Roelof Willemze

Nonexpanded primary lung and bone marrow-derived mesenchymal cells promote the engraftment of umbilical cord blood-derived CD34 + cells in NOD/SCID mice

OBJECTIVE Previously, we have found that human culture-expanded fetal lung-derived mesenchymal stem cells (MSC) promote the engraftment of umbilical cord blood (UCB)-derived CD34((+)) cells. The high frequency of MSC in fetal lung allowed us to study whether this represented a biological feature of these cells or a property that was acquired during expansion in culture. MATERIALS AND METHODS Irradiated NOD/SCID mice (n=80) were transplanted with 0.1x10(6) UCB CD34(+) cells in the presence or absence of 10(6) primary nonexpanded or culture-expanded fetal lung, liver, or BM CD45(-) cells, or with nonexpanded fetal lung liver or BM CD45(-) cells only. RESULTS In comparison with transplantation of UCB CD34(+) cells only, cotransplantation of UCB CD34(+) cells and primary fetal lung or BM CD45(-) cells resulted in a significantly higher level of engraftment (% hCD45(+) cells) in BM, PB, and spleen. In addition, primary mesenchymal cells derived from adult BM had a similar promoting effect. The engraftment-enhancing effect was similar to that of culture-expanded fetal lung and BM MSC. Primary mesenchymal cells, but not culture-expanded MSC, were detected in recipient mice, suggesting that the primary cells were able to home and that this capacity was lost after expansion. CONCLUSIONS These results show that primary mesenchymal cells from fetal lung and BM promote the engraftment of UCB-derived CD34(+) cells to a similar degree as culture-expanded MSC, indicating that it reflects a biological property of primary MSC that is preserved during expansion in culture.

Mixed T cell receptor dimers harbor potentially harmful neoreactivity

Adoptive transfer of T cell receptor (TCR)-transduced T cells may be an attractive strategy to target both hematological malignancies and solid tumors. By introducing a TCR, large numbers of T cells with defined antigen (Ag) specificity can be obtained. However, by introduction of a TCR, mixed TCR dimers can be formed. Besides the decrease in TCR expression of the introduced and endogenous TCR, these mixed TCR dimers could harbor potentially harmful specificities. In this study, we demonstrate that introduction of TCRs resulted in formation of neoreactive mixed TCR dimers, composed of the introduced TCR chains pairing with either the endogenous TCR α or β chain. Neoreactivities observed were HLA class I or class II restricted. Most neoreactive mixed TCR dimers were allo-HLA reactive; however, neoreactive mixed TCR dimers with autoreactive activity were also observed. We demonstrate that inclusion of an extra disulfide bond between the constant domains of the introduced TCR markedly reduced neoreactivity, whereas enhanced effectiveness of the introduced TCR was observed. In conclusion, TCR transfer results in the formation of neoreactive mixed TCR dimers with the potential to generate off-target effects, underlining the importance of searching for techniques to facilitate preferential pairing.

Allogeneic hematopoietic stem cell transplantation in Fanconi anemia: the European Group for Blood and Marrow Transplantation experience

Although allogeneic hematopoietic stem cell transplantation (HSCT) remains the only curative treatment for patients with Fanconi anemia (FA), published series mostly refer to single-center experience with limited numbers of patients. We analyzed results in 795 patients with FA who underwent first HSCT between May 1972 and January 2010. With a 6-year median follow-up, overall survival was 49% at 20 years (95% confidence interval, 38-65 years). Better outcome was observed for patients transplanted before the age of 10 years, before clonal evolution (ie, myelodysplastic syndrome or acute myeloid leukemia), from a matched family donor, after a conditioning regimen without irradiation, the latter including fludarabine. Chronic graft-versus-host disease and secondary malignancy were deleterious when considered as time-dependent covariates. Age more than 10 years at time of HSCT, clonal evolution as an indication for transplantation, peripheral blood as source of stem cells, and chronic graft-versus-host disease were found to be independently associated with the risk for secondary malignancy. Changes in transplant protocols have significantly improved the outcome of patients with FA, who should be transplanted at a young age, with bone marrow as the source of stem cells.

A mechanistic rationale for combining alemtuzumab and rituximab in the treatment of ALL.

B-lineage acute lymphoblastic leukemia (ALL) may express CD52 and CD20. Alemtuzumab (ALM) and rituximab (RTX) are therapeutic antibodies directed against CD52 and CD20, respectively, but showed limited activity against ALL in clinical trials. The mechanisms for the impaired responses remained unclear. We studied expression of CD52 and CD20 on ALL cells and found that most cases coexpressed CD52 and CD20. However, distinct CD52-negative (CD52(-)) subpopulations were detected in most cases as the result of defective glycophosphatidyl-inositol anchoring. Although ALM efficiently eradicated CD52-positive (CD52(+)) cells in NOD/scid mice engrafted with primary human ALL, CD52(-) subclones escaped therapy. In the same model, RTX showed limited activity resulting from occurrence of CD20 down-modulation. However, CD52(-) cells concurrently lacked the glycophosphatidyl-inositol-anchored complement regulators CD55 and CD59 and showed increased susceptibility to RTX-mediated complement-dependent cytotoxicity in vitro. At the same time, ALM was shown to inhibit down-modulation of CD20 in response to RTX by depleting the trogocytic capacity of phagocytic cells. Probably because of these complementary mechanisms, combined administration of ALM and RTX induced complete responses in vivo. Based on these data, we propose a mechanistic rationale for combined application of RTX and ALM in ALL.

