Epitope Mismatch at HLA-DRB1 Associates with Reduced Relapse Risk in Cord Blood Transplantation for Standard-Risk Hematologic Malignancy.

Cord blood transplantation (CBT) is an attractive therapeutic option for patients with hematologic malignancies. CBT tolerates HLA mismatches between donors and recipients, but the HLA mismatches that generate graft-versus-tumor (GVT) effects remain unknown. Given that HLA molecules contain epitopes comprising polymorphic amino acids that determine their immunogenicity, we investigated associations between epitope-level HLA mismatches and relapse following single-unit CBT. A total of 492 patients with hematologic malignancies who underwent single-unit, T cell-replete CBT were included in this multicenter retrospective study. HLA epitope mismatches (EMs) were quantified using HLA matchmaker software from donor and recipient HLA-A, -B, -C, and -DRB1 allele data. Patients were dichotomized by median EM value and divided into 2 groups: patients who underwent transplantation in complete/partial remission (standard stage: 62.4%) and others (advanced stage: 37.6%). The median number of EMs in the graft-versus-host direction (GVH-EM) was 3 (range, 0 to 16) at HLA class I and 1 (range, 0 to 7) at HLA-DRB1. Higher HLA class I GVH-EM was associated with increased nonrelapse mortality (NRM) in the advanced stage group (adjusted hazard ratio [HR], 2.12; P = .021), with no significant advantage for relapse in either stage. In contrast, higher HLA-DRB1 GVH-EM was associated with better disease-free survival in the standard stage group (adjusted HR, .63; P = .020), which was attributed to lower relapse risk (adjusted HR, .46; P = .014). These associations also were observed even within HLA-DRB1 allele-mismatched transplantations in the standard stage group, indicating that EM might have an impact on relapse risk independent of allele mismatch. High HLA-DRB1 GVH-EM did not increase NRM in either stage. High HLA-DRB1 GVH-EM may lead to potent GVT effects and a favorable prognosis following CBT, especially in patients who underwent transplantation at the standard stage. This approach may facilitate appropriate unit selection and improve the overall prognosis of patients with hematologic malignancies who undergo CBT.

Allogeneic stem cell transplantation for trisomy 8-positive myelodysplastic syndrome or myelodysplastic/myeloproliferative disease with refractory Behçet's disease: Case report and the review of literature.

We had two cases of trisomy 8-positive myelodysplastic syndrome (MDS) with incomplete Behçet's disease (BD) in which the remissions of both diseases were maintained by allogeneic stem cell transplantation (allo-SCT). Among MDS with BD patients, sometimes it is difficult to control the symptoms of BD with standard therapies such as corticosteroids and tumor necrosis factor (TNF) inhibitors. Although there should be careful consideration regarding indications for transplantation, our two cases, in which refractory BD was completely controlled by allo-SCT, suggest that allo-SCT can be one of the treatment options for higher-risk MDS with BD patients.

A sporadic case of CTLA4 haploinsufficiency manifesting as Epstein-Barr virus-positive diffuse large B-cell lymphoma.

Cytotoxic T-lymphocyte-associated antigen 4 (CTLA4) is a coinhibitory receptor that plays an essential role in maintaining immune system homeostasis by suppressing T-cell activation. We report a sporadic case of CTLA4 haploinsufficiency in a patient with Epstein-Barr virus-positive diffuse large B-cell lymphoma and subsequent benign lymphadenopathy. A missense mutation in exon 2 of the CTLA4 gene (c.251T>C, p.V84A) was found in the patient's peripheral blood and buccal cell DNA, but not in her parents' DNA. CTLA4 expression decreased in the peripheral regulatory T cells upon stimulation, whereas CTLA4 and PD-1-positive T cell subsets increased, possibly to compensate for the defective CTLA4 function. This case suggests that some adult lymphoma patients with no remarkable medical history have primary immune disorder. As immune-targeted therapies are now widely used for the treatment of malignancies, it is increasingly important to recognize the underlying primary immune disorders to properly manage the disease and avoid unexpected complications of immunotherapies.

[Treatment for acute leukemia showing PCR-positivity of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) at initial diagnosis: a case report and review of literature].

