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Avichai Shimoni

Publications and source records attributed to Avichai Shimoni.

16 recordsLinked to original sources
PubMed2006

Changes in gene expression pattern following granulocyte colony-stimulating factor administration to normal stem cell sibling donors.

UNLABELLED: Granulocyte colony-stimulating factor (G-CSF) is widely used for the mobilization of hematopoietic stem cells from normal donors. The mechanism of induced mobilization has recently been elucidated. Treatment with G-CSF is considered safe; however, long-term effects are largely unknown. The aim of this study was, therefore, to determine whether it leads to significant changes in gene expression modifications. Affymetrix Gene Chip array technology was used. Samples were collected before and at various time points (up to 9 months) after mobilization. The expression levels of 122 genes were transiently modified before and after mobilization (p < 0.05). Fifty-three genes belonging to cell growth, proliferation and communication gene ontology categories were upregulated, while 69 genes were downregulated. CONCLUSION: The administration of G-CSF is associated with transient DNA and gene expression modifications in the lymphocytes of normal mobilized donors. A long-term follow-up of stem cell donors is recommended.

Down-Regulation↗
PubMed2005

BCL6 is regulated by p53 through a response element frequently disrupted in B-cell non-Hodgkin lymphoma.

The BCL6 transcriptional repressor mediates survival, proliferation, and differentiation blockade of B cells during the germinal-center reaction and is frequently misregulated in B-cell non-Hodgkin lymphoma (BNHL). The p53 tumor-suppressor gene is central to tumorigenesis. Microarray analysis identified BCL6 as a primary target of p53. The BCL6 intron 1 contains a region in which 3 types of genetic alterations are frequent in BNHL: chromosomal translocations, point mutations, and internal deletions. We therefore defined it as TMDR (translocations, mutations, and deletions region). The BCL6 gene contains a p53 response element (p53RE) residing within the TMDR. This p53RE contains a motif known to be preferentially targeted by somatic hypermutation. This p53RE is evolutionarily conserved only in primates. The p53 protein binds to this RE in vitro and in vivo. Reporter assays revealed that the BCL6 p53RE can confer p53-dependent transcriptional activation. BCL6 mRNA and protein levels increased after chemotherapy/radiotherapy in human but not in murine tissues. The increase in BCL6 mRNA levels was attenuated by the p53 inhibitor PFT-alpha. Thus, we define the BCL6 gene as a new p53 target, regulated through a RE frequently disrupted in BNHL.

Animals↗
PubMed2005

Outcomes for reduced-intensity allogeneic transplantation for multiple myeloma: an analysis of prognostic factors from the Chronic Leukaemia Working Party of the EBMT.

We report the outcome of 229 patients who received an allograft for myeloma with reduced-intensity conditioning (RIC) regimens from 33 centers within the European Group for Blood and Marrow Transplantation (EBMT). The median age was 52 years and 64% were male. Conditioning regimens were heterogeneous, but most were fludarabine based and T cell depleted with antithymocyte globulin or alemtuzumab. Transplantation-related mortality (TRM) at 1 year was 22%. The 3-year overall survival (OS) and progression-free survival (PFS) were 41% and 21%, respectively. Adverse OS was associated with chemoresistant disease (relative risk [RR], 2.9), more than 1 prior transplantation (RR, 2.0), and male patients with female donors (RR, 1.45). Adverse PFS was associated with chemoresistance (RR, 2.4) and alemtuzumab (RR, 1.8). TRM was increased with female-to-male donation (RR, 2.5) and transplantation more than 1 year from diagnosis (RR, 2.3). Grades II to IV acute graft-versus-host disease (aGvHD) occurred in 31%. Chronic GvHD was associated with better OS and PFS and were 84% and 46% for limited, 58% and 30% for extensive, and 29% and 12% in its absence suggesting that a graft-versus-myeloma effect is important. While RIC is feasible, heavily pretreated patients and patients with progressive disease do not benefit.

Adult↗
PubMed2005

Comparison between antithymocyte globulin and alemtuzumab and the possible impact of KIR-ligand mismatch after dose-reduced conditioning and unrelated stem cell transplantation in patients with multiple myeloma.