Dose finding study of imatinib in combination with intravenous cytarabine: feasibility in newly diagnosed patients with chronic myeloid leukemia

The HOVON cooperative study group performed a feasibility study of escalated imatinib and intravenous cytarabine in 165 patients with early chronic-phase chronic myeloid leukemia (CML). Patients received 2 cycles of intravenous cytarabine (200 mg/m(2) or 1000 mg/m(2) days 1-7) in conjunction with imatinib (200 mg, 400 mg, 600 mg, or 800 mg), according to predefined, successive dose levels. All dose levels proved feasible. Seven dose-limiting toxicities (DLTs) were observed in 302 cycles of chemotherapy, which were caused by streptococcal bacteremia in 5 cases. Intermediate-dose cytarabine (1000 mg/m(2)) prolonged time to neutrophil recovery and platelet recovery compared with a standard dose (200 mg/m(2)). High-dose imatinib (600 mg or 800 mg) extended the time to platelet recovery compared with a standard dose (400 mg). More infectious complications common toxicity criteria (CTC) grade 3 or 4 were observed after intermediate-dose cytarabine compared with a standard-dose of cytarabine. Early response data after combination therapy included a complete cytogenetic response in 48% and a major molecular response in 30% of patients, which increased to 46% major molecular responses at 1 year, including 13% complete molecular responses. We conclude that combination therapy of escalating dosages of imatinib and cytarabine is feasible. This study was registered at www.kankerbestrijding.nl as no. CKTO-2001-03.

Dexamethasone compared to prednisolone for adults with acute lymphoblastic leukemia or lymphoblastic lymphoma: final results of the ALL-4 randomized, phase III trial of the EORTC Leukemia Group

Background Corticosteroids are a standard component of the treatment of acute lymphoblastic leukemia and lymphoblastic lymphoma. Our aim was to determine whether dexamethasone results in a better outcome than prednisolone. Design and Methods Adult patients with acute lymphoblastic leukemia or lymphoblastic lymphoma were randomized to receive, as part of their induction therapy on days 1–8 and 15–22, either dexamethasone 8 mg/m2 or prednisolone 60 mg/m2. Those who reached complete remission were given two courses of consolidation therapy with high-dose cytarabine and mitoxantrone and methotrexate and asparaginase. Subsequently patients younger than 50 years, with a suitable donor, were to undergo allogeneic stem cell transplantation, whereas the others were planned to receive either an autologous stem cell transplant or high-dose maintenance chemotherapy with prophylactic central nervous system irradiation. Randomization was done with a minimization technique. The primary endpoint was event-free survival and the analyses was conducted on an intention-to-treat basis. Results Between August 1995 and October 2003, 325 patients between 15 to 72 years of age were randomized to receive either dexamethasone (163 patients) or prednisolone (162 patients). After induction and the course of first consolidation therapy, 131 (80.4%) patients in the dexamethasone group and 124 (76.5%) in the prednisolone group achieved complete remission. No significant difference was observed between the two treatment groups with regards to 6-year event-free survival rates (±SE) which were 25.9% (3.6%) and 28.7% (3.5%) in the dexamethasone and prednisolone groups, respectively (P=0.82, hazard ratio 0.97; 95% confidence interval, 0.75–1.25). Disease-free survival after complete remission was also similar in the dexamethasone and prednisolone groups, the 6-year rates being 32.3% and 37.5%, respectively (hazard ratio 1.03; 95% confidence interval 0.76–1.40). The 6-year cumulative incidences of relapse were 49.8% and 53.5% (Gray’s test: P=0.30) while the 6-year cumulative incidences of death were 18% and 9% (Gray’s test: P=0.07). Conclusions In the ALL-4 trial in adult patients with acute lymphoblastic leukemia or lymphoblastic lymphoma, treatment with dexamethasone did not show any advantage over treatment with prednisolone.

Results of syngeneic hematopoietic stem cell transplantation for acute leukemia: risk factors for outcomes of adults transplanted in first complete remission

