Adapting Immunotherapy and Gene Editing Based Strategies for Targeting HIV Reservoirs in the CNS: Potential Benefits and Risks (R01 Clinical Trial Optional) | RFA MH 21 225

FAQs: NIH RFA-MH-21-225 (R01) - HIV Cure Strategies Targeting CNS Reservoirs

What is this funding opportunity?

This is a National Institutes of Health (NIH) funding opportunity announcement (FOA) identified as RFA-MH-21-225. It supports R01 research projects focused on improving and adapting HIV cure strategies that use immunotherapy and/or gene editing to address HIV reservoirs in the central nervous system (CNS).

What is the main scientific goal of the program?

The central goal is to advance HIV cure research specifically for the brain and other CNS compartments by improving approaches that can reliably identify and clear HIV reservoir cells. The FOA emphasizes going beyond simply reactivating latent HIV and instead addressing the more difficult challenge of eliminating infected cells, especially in CNS settings where biology, drug delivery, and safety constraints differ from peripheral tissues.

Why does this FOA emphasize the CNS (brain) as a target?

The CNS is highlighted as uniquely challenging because of limited access, the presence of the blood-brain barrier (which restricts many therapeutics and delivery systems), and CNS-specific safety concerns. The FOA is designed to push cure strategies into this compartment and to support work that can deliver, evaluate, and manage risk for interventions aimed at CNS HIV persistence.

How does this relate to the classic "shock and kill" approach?

The FOA is rooted in recognition that the traditional "shock and kill" strategy (reactivate latent HIV using latency-reversing agents and then eliminate infected cells) has not been consistently effective on its own. The opportunity is oriented toward work that improves the elimination/clearance step, including strategies that can function after reactivation or potentially as stand-alone reservoir-targeting approaches.

What types of immunotherapy approaches are specifically encouraged?

The FOA emphasizes immunotherapy strategies that strengthen or redirect immune responses to recognize and eliminate HIV-infected cells. Examples explicitly highlighted include:

• Therapeutic vaccines designed to boost HIV-specific cytotoxic T lymphocyte (CTL) activity
• CAR-T cell approaches engineered to target HIV-infected cells
• Antibody-based strategies such as broadly neutralizing antibodies
• Dual-affinity retargeting antibodies that bind HIV envelope antigens while also engaging or activating CTLs (bridging effector cells to infected targets)

Does the FOA mention immune checkpoint strategies?

Yes. The FOA names immune checkpoint or immune modulation strategies (for example anti-PD-1 or anti-CTLA-4 approaches) as potential ways to reverse immune exhaustion that can persist even in people receiving antiretroviral therapy (ART), which may contribute to difficulty clearing reservoirs.

What gene editing or gene excision concepts are in scope?

The FOA encourages gene editing and gene excision approaches intended to directly damage or remove proviral HIV DNA in latently infected cells. It calls out TALENs and CRISPR/Cas9 platforms and emphasizes designs that cut highly conserved regions of the integrated HIV genome to reduce viral escape and increase the likelihood of durable disruption.

Is this FOA focused only on peripheral HIV reservoirs?

No. A key theme is that much prior work has focused on peripheral reservoirs in blood and lymphoid tissues, while this FOA centers on the CNS. It supports work that addresses feasibility, delivery, safety, and evaluation in the brain, where open questions remain.

What kinds of CNS-specific challenges does the FOA expect applicants to address?

Based on the description, applicants are expected to grapple with practical and mechanistic CNS issues such as:

• How to get therapeutics across or around the blood-brain barrier
• How to target relevant CNS cell populations with specificity
• How CNS reservoirs may differ from peripheral reservoirs
• How to evaluate whether an intervention meaningfully impacts HIV persistence in the brain

What does the FOA say about safety and risk in the CNS?

Safety and risk assessment in the CNS is a clear priority. The FOA raises concerns that immunotherapy and gene-editing approaches under clinical exploration may carry potential CNS toxicities and signals the need to understand and rigorously evaluate those risks in CNS-relevant ways.

What types of CNS-related risks are mentioned or implied?

The FOA points to potential risks such as neuroinflammation, off-target immune activation, unintended effects of immune checkpoint manipulation in the brain, and gene-editing-related risks like off-target cuts, delivery-vector toxicity, or other neurologic adverse outcomes. The overall emphasis is that the CNS is highly sensitive, so benefits must be weighed carefully against neurologic risk.

Does the FOA support adapting existing cure concepts or creating new ones?

Both. The FOA is positioned to support research that adapts existing HIV cure strategies for CNS application and research that creates new approaches specifically designed for the brain compartment.

Are clinical trials required under this opportunity?

No. The FOA is described as "clinical trial optional," meaning applicants may propose projects that are preclinical/mechanistic, translational, or include a clinical trial component, depending on how mature the approach is and what the project aims to accomplish.

What kinds of projects fit within "clinical trial optional"?

Based on the provided description, the range can include CNS-targeted delivery platform development, reservoir measurement approaches, and early-stage human studies assessing feasibility, biomarkers, and safety, as well as other preclinical or translational projects aligned with CNS reservoir targeting.

What grant mechanism and activity code does this use?

This opportunity uses the NIH R01 mechanism (R01 activity code) as a discretionary NIH grant mechanism.

Who is the sponsoring agency?

The sponsoring agency is the National Institutes of Health (NIH).

Which health-related funding activity categories (CFDA numbers) are associated with this FOA?

The description associates this opportunity with CFDA numbers 93.242 and 93.853.

Who is eligible to apply?

Eligibility is broad and includes many organization types, including:

• U.S. governmental entities (state, county, city/township, and special districts)
• Public and private institutions of higher education
• Independent school districts
• Tribal governments and tribal organizations
• Public housing authorities / Indian housing authorities
• Nonprofits with or without 501(c)(3) status
• For-profit organizations (other than small businesses)
• Small businesses

Are specific institution types or communities explicitly highlighted as eligible?

Yes. The FOA highlights additional eligible applicant categories such as HBCUs, Hispanic-serving institutions, AANAPISIs, tribal colleges and universities, Alaska Native and Native Hawaiian-serving institutions, faith-based or community-based organizations, U.S. territories or possessions, and non-U.S. (foreign) organizations and regional organizations.

Are non-U.S. organizations eligible?

Yes. The description explicitly includes non-U.S. (foreign) organizations and regional organizations among the eligible applicant categories.

What is the listed closing date and creation date for this opportunity?

The original closing date listed is 2021-08-27, and the creation date is 2021-05-24.

What is the main take-home focus of this FOA?

The FOA focuses on pushing HIV cure science into the CNS arena by adapting immunotherapies and gene-editing tools (often optimized for peripheral reservoirs) to the brain, while directly addressing two major barriers: delivering interventions across or around the blood-brain barrier and understanding, anticipating, and measuring neurologic toxicity and other CNS-specific risks.