Kinya Ohata

Mycophenolic Acid Inhibits Natural Killer Cell Proliferation and Cytotoxic Function: A Possible Disadvantage of Including Mycophenolate Mofetil in the Graft-Versus-Host Disease Prophylaxis Regimen

To determine how immunosuppressant agents used for graft-versus-host disease (GVHD) prophylaxis affect natural killer (NK) cells, we examined the effects of cyclosporine (CSP), tacrolimus (TAC), mycophenolic acid (MPA, an active form of mycophenolate mofetil), and methotrexate (MTX) on the proliferation and cytotoxicity of NK cells. The proliferation of NK cells from healthy individuals in the presence of interleukin (IL)-2 and IL-15 was suppressed to 51% ± 16% of that of the controls with CSP, to 31% ± 19% with TAC, to 14% ± 6% with MPA, and to 87% ± 18% with MTX. Both CSP and TAC increased the proportion of CD16(-)CD56(bright) cells, a NK cell subset capable of secreting high amount of cytokines, and also enhanced NKp30 expression, whereas MPA markedly decreased the proportion of CD16(-)CD56(bright) cells and reduced the expression of all activating NK cell receptors, including NKG2D, NKp30, NKp44, and NKp46. MPA also reduced the cytotoxicity against K562 cells from 61% ± 15% to 17% ± 7% and that against Daudi cells from 44% ± 4% to 4% ± 4%, whereas the other 3 drugs did not diminish these cytotoxicities. The inhibition of NK cell proliferation and cytotoxicity against leukemic cell lines by MPA was partially abolished by the inclusion of guanosine in the culture. Similar to the effect of MPA on T cells, MPA inhibited the down-regulation of p27 on NK cells induced by the incubation of NK cells in the presence of IL-2. These results suggest that MPA is a potent inhibitor of NK cells, and that its inclusion in the GVHD prophylaxis regimen might diminish the graft-versus-leukemia effect of NK cells.

Hydroxyurea upregulates NKG2D ligand expression in myeloid leukemia cells synergistically with valproic acid and potentially enhances susceptibility of leukemic cells to natural killer cell-mediated cytolysis.

(Cancer Sci 2010; 101: 609–615)

Long-term survival following autologous and allogeneic stem cell transplantation for blastic plasmacytoid dendritic cell neoplasm

We sought to clarify the role of high-dose chemotherapy followed by autologous hematopoietic stem cell transplantation (auto-HSCT) and allogeneic hematopoietic stem cell transplantation (allo-HSCT) to treat blastic plasmacytoid dendritic cell neoplasm (BPDCN). We retrospectively identified 25 BPDCN patients (allo-HSCT, n = 14; auto-HSCT, n = 11) from registry data of the Japan Society for Hematopoietic Cell Transplantation and analyzed clinicopathologic data and clinical outcomes after transplantation. The median age at HSCT was 58 years (range, 17-67 years). All 11 patients who underwent auto-HSCT were in the first complete remission (CR1). With a median follow-up of 53.5 months, the overall survival rates at 4 years for patients who underwent auto-HSCT and allo-HSCT were 82% and 53% (P = .11), respectively, and progression-free survival rates were 73% and 48% (P = .14), respectively. Auto-HSCT for BPDCN in CR1 appears to provide promising results and deserves further evaluation in the setting of prospective trials.

Safety of pre-engraftment prophylactic foscarnet administration after allogeneic stem cell transplantation

K. Ishiyama, T. Katagiri, K. Ohata, K. Hosokawa, Y. Kondo, H. Yamazaki, A. Takami, S. Nakao. Safety of pre‐engraftment prophylactic foscarnet administration after allogeneic stem cell transplantation. Transpl Infect Dis 2011. All rights reserved

CD16+ CD56− NK cells in the peripheral blood of cord blood transplant recipients: a unique subset of NK cells possibly associated with graft-versus-leukemia effect

A marked increase in CD16+ CD56− NK cells in the peripheral blood (PB) was observed in a cord blood transplant (CBT) recipient with refractory acute myeloid leukaemia (AML) in association with attaining molecular remission. CD16+ CD56− NK cells isolated from the patient became CD16+CD56+NKG2D+ when they were cultured in the presence of IL‐2. Although cultured CD16+CD56− NK cells retained the killer‐cell immunoglobulin receptor (KIR)‐ligand (KIR‐L) specificity and the patient’s leukemic cells expressed corresponding KIR ligands, they killed patient’s leukemic cells expressing ULBP2. The cytotoxicity by cultured CD16+CD56− NK cells was abrogated by anti‐ULBP2 antibodies. When leukemic cells obtained at relapse after CBT were examined, both the ULBP2 expression and susceptibility to the cultured NK cells decreased in comparison to leukemic cells obtained before CBT. An increase in the CD16+CD56− NK cell count (0.5 × 109/L or more) in PB was observed in seven of 11 (64%) CBT recipients but in none of 13 bone marrow (BM) and eight peripheral blood stem cell (PBSC) transplant recipients examined during the similar period after transplantation. These findings suggest an increase in CD16+CD56− NK cells to be a phenomenon unique to CBT recipients and that mature NK cells derived from this NK cell subset may contribute to the killing of leukemic cells expressing NKG2D ligands in vivo.