The novel coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is rapidly spreading across the world. We encountered two patients with COVID-19 who underwent treatment for acute leukemia at initial diagnosis. Both the patients received conventional induction therapy without the exacerbation of COVID-19. Although the impact of SARS-CoV-2 on the treatment of leukemia is unclear, our treatment experience suggests that there is no major contraindication to standard chemotherapy for acute leukemia in patients with COVID-19. As COVID-19 continues to be a threat worldwide, further evaluations of large cohorts are needed for future treatment decisions for acute leukemia with COVID-19.

The EZH2 inhibitor tazemetostat upregulates the expression of CCL17/TARC in B-cell lymphoma and enhances T-cell recruitment.

An inhibitor of the histone methyltransferase enhancer of zeste homologue 2 (EZH2), tazemetostat, has been developed for the treatment of B-cell lymphoma, but its mechanisms of action are not fully elucidated. We screened for genes targeted by tazemetostat in eleven B-cell lymphoma cell lines and found that tazemetostat significantly increased the expression of chemokine (C-C motif) ligand 17 (CCL17)/thymus- and activation-regulated chemokine (TARC) in all, which codes for a chemokine that is a hallmark of Hodgkin/Reed-Sternberg (H/RS) cells in Hodgkin lymphoma. Notably, gene set enrichment analysis demonstrated a positive correlation between the genes upregulated by tazemetostat in five follicular lymphoma (FL) cell lines and those reported to be overexpressed in H/RS cells. The CCL17 promoter region was enriched in repressive histone modification H3K27me3, and tazemetostat induced H3K27 demethylation and activated gene transcription. CCL17 protein secretion was also induced by EZH2 inhibition, which was further enhanced by concurrent CpG stimulation. In vitro transwell migration assay demonstrated that CCL17 produced by tazemetostat-treated B cells enhanced the recruitment of T cells, which had the potential to exert antilymphoma response. Analysis of publicly available human lymphoma databases showed that CCL17 gene expression was inversely correlated with the EZH2 activation signature and significantly paralleled the CD4+ and CD8+ T-cell-rich signature in FL and germinal center B-cell-like diffuse large B-cell lymphoma. Our findings indicate that tazemetostat can potentially activate antilymphoma response by upregulating CCL17 expression in B-cell lymphoma cells and promote T-cell recruitment, which provides a rationale for its combination with immunotherapy.

Programmed cell death 1-expressing CD56-negative natural killer (NK) cell expansion is a hallmark of chronic NK cell activation during dasatinib treatment.

Dasatinib treatment markedly increases the number of large granular lymphocytes including natural killer (NK) cells in a proportion of Ph+ leukemia patients, which associates with a better prognosis. In-depth immune profiling of NK cells can predict therapeutic response in these patients. In the present study, we showed that CD56-negative (CD56neg ) NK cells increased exclusively in cytomegalovirus-seropositive (CMV+ ) patients treated with dasatinib. The increase longitudinally paralleled with progressive differentiation of CD56dim NK cells during dasatinib therapy driven by CMV reactivation as shown by principal component analysis on 19 NK cell markers. The CD56neg NK cells showed downregulation of NK-activating receptors, upregulation of PD-1, and lower cytotoxicity and cytokine production, indicating that these cells are anergic and dysfunctional as seen in chronic infections with HIV-1 or hepatitis C virus. Moreover, cytolytic activity of CD56dim and CD56neg NK cells against leukemia cells was partially restored by nivolumab in proportion to the frequency of PD-1+ NK cells. The proportion of patients who achieved deep molecular responses at 2 years was significantly higher in dasatinib-treated patients with ≥3% CD56neg NK cells than in those with fewer CD56neg NK cells (54.5% vs 15.8%, P = .0419). These findings suggest that CD56neg NK cells may be an exhausted population induced by chronic activation through CMV reactivation during dasatinib therapy. Expansion of CD56neg NK cells is a hallmark of chronic NK cell activation in patients treated with dasatinib and may predict a better clinical outcome. Furthermore, PD-1 blockade may enhance anti-leukemia responses of such NK cells.

Establishment and characterization of a MALT lymphoma cell line carrying an API2-MALT1 translocation.

