Phenotypic and functional characterization of the CD6-ALCAM T-cell co-stimulatory pathway after allogeneic cell transplantation.

CD6 is a co-stimulatory receptor expressed on T cells that binds activated leukocyte cell adhesion molecule (ALCAM), expressed on antigen presenting cells, epithelial and endothelial tissues. The CD6-ALCAM pathway plays an integral role in modulating T-cell activation, proliferation, and trafficking. In this study we examined expression of CD6 by reconstituting T cells in 95 patients after allogeneic cell transplantation and evaluated the effects of itolizumab, an anti- CD6 monoclonal antibody, on T-cell activation. CD6 T cells reconstituted early after transplant with CD4 regulatory T cells (Treg)-expressing lower levels of CD6 compared to conventional CD4 T cells (Tcon) and CD8 T cells. After onset of acute graft-versus-host disease (aGvHD), CD6 expression was further reduced in Treg and CD8 T cells compared to healthy donors, while no difference was observed for Tcon. ALCAM expression was highest in plasmacytoid dendritic cells (pDC), lowest in myeloid dendritic cells (mDC) and intermediate in monocytes and was generally increased after aGvHD onset. Itolizumab inhibited CD4 and CD8 T-cell activation and proliferation in preGvHD samples, but inhibition was less prominent in samples collected after aGvHD onset, especially for CD8 T cells. Functional studies showed that itolizumab did not mediate direct cytolytic activity or antibody-dependent cytotoxicity in vitro. However, itolizumab efficiently abrogated the costimulatory activity of ALCAM on T-cell proliferation, activation and maturation. Our results identify the CD6-ALCAM pathway as a potential target for aGvHD control and a phase I/II study using itolizumab as first line treatment in combination with steroids for patients with aGvHD is currently ongoing (clinicaltrials gov. Identifier: NCT03763318).

[Cunninghamella bertholletiae-infective endocarditis complicated by tricuspid valve giant vegetation in a patient with aplastic anemia].

A 62-year-old female was presented to the hospital of the current study for pancytopenia and was diagnosed with severe aplastic anemia. She was treated with a combination therapy of antithymocyte globulin, cyclosporine A, and eltrombopag. The patient also presented with febrile neutropenia after commencement of the treatment and did not respond to the various antibiotics and antifungal agents. Echocardiography showed a giant vegetation attached to the tricuspid valve on Day 78 of the immunosuppressive therapy, and the tricuspid valve replacement was performed. The vegetation was formed by Cunninghamella bertholletiae, a mucor type, and was treated with high-dose liposomal amphotericin B (L-AMB), which was terminated after six weeks due to decreased renal function. In addition, mucormycosis was controlled by posttreatment with posaconazole (PSCZ). This is a rare case of mucormycosis that developed into a giant vegetation during the immunosuppressive therapy for aplastic anemia. It was believed to be a valuable case to consider in future mucormycosis treatment, including the success of the treatment by switching from L-AMB to PSCZ.

[Successful treatment with blinatumomab for refractory B lymphoblastic leukemia complicated with malignant pleural effusion].

A 77-year-old man diagnosed with mixed-phenotype acute leukemia (MPAL (B/Myeloid), NOS) achieved complete remission (CR) after eight courses of hyper-CVAD/MA therapy. However, 6 months later, blasts were observed on peripheral blood smear, and bone marrow aspiration revealed that the disease had relapsed as B lymphoblastic leukemia (ALL). At this time, he had left pleural effusion. He received two courses of inotuzumab ozogamicin (InO) and achieved second hematological CR, but the left pleural effusion worsened over time, suggesting poor disease control. After changing the regimen to blinatumomab, aspiration biopsy cytology showed that the blasts in the pleural fluid disappeared and respiratory distress improved after one course of treatment. Flow cytometry results showed increased populations of CD3-positive T-cells, suggesting that blinatumomab may have migrated into the pleural fluid and exerted an antitumor effect. Although new ALL-specific antibody drugs, such as InO and blinatumomab, are expected to improve prognosis, only few reports have described their tissue migration. The difference between InO and blinatumomab in terms of efficacy of treating malignant pleural effusion remains unclear and should be explored in additional cases.

PD-1 modulates regulatory T-cell homeostasis during low-dose interleukin-2 therapy.

