Acute graft-versus-host disease (aGvHD) is a major complication following hematopoietic stem cell transplant (HSCT) that contributes to high non-relapse mortality. The disease process is initiated by the migration of donor T cells to the host secondary lymphoid organs and their activation by allo-antigens on host antigen-presenting cells (APC).1 CCR7, a chemokine receptor, and its ligands CCL19 and CCL21 expressed by donor T cells is critically important for lymph node specific homing and activation of T cells by APCs.2
Previous reports demonstrated that a high proportion of CCR7+ donor T-cell subsets in the graft was an independent risk factors for aGvHD and correlated with poorer outcome.3
A study published by Carlos Cuesta-Mateos and colleagues explored whether apheresis with a low proportion of CCR7+ cells or blocking the function of CCR7 with an anti-human CCR7 monoclonal antibody (mAb) could prevent or treat aGvHD in preclinical models.4
- Apheresis samples were stained with a panel of antibodies including anti-CD45RA, anti-CD62L, anti-CD3, anti-CD4 to identify the following T cell subsets:
- T cells considered as primary mediators of aGVHD
- CCR7+ naïve T cells (TN)
- central memory T cells (TCM)
- T cells associated with responses against infections and graft-versus-leukemia (GvL) effect
- CCR7- effector memory T cells (TEM)
- CCR7- CD45RA+ TEM cells (TEMRA)
- T cells considered as primary mediators of aGVHD
- Migration and complement-dependent cytotoxicity (CDC) assays were performed on peripheral blood mononuclear cells (PBMC) from apheresis samples
- Xenogeneic models of aGvHD were induced by engrafting human (h) PBMC in sub-lethally irradiated NSG mice
In total, 103 donor–recipient pairs who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) were analyzed. Transplant characteristics are presented in Table 1.
Table 1. Selected transplant characteristics
Diagnosis of the underlying disease (Relapse rate, %)
Acute lymphoid leukemia
Acute myeloid leukemia
Chronic lymphocytic leukemia
Male to male
Female to female
HLA-identical (10/10) unrelated
HLA mismatched (9/10) unrelated
Source of graft
Infused CD34+ 106/kg of recipient weight
Infused CD3+ 106/kg of recipient weight
CsA and MTX
CsA and MMF
BMSC, bone marrow stem cells; CsA, cyclosporin A; MMF, mycophenolate mofetil; MTX, methotrexate; PBSC, peripheral blood stem cells;
Correlating rate of transfused CCR7+ cells with induction of GvHD in humans and mice
In patients, apheresis with < 3.6% of CD4+ CCR7+ cells showed low risk of developing aGvHD, with 87.88% (75.23–100%) of patients not developing the complication. The cut off for CD8+ CCR7+ was < 2.2% cells in the apheresis, with 88.57% (76.60–100%) of patients free from chronic (c)GvHD.
In contrast, xenograft models of GvHD demonstrated that lowering the proportion of CCR7+ cells used for apheresis failed to prevent or delay GvHD. The median overall survival (OS) was 14 days for animals engrafted with apheresis products containing ≤3% of CD4+ CCR7+ (n = 6) vs 13 days for mice with apheresis around 20% of CCR7+ cells.
Using anti-CCR7 mAb impairs CCR7+ TN and TCM cells chemotaxis and induces CDC
The addition of anti-CCR7 mAb to PBMC reduced the migration of CCR7+ TN and TCM cells stimulated with CCL19 or CCL21. CCR7 ligands and anti-CCR7 mAb did not induce responses in TEM and TEMRA cells which were CCR7-. Moreover, in vitro assays using anti-CCR7 mAb with fresh hPBMC from apheresis demonstrated strong depletion of CCR7+ but not CCR7- human TN and TCM cells via CDC.
CCR7+ T-cells are not involved in CMV reactivation and GvL effect
In patients, the levels of donor CCR7+ T cells in the apheresis did not correlate with cytomegalovirus (CMV) reactivation within the first six months after transplantation or with a relapse of the underlying disease.
Anti-hCCR7 mAb prevents aGvHD in xenograft models
In xenogenic models of aGvHD induced by engrafting of hPBMC, early administration of anti-CCR7 mAb, after hPBMC inoculation, prevented the development of aGvHD. Animals treated later than on Day 5 after engraftment had infiltration of human T cells in all tissues, which was, however, lower than in control mice.
- In animals that started treatment two hours before engraftment and had additional four doses given every three days, there was an increased median OS with the anti-hCCR7 mAb vs control (30 days vs 12 days; p = 0.0025)
- In animals that started treatment on Day 5 after engraftment and had additional four doses administered, anti-hCCR7 mAb was able to reverse first clinical signs of aGvHD and provide survival benefit compared to control treatment (median OS of 33 days vs 18 days; p = 0.0211)
- In animals that started treatment on Day 3, Day 7, or Day 10 after engraftment and had additional four doses given every three days, best responses were seen at Day 3 (median OS of 26 days with anti-hCCR7 mAb vs 12 days with control; p = 0.0026) compared to Day 7 (median OS 18 days vs 12 days, respectively; p = 0.0742) and Day 10 (median OS 17 days vs 12 days, respectively; p = 0.0181)
The authors of the article demonstrated that selective targeting of CCR7 with antibodies is a feasible and promising way to prevent donor T-cell migration to secondary lymphoid organs and to reduce the severity of aGVHD. Importantly, CCR7+ T cells seem not to be involved in the GvL effect or CMV reactivation. Other than in humans, xenograft models suggest that even small amounts of CCR7+ T cells can induce GvHD. The most profound anti-aGvHD effect was observed in transplanted mice, when an anti-hCCR7 mAb was administrated within the first five days after transplantation. This novel prophylactic approach could offer a benefit to patients in haploidentical settings, who have a particularly large unmet need for safe and effective therapies preventing GvHD.