Successful treatment of Trichosporon fungemia in a patient with refractory acute myeloid leukemia using voriconazole combined with liposomal amphotericin B

Trichosporon fungemia is a rare and fatal fungal infection that occurs in patients with prolonged neutropenia associated with hematologic malignancies. A 21‐year‐old male developed Trichosporon fungemia during remission induction therapy for acute myeloid leukemia (AML). Although two courses of induction therapy failed to induce a remission of AML, combination therapy with voriconazole and liposomal amphotericin B (L‐AmB) followed by monocyte colony‐stimulating factor ameliorated the Trichosporon fungemia and enabled the patient to receive reduced‐intensity bone marrow transplantation (BMT) from his human leukocyte antigen‐A one‐locus mismatched mother. The patient achieved a durable remission after BMT without exacerbation of Trichosporon fungemia. The combination therapy with voriconazole and L‐AmB may therefore be useful in controlling Trichosporon fungemia associated with prolonged neutropenia after remission induction therapy for AML.

Reduced-intensity unrelated cord blood transplantation for treatment of metastatic renal cell carcinoma: first evidence of cord-blood-versus-solid-tumor effect

We report a 69-year-old man with cytokine-resistant metastatic renal cell carcinoma treated with reduced-intensity unrelated cord blood transplantation. The patient achieved durable donor engraftment with minimal graft-versus-host disease. The patient showed regression of metastatic disease, providing the first evidence of a graft-versus-tumor effect on a solid tumor resulting from cord blood graft.

An Epstein-Barr virus-associated leukemic lymphoma in a patient treated with rabbit antithymocyte globulin and cyclosporine for hepatitis-associated aplastic anemia.

Lymphoproliferative disorders (LPDs) are generally caused by uncontrolled B-cell proliferation induced by the Epstein-Barr virus (EBV) in the setting of impaired EBV-specific T-cell immunity, particularly when there is pharmacological immunosuppression including antithymocyte globulin. We herein present an unusual case of EBV associated with LPD (EBV-LPD) in which LPD occurred 3 weeks after the use of rabbit antithymocyte globulin administered for severe hepatitis-associated aplastic anemia; the patient died of fulminant leukemic lymphoma 5 days after the onset. We also review the pertinent literature on EBV-LPD after immunosuppressive therapy and document the efficacy of EBV viral load monitoring and the need for preemptive therapy.

Imatinib for bronchiolitis obliterans after allogeneic hematopoietic stem cell transplantation.

Imatinib for bronchiolitis obliterans after allogeneic hematopoietic stem cell transplantation

Detection of minimal residual disease in patients with multiple myeloma using clonotype-specific PCR primers designed from DNA extracted from archival bone marrow slides

Polymerase chain reaction (PCR)-negative molecular complete remission (mCR) can be induced by stem cell transplantation in some patients with multiple myeloma (MM) and is associated with long-term progression-free survival (PFS). The detection of molecular minimal residual disease (MRD), however, requires fresh or frozen materials for designing clone-specific primers, which are not always readily available. In this study, we used DNA extracted from archival bone marrow (BM) slides for PCR to detect MRD in 50 patients with MM who received various induction therapies and autologous peripheral blood stem cell transplantation (ASCT). Clonotype-specific immunoglobulin (Ig) H PCR primers were prepared for 32 of 50 cases (64%) using BM slides, and for 9 of 14 cases (64%) using fresh BM cells. DNA in peripheral blood stem cell autografts of the 22 patients who achieved at least a partial response after ASCT was subjected to PCR to amplify clonotype-specific rearranged IgH gene sequences. The median PFS of the eight patients with MRD-positive autografts was 18 months, whereas that of 14 patients with MRD-negative autografts was not reached at a median follow-up of 27 months (p = 0.012). Post-ASCT PFS of the four patients who achieved mCR was 100% at a median follow-up of 47 months. These results indicate that archival BM slides can serve as a source of DNA for preparing clonotype-specific primers for MRD monitoring in patients with MM whose cryopreserved myeloma cells are not available for DNA preparation. Our results also suggest that patients with MM who received MRD-negative autografts and achieved mCR have a long PFS.