We compared antithymocyte globulin (ATG) with alemtuzumab in 73 patients with multiple myeloma, who underwent reduced conditioning with melphalan/fludarabine, followed by allogeneic stem cell transplantation from human leucocyte antigen-matched or -mismatched unrelated donors. The ATG group had more prior high-dose chemotherapies (P < 0.001), while bone marrow was used more as the stem cell source in the alemtuzumab group (P < 0.001). Alemtuzumab resulted in faster engraftment of leucocytes (P = 0.03) and platelets (P = 0.02) and in a lower incidence of acute graft versus host disease (GvHD) grades II-IV (24% vs. 47%, P = 0.06). More cytomegalovirus (CMV) seropositive patients in the alemtuzumab group experienced CMV reactivation (100% vs. 47%, P = 0.001). The cumulative incidence of treatment-related mortality at 2 years was 26% [95% confidence interval (CI) = 12-37%] for ATG vs. 28% (95% CI = 15-55%) for alemtuzumab, P = 0.7. There was no significant difference in the estimated 2-year overall and progression-free survival between ATG and alemtuzumab: 54% (95% CI: 39-75%) vs. 45% (95% CI: 28-73%) and 30% (95% CI: 16-55%) vs. 36% (95% CI: 20-62%) respectively. In multivariate analysis, treatment with alemtuzumab had a higher risk for relapse (hazard ratio: 2.37; P = 0.05) while killer immunoglobulin-like receptor (KIR)-ligand mismatch was protective for relapse (P < 0.0001). We conclude that alemtuzumab produced less acute GvHD, but higher probability of relapse. The data implicated a major role of KIR-ligand mismatched transplantation in multiple myeloma.

Alemtuzumab↗
PubMed2004

Low-dose thalidomide and donor lymphocyte infusion as adoptive immunotherapy after allogeneic stem cell transplantation in patients with multiple myeloma.

To improve the antimyeloma effect of donor lymphocyte infusion (DLI) after allogeneic stem cell transplantation in multiple myeloma, we investigated in a phase 1/2 study the effect of low-dose thalidomide (100 mg) followed by DLI in 18 patients with progressive disease or residual disease and prior ineffective DLI after allografting. The overall response rate was 67%, including 22% complete remission. Major toxicity of thalidomide was weakness grade I/II (68%) and peripheral neuropathy grade I/II (28%). Only 2 patients experienced mild grade I acute graft versus host disease (aGvHD) of the skin, while no grades II to IV aGvHD was seen. De novo limited chronic GvHD (cGvHD) was seen in 2 patients (11%). The 2-year estimated overall and progression-free survival were 100% and 84%, respectively. Adoptive immunotherapy with low-dose thalidomide and DLI induces a strong antimyeloma effect with low incidence of graft versus host disease.

Adult↗
PubMed2004

Deletion of chromosome band 13q14 as detected by fluorescence in situ hybridization is a prognostic factor in patients with multiple myeloma who are receiving allogeneic dose-reduced stem cell transplantation.

We investigated in a retrospective multicenter study the impact of chromosome arm 13q deletion (13q-) as detected by fluorescence in situ hybridization (FISH) on outcome after dose-reduced allografting in patients with multiple myeloma. In 68 of 140 patients, data on chromosome 13q status were available. Most patients included had advanced myeloma. At 2 years, patients with 13q deletion (n = 31) had a shorter event-free (18% vs 42%; P =.05) and overall survival (18% vs 67%; P =.03) than patients without 13q- (n = 37). Patients with 13q- experienced a higher relapse rate (77% vs 44%; P <.001) but a similar incidence of transplantation-related mortality at one year (24% vs 18%). In a multivariate analysis, 13q- remained a significant risk factor for a higher relapse rate (hazard ratio [HR], 3.28; 95% confidence interval [CI], 1.31-8.24; P =.01) and a shorter event-free survival (HR, 1.94; 95% CI, 1.03-3.67; P =.04). Concerning overall survival, 2 or more cycles of prior high-dose chemotherapy were associated with a significantly higher probability of death (HR, 2.48; 95% CI, 1.19-5.17; P =.02), while patients with deletion 13q had a nearly 2 times higher risk of death (HR, 1.94; 95% CI, 0.95-3.98; P =.07) after dose-reduced allogeneic stem cell transplantation.

