs) submitted under section 351(a) of the Public Health Service Act (PHS Act).
Biomarkers
For general information on Biomarkers, please see About Biomarkers and Qualification
Biomarker Qualification: Evidentiary Framework
This draft guidance provides recommendations on general considerations to address when developing a biomarker for qualification under the 21st Century Cures Act (Cures Act), enacted on December 13, 2016, that added a new section to the Federal Food, Drug, and Cosmetic Act (FD&C Act). Qualification of a biomarker is a determination that within the stated context of use, the biomarker can be relied on to have a specific interpretation and application in drug development and regulatory review.
Qualification Process for Drug Development Tools
This guidance describes the qualification process for drug development tools (DDTs) intended for potential use, over time, in multiple drug development programs.
Clinical Outcome Assessments (COAs) and Endpoints
For information on the COA Qualification Program, please see Clinical Outcome Assessment (COA) Qualification Program
Patient-Focused Drug Development: Selecting, Developing, or Modifying Fit-for-Purpose Clinical Outcome Assessments
This guidance (Guidance 3) is the third in a series of four methodological patient-focused drug development (PFDD) guidance documents that describe how stakeholders (patients, caregivers, researchers, medical product developers, and others) can collect and submit patient experience data and other relevant information from patients and caregivers to be used for medical product development and regulatory decision-making.
Patient-Focused Drug Development: Incorporating Clinical Outcome Assessments Into Endpoints for Regulatory Decision-Making
This guidance (Guidance 4) is the fourth in a series of four methodological patient-focused drug development (PFDD) guidance documents that describe how stakeholders (patients, caregivers, researchers, medical product developers, and others) can collect and submit patient experience data and other relevant information from patients and caregivers to be used for medical product development and regulatory decision-making.
Multiple Endpoints in Clinical Trials Guidance for Industry
This guidance provides sponsors and review staff with the Agency’s thinking about the problems posed by multiple endpoints in the analysis and interpretation of study results and how these problems can be managed in clinical trials for human drugs, including drugs subject to licensing as biological products.
Clinical Pharmacology
Exposure-Response Relationships — Study Design, Data Analysis, and Regulatory Applications
This document provides recommendations for sponsors of investigational new drugs (INDs) and applicants submitting new drug applications (NDAs) or biologics license applications (BLAs) on the use of exposure-response information in the development of drugs, including therapeutic biologics. It can be considered along with the International Conference on Harmonisation (ICH) E4 guidance on Dose-Response Information to Support Drug Registration and other pertinent guidances (see Appendix A).
Bioavailability Studies Submitted in NDAs or INDs – General Considerations
This guidance provides recommendations to sponsors and applicants submitting bioavailability (BA) information for drug products in investigational new drug applications (INDs), new drug applications (NDAs), and NDA supplements. This guidance contains recommendations on how to meet the BA requirements set forth in 21 CFR part 320 as they apply to dosage forms intended for oral administration.
General Clinical Pharmacology Considerations for Pediatric Studies of Drugs, Including Biological Products
This guidance assists sponsors of investigational new drug applications (INDs) and applicants of new drug applications (NDAs) under section 505 of the Federal Food, Drug, and Cosmetic Act (the FD&C Act), biologics license applications (BLAs) under section 351(a) of the Public Health Service Act (PHS Act), and supplements to such applications who are planning to conduct clinical studies in pediatric populations.
General Clinical Pharmacology Considerations for Neonatal Studies for Drugs and Biological Products Guidance for Industry
This guidance is intended to assist sponsors of investigational new drug applications (INDs) and applicants of new drug applications (NDAs), biologics license applications (BLAs), and supplements to such applications who are planning to conduct clinical studies in neonatal populations. This guidance provides recommendations for neonatal clinical pharmacology studies, whether the studies are conducted pursuant to section 505A of the Federal Food, Drug, and Cosmetic Act (FD&C Act), section 505B of the FD&C Act, or neither.
Assessing the Effects of Food on Drugs in INDs and NDAs – Clinical Pharmacology Considerations
This guidance provides recommendations to sponsors planning to conduct food-effect (FE) studies for orally administered drug products under investigational new drug applications (INDs) to support new drug applications (NDAs) and supplements to these applications for drugs being developed under section 505 of the Federal Food, Drug, and Cosmetic Act (21 U.S.C. 355).
Population Pharmacokinetics
This guidance is intended to assist sponsors and applicants of new drug applications (NDAs), biologics license applications (BLAs), abbreviated new drug applications (ANDAs), and investigational new drugs (IND) applications in the application of population pharmacokinetic (PK) analysis.
Clinical Pharmacology Considerations for Antibody-Drug Conjugates Guidance for Industry
This guidance provides recommendations to assist industry and other parties involved in the development of antibody-drug conjugates (ADCs) with a cytotoxic small molecule drug or payload. Specifically, this guidance addresses the FDA’s current thinking regarding clinical pharmacology considerations and recommendations for ADC development programs, including bioanalytical methods, dosing strategies, dose- and exposure-response analysis, intrinsic factors, QTc assessments, immunogenicity, and drug-drug interactions (DDIs).
Drug-Drug Interaction Assessment for Therapeutic Proteins Guidance for Industry
The purpose of this guidance is to help sponsors of investigational new drug applications (INDs) and applicants of biologic license applications (BLAs) determine the need for drug-drug interaction (DDI) studies for a therapeutic protein (TP) by providing a systematic, risk-based approach.
