Key Points• IL-33 and ST2 expression are increased post-conditioning and with GVHD, resulting in increased T-cell activation via the IL-33/ST2 axis.• Infusion of ST2-Fc protein exploits sST2's function as a negative regulator of acute GVHD inhibiting proinflammatory cytokines.Interleukin (IL)-33 binding to the receptor suppression of tumorigenicity 2 (ST2) produces pro-inflammatory and anti-inflammatory effects. Increased levels of soluble ST2 (sST2) are a biomarker for steroid-refractory graft-versus-host disease (GVHD) and mortality. However, whether sST2 has a role as an immune modulator or only as a biomarker during GVHD was unclear. We show increased IL-33 production by nonhematopoietic cells in the gastrointestinal (GI) tract in mice post-conditioning and patients during GVHD. Exogenous IL-33 administration during the peak inflammatory response worsened GVHD. Conversely, GVHD lethality and tumor necrosis factor-a production was significantly reduced in il33 2/2 recipients. ST2 was upregulated on murine and human alloreactive T cells and sST2 increased as experimental GVHD progressed. Concordantly, st2 2/2 vs wild-type (WT) donor T cells had a marked reduction in GVHD lethality and GI histopathology. Alloantigen-induced IL-18 receptor upregulation was lower in st2 2/2 T cells, and linked to reduced interferon-g production by st2 2/2 vs WT T cells during GVHD. Blockade of IL-33/ST2 interactions during allogeneic-hematopoietic cell transplantation by exogenous ST2-Fc infusions had a marked reduction in GVHD lethality, indicating a role of ST2 as a decoy receptor modulating GVHD. Together, these studies point to the IL-33/ST2 axis as a novel and potent target for GVHD therapy. (Blood. 2015;125(20):3183-3192)

Key Points• Absence of B7-H3 expression in allogeneic recipients or on allogeneic donor T cells leads to accelerated GVHD lethality.• Increased GVHD lethality is a result of increased T-cell proliferation, colon inflammatory cytokines, and intestinal permeability.Members of the B7 family have been shown to be important for regulating immune responses by providing either positive or negative costimulatory signals. The function of B7-H3 has been controversial. We show that B7-H3 is upregulated in graft-versus-host disease (GVHD) target organs, including the colon, liver, and lung. Infusion of allogeneic donor T cells into B7-H3 2/2 vs wild-type (WT) recipients resulted in increased GVHD lethality associated with increased T-cell proliferation, colonic inflammatory cytokines, and destruction of epithelial barriers. Allogeneic B7-H3 2/2 vs WT donor T cells also had increased T-cell proliferation and GVHD lethality associated with increased proliferation and cytokine secretion in the spleen, intraepithelial lymphocyte inflammatory cytokines, and intestinal permeability. Both resting and activated regulatory T cells (Tregs) lack B7-H3 messenger RNA. Consistent with these data, GVHD was augmented in recipients of B7-H3 2/2 Treg-depleted grafts. In two delayed lymphocyte infusion (DLI) models, T cells lacking B7-H3 are capable of providing graft-versus-leukemia (GVL) effects. We conclude that B7-H3 is responsible for providing a negative costimulatory signal. Our studies provide support for developing and testing new therapies directed toward the B7-H3 pathway, including approaches to augment host B7-H3 early after bone marrow transplantation to prevent GVHD and to develop potent antagonistic antibodies later after transplant to facilitate DLI-mediated GVL without GVHD complications. (Blood. 2015;125(21):3335-3346)

Background: Patients with squamous-cell carcinoma of the head and neck (SCCHN) on palliative therapy usually have a bad prognosis and suffer from various symptoms. With increasing use of targeted agents in cancer patients at the end of life, the correct assignment of therapy-related symptoms becomes increasingly difficult as cancer-related symptoms usually increase as well. Case Report: We report on 2 cases of patients with SCCHN who received multimodal treatment including palliative therapy with cetuximab. Both patients developed severe thoracic and cervicothoracic pain following treatment. In both cases, extensive paraspinal abscess formation proved to be the underlying cause. One patient was treated conservatively; the other one had to undergo surgical intervention. Conclusions: Awareness of multifaceted therapy-related complications is mandatory when patients receive multimodal treatment including targeted therapies. Unexplained pain syndromes in this context should raise suspicions concerning possible infectious complications and should lead to early use of magnetic resonance imaging.