Adult↗
PubMed2004

Thrombotic microangiopathy after allogeneic stem cell transplantation in the era of reduced-intensity conditioning: The incidence is not reduced.

Thrombotic microangiopathy (TMA) is one of the most severe complications of stem cell transplantation (SCT). Endothelial cell injury caused by the toxic effects of high-dose chemoradiotherapy is likely the primary event in pathogenesis. The incidence, clinical settings, and risk factors for TMA in the era of nonmyeloablative conditioning have not been well defined. The data on 147 consecutive SCTs in a single center were collected, and patients with TMA were identified. Patient characteristics, response to therapy, and outcome were recorded, and risk factors were determined. TMA occurred in 22 of 147 transplantations, with a projected incidence of 20% +/- 4%. TMA occurred in 3 clinical settings: classic multifactorial TMA, TMA associated with severe hepatic graft-versus-host disease (GVHD), and TMA associated with second SCT, with a projected incidence of 8% +/- 3%, 73% +/- 14%, and 70% +/- 16% of patients at risk, respectively. TMA occurred after 23% +/- 6% of nonmyeloablative and 16% +/- 5% of myeloablative conditioning regimens (not significant). Univariate analysis determined SCT from unrelated donors, SCT during advanced or active disease, second SCT within 6 months of a prior SCT, and acute GVHD as risk factors for TMA. The last 2 factors remained significant in a multivariate model. Thirty-two percent of patients responded to therapy. The peri-TMA mortality rate was 68% +/- 10%. Six patients had diffuse alveolar hemorrhage complicating TMA. SCT-associated TMA is a relatively common complication with unsatisfactory therapy and grim prognosis. Fludarabine-based nonmyeloablative conditioning does not confer a lesser risk for TMA. This observation may relate to the selective use of these regimens in elderly and heavily pretreated patients or to the lack of reduction of GVHD with these regimens, and fludarabine itself may be involved in causing endothelial damage. Further exploration of novel preventive and therapeutic measurements is required in high-risk settings.

Adolescent↗
PubMed2004

Relapse to prior autograft and chronic graft-versus-host disease are the strongest prognostic factors for outcome of melphalan/fludarabine-based dose-reduced allogeneic stem cell transplantation in patients with multiple myeloma.

We evaluated prognostic factors of melphalan/fludarabine-based dose-reduced allografts in patients with multiple myeloma. From 1998 to 2002, 120 patients with multiple myeloma were treated with melphalan/fludarabine followed by allogeneic stem cell transplantation. The cumulative risk at 1 year for treatment-related mortality (TRM) was 18% (95% confidence interval [CI], 12%-28%). In a multivariate analysis, relapse after prior high-dose chemotherapy was the most significant risk factor for TRM (hazard ratio [HR], 2.80; 95% CI, 1.16-6.74; P =.02), relapse (HR, 4.14; 95% CI, 2.04-8.38; P <.001), event-free survival (HR, 3.11; 95% CI, 1.77-5.46; P <.001), and overall survival (HR, 2.69; 95% CI, 1.35-5.35; P =.005). In addition, relapse was also significantly diminished by chronic graft-versus-host disease (GVHD) in a time-dependent Cox model (HR, 0.37; 95% CI, 0.16-0.87; P =.02). At transplantation, 8% of the patients were in complete remission, whereas 27% had progressive disease. After allografting, 49% achieved complete remission, and 38% achieved partial remission. In a subgroup of patients with chemosensitivity at transplantation and no relapse after prior high-dose chemotherapy who underwent transplantation with peripheral blood stem cells (n = 46), the cumulative risk of TRM at 1 year was only 8% (95% CI, 1%-54%). The 2-year estimated event-free and overall survival was 60% (95% CI, 42%-78%) and 75% (95% CI, 59%-91%), respectively, for related donors (n = 34) and was 81% (95% CI, 59%-100%) and 92% (95% CI, 76%-100%), respectively, for unrelated donors (n = 12).