CD4+Foxp3+ regulatory T cells (Tregs) play a central role in the maintenance of immune tolerance after hematopoietic stem cell transplantation. We previously reported that low-dose interleukin-2 (IL-2) therapy increased circulating Tregs and improved clinical symptoms of chronic graft-versus-host-disease (cGVHD); however, the mechanisms that regulate Treg homeostasis during IL-2 therapy have not been well studied. To elucidate these regulatory mechanisms, we examined the role of inhibitory coreceptors on Tregs during IL-2 therapy in a murine model and in patients with cGVHD. Murine studies demonstrated that low-dose IL-2 selectively increased Tregs and simultaneously enhanced the expression of programmed cell death 1 (PD-1), especially on CD44+CD62L+ central-memory Tregs, whereas expression of other inhibitory molecules, including CTLA-4, LAG-3, and TIM-3 remained stable. PD-1-deficient Tregs showed rapid Stat5 phosphorylation and proliferation soon after IL-2 initiation, but thereafter Tregs became proapoptotic with higher Fas and lower Bcl-2 expression. As a result, the positive impact of IL-2 on Tregs was completely abolished, and Treg levels returned to baseline despite continued IL-2 administration. We also examined circulating Tregs from patients with cGVHD who were receiving low-dose IL-2 and found that IL-2-induced Treg proliferation was promptly followed by increased PD-1 expression on central-memory Tregs. Notably, clinical improvement of GVHD was associated with increased levels of PD-1 on Tregs, suggesting that the PD-1 pathway supports Treg-mediated tolerance. These studies indicate that PD-1 is a critical homeostatic regulator for Tregs by modulating proliferation and apoptosis during IL-2 therapy. Our findings will facilitate the development of therapeutic strategies that modulate Treg homeostasis to promote immune tolerance.

Plasma exchange eliminates residual mogamulizumab but does not warrant prompt recovery of peripheral Treg levels.

Mogamulizumab (Mog), a humanized anti-CCR4 antibody, provides an important treatment option for relapsed/refractory adult T cell leukemia/lymphoma. However, administration of Mog before allogenic hematopoietic stem cell transplantation has been reported to be a risk factor for severe acute graft-versus-host disease (GVHD). The etiological hypothesis is Mogamulizumab may eradicate CCR4-positive regulatory T cells (Tregs). Theoretically, Treg homeostasis and course of GVHD can be affected by plasma exchange (PE) with decreasing plasma Mog concentration. Here, we present a case of severe acute GVHD after pretransplantation Mog, in which PE was performed for liver failure. As a result, plasma Mog concentration was decreased but it did not lead to the prompt elevation of Treg levels in peripheral blood and clinical responses of GVHD were limited to partial remission. Our case suggests that recovery of donor-derived Treg in the acute phase after HSCT is multifactorial and the single procedure of PE-based Mog depletion does not necessarily warrant the quick restoration of Treg homeostasis.

Progressive multifocal leukoencephalopathy after T-cell replete HLA-haploidentical transplantation with post-transplantation cyclophosphamide graft-versus-host disease prophylaxis.

A 52-year-old man suffered from progressive multifocal leukoencephalopathy (PML) after human leukocyte antigen (HLA)-haploidentical transplantation with post-transplantation cyclophosphamide (PTCY). Mirtazapine, mefloquine, and cytarabine failed to improve his symptoms, and he finally died 4.5 months after PML onset. This is the first case report of a patient with PML after HLA-haploidentical transplantation with PTCY. Although T-cell replete HLA-haploidentical transplantation with PTCY has enabled early immune reconstitution, PML should be considered if a patient's mental condition deteriorates.

Vigorous inflammatory responses in noninfectious pulmonary complication induced by donor lymphocyte infusion.

BACKGROUND: Donor lymphocyte infusion (DLI) is used for treatment of hematologic malignancy relapse or mixed chimerism after allogeneic hematopoietic stem cell transplantation. Although graft-versus-host disease is well recognized as one of the adverse effects of DLI, there are limited reports on noninfectious pulmonary complications (NIPCs) after DLI. CASE REPORT: A 55-year-old woman with acute myeloid leukemia received DLI for conversion from recipient predominant to complete donor chimerism on Day +193 after allogeneic HSCT. Eight weeks later, she complained of dyspnea with fever; chest computed tomography revealed diffuse, bilateral, ground glass opacity and reticular appearance. She was diagnosed as having NIPC based on serum and bronchoalveolar lavage fluid (BALF) findings. She was successfully treated with prednisolone (PSL) and completely recovered. DISCUSSION: We analyzed the cell profile from the BALF and 27 cytokines and chemokines in the serum using the Bio-Plex platform. The cells consisted of recipient predominant macrophages and T cells. The serum cytokine and chemokine profile showed significant elevation of interleukin (IL)-1ß, IL-6, IL-8, tumor necrosis factor-α, macrophage inflammatory protein (MIP)-1α, and MIP-1ß, which declined with the improvement of symptoms after initiation of PSL treatment. CONCLUSION: Inflammatory effectors by recipient cells, rather than allogeneic responses by donor cells, played an important role in the pathogenesis of NIPCs after DLI in the present case.

