R. Willemze

Revised Recommendations of the International Working Group for Diagnosis, Standardization of Response Criteria, Treatment Outcomes, and Reporting Standards for Therapeutic Trials in Acute Myeloid Leukemia

An International Working Group met to revise the diagnostic and response criteria for acute myelogenous leukemia originally published in 1990, as well as to provide definitions of outcomes and reporting standards to improve interpretability of data and comparisons among trials. Since the original publication, there have been major advances in our understanding of the biology and molecular genetics of acute leukemia that are clinically relevant and warrant incorporation into response definitions. Differences from the 1990 recommendations included a category of leukemia-free state, new criteria for complete remission, including cytogenetic and molecular remissions and remission duration. Storage of viable blasts for correlative studies is important for future progress in the therapy of these disorders.

Autologous or allogeneic bone marrow transplantation compared with intensive chemotherapy in acute myelogenous leukemia

BACKGROUND Allogeneic or autologous bone marrow transplantation and intensive consolidation chemotherapy are used to treat acute myelogenous leukemia in a first complete remission. METHODS After induction treatment with daunorubicin and cytarabine, patients who had a complete remission received a first course of intensive consolidation chemotherapy, combining intermediate-dose cytarabine and amsacrine. Patients with an HLA-identical sibling were assigned to undergo allogeneic bone marrow transplantation; the others were randomly assigned to undergo autologous bone marrow transplantation (with unpurged bone marrow) or a second course of intensive chemotherapy, combining high-dose cytarabine and daunorubicin. Comparisons were made on the basis of the intention to treat. RESULTS A total of 623 patients had a complete remission; 168 were assigned to undergo allogeneic bone marrow transplantation, and 254 were randomly assigned to one of the other two groups. Of these patients, 343 completed the treatment assignment: 144 in the allogeneic-transplantation group, 95 in the autologous-transplantation group, and 104 in the intensive-chemotherapy group. The relapse rate was highest in the intensive-chemotherapy group and lowest in the allogeneic-transplantation group, whereas the mortality rate was highest after allogeneic transplantation and lowest after intensive chemotherapy. The projected rate of disease-free survival at four years was 55 percent for allogeneic transplantation, 48 percent for autologous transplantation, and 30 percent for intensive chemotherapy. However, the overall survival after complete remission was similar in the three groups, since more patients who relapsed after a second course of intensive chemotherapy had a response to subsequent autologous bone marrow transplantation. Other differences were also observed, especially with regard to hematopoietic recovery (it occurred later after autologous transplantation) and the duration of hospitalization (it was longer with bone marrow transplantation). CONCLUSIONS Autologous as well as allogeneic bone marrow transplantation results in better disease-free survival than intensive consolidation chemotherapy with high-dose cytarabine and daunorubicin. Transplantation soon after a relapse or during a second complete remission might also be appropriate.

Mesenchymal Stem Cells Inhibit Generation and Function of Both CD34+-Derived and Monocyte-Derived Dendritic Cells

Mesenchymal stem cells (MSCs) are not only able to evade the immune system, but they have also been demonstrated to exert profound immunosuppressive properties on T cell proliferation. However, their effect on the initiators of the immune response, the dendritic cells (DCs), are relatively unknown. In the present study, the effects of human MSCs on the differentiation and function of both CD34+-derived DCs and monocyte-derived DCs were investigated. The presence of MSCs during differentiation blocked the differentiation of CD14+CD1a− precursors into dermal/interstitial DCs, without affecting the generation of CD1a+ Langerhans cells. In line with these observations, MSCs also completely prevented the generation of immature DCs from monocytes. The inhibitory effect of MSCs on DC differentiation was dose dependent and resulted in both phenotypical and functional modifications, as demonstrated by a reduced expression of costimulatory molecules and hampered capacity to stimulate naive T cell proliferation. The inhibitory effect of MSCs was mediated via soluble factors. Taken together, these data demonstrate that MSCs, next to the antiproliferative effect on T cells, have a profound inhibitory effect on the generation and function of both CD34+-derived and monocyte-derived DCs, indicating that MSCs are able to modulate immune responses at multiple levels.

