Noga Shem-Tov

CXCR4 Regulates Migration and Development of Human Acute Myelogenous Leukemia Stem Cells in Transplanted NOD/SCID Mice

The chemokine stromal cell-derived factor-1 (SDF-1) and its receptor CXCR4 participate in the retention of normal hematopoietic stem cells within the bone marrow (BM) and their release into the circulation. Homing and engraftment of human stem cells in immunodeficient mice are dependent on cell surface CXCR4 expression and the production of BM SDF-1, which acts also as a survival factor for both human and murine stem cells. However, the role of SDF-1/CXCR4 interactions in the control of human acute myelogenous leukemia (AML) cell trafficking and disease progression is poorly understood. In this study, we report that although some AML cells do not express surface CXCR4, all AML cells tested express internal CXCR4 and SDF-1. Culture of AML cells with SDF-1 promoted their survival, whereas addition of neutralizing CXCR4 antibodies, SDF-1 antibodies, or AMD3100 significantly decreased it. Pretreatment of primary human AML cells with neutralizing CXCR4 antibodies blocked their homing into the BM and spleen of transplanted NOD/SCID/B2m(null) mice. Furthermore, weekly administrations of antihuman CXCR4 to mice previously engrafted with primary AML cells led to a dramatic decrease in the levels of human AML cells in the BM, blood, and spleen in a dose- and time-dependent manner. Interestingly, the same treatment did not affect significantly the levels of normal human progenitors engrafted into NOD/SCID mice. Taken together, our findings demonstrated the importance of the SDF-1/CXCR4 axis in the regulation of in vivo motility and development of human AML stem cells and identified CXCR4 neutralization as a potential treatment for AML.

Allogeneic hematopoietic stem-cell transplantation in AML and MDS using myeloablative versus reduced-intensity conditioning: the role of dose intensity.

Allogeneic stem-cell transplantation (SCT) with both myeloablative and reduced-intensity conditioning (RIC) is an effective therapy in AML/MDS. However, the relative merits of each may differ in different settings. To define the role of dose intensity, we analyzed SCT outcomes of 112 consecutive patients with AML/MDS. A total of 45 patients met eligibility criteria for standard myeloablative conditioning and were given intravenous-busulfan (12.8 mg/kg) and cyclophosphamide (ivBuCy). A total of 67 noneligible patients were given RIC with fludarabine and intravenous-busulfan (6.4 mg/kg, FB2, n=41) or a modified myeloablative regimen with fludarabine and myeloablative doses of intravenous-busulfan (12.8 mg/kg, FB4, n=26). The overall survival (OS) at 2 years was 50, 49 and 47% after ivBuCy, FB4 and FB2, respectively (P=NS). Nonrelapse mortality was higher after ivBuCy, 22 vs 8% (P=0.05), but relapse rates were lower. Active disease at SCT was the most significant predictor of reduced survival in multivariable analysis (HR 4.5, P=0.0001). Myeloablative and RIC regimens had similar outcomes when leukemia was in remission at SCT; however, patients with active disease could only be salvaged by myeloablative conditioning. Among the latter, OS was 45% after ivBuCy but no FB2 recipient survived (P=0.02). Patients with active disease, ineligible for standard myeloablation, could tolerate modified myeloablation well; however, long-term outcome cannot be determined yet.

Hematopoietic stem-cell transplantation from unrelated donors in elderly patients (age>55 years) with hematologic malignancies: older age is no longer a contraindication when using reduced intensity conditioning

Allogeneic stem cell transplantation (SCT) is a potentially curative approach for patients with hematological malignancies. Reduced-intensity conditioning regimens allow SCT in elderly patients; however, there are only limited data on the feasibility and outcomes of unrelated donor SCT in these patients. In this study, we analyzed, retrospectively, data of 36 patients with various hematological malignancies and median age 58 years (range, 55–66), who were given unrelated donor SCT after reduced-intensity conditioning. The preparative regimen consisted of fludarabine combined with oral busulfan (8 mg/kg, n=8), intravenous busulfan (6.4 mg/kg, n=11), treosulfan (30 g/m2, n=5) or melphalan (100–150 mg/m2, n=12). Patients were also given serotherapy, ATG (n=32), or alemtuzumab (n=4). The probabilities of overall survival, disease-free survival, and nonrelapse mortality at 1 year after SCT were 52, 43, and 39%, respectively. Acute graft-versus-host disease (GVHD) grade II–IV and chronic GVHD occurred in 31 and 45%, respectively. Multivariable analysis determined that survival rates were higher in patients with chemosensitive disease (HR 4.5), and patients conditioned with intravenous busulfan or treosulfan (HR 3.9). Unrelated donor SCT is feasible in elderly patients, with outcomes that are similar to younger patients. Favorable outcome was observed in patients with myeloid malignancies, and those transplanted in remission and early in the course of disease. Age alone should not be considered a contraindication to unrelated donor SCT.

