Understanding FDA Review Structure: Why Your Audience Matters in Regulatory Strategy
Sponsors often talk about "the FDA" as if it were a single decision-maker with one set of expectations. It is not. The U.S. Food and Drug Administration is composed of multiple centers, offices, and review divisions, each with its own statutory mandate, expertise, and evidentiary expectations. The reviewer who evaluates one submission is not the reviewer who evaluates another. The audience matters.
For orphan drug designation (ODD), that audience is the Office of Orphan Products Development (OOPD). OOPD sits outside the Center for Drug Evaluation and Research (CDER) and the Center for Biologics Evaluation and Research (CBER), the centers that will eventually review the marketing application for the same drug. Understanding the difference between these audiences is one of the most underrated levers in regulatory strategy.
FDA Is Composed of Multiple Centers, Offices, and Review Divisions
FDA's medical product review work is divided across several distinct components, each with its own scope:
- CDER: Center for Drug Evaluation and Research reviews drugs. After the 2003 transfer of certain therapeutic biologics from CBER, CDER also reviews monoclonal antibodies for in vivo use and most proteins intended for therapeutic use, including cytokines and enzymes.
- CBER: Center for Biologics Evaluation and Research reviews vaccines, blood and blood-derived products, cellular therapy products, gene therapy products, allergenic products, and certain tissue products.
- OOPD: Office of Orphan Products Development administers the major provisions of the Orphan Drug Act, including orphan drug designation, rare pediatric disease designation, humanitarian use device designation, and several rare disease grant programs. OOPD reviews designation requests for over 8000 rare diseases.
Within CDER and CBER, review divisions are further specialized by therapeutic area. CDER's Office of New Drugs is organized into therapeutic-area offices and divisions covering oncology, neuroscience, infectious diseases, cardiovascular and renal medicine, and others. Each division has its own reviewers, its own backlog, its own interpretive practice, and its own evidentiary expectations for a marketing application. A submission landing on one division's desk is not the same exercise as a submission landing on another.
This structure has a practical implication: a regulatory strategy written for the wrong audience is a strategy that does not land.
Who Reviews Your Orphan Drug Designation Application
Orphan drug designation requests are reviewed by OOPD, not by the CDER or CBER review divisions that will later evaluate the eventual NDA or BLA for marketing approval. Under FDA's Orphan Drug Modernization Plan, OOPD's target is to respond to 100 percent of new designation requests.
For rare pediatric disease designation, OOPD has co-administered the program with the Office of Pediatric Therapeutics since May 15, 2017, with OPT conducting the pediatric review portion. The primary decision-maker for orphan drug designation, however, remains OOPD.
What OOPD Looks For: A Medically Plausible Basis
OOPD's review centers on two questions defined by statute and regulation:
Does the disease qualify as rare in the United States?
Under 21 CFR 316.21, the primary pathway requires that the disease affect fewer than 200,000 people in the United States. The statute also includes a less commonly used cost-recovery pathway: a disease affecting 200,000 or more people may qualify if the sponsor can demonstrate there is no reasonable expectation that costs of developing and marketing the drug for the U.S. market will be recovered from U.S. sales. In practice, the vast majority of designations rely on the under-200,000 prevalence pathway. Where a drug targets a subset of a more common disease, 21 CFR 316.20(b)(6) allows designation if the sponsor can show that the remaining patients with the disease would not be appropriate candidates for the drug because of one or more properties of the drug itself.
Has the sponsor established a medically plausible basis for using the drug in the proposed rare disease?
Related Read: FDA Orphan Drug Designation
Why Efficacy Data Carries So Much Weight
Of the two questions OOPD asks, the prevalence question is generally tractable. Epidemiology can be documented, subsets can be defined, and the cost-recovery pathway exists for sponsors who need it. The medically plausible basis question is where most of the substantive review effort sits.
That is because the regulation requires the sponsor to make an affirmative scientific case that the drug is likely to have an effect in the proposed rare disease. Prevalence alone does not establish this. The data demonstrating efficacy, whether from in vivo animal models or clinical experience, is what supports the medical plausibility argument that OOPD has to be persuaded by.
This is also why timing matters. Sponsors become eligible to apply once they have generated efficacy data from a relevant in vivo animal model of the human rare disease. Sponsors already in the clinical stage can support eligibility with case reports or other early human data. The earlier the designation is in place, the longer the window for several incentives the Orphan Drug Act provides to operate.
If your program has only in vitro data at this stage, that is usually not enough on its own to support a designation request. Talk to our team before drafting the request, and we can review your data on a call.