Mesenchymal stem cells promote engraftment of human umbilical cord blood–derived CD34+ cells in NOD/SCID mice

OBJECTIVE Mesenchymal stem cells (MSC) have been implicated as playing an important role in hematopoietic stem cell engraftment. We identified and characterized a new population of MSC derived from human fetal lung. In cotransplantation experiments, we examined the homing of MSC as well as the effect on engraftment of human umbilical cord blood (UCB)-derived CD34(+) cells in NOD/SCID mice. MATERIALS AND METHODS Culture-expanded fetal lung-derived CD34(+) cells were characterized by immune phenotyping and cultured under conditions promoting differentiation to osteoblasts or adipocytes. Irradiated (3.5 Gy) NOD/SCID mice (n = 51) were transplanted intravenously with 0.03 to 1.0 x 10(6) UCB CD34(+) cells in the presence or absence of 1 x 10(6) culture-expanded fetal lung-derived MSC, irradiated CD34(-) cells, B cells, or with cultured MSC only. RESULTS Culture-expanded fetal lung CD34(+) cells were identified as MSC based on phenotype (CD105(+), SH3(+), SH4(+), CD160(+)) and their multilineage potential. Cotransplantation of low doses of UCB CD34(+) cells and MSC resulted in a three-fold to four-fold increase in bone marrow engraftment after 6 weeks, whereas no such effect was observed after cotransplantation of irradiated CD34(-) or B cells. Homing experiments indicated the presence of MSC in the lung, but not in the bone marrow, of NOD/SCID mice. CONCLUSIONS We identified a population of MSC derived from human fetal lung. Upon cotransplantation, MSC, but not irradiated CD34(-) or B cells, promote engraftment of UCB CD34(+) cells in bone marrow, spleen, and blood by mechanisms that may not require homing of MSC to the bone marrow.

Hematopoiesis-restricted minor histocompatibility antigens HA-1- or HA-2-specific T cells can induce complete remissions of relapsed leukemia

Donor lymphocyte infusion (DLI) into patients with a relapse of their leukemia or multiple myeloma after allogeneic stem cell transplantation (alloSCT) has been shown to be a successful treatment approach. The hematopoiesis-restricted minor histocompatibility antigens (mHAgs) HA-1 or HA-2 expressed on malignant cells of the recipient may serve as target antigens for alloreactive donor T cells. Recently we treated three mHAg HA-1- and/or HA-2-positive patients with a relapse of their disease after alloSCT with DLI from their mHAg HA-1- and/or HA-2-negative donors. Using HLA-A2/HA-1 and HA-2 peptide tetrameric complexes we showed the emergence of HA-1- and HA-2-specific CD8+ T cells in the blood of the recipients 5–7 weeks after DLI. The appearance of these tetramer-positive cells was followed immediately by a complete remission of the disease and restoration of 100% donor chimerism in each of the patients. Furthermore, cloned tetramer-positive T cells isolated during the clinical response specifically recognized HA-1 and HA-2 expressing malignant progenitor cells of the recipient and inhibited the growth of leukemic precursor cells in vitro. Thus, HA-1- and HA-2-specific cytotoxic T lymphocytes emerging in the blood of patients after DLI demonstrate graft-versus-leukemia or myeloma reactivity resulting in a durable remission. This finding implies that in vitro generated HA-1- and HA-2-specific cytotoxic T lymphocytes could be used as adoptive immunotherapy to treat hematological malignances relapsing after alloSCT.

KIR-ligand incompatibility in the graft-versus-host direction improves outcomes after umbilical cord blood transplantation for acute leukemia.

