Jingxin Qiu

A phase 1 study of imatinib for corticosteroid-dependent/refractory chronic graft-versus-host disease: response does not correlate with anti-PDGFRA antibodies

Stimulatory antiplatelet derived growth factor receptor α (PDGFRA) antibodies have been associated with extensive chronic graft-versus-host disease (cGVHD). We performed a phase 1 dose escalation trial of imatinib in corticosteroid-dependent/refractory cGVHD to assess the safety of imatinib and test the hypothesis that abrogation of PDGFRA signaling can ameliorate the manifestations of cGVHD. Fifteen patients were enrolled. Mean follow-up time was 56.6 weeks (range, 18-82.4 weeks). Imatinib 400 mg daily was associated with more frequent moderate to life-threatening adverse events than 200 mg daily. The main adverse events were nausea, edema, confusion, diarrhea, liver function test elevation, fatigue, and myalgia. The overall response rate was 40% (6 of 15). The treatment failure rate was 40% (6 of 15). Twenty percent (3 of 15) of subjects had stable disease. Of 4 subjects with phospho-PDGFRA and phospho-PDGFRB immunohistochemistry studies before and after treatment, inhibition of phosphorylation was observed in 3 but correlated with response in one. Anti-PDGFRA antibodies were observed in 7 of 11 evaluable subjects but correlated with clinical activity in 4. We conclude that cGVHD responds to imatinib through multiple pathways that may include PDGFRA signal transduction. This study is registered at www.clinicaltrials.gov as #NCT00760981.

A TLR5 Agonist Enhances CD8+ T Cell-Mediated Graft-versus-Tumor Effect without Exacerbating Graft-versus-Host Disease

Allogeneic hematopoietic cell transplantation is an established treatment for hematologic and nonhematologic malignancies. Donor-derived immune cells can identify and attack host tumor cells, producing a graft-versus-tumor (GVT) effect that is crucial to the effectiveness of the transplantation therapy. CBLB502 is a novel agonist for TLR5 derived from Salmonella flagellin. On the basis of TLR5-mediated immunomodulatory function, we examined the effect of CBLB502 on GVT activity. Using two tumor models that do not express TLR5, and thereby do not directly respond to CBLB502, we found that CBLB502 treatment significantly enhanced allogeneic CD8+ T cell-mediated GVT activity, which was evidenced by decreased tumor burden and improved host survival. Importantly, histopathologic analyses showed that CBLB502 treatment did not exacerbate the moderate graft-versus-host disease condition caused by the allogeneic CD8+ T cells. Moreover, mechanistic analyses showed that CBLB502 stimulates CD8+ T cell proliferation and enhances their tumor killing activity mainly indirectly through a mechanism that involves the IL-12 signaling pathway and the CD11c+ and CD11b+ populations in the bone marrow cells. This study demonstrates a new beneficial effect of CBLB502, and suggests that TLR5-mediated immune modulation may be a promising approach to improve GVT immunity without exacerbating graft-versus-host disease.

Granzyme B–Mediated Damage of CD8+ T Cells Impairs Graft-versus-Tumor Effect

Allogeneic hematopoietic cell transplantation is an established treatment for hematologic and other malignancies. Donor-derived immune cells can identify and attack host tumor cells, producing a graft-versus-tumor (GVT) effect that is crucial to the treatment. Using multiple tumor models and diverse donor–host combinations, we have studied the role of granzyme B (GzmB) in GVT effect. We first confirmed previous findings that GzmB deficiency diminished the ability of a high dose of CD8+ T cells to cause lethal graft-versus-host disease. However, when GVT studies were performed using a moderate cell dose that the hosts could tolerate, GzmB−/− CD8+ T cells demonstrated a significantly enhanced GVT effect. GzmB-mediated, activation-induced cell death in wild-type CD8+ T cells was found responsible for their reduced GVT activity. Conversely, GzmB−/− CD8+ T cells exhibited enhanced expansion, skewed toward an effector or effector memory phenotype, and produced higher amounts of IFN-γ and Fas ligand that might contribute to GzmB-independent tumor control. These findings demonstrate for the first time, to our knowledge, that GzmB-mediated damage of CD8+ T cells impairs the desired GVT effect. This study suggests that inhibiting donor-derived GzmB function may represent a promising strategy to improve GVT effect without exacerbating graft-versus-host disease.

Housing Temperature-Induced Stress Is Suppressing Murine Graft-versus-Host Disease through β2-Adrenergic Receptor Signaling.