Adult↗
PubMed2004

Determination of chromosome 13 status in bone marrow cells of patients with multiple myeloma using combined morphologic and fluorescence in situ hybridization analysis.

Deletion of chromosome 13q is believed to be an adverse prognostic marker in patients with multiple myeloma (MM). Interphase fluorescence in situ hybridization (I-FISH) is the method of choice for detection of chromosome 13q deletion (del13q). However, I-FISH has high false-positive rates attributed to a low percentage of plasma cells (PC), which are responsible for MM, in bone marrow (BM) samples from MM patients. In an attempt to overcome this problem, combined morphologic and I-FISH analyses were performed by a unique system that allows rapid automatic scanning of a large number of cells with simultaneous determination of the lineage of specific cells carrying del13q. The percentage of PC with del13q in BM samples from 40 MM patients was calculated. In addition, we established a useful prognostic ratio defined as the number of PC with del13q divided by the number of non-PC with del13q (PDP/PDNP), which may help to precisely define the putative role of del13q in prediction response of MM patients to new therapeutic compounds. We suggest this technique as a novel sensitive and specific method for detection of del13q in a minor PC population of MM patients.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2004

Clinical implications of minimal residual disease monitoring for stem cell transplantation after reduced intensity and nonmyeloablative conditioning.

Allogeneic stem cell transplantation (SCT) is a potentially curative therapy for a variety of hematological malignancies; however, relapse and treatment-related toxicities are major obstacles to cure. Nonmyeloablative and reduced-intensity conditioning regimens were designed not to eradicate the malignancy completely, but rather to be immunosuppressive enough to allow engraftment, and to serve as a platform for additional cellular immunotherapy. Minimal residual disease (MRD) typically persists after SCT, and is gradually eliminated with different kinetics typical of each disease. Significant progress has been achieved with technologies for MRD assessment. Quantitative PCR tests are very sensitive in detecting tumor-associated transcripts, allowing serial monitoring. Threshold levels have been established for some malignancies, above which relapse is imminent. Persistent negative tests, a low level or a decreasing MRD level are consistent with continuous remission, whereas high-level MRD or increasing levels predict an incipient relapse. Patients at high risk of relapse are candidates for additional cellular or targeted therapy. Immunotherapy is more effective for MRD than at frank relapse. Timing and dosing of therapy are not yet well established and depend on aggressiveness of the disease, type of conditioning, level and kinetics of MRD.

Hematologic Neoplasms↗
PubMed2004

Nonmyeloablative stem cell transplantation: lessons from the first decade of clinical experience.

Allogeneic stem cell transplantation is an effective and potentially curative therapy for hematologic malignancies. However, the procedure may be associated with significant morbidity and mortality resulting from toxicity of the conditioning regimen, limiting it to younger patients in good medical conditioning. Over the past decade, nonmyeloablative and reduced-intensity conditioning regimens have been designed to reduce toxicity and allow stem cell transplantation in elderly and medically infirm patients. These are relatively nontoxic and tolerable regimens designed not to maximally eradicate the malignancy, but rather to provide sufficient immune suppression to achieve engraftment and to allow induction of graft-versus-leukemia effect as the primary treatment. After transplantation, immune interventions are often required to hasten this graft-versus-leukemia effect. In this review, we discuss emerging data defining the relative toxicities and outcomes after nonmyeloablative transplantation in certain settings and our approach to patient selection and post-transplant immune interventions trying to improve overall outcome.

Graft vs Host Disease↗
PubMed2003

Intravenous busulfan-based conditioning prior to allogeneic hematopoietic stem cell transplantation: myeloablation with reduced toxicity.