Two cycles of escalated BEACOPP followed by four cycles of ABVD utilizing early-interim PET/CT scan is an effective regimen for advanced high-risk Hodgkin's lymphoma

BACKGROUND Escalated combination therapy with bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine and prednisone (escBEACOPP) regimen is superior to cyclophosphamide, vincristine, procarbazine and prednisone alternating with doxorubicin, bleomycin, vinblastine and dacarbazine (COPP-ABVD) for advanced-stage Hodgkins lymphoma (HL) patients. However, the original schedule of eight cycles of escBEACOPP was associated with significant toxicity. This study was conducted in an attempt to reduce the toxicity of the original schedule, while attempting to preserve improved initial tumor control. PATIENTS AND METHODS Forty-five newly diagnosed patients with advanced-stage HL and International Prognostic Score > or = 3 received two initial cycles of escBEACOPP and then were evaluated by positron emission tomography (PET)/computed tomography scan. If a good imaging response was obtained, they were treated by four cycles of ABVD. RESULTS Following the first two cycles of escBEACOPP, the overall response was 100% and at the end of all therapy, 40 (89%) patients were in complete response (disappearance of all clinical evidence of disease and PET negativity), three (7%) in partial response (PET-positive residual lesions and a size reduction of the majority of large masses by >50%), while two (4%) had progressive disease. After a median follow-up of 48 months, progression-free survival (PFS) and overall survival at 4 years were 78% and 95%, respectively. The 4-year PFS for early PET-negative patients (n = 31) and early PET-positive patients (n = 13) were 87% and 53%, respectively (P = 0.01). CONCLUSIONS These data indicate that combined escBEACOPP-ABVD may improve the outcome in patients with high-risk advanced HL. The potential benefit of early-interim PET activity as a guide to continuing therapy in these patients merits further study in the future.

Comparison between two fludarabine-based reduced-intensity conditioning regimens before allogeneic hematopoietic stem-cell transplantation: fludarabine/melphalan is associated with higher incidence of acute graft-versus-host disease and non-relapse mortality and lower incidence of relapse than fludarabine/busulfan.

Reduced-intensity conditioning (RIC) regimens are increasingly used in allogeneic stem-cell transplantation (SCT). There are no data whether any of these regimens has advantage and in what setting. We retrospectively analyzed SCT outcomes in 151 patients given fludarabine-based RIC for various hematological malignancies; 72 conditioned with fludarabine and intravenous-busulfan (FB) and 79 with fludarabine and melphalan (FM). FM was more myelosuppressive. Grade III–IV organ toxicity occurred in 31 and 53% of FB and FM recipients (P=0.005) and acute graft-versus-host disease grade II–IV in 33 and 53%, respectively (P=0.01). Non- relapse mortality rate (NRM) was 16 and 40%, respectively (P=0.003). Active disease (HR 2.2, P=0.003) and prior autologous SCT (HR 1.7, P=0.04) predicted inferior overall survival (OS). Among patients transplanted in remission, OS was 72 and 36% after FB and FM, respectively (P=0.03) due to increased NRM with FM. Similarly, patients transplanted in active disease experienced higher NRM with FM, however lower relapse rates resulted in equivalent OS. In conclusion, there are marked differences in outcome between RIC regimens that are theoretically dose-equivalent. The FM regimen is more myelosuppressive and toxic but controls disease better. FB was associated with improved survival in patients transplanted in remission. These observations merit further study in prospective studies.

Ibritumomab tiuxetan (Zevalin) combined with reduced-intensity conditioning and allogeneic stem-cell transplantation (SCT) in patients with chemorefractory non-Hodgkin's lymphoma

Allogeneic SCT is an effective therapy for lymphoma. Reduced-intensity conditioning (RIC) reduces non-relapse mortality (NRM) associated with myeloablative conditioning but relapse rates are high when performed in active disease. This study was designed to explore the safety and outcome of ibritumomab tiuxetan (Zevalin) combined with RIC in patients with advanced lymphoma. The study included 12 patients, median age 54 years (37–62), with a median of four prior treatments (2–6) and active disease documented on PET–CT. Zevalin 0.4 mCi/kg was given on day −14 and fludarabine combined with BU (n=6) or melphalan (n=6) was started on day −6. GVHD prevention was tapered 3 months after SCT to augment the graft-versus-lymphoma effect. All patients engrafted, a median of 14 days after SCT. Eighty-three percent achieved CR/PR. With a median follow-up of 21 months (12–37), 2-year PFS is 33%. Only three patients relapsed; cumulative incidence 25%. NRM was 42%, predominantly due to acute GVHD. Zevalin–RIC is feasible with consistent engraftment, acceptable organ toxicity, but high rates of acute GVHD. The low incidence of relapse suggests augmented anti-lymphoma effect. Zevalin–RIC merits further study. Better results may be achieved in patients earlier in disease course and with longer duration of immune-suppression.

