# Targeting T-cell costimulation and cytokine activation to prevent GVHD and preserve GVL

> **NIH NIH R01** · UNIVERSITY OF MINNESOTA · 2020 · $409,210

## Abstract

ABSTRACT
Graft-versus-host disease (GVHD) is a leading cause of non-relapse mortality after allogeneic hematopoietic
cell transplantation (alloHCT). Current GVHD prophylaxis relies on broadly suppressive tacrolimus-based
combinations that fail to tolerize donor T-cells. Tacrolimus inhibits T-cell receptor (TCR) activation and impairs
regulatory T-cell (Treg) longevity and function. Rather than targeting the TCR, the novel approach tested in
this application is concurrent blockade of T-cell costimulation and cytokine activation as a strategy to spare
Tregs, prevent GVHD, and maintain graft-versus-leukemia (GVL). CD28 costimulation of T-cells requires
signal transduction by mTOR and Aurora kinase, where inhibiting either molecule ameliorates GVHD in
rodents. The IL-6 receptor directs JAK2 to phosphorylate STAT3, which polarizes pathogenic Th1 and Th17
development over beneficial Tregs. We observed that STAT3 activity is increased in alloHCT recipients who
later develop acute GVHD. Blockade of JAK2 or STAT3 also reduces murine GVHD. Our data support the
concept that dual inhibition of CD28 and IL-6 activity is synergistic and offers durable GVHD prevention with
intact GVL. Aim 1 of this application will test this hypothesis in a proof-of-principle clinical trial by combing
pacritinib with sirolimus-based immune suppression to respectively target JAK2 and mTOR signaling and
reduce GVHD. Aims 2 and 3 will test the hypotheses that neutralization of downstream signaling molecules
directed by CD28 and IL-6 will yield distinct immune outcomes and collectively more complete control over
donor T-cells. Unlike JAK2, STAT3 molecularly counteracts Treg development. We provide evidence that
JAK2 blockade permits natural Treg development, while STAT3 inhibition increases inducible Tregs (iTreg). In
Aim 2, we will investigate whether STAT3/mTOR inhibition is better than JAK2/mTOR inhibition in reducing
GVHD in mice by enhancing iTreg differentiation. We provide evidence that inhibition of Aurora kinase
significantly increases iTreg suppressive potency. In Aim 3, we will determine whether targeting STAT3/Aurora
is better than JAK2/Aurora to prevent GVHD by increasing both iTreg differentiation and function. These
experiments will direct future translation and development of tacrolimus-free GVHD prophylaxis regimens. Our
long-term goal is to develop selective immune suppression strategies that effectively prevent GVHD and
maintain essential T-cell responses needed to preserve GVL.

## Key facts

- **NIH application ID:** 9918445
- **Project number:** 5R01HL133823-06
- **Recipient organization:** UNIVERSITY OF MINNESOTA
- **Principal Investigator:** Brian C Betts
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $409,210
- **Award type:** 5
- **Project period:** 2018-10-01 → 2023-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9918445

## Citation

> US National Institutes of Health, RePORTER application 9918445, Targeting T-cell costimulation and cytokine activation to prevent GVHD and preserve GVL (5R01HL133823-06). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9918445. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*