MALT lymphomas with API2(BIRC3)-MALT1 translocation usually have an indolent clinical course and rarely transform into aggressive lymphoma, and there have been no lymphoma cell lines carrying API2-MALT1 translocation reported to date. We established a novel lymphoma cell line named BMA19, carrying the API2-MALT1 translocation from a patient with histologic transformation of intestinal MALT lymphoma. The cells were suggested to carry API2-MALT1 and MYC-IGH translocations by chromosomal analysis, and these translocations were confirmed by polymerase chain reaction analysis. The expression of MYC was shown to be enhanced as a result of the MYC-IGH translocation, and it is considered to have played a role in the histologic transformation of MALT lymphoma. Whole exome sequencing of BMA19 identified several nucleotide variations in genes reported to be mutated in previous studies of marginal zone lymphomas. The MALT1 inhibitor MI-2 specifically decreased cell growth, and the BMA19 cell line was suggested to be still dependent on the API2-MALT1 signal. Subtractive microarray analysis showed that one of the earliest events resulting from MALT1 inhibition is increased susceptibility to endoplasmic reticulum stress-induced apoptosis. The BMA19 cell line is considered to conserve the biological properties of MALT lymphoma and is expected to be a valuable tool for research into the pathogenesis of MALT lymphoma with an API2-MALT1 translocation.

SLAM family member 8 is expressed in and enhances the growth of anaplastic large cell lymphoma.

Signaling lymphocytic activation molecule family member 8 (SLAMF8) / B-lymphocyte activator macrophage expressed/CD353 is a member of the CD2 family. SLAMF8 suppresses macrophage function but enhances the growth of neoplastic mast cells via SHP-2. In this study, we found that some anaplastic large cell lymphoma (ALCL) samples were immunohistochemically positive for SLAMF8. However, we found no significant differences between SLAMF8-positive and SLAMF8-negative ALCL samples with respect to age, gender, site, or prognosis. We also identified SLAMF8 expression in ALCL cell lines, Karpas299, and SU-DHL-1. SLAMF8 knockdown decreased the activation of SHP-2 and the growth of these cell lines, and increased the apoptosis of these cell lines. In addition, we observed the interaction between SLAMF8 and SHP-2 in these cell lines using the DuoLink in situ kit. Taken together, these results suggest that SLAMF8 may enhance the growth of ALCL via SHP-2 interaction.

EZH2 inhibitors restore epigenetically silenced CD58 expression in B-cell lymphomas.

Loss of CD58 is a common mechanism for tumor immune evasion in lymphoid malignancies. CD58 loss is known to occur due to both genetic and non-genetic causes; therefore, we hypothesized that restoring CD58 expression in lymphoma cells may be an effective treatment approach. To explore the potential for restoring CD58 expression, we first screened 11 B-cell lymphoma lines and found that 3 had decreased CD58 expression. Among these, CD58 was genetically damaged in two lines but not in the third line. Using the cell line with downregulated CD58 without a genetic abnormality, we performed epigenetic library screening and found that two EZH2 inhibitors, EPZ6438 and GSK126, specifically enhanced CD58 expression. By examining the effect of three EZH2 inhibitors with different selectivity profiles in different B-cell lines, EZH2 inhibition was shown to have a common activity in upregulating CD58 expression. Restoring the expression of CD58 in lymphoma cells using an EZH2 inhibitor was shown to enhance interferon-γ production of T and NK cells against lymphoma cells. H3K27 was shown to be highly trimethylated in the CD58 promoter region, and EZH2 inhibition induced its demethylation and activated transcription of the CD58 gene. These results indicated that EZH2 is involved in the epigenetic silencing of CD58 in lymphoma cells as a mechanism for tumor immune escape, and EZH2 inhibitors are able to restore epigenetically suppressed CD58 expression. Our findings provide a molecular basis for the combination of an EZH2 inhibitor and immunotherapy for lymphoma treatment.

Relapse of follicular lymphoma arising from a non-t(14;18) clone.