Donor killer cell immunoglobulin-like receptor (KIR)-ligand incompatibility is associated with decreased relapse incidence (RI) and improved leukemia-free survival (LFS) after haploidentical and HLA-mismatched unrelated hematopoietic stem cell transplantation. We assessed outcomes of 218 patients with acute myeloid leukemia (AML n=94) or acute lymphoblastic leukemia (n=124) in complete remission (CR) who had received a single-unit unrelated cord blood transplant (UCBT) from a KIR-ligand-compatible or -incompatible donor. Grafts were HLA-A, -B or -DRB1 matched (n=21) or mismatched (n=197). Patients and donors were categorized according to their degree of KIR-ligand compatibility in the graft-versus-host direction by determining whether or not they expressed HLA-C group 1 or 2, HLA-Bw4 or HLA-A3/-A11. Both HLA-C/-B KIR-ligand- and HLA-A-A3/-A11 KIR-ligand-incompatible UCBT showed a trend to improved LFS (P=0.09 and P=0.13, respectively). Sixty-nine donor–patient pairs were HLA-A, -B or -C KIR-ligand incompatible and 149 compatible. KIR-ligand-incompatible UCBT showed improved LFS (hazards ratio=2.05, P=0.0016) and overall survival (OS) (hazards ratio=2.0, P=0.004) and decreased RI (hazards ratio=0.53, P=0.05). These results were more evident for AML transplant recipients (2-year LFS and RI with or without KIR-ligand incompatibility 73 versus 38% (P=0.012), and 5 versus 36% (P=0.005), respectively). UCBT for acute leukemia in CR from KIR-ligand-incompatible donors is associated with decreased RI and improved LFS and OS.

The Polycomb group protein EZH2 is upregulated in proliferating, cultured human mantle cell lymphoma

Polycomb group (PcG) proteins are involved in the stable transmittance of the repressive state of their gene targets throughout the cell cycle. Mis‐expression of PcG proteins can lead to proliferative defects and tumorigenesis. There are two separate multimeric PcG protein complexes: an EED–EZH2‐containing complex and a BMI1–RING1‐containing complex. In the normal human follicle mantle, both PcG complexes have mutually exclusive expression patterns. BMI1–RING1 is expressed, but EZH2–EED is not. Here, we studied the expression of both complexes in six cases of mantle cell lymphoma (MCL), which is derived from the follicle mantle. MCL cells can be cultured in vitro and stimulated to proliferation. We found that resting MCL cells expressed BMI1–RING1, but not EZH2–EED, like normal mantle cells. Proliferating MCL cells, however, showed strongly enhanced expression of EZH2. Also, BMI1 and RING1 continued to be expressed in proliferating MCL. This is the first demonstration that EZH2 expression can be upregulated in fresh lymphoma cells. To test whether the enhanced EZH2 expression was causal for the increased proliferation in MCL, we overexpressed EZH2 in two different cell lines. In the B cell‐derived Ramos cell line, EZH2 overexpression caused an increase in the proliferation rate. This suggests a possible causal effect between EZH2 upregulation and increased proliferation in haematopoietic cells.

Allogeneic Hematopoietic Stem-Cell Transplantation for Patients 50 Years or Older With Myelodysplastic Syndromes or Secondary Acute Myeloid Leukemia

PURPOSE This study was performed to examine the characteristics of transplant activity for patients with myelodysplastic syndromes (MDS) older than 50 years within the European Group for Blood and Marrow Transplantation, and to evaluate the factors predicting outcome within this group of patients. PATIENTS AND METHODS We performed a retrospective multicenter analysis of 1,333 MDS patients age 50 years or older who received transplantation within the EBMT since 1998. The median recipient age was 56 years, with 884 patients (66%) age 50 to 60 years and 449 (34%) patients older than 60 years. There were 811 HLA-matched sibling (61%) and 522 (39%) unrelated donor transplants. Five hundred patients (38%) received standard myeloablative conditioning (SMC), and 833 (62%) received reduced intensity conditioning (RIC). RESULTS The 4-year estimate for overall survival of the whole cohort was 31%. On multivariate analysis, use of RIC (hazard ratio [HR], 1.44; 95% CI, 1.13 to 1.84; P < .01) and advanced disease stage at transplantation (HR, 1.51; 95% CI, 1.18 to 1.93; P < .01) were associated with an increased relapse rate. In contrast, advanced disease stage at transplantation (HR, 1.43; 95% CI, 1.13 to 1.79; P = .01), use of an unrelated donor (P = .03), and RIC (HR, 0.79; 95% CI, 0.65 to 0.97; P = .03) were independent variables associated with nonrelapse mortality. Advanced disease stage at transplantation (HR, 1.55; 95% CI, 1.32 to 1.83; P < .01) was the major independent variable associated with an inferior 4-year overall survival. CONCLUSION Allogeneic hematopoietic stem-cell transplantation remains a potential curative therapeutic option for many older patients with MDS. In this analysis, disease stage at time of transplantation, but not recipient age or the intensity of the conditioning regimens, was the most important factor influencing outcomes.

