Preclinical Proof of Concept Studies for Rare Diseases (R21 Clinical Trial Not Allowed)
Can you apply?
This grant is for research teams conducting early-stage exploratory research on rare diseases where clinical trial data is not yet available. Applicants must be researchers affiliated with domestic institutions eligible to receive NIH funding, typically including universities, medical schools, research hospitals, and certain nonprofit research organizations. The grant supports proof-of-concept studies using preclinical models, in vitro systems, and other non-human subject research methodologies. Work must focus on developing preliminary evidence for therapeutic approaches to rare diseases. International collaborators may participate, but the applicant institution must be U.S.-based. Research must comply with NIH policies on use of human subjects (which are not permitted at the clinical level under this mechanism) and animal welfare standards where applicable.
This grant is for research teams conducting early-stage exploratory research on rare diseases where clinical trial data is not yet available. Applicants must be researchers affiliated with domestic institutions eligible to receive NIH funding, typically including universities, medical schools, research hospitals, and certain nonprofit research organizations. The grant supports proof-of-concept studies using preclinical models, in vitro systems, and other non-human subject research methodologies. Work must focus on developing preliminary evidence for therapeutic approaches to rare diseases. International collaborators may participate, but the applicant institution must be U.S.-based. Research must comply with NIH policies on use of human subjects (which are not permitted at the clinical level under this mechanism) and animal welfare standards where applicable.
Program description
This notice of funding opportunity (NOFO) provides funding to conduct efficacy studies in an established rare disease preclinical model to demonstrate that a proposed therapeutic agent warrants further development. In addition to preclinical efficacy, accompanying pharmacodynamic and pharmacokinetic studies would be supported. Therapeutic agents include small molecules, biologics or biotechnology-derived products. The goal of this NOFO is to spur therapeutic development for a variety of rare diseases by advancing projects to the point where they would attract subsequent investment supporting full Investigational New Drug (IND) application development or progression to clinical trials in the case of repurposing or repositioning.
Who can apply
Eligible applicants
- 501(c)(3) Public Charity
- City / Municipal Government
- County Government
- Hospital
- Nonprofits
- Private University
- Public Authority
- Public K-12 School
- Public University
- Small Business (SBA-defined)
- Special District
- State Government
- Tribal Nation
- Tribal Organization
Details
This grant is for research teams conducting early-stage exploratory research on rare diseases where clinical trial data is not yet available. Applicants must be researchers affiliated with domestic institutions eligible to receive NIH funding, typically including universities, medical schools, research hospitals, and certain nonprofit research organizations. The grant supports proof-of-concept studies using preclinical models, in vitro systems, and other non-human subject research methodologies. Work must focus on developing preliminary evidence for therapeutic approaches to rare diseases. International collaborators may participate, but the applicant institution must be U.S.-based. Research must comply with NIH policies on use of human subjects (which are not permitted at the clinical level under this mechanism) and animal welfare standards where applicable.
How to apply
Application links
Required documents
- NIH Form SF-424 (R&R) Application for Federal Assistance
- Project Narrative (specific aims, background, research design, expected outcomes)
- Budget and Budget Justification (Form PHS 398)
- Biographical sketches for all key personnel (NIH format)
- Facilities and Administrative Resources documentation
- References cited
- Letters of support (if applicable, e.g., from collaborators)
- Protection of Human Subjects form (typically N/A for preclinical work, but required if any human samples or data are used)
- Vertebrate Animals section (if animal models are used)
- Data Management and Sharing Plan
- NIH eRA Commons registration for all personnel
Program contact
- 👤 National Institutes of Health
- 📧 grantsinfo@nih.gov
- 📞 301-402-2541
Funding track record
Recent awards under CFDA 93.350 from the last 3 years — real organizations that won funding through this same program.
Top 10 Largest Recent Awards
-
$139,753,636
-
$118,592,298
-
$112,138,469
-
$108,393,831
-
$102,422,256
-
$100,095,982
-
$99,978,264
-
$98,955,036
-
$98,090,822
-
$97,784,066
Top States by Funding
- CA 13 awards $642.2M
- NY 11 awards $496.8M
- MA 6 awards $321.4M
- NC 5 awards $304.8M
- OH 5 awards $162.0M
Source: USAspending.gov — federal spending transparency. Data covers last 3 years.
Funding history
Annual funding for this program — Federal obligations (CFDA 93.350). How funding has trended year over year.
| 2024 | $595,597,945 | |
| 2025 | $626,227,752 |
FAQ
What types of institutions can apply for this R21 grant?
U.S. domestic institutions eligible for NIH funding, including universities, medical schools, research institutes, hospitals, and nonprofit research organizations. The principal investigator must have a doctoral degree and institutional affiliation.
Are clinical trials allowed under this funding mechanism?
No. This R21 explicitly prohibits clinical trial activities. Research must remain at the preclinical and proof-of-concept stage using laboratory models, cell culture, or animal models.
What is the typical funding range and project period for R21 mechanisms?
R21 awards typically provide $225,000 to $300,000 in total costs for a 2-year project period. Consult the specific funding opportunity announcement (FOA) for exact limits.
How competitive is this grant, and what makes an application stand out?
R21 mechanisms are moderately competitive. Successful applications clearly articulate the innovation, unmet need in the rare disease space, feasibility of the preclinical approach, and a realistic path toward translational impact.
What preliminary data do I need to submit?
You should have sufficient preliminary data to demonstrate proof-of-concept rationale, though R21 mechanisms are designed for early-stage ideas. Pilot data, literature review, or feasibility studies strengthen applications but are not always mandatory.
💡 Tips for applicants
- Focus your application on innovation and feasibility. R21 reviewers want to see that your preclinical approach is novel and likely to yield high-impact preliminary data for future clinical development.
- Clearly define the rare disease of interest and justify why preclinical proof-of-concept is necessary before pursuing clinical trials. Demonstrate the unmet medical need.
- Avoid over-ambitious scope. R21 budgets are modest, so limit your specific aims to 2–3 focused preclinical objectives that can realistically be completed in 24 months.
- Use strong mentorship and collaboration language if your team is early-stage. NIH values demonstrated capacity to execute even for exploratory research.
- Anticipate reviewer concerns about clinical translatability. Even though clinical work is prohibited, explain how your preclinical findings will inform the design of future clinical studies.
⚠️ Common mistakes
Applications often fail because they propose work that is too applied or clinical in nature, crossing the boundary of what R21 will fund. Additionally, some applicants submit preliminary data that is insufficient or fail to justify why the preclinical approach is necessary; reviewers want to see clear gaps in current knowledge. Another common pitfall is scope creep—trying to accomplish too much within the R21 budget and timeline, leading to concerns about feasibility.
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