# Exploiting the VISTA Pathway to Prevent Acute GVHD and Control Steroid Refractory Disease

> **NIH NIH R01** · UNIVERSITY OF MINNESOTA · 2022 · $662,404

## Abstract

Abstract Despite multi-drug prophylaxis, aGVHD affects 20-70% of allogeneic hematopoietic cell transplant
(allo-HCT) patients. V-region Immunoglobulin-containing Suppressor of T cell Activation (VISTA), a negative
checkpoint regulator expressed on resting naïve mouse and human T cells. A single dose of agonist VISTA
monoclonal antibody (mAb) on allo-HCT day 0 causes antigen-specific operational tolerance by deletion and
anergy in resting naïve T cells that have concurrent T cell receptor (TCR) signals and 90-100% long-term
survival. VISTA has been linked to induced Treg generation, expansion, stability and maintenance. In acute
graft-vs-host disease (aGVHD), agonist mAb increases peripheral Tregs; the extent to which pTregs contribute
to operational tolerance will be explored (aim 1A). Limited data exist for aGVHD prevention. Polyclonal CD4 T
cells are the dominant aGVHD effectors in MHC disparate aGVHD models and TCR signaling is critical for
deletion/anergy; studies are proposed using high affinity donor TCR transgenic and polyclonal CD4 and/or
CD8 T cells will assess operation tolerance and long-term survival in MHC and minor antigen disparate
models. Tetramers will track polyclonal and monoclonal donor allospecific T cells in agonist mAb treated mice.
Frequently used calcineurin inhibitors (CNIs) may alter TCR signals below a threshold needed for agonist mAb
effects; testing is required before translation (aim 1C). A unique feature of VISTA is downregulation with T cell
activation. Non-alloreactive T cells and alloreactive T cells escaping agonist mAb induced deletion/anergy may
permit generation of leukemia-specific T cells (aim 1B). Steroids are first line therapy for aGVHD patients but
only half the patients have day 28 complete responses; 1-year survival rate for steroid refractory (SR) aGVHD
patients is dismal. In mice and patients, we show myeloid cell infiltration is 2.5-fold higher than T cells in gut, a
primal aGVHD organ in SR aGVHD. VISTA is expressed on myeloid cells at >10-fold higher levels than T cells.
Agonist mAb inhibits myeloid cell chemotaxis and reprograms inflammatory monocytes/macrophages into anti-
inflammatory cells. We hypothesize that agonist mAb reprograming of gut monocytes/macrophages can treat
SR aGVHD (aim 2). Our central hypothesis is agonist VISTA mAb has dual uses for aGVHD prevention,
inducing T cell operational tolerance, and SR aGVHD therapy, reprogramming myeloid cells to be anti-
inflammatory. Our aims will test the hypotheses that: Operational tolerance induced by agonist mAb
allospecific deletion/anergy of donor T cells depends on in vivo Treg induction, permits unaffected T cells to
generate leukemia-specific responses, and is subverted by day 0 inflammation or CNIs initiated pre-transplant
(aim 1). In aim 2, we will test the hypothesis that agonist mAb reprograms inflammatory monocytes and
macrophages in the gut to be anti-inflammatory and locally release of immune suppressive cytokines,
amelioratin...

## Key facts

- **NIH application ID:** 10348683
- **Project number:** 5R01HL155114-02
- **Recipient organization:** UNIVERSITY OF MINNESOTA
- **Principal Investigator:** Bruce R Blazar
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $662,404
- **Award type:** 5
- **Project period:** 2021-02-15 → 2025-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10348683

## Citation

> US National Institutes of Health, RePORTER application 10348683, Exploiting the VISTA Pathway to Prevent Acute GVHD and Control Steroid Refractory Disease (5R01HL155114-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10348683. Licensed CC0.

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