Phase I/IIa Study of Low Dose Subcutaneous Interleukin-2 (IL-2) for Treatment of Refractory Chronic Graft Versus Host Disease.

Chronic graft versus host disease (cGVHD) remains a major problem for long survivors after allogeneic hematopoietic stem cell transplantation (HSCT). Currently, corticosteroid therapy is effective for cGVHD as the first line therapy. However, prolonged therapy with corticosteroids causes various severe adverse events. To develop the new therapeutic strategy of cGVHD, we have launched a multicenter phase I/IIa clinical trial of low dose subcutaneous interleukin-2 (IL-2) for treatment of steroid refractory cGVHD, which is constituted of 2 sequential phases (induction phase and maitanance phase). This study will provide the new therapeutic option for patients with refractory cGVHD after allogeneic HSCT.

Responses of regulatory and effector T-cells to low-dose interleukin-2 differ depending on the immune environment after allogeneic stem cell transplantation.

CD4+Foxp3+ regulatory T cells (Tregs) play a central role in the maintenance of immune tolerance after allogeneic hematopoietic stem cell transplantation (HSCT). Tregs promptly respond to low concentrations of IL-2 through the constitutive expression of high-affinity IL-2 receptors. It has been reported that low-dose IL-2 therapy increased circulating Tregs and improved clinical symptoms of chronic GVHD. Clinical studies of IL-2 therapy so far have mainly targeted patients in the chronic phase of transplantation when acute immune responses has subsided. However, the biological and clinical effects of exogenous IL-2 in an acute immune environment have not been well investigated. In the current study, we investigated the impact of exogenous IL-2 therapy on the post-transplant homeostasis of T cell subsets which influence the balance between GVHD and GVL in the acute phase, by setting the various immune environments early after HSCT in murine model. We initially found that 5,000 IU of IL-2 was enough to induce the active proliferation of Treg without influencing other conventional T cells (Tcons) when administered to normal mice. However, activated Tcons showed the response to the same dose of IL-2 in recipients after allogeneic HSCT. In a mild inflammatory environment within a threshold, exogenous IL-2 could effectively modulate Treg homeostasis with just limited influence to activated T cells, which resulted in an efficient GVHD suppression. In contrast, in a severely inflammatory environment, exogenous IL-2 enhanced activated T cells rather than Tregs, which resulted in the exacerbation of GVHD. Of interest, in an immune-tolerant state after transplant, exogenous IL-2 triggered effector T-cells to exert an anti-tumor effect with maintaining GVHD suppression. These data suggested that the responses of Tregs and effector T cells to exogenous IL-2 differ depending on the immune environment in the host, and the mutual balance of the response to IL-2 between T-cell subsets modulates GVHD and GVL after HSCT. Our findings may provide useful information in the optimization of IL-2 therapy, which may be personalized for each patient having different immune status.

Sequential Combination of FLAM and Venetoclax plus Azacitidine to Bridge to Cord Blood Transplantation in a Patient with Primary Induction Failure Acute Myeloid Leukemia.

Venetoclax (VEN) is an oral B-cell lymphoma-2 (BCL-2) inhibitor that has been widely used to treat various hematological disorders. Recent studies have demonstrated that VEN in combination with fludarabine-enhanced high-dose cytarabine (FLA) is effective for treating relapsed or refractory acute myeloid leukemia (AML). In the combination therapy, salvage chemotherapy and VEN are basically concurrently administrated; however, further optimization may enable the treatment to apply to larger numbers of patients with various clinical backgrounds. Here, we describe a case of refractory AML treated with a sequential combination of the intensive chemotherapy (fludarabine, cytarabine, and mitoxantrone; FLAM) and VEN/AZA to bridge to an unrelated cord blood transplantation (uCBT). By continuously adding VEN/AZA after FLAM, the patient achieved morphologic leukemia free state with only minor toxicities. Blood cell counts did not recover until the time of transplantation because of the deep myelosuppression caused by the treatment sequence, but the infection risk was safely managed during this period. After engraftment, maintenance therapy with VEN/AZA was performed, and the patient has survived without disease recurrence for over 9 months after transplantation. Our case suggests that bridging therapy with VEN and AZA from the time of the last chemotherapy to allogeneic transplantation may provide an effective and tolerable treatment strategy for refractory AML. Further studies of larger numbers of cases are needed to validate the effectiveness of this treatment.