Intraclonal diversity is commonly observed in patients with follicular lymphoma (FL), whereas tumor cells at the onset and relapse usually share early genetic events such as VDJ rearrangement of the immunoglobulin genes and t(14;18) translocation. We report a case of FL with relapse with FL that was clonally different from the tumor cells at onset. A 59-year-old male presented with paraaortic lymph node swelling and thickening of the right renal pelvic and ureteral wall was histologically diagnosed as FL, grade 1. Karyotypic analysis revealed t(14;18)(q32;q21) with +12 and +der(18)t(14;18). Ten years after the initial diagnosis, he suddenly developed systemic lymphadenopathy as a second relapse, and histological examination led to the diagnosis of FL grade 3B with diffuse large B-cell lymphoma. Surprisingly, karyotypic analysis demonstrated the presence of +12 and 3q27 abnormality, which was proved to be a BCL6 translocation by fluorescence in situ hybridization, but the absence of t(14;18)(q32;q21). We compared VDJ rearrangement of the FL cells at onset and relapse and found that they were completely independent of each other. These tumor cells sharetrisomy 12 as a common genetic abnormality, and it is speculated that trisomy 12 may have occurred earlier than BCL2 and BCL6 translocations. These results suggest that there can even be cases of "relapse" of FL with an independent origin of the primary tumor cells. Our observation highlights the importance of re-biopsy of relapsed FL, especially when it occurs after a long remission with different clinical presentation from that at the onset.

[Successful treatment with recombinant thrombomodulin in transplant-associated thrombotic microangiopathy following HLA-haploidentical transplantation].

In March 2009, a 17-year-old woman was first diagnosed with acute myelogenous leukemia and myelodysplasia-related changes. She underwent chemotherapy and allogeneic hematopoietic stem cell transplantation, which resulted in complete remission. However, she experienced relapse, and remission was achieved each time with repeated transplantation. In September 2014, a human leukocyte antigen (HLA)-haploidentical transplantation, which was the fifth allogeneic transplantation, was performed to treat the third relapse. Platelet transfusion refractoriness, hemolytic anemia with schistocytes, and renal dysfunction were observed from approximately the day of engraftment; therefore, transplantation-associated thrombotic microangiopathy (TA-TMA) was diagnosed. Recombinant human soluble thrombomodulin (rTM) was administered, and fresh-frozen plasma (FFP) was infused; this resulted in gradual improvement of TA-TMA. Treatment with rTM and FFP was discontinued on the 70th day after transplantation. Because the HLA-haploidentical transplantation was the fifth allogeneic transplantation, the risk of aggravation of TA-TMA was very high. Combined treatment with rTM and FFP, however, resulted in improvement of TA-TMA. Further investigation of similar cases is necessary for clarifying the usefulness of rTM for TA-TMA.

B cells with aberrant activation of Notch1 signaling promote Treg and Th2 cell-dominant T-cell responses via IL-33.

The Notch-signaling pathway in a variety of mature B-cell neoplasms is often activated by gene alterations, but its role remains unclear. Here, we show that B cells harboring dysregulated activation of Notch1 signaling have an immunomodulatory effect on T cells by amplifying regulatory T (Treg) and T helper 2 (Th2) cell responses in an interleukin-33 (IL-33)-dependent manner. A conditional mouse model, in which constitutive expression of an active form of Notch1 is induced in B cells by Aicda gene promoter-driven Cre recombinase, revealed no obvious phenotypic changes in B cells; however, mice demonstrated an expansion of Treg and Th2 cell subsets and a decrease in cytokine production by Th1 and CD8+ T cells. The mice were susceptible to soft tissue sarcoma and defective production of CD8+ T cells specific for inoculated tumor cells, suggesting impaired antitumor T-cell activity. Gene-expression microarray revealed that altered T-cell responses were due to increased IL-33 production by Notch1-activated B cells. Knockout of IL33 or blockade of IL-33 by a receptor-blocking antibody abrogated the Treg and Th2 cell-dominant T-cell response triggered by B cells. Gene-expression data derived from human diffuse large B-cell lymphoma (DLBCL) samples showed that an activated Notch-signaling signature correlates positively with IL33 expression and Treg cell-rich gene-expression signatures. These findings indicate that B cells harboring dysregulated Notch signaling alter T-cell responses via IL-33, and suggest that aberrant activation of Notch signaling plays a role in fostering immune privilege in mature B-cell neoplasms.

Persistence of a t(11;14)-positive clone in a patient with mantle cell lymphoma for 20 years.

We report here a patient with extremely indolent mantle cell lymphoma (MCL) who had progressed and required immunochemotherapy 20 years after diagnostic splenectomy. Non-nodal, indolent MCL patients may progress after such an extraordinary long indolent phase, and we recommend lifelong follow up for such cases.