# Nongenotoxic conditioning to enhance stem cell engineering and virus-specific immunity in nonhuman primates

> **NIH NIH U19** · UNIVERSITY OF SOUTHERN CALIFORNIA · 2022 · $498,553

## Abstract

ABSTRACT
Although hematopoietic stem and progenitor cell (HSPC) transplantation now underlies two clinical cases of HIV-
1 remission/functional cure, a means to apply this approach to a wider array of patients has not yet been
identified. In this project, we will address a key limitation for HSPC-based anti-HIV strategies: the engraftment
and potency of gene-edited HSPC and their progeny. Although our previous findings demonstrate that gene
edited HSPCs engraft long-term in vivo, only a limited proportion persist over time, and are incapable of
supporting antiretroviral therapy (ART)-free virus remission. To address this, we have i) adapted a more
advanced strategy to edit our locus of interest, CCR5, ii) identified an approach to not only disrupt the CCR5
gene, but simultaneously insert therapeutic anti-HIV transgenes, and iii) designed experiments to evaluate this
strategy in our robust nonhuman primate (NHP) model of suppressed HIV infection. We will target two rationally
designed, highly potent anti-HIV transgenes to the gene-edited CCR5 locus: the virus-specific chimeric antigen
receptor CD4CAR, and the broadly neutralizing antibody-like molecule eCD4-Ig. Our preliminary data
demonstrate our ability to insert defined genetic sequences at up to 50% of targeted CCR5 alleles in primary
NHP HSPCs. Here, we will optimize our approach to insert CD4CAR or eCD4-Ig, and safely engraft an
autologous HSPC product containing both CD4CAR∆CCR5 and eCD4-Ig∆CCR5 HSPCs into the same animal.
As we are introducing two therapeutic transgenes and simultaneously disrupting the CCR5 coreceptor, we refer
to this as a “three for one” approach. In addition to generating a potent and efficiently modified HSPC product,
we will work closely with each project in our U19 consortium. We will coordinate with Project 3/Cannon to identify
the most efficient means to modify HSPCs, prior to in vivo studies in our respective animal models. With Project
1/Scadden, we will evaluate a bone marrow cryogel (BMC) scaffold designed to enhance the differentiation of
HSPC-derived T-cells, namely CD4CAR∆CCR5 T-cells. Finally, we will investigate the impact of safer,
nongenotoxic conditioning (NGC) regimens characterized by Project 2/Magenta on infection with simian/human
immunodeficiency virus (SHIV) and suppression by ART. We believe that safe and efficacious engraftment of
gene-modified, virus-specific HSPCs and their progeny will enable robust protection against de novo SHIV
challenge, and significantly impact viral reservoirs in infected, suppressed animals.

## Key facts

- **NIH application ID:** 10409806
- **Project number:** 5U19HL156247-03
- **Recipient organization:** UNIVERSITY OF SOUTHERN CALIFORNIA
- **Principal Investigator:** HANS-PETER KIEM
- **Activity code:** U19 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $498,553
- **Award type:** 5
- **Project period:** 2020-05-15 → 2025-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10409806

## Citation

> US National Institutes of Health, RePORTER application 10409806, Nongenotoxic conditioning to enhance stem cell engineering and virus-specific immunity in nonhuman primates (5U19HL156247-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10409806. Licensed CC0.

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