Graft-versus-host disease (GVHD) is the major complication of allogeneic hematopoietic cell transplantation, a potentially curative therapy for hematologic diseases. It has long been thought that murine bone marrow–derived T cells do not mediate severe GVHD because of their quantity and/or phenotype. During the course of experiments testing the impact of housing temperatures on GVHD, we discovered that this apparent resistance is a function of the relatively cool ambient housing temperature. Murine bone marrow–derived T cells have the ability to mediate severe GVHD in mice housed at a thermoneutral temperature. Specifically, mice housed at Institutional Animal Care and Use Committee–mandated, cool standard temperatures (∼22°C) are more resistant to developing GVHD than are mice housed at thermoneutral temperatures (∼30°C). We learned that the mechanism underlying this housing-dependent immunosuppression is associated with increased norepinephrine production and excessive signaling through β-adrenergic receptor signaling, which is increased when mice are cold stressed. Treatment of mice housed at 22°C with a β2-adrenergic antagonist reverses the norepinephrine-driven suppression of GVHD and yields similar disease to mice housed at 30°C. Conversely, administering a β2-adrenergic agonist decreases GVHD in mice housed at 30°C. In further mechanistic studies using β2-adrenergic receptor–deficient (β2-AR−/−) mice, we found that it is host cell β2-AR signaling that is essential for decreasing GVHD. These data reveal how baseline levels of β-adrenergic receptor signaling can influence murine GVHD and point to the feasibility of manipulation of β2-AR signaling to ameliorate GVHD in the clinical setting.

Tumoral Bing-Neel Syndrome presenting as a cerebellar mass

Waldenstrom’s macroglobulinemia (WM) is a low-grade alignant monoclonal proliferation of immunoglobulin M (IgM)roducing lymphocytes capable of exhibiting plasmacytoid or lasma cell differentiation [1]. According to the World Health Orgaization’s classification of neoplastic diseases of hematopoietic and ymphoid tissues, WM is classified as lymphoplasmacytic lymhoma. Clinical features of WM may include cytopenia, bleeding, ymphadenopathy, splenomegaly, and, most commonly, a hyperiscosity syndrome related to high serum levels of monoclonal IgM. entral nervous system (CNS) complications arise in approximately 5% of WM cases, usually as a result of the hyperviscosity syndrome r an immune-related neuropathy [1,2]. Rare cases of WM involvng direct CNS infiltration by malignant cells have been referred to s Bing-Neel Syndrome (BNS). To date, limited data exist regardng BNS. The authors describe a rare case of BNS presenting as a erebellar mass with associated brainstem infiltration and subacute eurologic deterioration.

Granzyme B–Mediated Activation-Induced Death of CD4 + T Cells Inhibits Murine Acute Graft-versus-Host Disease

Granzyme B (GzmB) has previously been shown to be critical for CD8+ T cell–mediated graft-versus-host disease (GVHD) but dispensable for GVHD mediated by CD4+ T cells. However, previous studies used high doses of CD4+ T cells in MHC-mismatched models that caused rapid and lethal GVHD. Because of the hyperacute lethality, it is possible that the role of GzmB was concealed by the system. Therefore, in this study, we have titrated down the T cell dose to precisely determine the contribution of GzmB in GVHD mediated by CD4+CD25– T cells. Surprisingly, we have found that GzmB−/−CD4+CD25– T cells cause more severe GVHD compared with wild-type CD4+CD25– T cells in both MHC-matched and mismatched models. Mechanistic analyses reveal that although GzmB does not affect donor T cell engraftment, proliferation or tissue-specific migration, GzmB−/− CD4+CD25– T cells exhibit significantly enhanced expansion because of GzmB-mediated activation-induced cell death of wild-type CD4+CD25– T cells. As a result of enhanced expansion, GzmB−/− T cells produced higher amounts of proinflammatory cytokines (e.g., TNF-α and IFN-γ) that may contribute to the exacerbated GVHD. These results reveal that GzmB diminishes the ability of CD4+ T cells to cause acute GVHD, which contradicts its established role in CD8+ T cells. The differential roles suggest that targeting GzmB in selected T cell subsets may provide a strategy to control GVHD.

Survivin as a Cancer Vaccine Target

Survivin expression is associated with a poor prognosis in many cancers. While survivin is being studied as a potentially important target for cancer therapy, its many biological functions in both normal and cancerous cells remain to be fully elucidated. There are at least six specific survivin splice variants that have been identified to date which appear to be self-regulating and may have distinct functions. Several survivin peptide vaccines are currently under development by different groups. Survivin vaccine strategies for the most part have focused upon particular regional epitopes of the molecule that are bound by MHC class I and can lead to a cytotoxic T cell response. Immunotherapy targeting survivin is still at an early stage of development; however, several agents are progressing through early phase clinical trials. Recent studies using SurVaxM, a multi-epitope cryptic peptide, survivin, mimic show specific CD8+ T cell responses, as well as specific CD4+ T cell stimulation. Currently SurVaxM is in Phase I clinical trials designed to study its safety, tolerability and immunological effects in patients with survivin-positive recurrent malignant gliomas and multiple myeloma.