Reprogramming of virus-specific T cells into leukemia-reactive T cells using T cell receptor gene transfer.

T cells directed against minor histocompatibility antigens (mHags) might be responsible for eradication of hematological malignancies after allogeneic stem cell transplantation. We investigated whether transfer of T cell receptors (TCRs) directed against mHags, exclusively expressed on hematopoietic cells, could redirect virus-specific T cells toward antileukemic reactivity, without the loss of their original specificity. Generation of T cells with dual specificity may lead to survival of these TCR-transferred T cells for prolonged periods of time in vivo due to transactivation of the endogenous TCR of the tumor-reactive T cells by the latent presence of viral antigens. Furthermore, TCR transfer into restricted T cell populations, which are nonself reactive, will minimize the risk of autoimmunity. We demonstrate that cytomegalovirus (CMV)-specific T cells can be efficiently reprogrammed into leukemia-reactive T cells by transfer of TCRs directed against the mHag HA-2. HA-2-TCR–transferred CMV-specific T cells derived from human histocompatibility leukocyte antigen (HLA)-A2+ or HLA-A2− individuals exerted potent antileukemic as well as CMV reactivity, without signs of anti–HLA-A2 alloreactivity. The dual specificity of these mHag-specific, TCR-redirected virus-specific T cells opens new possibilities for the treatment of hematological malignancies of HLA-A2+ HA-2–expressing patients transplanted with HLA-A2–matched or –mismatched donors.

Differences in clinical behaviour and immunophenotype between primary cutaneous and primary nodal anaplastic large cell lymphoma of T-cell or null cell phenotype

The histological, immunophenotypic and clinical features of 19 primary cutaneous anaplastic large cell lymphomas (cutaneous ALCL) were compared with those of 18 primary nodal anaplastic large cell lymphomas (nodal ALCL) of T‐cell or null cell type. Although cutaneous ALCL and nodal ALCL had identical morphological features, differences in surface marker expression and clinical behaviour were found. Immunophenotypical differences concerned the expression of epithelial membrane antigen (82% of the nodal ALCL were positive v. none of the cutaneous ALCL) and the cutaneous lymphocyte antigen (HECA‐452), a possible skin‐homing receptor on cutaneous T‐lymphocytes (most tumour cells in 44% of cutaneous ALCL cases were positive, whereas nodal ALCL showed expression of HECA‐452 on only few tumour cells (< 25%) in 18% of cases tested). Loss of T‐cell markers was more pronounced for nodal ALCL. Patients with cutaneous ALCL were generally older (median 61 years) than patients with nodal ALCL (median 24 years) and, in contrast to the latter group, did not show bimodal age distribution. Survival after 4 years, using lymphoma‐related death as an end‐point, differed significantly between cutaneous ALCL and nodal ALCL; 92% for cutaneous ALCL and 65% for nodal ALCL (P=0.04). The better survival of cutaneous ALCL patients could not be ascribed to differences in age, stage or initial mode of treatment. These data indicate that differences in ismmunophenotype and clinical behaviour exist between morphologically identical primary cutaneous and primary node‐based ALCL. They indicate that the primary site is an important prognostic factor in predicting the clinical outcome of ALCL.