OOPD Review
| Feature | OOPD (Orphan Designation) |
|---|---|
| Statutory basis | Orphan Drug Act; 21 CFR Part 316 |
| Purpose | Determine orphan eligibility and grant designation |
| Stage of development | Early, often preclinical or early clinical |
| Required evidence | Medically plausible basis supported by in vitro, or clinical data |
| Population focus | Rarity under 21 CFR 316.21 |
| Target timeline | 90-150 daysfor a one-time application review. |
| Outcome | Designation granted or deficiency letter |
| Relationship | Designation does not guarantee approval |
Sources: 21 CFR Part 316; 21 CFR Parts 314 and 601; FDA Orphan Drug Modernization Plan, 2017.
The Incentives ODD Unlocks
There are 4 benefits written in the law:
Orphan drug exclusivity: If a designated drug is approved for the orphan indication, the sponsor may receive seven years of orphan drug exclusivity for that approved use under 21 USC 360cc. During this period, FDA will not approve another application for the same drug for the same disease, with certain statutory exceptions, including a demonstration of clinical superiority, insufficient supply, or consent of the original sponsor. Exclusivity attaches on the date of approval, not on the date of designation. Multiple sponsors may hold designation for the same drug-disease pairing, but only the first to obtain marketing approval receives exclusivity.
PDUFA application fee exemption: Under section 736(a)(1)(F) of the FD&C Act, a marketing application for a drug designated for a rare disease or condition is exempt from the application fee, unless the application includes an indication other than the rare disease or condition. For fiscal year 2026, the PDUFA application fee is $4,682,003 for an application requiring clinical data and $2,341,002 for an application not requiring clinical data, per the Federal Register notice of July 30, 2025. The fee rate is set each fiscal year.
Orphan drug tax credit: Under IRC Section 45C, sponsors may claim a federal tax credit equal to 25 percent of qualified clinical testing expenses incurred for the development of a drug designated for a rare disease or condition. Qualified clinical testing covers human clinical testing that occurs after the date of designation and before the date of approval. The 25 percent rate reflects the reduction from 50 percent under the Tax Cuts and Jobs Act of 2017.
PREA exemption: Drugs with orphan designation are exempt from the Pediatric Research Equity Act requirement to conduct pediatric studies for the orphan-designated indication.
How Only Orphans Cote Supports OOPD Submissions
Dr. Timothy Cote, the firm's CEO, is the former Director of FDA's Office of Orphan Products Development. The firm's own published materials report that Dr. Cote personally decided on approximately 1,400 orphan designation applications during his tenure at FDA and has written approximately 900 orphan designation applications as a consultant since leaving the agency.
Only Orphans Cote also supports parallel European submissions. Learn more about EMA orphan drug designation and the differences between the FDA and EMA pathways. For a broader look at the post-approval value of designation, see the firm's article on the benefits of orphan drug designation and market exclusivity.
Frequently Asked Questions
Q: Who at FDA reviews orphan drug designation applications?
The Office of Orphan Products Development (OOPD) reviews orphan drug designation applications. OOPD sits within FDA's Office of the Chief Medical Officer in the Office of the Commissioner, separate from CDER and CBER. Under a pilot launched in the 2017 Orphan Drug Modernization Plan, CDER and CBER reviewers conduct preliminary primary reviews on a subset of designation requests, with OOPD performing the secondary review.
Q: How long does OOPD take to review an orphan drug designation application?
Under FDA's Orphan Drug Modernization Plan, OOPD targets a response to all new orphan drug designation requests within 90-150 days of receipt. Sponsors may receive a designation letter, a deficiency letter requesting additional information, or a denial letter.
Q: What evidence does OOPD require to grant orphan drug designation?
Per 21 CFR 316.20(b)(4), the sponsor must provide a scientific rationale that establishes a medically plausible basis for the drug's use in the rare disease. FDA states the rationale is best supported by clinical data and, in the absence of human data, may be satisfactorily supported by preclinical data from a relevant animal model. In vivo animal model data and clinical experience may all contribute.
Q: Does orphan drug designation guarantee FDA marketing approval?
No. Designation is granted by OOPD based on rarity and a medically plausible basis. Marketing approval is a separate decision made by CDER or CBER based on the full clinical safety and efficacy package. Designation provides eligibility for certain incentives but does not by itself authorize commercialization.
Q: When should I submit my orphan drug designation application?
Sponsors generally become eligible to apply once efficacy data from a relevant in vivo animal model has been generated. Sponsors with early clinical data may also rely on case reports or other human evidence to support the medically plausible basis. Applying early secures the designation, opens access to the orphan drug tax credit on qualified clinical testing expenses incurred after designation, and supports fundraising and partnership discussions.
Accelerate Your Orphan Drug Strategy
Only Orphans Cote helps sponsors secure orphan drug designation faster. Contact us today to schedule a consultation with Dr. Tim Cote and our team.