Circulating CD9+/GFAP+/survivin+ exosomes in malignant glioma patients following survivin vaccination

Glioma cells release exosomes in culture and into the extracellular matrix in vivo. These nanobodies transport an array of biomolecules and are capable of mediating cell-cell communication. Circulating exosomes in cancer patients may be indicative of disease status and response to therapy. The inhibitor of apoptosis protein (IAP) survivin (SVN) promotes cancer cell proliferation, local immune suppression and resistance to chemotherapy and it is a potential cancer biomarker. We used imaging flow cytometry to perform quantitative measurements of circulating SVN+ exosomes in the serum of malignant glioma patients undergoing investigational treatment with an anti-survivin vaccine (SurVaxM). Serum from glioma patients contained abundant CD9+ exosomes with both SVN and glial fibrillary acidic protein (GFAP) on their surface. Survivin and GFAP were evaluated both independently and together as possible tumor markers on CD9+ exosomes. Patients with longer time to tumor progression generally exhibited a decrease in circulating CD9+/SVN+ and CD9+/GFAP+/SVN+ exosomes immediately following survivin vaccination; whereas, those with early tumor progression had an increase in exosomes, despite anti-survivin immunotherapy. Serum from non-cancer healthy control individuals had very few detectable CD9+/GFAP+/SVN+ exosomes, although CD9+/GFAP+ exosomes were detectable in small numbers. This study demonstrates that patients with malignant gliomas have CD9+/GFAP+/SVN+ and CD9+/SVN+ exosomes that are released into the circulation and that early reductions in their numbers following anti-survivin immunotherapy might be associated with longer progression-free survival.

Host-Derived CD70 Suppresses Murine Graft-versus-Host Disease by Limiting Donor T Cell Expansion and Effector Function

Allogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative treatment for hematologic and immunologic diseases. However, graft-versus-host disease (GVHD) may develop when donor-derived T cells recognize and damage genetically distinct normal host tissues. In addition to TCR signaling, costimulatory pathways are involved in T cell activation. CD27 is a TNFR family member expressed on T cells, and its ligand, CD70, is expressed on APCs. The CD27/CD70 costimulatory pathway was shown to be critical for T cell function and survival in viral infection models. However, the role of this pathway in allo-HCT is previously unknown. In this study, we have examined its contribution in GVHD pathogenesis. Surprisingly, Ab blockade of CD70 after allo-HCT significantly increases GVHD. Interestingly, whereas donor T cell– or bone marrow–derived CD70 plays no role in GVHD, host-derived CD70 inhibits GVHD as CD70−/− hosts show significantly increased GVHD. This is evidenced by reduced survival, more severe weight loss, and increased histopathologic damage compared with wild-type hosts. In addition, CD70−/− hosts have higher levels of proinflammatory cytokines TNF-α, IFN-γ, IL-2, and IL-17. Moreover, accumulation of donor CD4+ and CD8+ effector T cells is increased in CD70−/− versus wild-type hosts. Mechanistic analyses suggest that CD70 expressed by host hematopoietic cells is involved in the control of alloreactive T cell apoptosis and expansion. Together, our findings demonstrate that host CD70 serves as a unique negative regulator of allogeneic T cell response by contributing to donor T cell apoptosis and inhibiting expansion of donor effector T cells.

Serine protease inhibitor 6 protects alloreactive T cells from Granzyme B-mediated mitochondrial damage without affecting graft-versus-tumor effect

ABSTRACT Allogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative therapy for hematologic malignancies. Donor T cells are able to eliminate residual tumor cells after allo-HCT, producing the beneficial graft-versus-tumor (GVT) effect, but can also cause graft-versus-host disease (GVHD) when attacking host normal tissues. We previously reported that granzyme B (GzmB) is involved in activation-induced cell death (AICD) of donor T cells and exerts differential impacts on GVHD and GVT effect. Serine protease inhibitor 6 (Spi6) is the sole endogenous inhibitor of GzmB that can protect immune and tissue cells against GzmB-mediated damage. This study is aimed to delineate the mechanism by which the GzmB-Spi6 axis regulates allogeneic T cell response. Using multiple clinically relevant murine allo-HCT models, we have found that Spi6 is concentrated in mitochondria during allogeneic T cell activation, while Spi6−/− T cells exhibit abnormal mitochondrial membrane potential, mass, reactive oxygen species (ROS) production and increased GzmB-dependent AICD mainly in the form of fratricide. Compared with WT T cells, Spi6−/− T cells exhibit decreased expansion in the host and cause significantly reduced GVHD. Notably, however, Spi6−/− T cells demonstrate the same level of GVT activity as WT T cells, which were confirmed by two independent tumor models. In summary, our findings demonstrate that Spi6 plays a novel and critical role in maintaining the integrity of T cell mitochondrial function during allogeneic response, and suggest that disabling Spi6 in donor T cells may represent a novel strategy that can alleviate GVHD without sacrificing the beneficial GVT effect.