Allogeneic hematopoietic stem-cell transplantation in AML and MDS using myeloablative versus reduced-intensity conditioning: long-term follow-up

Allogeneic hematopoietic stem-cell transplantation in AML and MDS using myeloablative versus reduced-intensity conditioning: long-term follow-up

Fludarabine and treosulfan: A novel modified myeloablative regimen for allogeneic hematopoietic stem-cell transplantation with effective antileukemia activity in patients with acute myeloid leukemia and myelodysplastic syndromes

Allogeneic stem-cell transplantation (SCT) is potentially curative treatment for AML and MDS. New conditioning regimens are continuously explored trying to reduce toxicity while maintaining antileukemia effect. Treosulfan is an alkylating agent with in vitro cytotoxicity against leukemia as well as myeloablative and immunosuppressive properties when used in escalated doses. We explored a regimen of fludarabine (30 mg/m2×5) and treosulfan (12 gr/m2×3) in 24 patients, median age 55 years (range, 30 – 69), with AML (n = 19) or MDS (n = 5), not eligible for standard myeloablation. Donors were HLA-matched siblings (n = 11) or matched-unrelated (n = 13). Twenty-one patients engrafted within a median of 15 days. Extramedullary toxicity was relatively limited. The incidence of acute and chronic GVHD was 15% and 47%, respectively. With median follow-up of 19 months (range, 8 – 34), 16 patients are alive and 8 died (relapse-2, treatment-related-6). Two-year disease-free survival rate was 60% (95% CI, 39 – 81). The cumulative incidence of relapse was only 15% (95% CI, 5 – 44) while nonrelapse mortality rate was 25% (95% CI, 13 – 50). The fludarabine/treosulfan regimen can be considered a fully intensive, modified myeloablative regimen with effective antileukemia activity and acceptable toxicity in patients with AML/MDS not eligible for standard myeloablation, and merits further study in larger scale studies.

Mobilized peripheral blood grafts include more than hematopoietic stem cells: the immunological perspective

Although stem cell mobilization has been performed for more than 20 years, little is known about the effects of mobilizing agents on apheresis composition and the impact of graft cell subsets on patients’ outcome. With the increasing use of plerixafor and the inclusion of poor mobilizers in autologous transplant procedures, new parameters other than CD34+ stem cell dose are emerging; plerixafor seems to mobilize more primitive CD34+/CD38− stem cells compared with G-CSF, but their correlation with stable hematopoietic engraftment is still obscure. Immune recovery is as crucial as hematopoietic reconstitution, and higher T and natural killer cells infused within the graft have been correlated with better outcome in autologous transplant; recent studies showed increased mobilization of immune effectors with plerixafor compared with G-CSF, but further data are needed to clarify the clinical impact of these findings. In the allogeneic setting, much evidence suggests that mobilized T-cell alloreactivity is tempered by G-CSF, probably with the mediation of dendritic cells, even though no clear correlation with GVL and GVHD has been found. Plerixafor is not approved in healthy donors yet; early data suggest it might mobilize a GVHD protective balance of immune effectors, but further studies are needed to define its role in allogeneic transplant.

Allo-SCT for AML and MDS with treosulfan compared with BU-based regimens: Reduced toxicity vs reduced intensity

Allo-SCT with reduced-intensity conditioning (RIC) results in lower non-relapse mortality (NRM), but higher relapse rate than myeloablative conditioning (MAC) in AML/myelodysplastic syndromes (MDS). Novel regimens with intensive anti-leukemic activity, but with limited toxicity will be of benefit. In all, 85 patients with AML/MDS, not eligible for MAC, were given fludarabine-treosulfan conditioning (FT). Outcomes were compared with those in patients given fludarabine-BU RIC (FB2, n=106) or reduced-toxicity (RTC) conditioning (FB4, fludarabine and myeloablative BU dose, n=85). The 5-year NRM was 29%, 20% and 18% after FT, FB2 and FB4, respectively (P=NS). Multivariate analysis (MVA) identified comorbidity score (HCT-CI) >2 and advanced disease as adverse factors with no independent impact of regimen. The 5-year relapse rate was 36%, 47% and 40%, respectively (P=0.17). MVA identified advanced disease as the major adverse factor, while FT had significantly lower relapse rate (hazard ratio 0.6, P=0.03). The 5-year survival (OS) was 37% with advanced disease. HCT-CI >2 and age ⩾50 were found as adverse factors. The 5-year OS was 46%, 44% and 50% after FT, FB2 and FB4 in early-intermediate-stage disease (P=NS) and 33%, 9% and 28% in advanced disease, respectively (P=0.02). FT is an RTC regimen with intensive anti-leukemia effect in MAC non-eligible patients.