Development and Application of PET and SPECT Imaging Ligands as Biomarkers for Drug Discovery and for Pathophysiological Studies of CNS Disorders (R01 Clinical Trial Not Allowed) | PAR 23 165

Opportunity Information: Apply for PAR 23 165

The National Institutes of Health (NIH) is soliciting R01 research grant applications under FOA PAR 23-165, titled "Development and Application of PET and SPECT Imaging Ligands as Biomarkers for Drug Discovery and for Pathophysiological Studies of CNS Disorders (R01 Clinical Trial Not Allowed)." The core purpose of this opportunity is to support the preclinical creation and validation of new radioligands that can be used as brain imaging biomarkers with positron emission tomography (PET) or single photon emission computed tomography (SPECT). In practical terms, NIH is looking for projects that design and optimize novel PET/SPECT ligands and then demonstrate, in rigorous preclinical settings, that these ligands can reliably measure relevant biological targets in the central nervous system (CNS). The broader motivation is to strengthen biomarker tools that can accelerate drug discovery and deepen understanding of disease mechanisms across CNS disorders.

This FOA emphasizes work that is fundamentally preclinical, with strong expectations for testing in rodent and nonhuman primate brain. The focus is on the step-by-step development pipeline that takes a candidate radiotracer from concept through evidence of performance, including appropriate model development when needed. The announcement also allows for incorporation of pilot or feasibility-style evaluation as part of the preclinical effort, meaning applicants can propose carefully scoped studies that show whether a ligand is likely to work as an imaging tool, how it behaves in the brain, and whether it has the properties needed to become a practical biomarker. At the same time, the FOA draws a clear line around clinical research: this is an "R01 Clinical Trial Not Allowed" announcement, and applicants who want to conduct clinical assessments of novel radioligands are directed to submit to a different FOA (referenced as PAR XX-XXX in the provided text).

The scientific scope centers on radioligand development for CNS applications, which typically includes activities such as identifying or engineering compounds with high affinity and selectivity for a biological target, radiolabeling chemistry suitable for PET or SPECT isotopes, and demonstrating brain penetration and signal quality. Competitive projects would be expected to show that a ligand provides a measurable and interpretable imaging signal, supports quantification strategies, and has acceptable properties related to specificity, kinetics, and overall feasibility for neuroimaging. Because the FOA explicitly frames these ligands as biomarkers, it is oriented toward tools that can be used to answer concrete questions in drug discovery (for example, target engagement, receptor occupancy, or pharmacodynamics) and in pathophysiological studies (for example, mapping target changes across disease models or probing mechanisms relevant to CNS disorders).

In terms of eligibility, the program is broadly open. Eligible applicants include a wide range of U.S. governmental entities (state, county, city or township, special districts), public and state-controlled institutions of higher education, private institutions of higher education, independent school districts, and public housing/Indian housing authorities. It also includes federally recognized Native American tribal governments, as well as Native American tribal organizations and tribal governments that are not federally recognized, and a variety of nonprofit organizations (both 501(c)(3) and non-501(c)(3), excluding institutions of higher education in those nonprofit categories). For-profit entities (other than small businesses) and small businesses are also eligible, and NIH explicitly highlights additional eligible applicant types such as Alaska Native and Native Hawaiian Serving Institutions, Asian American Native American Pacific Islander Serving Institutions (AANAPISISs), Hispanic-serving Institutions, Historically Black Colleges and Universities (HBCUs), Tribally Controlled Colleges and Universities (TCCUs), faith-based or community-based organizations, eligible federal agencies, U.S. territories or possessions, regional organizations, and non-U.S. entities (foreign organizations). This wide eligibility is consistent with the technical and interdisciplinary nature of radioligand development, which often draws on chemistry, pharmacology, imaging physics, neurobiology, and translational biomarker expertise.

Administratively, this is a discretionary grant opportunity using the NIH research project grant mechanism (R01). The funding activity category is health, and the opportunity is associated with CFDA numbers 93.242 and 93.866. The FOA was created on 2023-04-07, and the listed original closing date is 2026-05-07. The excerpt provided does not specify an award ceiling or expected number of awards, so applicants would need to consult the full FOA and related NIH budget guidance for details on typical award sizes, allowable costs, project duration expectations, and any institute- or center-specific priorities.

Overall, this opportunity is aimed at teams that can deliver strong, preclinical evidence that a new PET or SPECT radioligand can function as a credible CNS imaging biomarker. Projects should be framed around generating usable imaging tools that can meaningfully support drug discovery decisions and mechanistic studies of CNS disorders, while avoiding proposals that cross into clinical trial territory under this particular "clinical trial not allowed" R01 announcement.

• The National Institutes of Health in the health sector is offering a public funding opportunity titled "Development and Application of PET and SPECT Imaging Ligands as Biomarkers for Drug Discovery and for Pathophysiological Studies of CNS Disorders (R01 Clinical Trial Not Allowed)" and is now available to receive applicants.
• Interested and eligible applicants and submit their applications by referencing the CFDA number(s): 93.242, 93.866.
• This funding opportunity was created on 2023-04-07.
• Applicants must submit their applications by 2026-05-07. (Agency may still review applications by suitable applicants for the remaining/unused allocated funding in 2026.)
• Eligible applicants include: State governments, County governments, City or township governments, Special district governments, Independent school districts, Public and State controlled institutions of higher education, Native American tribal governments (Federally recognized), Public housing authorities/Indian housing authorities, Native American tribal organizations (other than Federally recognized tribal governments), Nonprofits having a 501 (c) (3) status with the IRS, other than institutions of higher education, Nonprofits that do not have a 501 (c) (3) status with the IRS, other than institutions of higher education, Private institutions of higher education, For-profit organizations other than small businesses, Small businesses, Others.

Apply for PAR 23 165

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