Takero Shindo

Effector Regulatory T Cells Reflect the Equilibrium between Antitumor Immunity and Autoimmunity in Adult T-cell Leukemia.

Anti-CCR4 treatment of ATL destroys leukemic and normal Tregs, which can lead to autoimmunity. Only leukemic Tregs expressed CADM1, distinguishing the two populations. Treg depletion was associated with autoimmunity and Treg reemergence with relapse of ATL. The regulatory T cells (Treg) with the most potent immunosuppressive activity are the effector Tregs (eTreg) with a CD45RA–Foxp3++CCR4+ phenotype. Adult T-cell leukemia (ATL) cells often share the Treg phenotype and also express CCR4. Although mogamulizumab, a monoclonal antibody to CCR4, shows marked antitumor effects against ATL and peripheral T-cell lymphoma, concerns have been raised that it may induce severe autoimmune immunopathology by depleting eTregs. Here, we present case reports for two patients with ATL who responded to mogamulizumab but developed a severe skin rash and autoimmune brainstem encephalitis. Deep sequencing of the T-cell receptor revealed that ATL cells and naturally occurring Tregs within the cell population with a Treg phenotype can be clearly distinguished according to CADM1 expression. The onset of skin rash and brainstem encephalitis was coincident with eTreg depletion from the peripheral blood, whereas ATL relapses were coincident with eTreg recovery. These results imply that eTreg numbers in the peripheral blood sensitively reflect the equilibrium between antitumor immunity and autoimmunity, and that mogamulizumab might suppress ATL until the eTreg population recovers. Close monitoring of eTreg numbers is crucial if we are to provide immunomodulatory treatments that target malignancy without severe adverse events. Cancer Immunol Res; 4(8); 644–9. ©2016 AACR.

Elderly Patients With Chronic Myeloid Leukemia Benefit From a Dasatinib Dose as Low as 20 mg

Micro‐Abstract A retrospective study of elderly patients with chronic myeloid leukemia aged ≥ 65 years was conducted to evaluate the efficacy and safety of low‐dose dasatinib treatment. Reducing the dose of dasatinib to < 100 mg/day (even to ≤ 20 mg/day) generated good responses in these patients. The doses were safe and induced rapid and deep molecular responses. Background: The clinical outcomes of patients with chronic myeloid leukemia (CML) treated with BCR‐ABL tyrosine kinase inhibitors has improved markedly; however, the occurrence of adverse events (AEs) means that elderly patients often cannot be administered the standard dose. Nevertheless, some patients treated with low doses of tyrosine kinase inhibitor have achieved good molecular responses. Patients and Methods: We retrospectively analyzed the efficacy and safety of low‐dose dasatinib treatment of elderly CML patients. The study enrolled 21 patients with newly diagnosed, imatinib‐resistant, or imatinib‐intolerant chronic phase CML. All the patients were aged ≥ 65 years and received dasatinib at a dose of < 100 mg/day. Of these 21 patients, 77% had newly diagnosed CML. Results: Overall, 91% and 72% of patients received a mean dasatinib dose of ≤ 50 mg and ≤ 20 mg, respectively. A molecular response of MR3 (major molecular response, indicating > 3 log reduction in the number of leukemic cells), MR4, and MR4.5 were achieved in 96%, 77%, and 62% of the patients, respectively. Of the 15 patients who received a mean dose of ≤ 20 mg, 94% achieved a major molecular response, and 74% achieved MR4. The most common nonhematologic AE was plural effusion (29%), which was controlled by diuretics and regulating the drug dose. Conclusion: Low‐dose (eg, ≤ 20 mg) dasatinib therapy generates an adequate molecular response in most elderly patients with chronic phase CML without causing severe AEs.

Graft‐Versus‐Host Disease Amelioration by Human Bone Marrow Mesenchymal Stromal/Stem Cell‐Derived Extracellular Vesicles Is Associated with Peripheral Preservation of Naive T Cell Populations