OBJECTIVE: Allogeneic transplantation is a potentially curative treatment for hematologic malignancies but is associated with a high rate of complications. Busulfan is a common component of pretransplant conditioning but has an erratic and unpredictable bioavailability when administered orally. Intravenous (IV) busulfan was recently introduced into clinical practice. Prior studies showed consistent and predictable drug delivery with tight control of busulfan plasma levels, avoiding over- and under-dosing. This study was designed to define the role of IV busulfan in different transplant and disease settings. PATIENTS AND METHODS: The study included 43 patients with various hematologic malignancies conditioned with high-dose IV busulfan-containing regimens prior to allogeneic transplantation. The donors were HLA-matched siblings (n=24), matched unrelated (n=14), or 1-antigen mismatched related donors (n=5). Outcome parameters were recorded. RESULTS: Forty-two patients had initial engraftment. The toxicity profile was favorable. No patient developed veno-occlusive disease of the liver. Acute graft-vs-host disease (GVHD) grades II-IV occurred in 18 patients (42%). Six patients died of treatment-related causes, five of complications related to acute GVHD, and only one died of organ toxicity. Actuarial non-relapse-related mortality risk was 10% at day 100 and 18% at 2 years posttransplant. The actuarial 2-year overall survival and disease-free survival (DFS) rates were 63% and 44%, respectively. Disease status other than refractory relapse, myeloid disease, and no severe GVHD posttransplant predicted for longer DFS in a multivariant model. CONCLUSIONS: IV busulfan-containing regimens allow consistent engraftment of allografts from related and unrelated donors such that myeloablation is administered with a toxicity profile typical of non-myeloablative conditioning. Favorable outcome was seen in patients with myeloid leukemias and in early or intermediately advanced disease; however, this regimen may not be sufficiently cytoreductive in patients with very advanced or active leukemia and in acute lymphoblastic leukemia. IV busulfan merits further study to better define its role as a preferred substitute for oral busulfan in pretransplant conditioning.

Adolescent↗
PubMed2003

Rituximab reduces relapse risk after allogeneic and autologous stem cell transplantation in patients with high-risk aggressive non-Hodgkin's lymphoma.

High-dose chemotherapy and autologous stem cell transplantation (SCT) have limited success in patients with refractory aggressive lymphoma. Allogeneic SCT may offer some advantage in this setting by providing graft-versus-lymphoma effect, but the relapse risk remains substantial. In this study, we evaluated the safety and efficacy of rituximab administration after SCT in patients at high-risk for post-transplant relapse, in order to reduce relapse risk. Twenty-eight patients were included with the intent to treat them with rituximab after autologous (n = 16) or allogeneic (n = 12) SCT. Twenty-four were given rituximab starting a median of 47 d post SCT. Three died of SCT complications prior to therapy. Nine patients not achieving a complete remission (CR) post SCT converted to CR with rituximab and with the onset of graft-versus-host disease (GVHD) in three. With a median follow-up of 12 months (range, 3-33 months) the estimated 2-year overall survival and disease-free survival was 85 +/- 7% and 55 +/- 13% respectively. When only those patients who were actually treated are analysed, these rates were 95 +/- 7% and 64 +/- 13% respectively. The relapse risk was 35 +/- 14%. Seven patients had recurrent neutropenia episodes associated with severe hypogammaglobulinaemia, which were further prevented with intravenous immunoglobulin. None of the 10 allogeneic SCT recipients treated with rituximab had severe GVHD. Rituximab may be an effective adjuvant therapy after SCT to reduce the relapse rate and improve the outcome in high-risk aggressive lymphoma. Larger scale comparative trials are necessary to better define its role in SCT.

Adult↗
PubMed2002

Non-myeloablative hematopoietic stem cell transplantation (NST) in the treatment of human malignancies: from animal models to clinical practice.