Asymmetrical and Isolated Hypoglossal Nerve Palsy Accompanied by a New Subset of Anti-ganglioside Antibodies in a Patient with Diffuse Large B Cell Lymphoma.

Malignant lymphoma sometimes involves peripheral nerves due to paraneoplastic syndrome associated with anti-ganglioside antibodies. We report a very rare case of malignant lymphoma accompanied by an asymmetrical and isolated hypoglossal nerve palsy associated with a new subset of anti-ganglioside antibodies. Magnetic resonance imaging and 18F-2-deoxy-2-fluoro-D-glucose position emission tomography showed no abnormalities of the hypoglossal nerve nucleus; however, the patient' s serum was positive for anti-sulfated glucuronyl paragloboside IgM antibodies as well as anti-GM1 IgM and anti-GQ1b IgM antibodies. The present case might suggest a paraneoplastic asymmetrical and isolated hypoglossal nerve palsy associated with a new subset of anti-ganglioside antibodies.

Mild renal dysfunction defined by creatinine clearance rate has limited impact on clinical outcomes after allogeneic hematopoietic stem cell transplantation.

Creatinine clearance rate (Ccr) is a more accurate indicator of renal function than serum creatinine. Data are sparse regarding the prognostic value of renal impairment calculated using Ccr in patients who undergo allogeneic hematopoietic stem cell transplantation (allo-HSCT). We performed a retrospective analysis of 185 patients who underwent allo-HSCT. These patients were divided into two groups by Ccr (ml/min) before transplantation; one showed normal renal function (Ccr ≥ 60, n = 156) and the other showed mild renal dysfunction (30 ≤ Ccr < 60, n = 29), and transplant outcomes were compared between the groups. We observed no significant difference between the groups in terms of clinical characteristics other than age, estimated glomerular filtration rate, serum creatinine, Ccr predicted by Cockcroft-Gault formula, primary disease, and conditioning intensity. With respect to transplant outcomes, no significant difference was observed in overall survival, relapse, or non-relapse mortality between the two groups. Multivariate analysis demonstrated that 30 ≤ Ccr < 60 before allo-HSCT was not an independent prognostic factor for transplant outcome. In conclusion, these results suggest that patients with mild renal dysfunction, defined as 30 ≤ Ccr < 60 ml/min, can safely undergo allo-HSCT. However, a larger series of patients is needed to evaluate the impact of mild renal dysfunction before allo-HSCT in more detail.

Complete resolution of steroid-resistant organizing pneumonia associated with myelodysplastic syndrome following allogeneic hematopoietic cell transplantation.

Pulmonary complications in patients with hematological malignancies are often caused by infection but are sometimes associated with an underlying disease such as organizing pneumonia (OP). Here, we report a case of life-threatening steroid-resistant OP associated with myelodysplastic syndrome (MDS) and successfully performed allogeneic hematopoietic cell transplantation (HSCT). A 33-year-old female with refractory anemia with excess blasts-1 that had progressed from refractory anemia with ringed sideroblasts and concomitant Sweet's syndrome was admitted. Multiple pulmonary infiltrates were revealed on a chest computed tomography scan, which progressively worsened even after chemotherapy and corticosteroid therapy. No evidence of infection was observed in bronchoalveolar lavage fluid. A histological examination of a transbronchial lung biopsy specimen showed lymphocyte invasion with fibrosis, indicating that the pulmonary infiltrates were OP associated with MDS. Before transplantation, she suffered from respiratory failure and required oxygen supplementation. She developed idiopathic pneumonitis syndrome on day 61 that responded well to corticosteroid therapy, and the OP pulmonary infiltrates improved gradually after HSCT, She was discharged on day 104 and is well without recurrence of OP or MDS 2 years after HSCT.