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Single-Site Investigator-Initiated Clinical Trials (R61/R33 Clinical Trial Required)

US · US National Institutes of Health (NIH) grant open #PAR-27-011
Response due Nov 02, 2028 · 00:00 UTC

Summary

The National Institutes of Health (NIH) is soliciting applications for single-site investigator-initiated clinical trials under the R61/R33 phased funding mechanism. The R61 phase typically supports milestone-driven feasibility or early-stage trial activities, while the R33 phase supports the full clinical trial upon successful completion of R61 milestones. This is a broad Program Announcement with Review (PAR), open to a wide range of clinical research topics across NIH mission areas. The opportunity is open for an extended multi-year window, accepting applications on a rolling basis from March 2026 through November 2028.

What they want

Applicants must propose and conduct a single-site investigator-initiated clinical trial using the NIH R61/R33 phased award mechanism. The R61 phase requires establishment and achievement of pre-specified milestones (e.g., feasibility, safety, proof-of-concept). Successful milestone completion triggers eligibility for the R33 phase, which funds the full execution of the clinical trial. Trials must be designed, led, and managed by the principal investigator at a single clinical site. All human subjects research requirements, clinical trial registration, and NIH clinical trial policies must be followed.
Deliverables
  • R61 phase milestone achievement report
  • Clinical trial protocol
  • IRB and human subjects documentation
  • Clinical trial registration (ClinicalTrials.gov)
  • R33 phase full clinical trial execution and results reporting
Technical requirements
  • Must propose a single-site clinical trial
  • Must use the R61/R33 phased funding mechanism
  • R61 phase requires pre-specified, measurable milestones
  • R33 phase contingent on successful R61 milestone completion
  • Must comply with NIH clinical trial registration and reporting requirements
  • Must adhere to NIH human subjects research policies
Key personnel
  • Principal Investigator (must be investigator-initiated, single-site lead)

How they evaluate

Submission: Electronic submission via Grants.gov federal grants portal

Eligibility & certifications

NIH grants.gov registrationInstitutional assurance for human subjects research (e.g., FWA)Clinical trial registration compliance

Risks & flags

  • No specific red flags identified; this is a broad, open Program Announcement with Review (PAR) accepting a wide range of clinical trial topics over a multi-year window
  • Extended open window (2026–2028) may indicate low urgency or niche applicant pool
  • R61/R33 milestone-gating mechanism means R33 funding is not guaranteed, which may deter smaller or under-resourced applicants

Market context

inferred from NAICS
Professional, Scientific & Technical Services
NAICS 541714
US market size
$2.0T
Typical award
$25K – $50M
Typical buyers
All federal civilianDoDStates
Commonly required
8(a)WOSBSDVOSBPE/PMP

Sector-level estimate — full code lookup not yet in catalog.

Single-Site Investigator-Initiated Clinica…
Due Nov 02
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