Background The possibility of performing syngeneic hematopoietic stem cell transplantation is rare and there are concerns about the absence of a graft-versus-leukemia effect following such a strategy. We report the outcomes of a large series of adult patients who underwent syngeneic hematopoietic stem cell transplantation for acute myeloblastic leukemia or acute lymphoblastic leukemia. Design and Methods The outcomes of all syngeneic transplants for acute myeloblastic or lymphoblastic leukemia reported to the European Group for Blood and Marrow Transplantation registry were analyzed; a study of prognostic factors was performed for those transplanted in first complete remission. Results One hundred and sixty-two patients, 109 with acute myeloblastic leukemia and 53 with acute lymphoblastic leukemia, were identified; 116 were in first complete remission. Most of the patients did not receive prophylaxis against graft-versus-host disease. Nineteen patients developed acute graft-versus-host disease and only three patients developed chronic graft-versus-host disease. The median follow-up was 60 months. At 5 years the non-relapse mortality was 8±5%, the relapse incidence 49±8% and the leukemia-free survival 43±3%. The corresponding figures for patients in first complete remission were 7±2%, 40±4% and 53±5% at 5 years. Analysis of patients in first complete remission showed that the number of courses of chemotherapy required to induce first complete remission was the main risk factor: the leukemia-free survival at 5 years was 66±6% when first complete remission was reached after one induction course of chemotherapy and was only 20±9% when first complete remission was reached after at least two induction courses of chemotherapy (p=0.0001); the relapse incidence was 30±6% and 54±10%, respectively (p=0.007). Conclusions Outcomes were better for patients transplanted in first complete remission than in second complete remission or a more advanced phase of the disease. When a syngeneic donor is available for patients with high risk acute leukemia, allotransplantation should be performed as soon as the first complete remission has been achieved, ideally with one course of chemotherapy.

Allogeneic hematopoietic stem cell transplantation in Fanconi anemia: the EBMT experience

Although allogeneic hematopoietic stem cell transplantation (HSCT) remains the only curative treatment for patients with Fanconi anemia (FA), published series mostly refer to single-center experience with limited numbers of patients. We analyzed results in 795 patients with FA who underwent first HSCT between May 1972 and January 2010. With a 6-year median follow-up, overall survival was 49% at 20 years (95% confidence interval, 38-65 years). Better outcome was observed for patients transplanted before the age of 10 years, before clonal evolution (ie, myelodysplastic syndrome or acute myeloid leukemia), from a matched family donor, after a conditioning regimen without irradiation, the latter including fludarabine. Chronic graft-versus-host disease and secondary malignancy were deleterious when considered as time-dependent covariates. Age more than 10 years at time of HSCT, clonal evolution as an indication for transplantation, peripheral blood as source of stem cells, and chronic graft-versus-host disease were found to be independently associated with the risk for secondary malignancy. Changes in transplant protocols have significantly improved the outcome of patients with FA, who should be transplanted at a young age, with bone marrow as the source of stem cells.

Intensification of GVHD prophylaxis interferes with the effects of pretransplant herpes virus serology on the occurrence of grades II–IV acute graft-versus-host disease

SummaryThe effects of pretransplant herpes virus serology on the occurrence of grades II–IV acute graft-versus-host disease (GVHD) were studied in 262 recipients and their HLA-identical family donors. In 131 recipients on standard GVHD prophylaxis (either methotrexate or cyclosporin A) significant effects were observed for donor HSV serology (seropositivity associated with increased risk for GVHD) and donor EBV serology (seronegativity associated with increased risk). However, these effects were nonsignificant in the other 131 recipients on intensified GVHD prophylaxis (i.e., methotrexate combined with cyclosporin A, in vivo anti-T-cell monoclonal antibodies, or various procedures to reduce the T-cell numbers in the transplants).

Cytogenetic clonal heterogeneity is not an independent prognosis factor in 15-60-year-old AML patients: results on 1291 patients included in the EORTC/GIMEMA AML-10 and AML-12 trials

The presence of cytogenetic clonal heterogeneity has been associated with poor prognosis in patients with acute myeloid leukemia (AML). Here, we reassessed this association. The study cohort consisted of all patients with an abnormal karyotype randomized in the EORTC/GIMEMA AML-10 and AML-12 trials. Abnormal karyotypes were classified as no subclones present (cytogenetic abnormality in a single clone), defined subclones present (presence of one to three subclones), and composite karyotypes (CP) (clonal heterogeneity not allowing enumeration of individual subclones). The main endpoints were overall survival (OS) and disease-free survival (DFS). Among 1291 patients with an abnormal karyotype, 1026 had no subclones, 226 at least 1 subclone, and 39 a CP. Patients with defined subclones had an OS similar to those with no subclones (hazard ratio (HR) 1.05, 95% confidence interval (CI) 0.88–1.26), but CP patients had a shorter OS (HR = 1.58, 95% CI 1.11–2.26). However, in a multivariate Cox model stratified by protocol and adjusted for age, cytogenetic risk group, secondary versus primary AML, and performance status, clonal heterogeneity lost its prognostic importance (HR = 1.10, 95% CI 0.91–1.32 for defined subclones versus no subclones; HR = 0.96, 95% CI 0.67–1.38 for CP versus no subclones). Also, the impact of having a donor on DFS was similar in the three clonal subgroups. In summary, in patients with cytogenetic abnormality, presence of subclones had no impact on OS. The dismal outcome in patients with a CP was explained by the known predictors of poor prognosis. Trial registration: AML-10: ClinicalTrials.gov identifier: NCT00002549, retrospectively registered July 19, 2004; AML12: ClinicalTrials.gov identifier: NCT00004128, registered January 27, 2003.