A substantial proportion of patients with acute graft‐versus‐host disease (aGVHD) respond to cell therapy with culture‐expanded human bone marrow mesenchymal stromal/stem cells (BM‐MSCs). However, the mechanisms by which these cells can ameliorate aGVHD‐associated complications remain to be clarified. We show here that BM‐MSC‐derived extracellular vesicles (EVs) recapitulated the therapeutic effects of BM‐MSCs against aGVHD. Systemic infusion of human BM‐MSC‐derived EVs prolonged the survival of mice with aGVHD and reduced the pathologic damage in multiple GVHD‐targeted organs. In EV‐treated GVHD mice, CD4+ and CD8+ T cells were suppressed. Importantly, the ratio of CD62L‐CD44+ to CD62L + CD44‐ T cells was decreased, suggesting that BM‐MSC‐derived EVs suppressed the functional differentiation of T cells from a naive to an effector phenotype. BM‐MSC‐derived EVs also preserved CD4 + CD25 + Foxp3+ regulatory T cell populations. In a culture of CD3/CD28‐stimulated human peripheral blood mononuclear cells with BM‐MSC‐derived EVs, CD3+ T cell activation was suppressed. However, these cells were not suppressed in cultures with EVs derived from normal human dermal fibroblasts (NHDFs). NHDF‐derived EVs did not ameliorate the clinical or pathological characteristics of aGVHD in mice, suggesting an immunoregulatory function unique to BM‐MSC‐derived EVs. Microarray analysis of microRNAs in BM‐MSC‐derived EVs versus NHDF‐derived EVs showed upregulation of miR‐125a‐3p and downregulation of cell proliferative processes, as identified by Gene Ontology enrichment analysis. Collectively, our findings provide the first evidence that amelioration of aGVHD by therapeutic infusion of BM‐MSC‐derived EVs is associated with the preservation of circulating naive T cells, possibly due to the unique microRNA profiles of BM‐MSC‐derived EVs. Stem Cells 2018;36:434–445

Deep sequencing of the T cell receptor visualizes reconstitution of T cell immunity in mogamulizumab-treated adult T cell leukemia

ABSTRACT Although the anti-CCR4 antibody mogamulizumab (moga) shows striking antitumor activity against adult T cell leukemia (ATL), it can also cause fatal immunological pathology such as severe skin rash and graft-versus-host disease, which might be attributed to depletion of CCR4+ regulatory T cells. We previously showed that next generation sequencing enables precise analysis of the T cell receptor (TCR) repertoire, and we here used the technique to reveal the immunological dynamics in moga-treated ATL patients. Treatment with moga resulted in remarkable reduction or elimination of clonal cells, and enhanced reconstitution of non-tumor polyclonal CD4+ T cells and oligoclonal CD8+ T cells. Interestingly, cutaneous T cells infiltrating moga-related skin rashes did not share the same major clones in peripheral blood, which minimizes the possibility of cross-reaction. Thus, deep sequencing of the TCR can reveal the immune reconstitution of moga-treated ATL and provides powerful insights into its mode of action.

Rituximab-induced Acute Thrombocytopenia in High Tumor Burden Follicular Lymphoma

Rituximab-induced acute thrombocytopenia (RIAT), a rare complication of rituximab administration, has not yet been described in follicular lymphoma (FL). A 65-year-old man received rituximab for the treatment of high tumor burden follicular lymphoma in the leukemic phase. The next day, his platelet count abruptly dropped from 85,000 to 5,000/μL, which spontaneously recovered in a few days without specific treatment. We speculate that the occurrence of infusion-related cytokine release syndrome in rituximab-sensitive high tumor burden FL contributed to the development of RIAT. Frequent monitoring of the platelet count is advisable for select patients considered to be at a high risk for RIAT.

Therapeutic management in cardiac lymphoma

1 Division of Hematology, Respiratory Medicine and Oncology, Department of Internal Medicine, 2 Department of Medical Science Technology, School of Health Sciences at Fukuoka, International University of Health and Welfare, Fukuoka, Japan, 3 Department of Thoracic and Cardiovascular Surgery, 4 Division of Cardiology, Department of Internal Medicine 5 Department of Laboratory and Blood Transfusion Medicine, Faculty of Medicine, Saga University, Saga, Japan and 6 Department of Hematology and Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan

Growth and Differentiation Advantages of CD4+OX40+ T Cells from Allogeneic Hematopoietic Stem Cell Transplantation Recipients