Developing Targeted Therapies in Low-Frequency Molecular Subsets of a Disease
The pharmacological effect of a targeted therapy is often related to a particular molecular alteration, and many diseases are caused by a range of different molecular alterations (some of which may be rare). Therefore, a targeted therapy may have differential effects among patients with the same disease who have different molecular alterations. The purpose of this guidance is to describe general approaches to evaluating the benefits and risks of targeted therapeutics within a clinically defined disease where some molecular alterations may occur at low frequencies.
Clinical Pharmacogenomics: Premarket Evaluation in Early-Phase Clinical Studies and Recommendations for Labeling
This guidance is intended to assist the pharmaceutical industry and other investigators engaged in new drug development in evaluating how variations in the human genome, specifically DNA sequence variants, could affect a drug’s pharmacokinetics (PK), pharmacodynamics (PD), efficacy, or safety. The guidance provides recommendations on when and how genomic information should be considered to address questions arising during drug development and regulatory review.
Clinical Trials
All clinical trials guidances are listed here.
Enhancing Participation in Clinical Trials — Eligibility Criteria, Enrollment Practices, and Trial Designs
This guidance recommends approaches that sponsors of clinical trials intended to support a new drug application or a biologics license application can take to increase enrollment of a representative population in their clinical trials. This guidance considers both demographic characteristics of study populations (e.g., sex, race, ethnicity, age, location of residency) and non-demographic characteristics of populations (e.g., patients with organ dysfunction, comorbid conditions, disabilities, those at the extremes of the weight range, and populations with diseases or conditions with low prevalence). Enrolling participants with a wide range of baseline characteristics may create a study population that more accurately reflects the patients likely to take the drug if it is approved and allow assessment of the impact of those characteristics on the safety and effectiveness of the study drug.
E8(R1) General Considerations for Clinical Studies
This guidance describes internationally accepted principles and practices in the design and conduct of clinical studies of drug and biological products. The guidance is intended to assist sponsors and other parties that design clinical studies, and to promote the quality of the studies submitted to regulatory authorities, while allowing for flexibility.
Multiple Endpoints in Clinical Trials Guidance for Industry
The purpose of this guidance is to describe various strategies for grouping and ordering endpoints for analysis and applying some well-recognized statistical methods for managing multiplicity within a study in order to control the chance of making erroneous conclusions about a drug’s effects. Basing a conclusion on an analysis where the risk of false conclusions has not been appropriately controlled can lead to false or misleading representations regarding a drug’s effects.
E17 General Principles for Planning and Design of Multi-Regional Clinical Trial
With the increasing globalization of drug development, it has become important that data from multiregional clinical trials (MRCTs) can be accepted by regulatory authorities across regions and countries as the primary source of evidence to support marketing approval of drugs (medicinal products). The purpose of this guidance is to describe general principles for the planning and design of MRCTs with the aim of increasing the acceptability of MRCTs in global regulatory submissions.
Decentralized Clinical Trials for Drugs, Biological Products, and Devices
This draft guidance provides recommendations for sponsors, investigators, and other stakeholders regarding the implementation of decentralized clinical trials (DCTs) for drugs, biological products, and devices. In this guidance, a DCT refers to a clinical trial where some or all of the trial-related activities occur at locations other than traditional clinical trial sites.
Enrichment Strategies for Clinical Trials to Support Approval of Human Drugs and Biological Products: Guidance for Industry
The purpose of this guidance is to assist industry in developing enrichment strategies that can be used in clinical investigations intended to demonstrate effectiveness (and in some cases safety) of human drugs and biological products. This guidance defines several types of enrichment strategies, provides examples of potential clinical trial designs, and discusses potential regulatory considerations when using enrichment strategies in clinical trials.
Ethical Considerations for Clinical Investigations of Medical Products Involving Children
Clinical investigations in children are essential for obtaining data on the safety and effectiveness of drugs, biological products, and medical devices in children and to protect children from the risks associated with exposure to medical products that may be unsafe or ineffective. Children are a vulnerable population who cannot consent for themselves and who therefore are afforded additional safeguards when participating in a clinical investigation. Such safeguards are an essential requirement for the initiation and conduct of pediatric investigations as part of a medical product development program.
Master Protocols for Drug and Biological Product Development
This guidance document provides recommendations on the design and analysis of trials conducted under a master protocol as well as guidance on the submission of documentation to support regulatory review.
There are some other Guidances which were issued and I will discuss them in another post. These include Guidances on minimizing use of animals for preclinical toxicology, Innovative clinical trial design especially for gene and cell therapies, and use of AI in designing of clinical trials.
For more information go to the FDA website at : https://www.fda.gov/drugs/guidances-drugs/guidance-documents-rare-disease-drug-development
Other Articles on FDA Guidances on this Open Access Scientific Journal Include:
FDA Guidance on Use of Xenotransplanted Products in Human: Implications in 3D Printing
FDA Guidance Documents Update Nov. 2015 on Devices, Animal Studies, Gene Therapy, Liposomes
FDA Cellular & Gene Therapy Guidances: Implications for CRSPR/Cas9 Trials
FDA Guidelines For Developmental and Reproductive Toxicology (DART) Studies for Small Molecules
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