The R61 and R33 mechanisms, often referred to jointly as R61/R33, fund exploratory/developmental grants in a phased approach. Phase 1 of the study is funded under the R61 and phase 2 is funded under the R33.
Most of us associate the R21 mechanism with exploratory research where proof of principle has not been established. The R61 is used in place of the R21 when larger budgets and/or project periods are needed in order to establish the feasibility of the project.
The R33 mechanism provides a second phase of funding for exploratory/developmental grants. While generally, only recipients of an R21 are eligible to apply for R33 support, certain program initiatives and NOFOs will establish criteria that allow applications to be received from awardees of other mechanisms, such as an R61.
R61/R33 applications may have different requirements, therefore be sure to check the NOFO:
- Some R61-specific NOFOs will reference the R61 and R33 jointly. In these situations, the issuing institute or center (IC) will require that applications include both an R61 phase and an R33 phase as part of the submission.
- Clinical trials may be not allowed, may be optional, or may be required.
- Number of years are generally up to two years for the R61 phase and up to 3 years for the R33 phase, but some NOFOs specify a 1-year/4-year split.
- Due dates differ from the NIH standard due dates.
- Award budget limits may vary by IC.
R61 versus R34? If you are looking for a mechanism to fund the development of essential elements of a clinical trial, you may be wondering whether to pursue an R34 or an R61.
The R34 mechanism typically provides 3 years of funding ($450K directs total, sometimes more) for the development of a clinical trial or research project. For example, when used as a clinical trial planning grant, an R34 would fund the collection of preliminary data or the conduct of pilot studies to support the rationale for the clinical trial, as well as establishing the research team and finalizing collaborations, developing tools for data management, developing the protocol, etc. — in essence, laying the groundwork so that by the end of the funding period, you have all the information you need to inform the design of the full-scale trial at the R01 level.
The R61 mechanism, conversely, typically only funds 1-2 years of work and the NOFO may not allow a clinical trial. As always, you should check to see if your IC offers either an R34 or an R61, and you should speak with the POs of any possible mechanisms to decide together which one would be the best fit for your early phase trial.