OX40 (CD134), an activation-induced costimulatory molecule, is mainly expressed on CD4(+) T cells. Several reports, including previous reports from our laboratory, suggest that OX40-mediated signaling plays an important role in the development of graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (Allo HSCT). Here, we show that peripheral blood CD4(+)OX40(+) T cells are a unique cell subset as they possess the homing receptors of lymph nodes, and some of them have an exceptional capacity to produce high levels of interleukin-2 (IL-2) upon the stimulation through T cell receptors. Stimulation with IL-7 acts selectively on CD4(+)OX40(+) T cells not only to induce antigen-independent growth but also to increase the frequency of cells with IL-2-producing potential. Simultaneous, but not sequential, ligation of the T cell receptor and OX40 induces CD4(+)OX40(+) T cells to produce far more IL-2, which causes them to proliferate abundantly and differentiate readily into Th1- or Th2-biased effector memory T cells, especially in Allo HSCT recipients. Although not all the CD4(+)OX40(+) T cells had IL-2-producing capacity, Allo HSCT recipients with chronic GVHD (cGVHD) had a significantly higher frequency of IL-2-producing OX40(+) cells in their peripheral blood CD4(+) T cell subset than Allo HSCT recipients without cGVHD. Collectively, CD4(+)OX40(+) T cells with IL-2-producing potential are expected to be privileged for growth and differentiation in lymph nodes upon antigen presentation, suggesting that they might be involved in the process of inducing or maintaining cGVHD.

Tocilizumab for severe cytokine-release syndrome after haploidentical donor transplantation in a patient with refractory Epstein-Barr virus-positive diffuse large B-cell lymphoma

It has been well documented that patients may develop cytokine‐release syndrome (CRS) following the administration of monoclonal antibodies, such as chimeric antigen receptor‐modified T cell. Cytokine‐release syndrome is a common complication in patients who have received haploidentical donor allogeneic haematopoietic cell transplantation (haplo‐HCT). Although severe CRS after haplo‐HCT is a potentially life‐threatening toxicity, a standard treatment has not been established. Cytokine blockade with tocilizumab, an anti‐IL‐6 receptor antibody, has been effective for the treatment of patients with CRS after chimeric antigen receptor‐modified T‐cell treatment and has also improved CRS after haplo‐HCT. A 46‐year‐old man was diagnosed with haemophagocytic syndrome associated with Epstein‐Barr virus‐positive diffuse large B‐cell lymphoma. Salvage chemotherapy was unsuccessful; consequently, he received haplo‐HCT. On day +4, he developed grade 3 CRS, subsequently high‐dose corticosteroid initiated. Nevertheless, on day +6, he developed grade 4 CRS, resulting in requirement for ventilator support and multiple vasopressors. Corticosteroid could not improve severe CRS; therefore, tocilizumab was administered on day +14. Serum C‐reactive protein level transiently decreased and weaned multiple vasopressors. Although CRS improved, he developed candidaemia; consequently, he died on day +34. Tocilizumab could transiently improve severe CRS after haplo‐HCT. Although tocilizumab may have led to the improvement of CRS, a remaining concern is whether it inhibited the patients ability to mount antifungal immunity, leading to their demise.

Outcomes of patients with relapsed aggressive adult T-cell leukemia-lymphoma: clinical effectiveness of anti-CCR4 antibody and allogeneic hematopoietic stem cell transplantation

Adult T-cell leukemia-lymphoma (ATL) is a distinct type of peripheral T-cell lymphoma (PTCL) caused by human T-cell lymphotropic virus type I with poor outcomes.[1][1] To improve these results, up-front allogeneic hematopoietic stem cell transplantation (allo-HSCT) is considered in transplant-

The MEK inhibitor trametinib separates murine graft-versus-host disease from graft-versus-tumor effects

The efficacy of allogeneic hematopoietic stem cell transplantation for hematologic malignancies is limited by the difficulty in suppressing graft-versus-host disease (GVHD) without compromising graft-versus-tumor (GVT) effects. We previously showed that RAS/MEK/ERK signaling depends on memory differentiation in human T cells, which confers susceptibility to selective inhibition of naive T cells. Actually, antineoplastic MEK inhibitors selectively suppress alloreactive T cells, sparing virus-specific T cells in vitro. Here, we show that trametinib, a MEK inhibitor clinically approved for melanoma, suppresses GVHD safely without affecting GVT effects in vivo. Trametinib prolonged survival of GVHD mice and attenuated GVHD symptoms and pathology in the gut and skin. It inhibited ERK1/2 phosphorylation and expansion of donor T cells, sparing Tregs and B cells. Although high-dose trametinib inhibited myeloid cell engraftment, low-dose trametinib suppressed GVHD without severe adverse events. Notably, trametinib facilitated the survival of mice transplanted with allogeneic T cells and P815 tumor cells with no residual P815 cells observed in the livers and spleens, whereas tacrolimus resulted in P815 expansion. These results confirm that trametinib selectively suppresses GVHD-inducing T cells while sparing antitumor T cells in vivo, which makes it a promising candidate for translational studies aimed at preventing or treating GVHD.