NST is becoming a widely accepted method for allogeneic HSCT. Much experience has been gained, and the biology, indications and limitations are becoming clearer. Nonmyeloablative conditioning allows consistent engraftment of allografts from matched related, unrelated, and even partially matched donors. NST has been able to reduce the toxicity of allogeneic HSCT. The better immediate outcome produces better overall DFS. NST was feasible in elderly patients with almost no upper age limit, and in patients with organ dysfunction or other comorbidities precluding standard ablative conditioning. NST has also reduced the regimen-related toxicity of allogeneic HSCT in high-risk setting such as HSCT in heavily pretreated patients or following failure of a prior transplant procedure and in the unrelated setting. NST is rapidly becoming the treatment of choice in these indications where toxicity of standard ablative therapy is unacceptable. In certain malignancies such as in NHL, Hodgkin's disease and multiple myeloma, standard ablative NST has been reported to result in exceptionally high treatment related mortality, and NST is being investigated as a more reasonable alternative. NST may reduce the toxicity of the procedure even in younger patients who are eligible for ablative HSCT as well, however the long-term impact on patient outcome in this group is not yet established, and NST merits further investigation in prospective comparative trials. As described above, the known susceptibility of the underlying malignancy to GVT, the response to prior chemotherapy and bulk of residual disease, and the type of donor are other factors to consider when considering NST, and when selecting a regimen. The optimal preparative regimen needs to be defined. Ultimately less chemotherapy will be used and more specific immune-modulation, rather than intense nonspecific immunosuppression, will be used to achieve HVG tolerance. Preliminary animal models using costimulation blockade for specific induction of tolerance are promising steps towards achievement of this goal. Although much progress has been achieved with consistent achievement of engraftment with NST, GVHD and disease recurrence remain major obstacles to successful treatment. Existing clinical data suggest that NST does limit the incidence and severity of GVHD. Limitation of regimen-related toxicity, and bilateral transplantation tolerance afforded by mixed chimerism, are believed to have a major role in limiting GVHD. However GVHD remains the primary cause of treatment-related mortality. The development of techniques to separate GVHD and GVL are essential for further improvement of NST outcome. Better understanding of the biology and targets of GVHD and GVL may allow the elimination of alloreactive T-cells responsible for GVHD from the graft while retaining T-cells with GVL and infection control potential. Recurrence of the underlying malignancy is a major complication when NST is attempted in patients with chemo-refractory diseases and with high tumor bulk. Reduced toxicity regimens such as the FB/ATG regimen have been somewhat more successful in controlling disease progression until a potent GVT effect is established. However novel approaches are urgently required. NST serves as a platform for cellular immunotherapy. Judicious use of pre-emptive DLI needs to be explored. DLI may be amplified by activation of donor lymphocytes with IL-2 or in vivo administration of IL-2. Identification of tumor antigens will lead the way to ex-vivo generation and expansion of tumor specific cytotoxic T-lymphocytes to be used as potent immunotherapy without the hazards of GVHD. Allogeneic transplantation is rapidly changing from administration of supralethal doses of chemotherapy and radiation, trying to physically eliminate the 'last tumor cell', to the more subtle and tolerated sophisticated immunotherapy. This effort will focus on specific induction of HVG tolerance followed by induction of tumor-specific GVT effect to cure the underlying malignancy.

Animals↗
PubMed2002

Tumor cell contamination in re-infused stem cell autografts: does it have clinical significance?

Tumor cells frequently contaminate autologous stem cell products in patients having a variety of malignancies. Mobilized peripheral blood stem cells may be less contaminated with tumor cells than bone marrow harvests are, but they are still frequently infiltrated. Gene-marking studies using retroviral vectors provide evidence that tumor cells contained in autografts contribute to relapse in myeloid leukemia and neuroblastoma patients. Also clinical studies have shown that tumor cell contamination of autografts is associated with shortened disease-free survival; on the other hand, successful ex vivo purging of tumor cells is associated with superior clinical outcome. However, the presence of tumor cells in autografts or insufficient purging may correlate with the extent of systemic residual disease and/or tumor chemosensitivity; therefore, there is no direct evidence that reinfused tumor cells alone cause relapse. Particularly in patients having highly chemosensitive disease and no detected systemic residual disease following high-dose transplant chemotherapy, the relative number of tumor cells contained in autografts and eventually reinfused, may become a determining factor for clinical outcome. There are no randomized trials showing improved (disease-free) survival with purging. In the absence of such trials, the contribution of tumor cells in the stem cell autografts to subsequent relapse remains controversial.

Bone Marrow Purging↗