Allogeneic blood or marrow transplantation for chronic lymphocytic leukaemia: timing of transplantation and potential effect of fludarabine on acute graft-versus-host disease

Comparison of Myeloablative Versus Reduced-Intensity Conditioning Regimens for Allogeneic Hematopoietic Stem Cell Transplantation in Acute Myeloid Leukemia: A Cohort Study

Objective

Allogeneic hematopoietic stem cell transplantation (HSCT) is an effective treatment modality for a variety of malignant and non-malignant hematologic disorders. Myeloablative conditioning (MAC) and reduced-intensity conditioning (RIC) regimens could have different clinical outcomes. This purpose of this study was to assess the long-term outcome of MAC versus RIC regimens in patients with acute myeloid leukemia (AML) undergoing allogeneic HSCT.

Materials and Methods

We retrospectively compared long-term outcomes with MAC and RIC regimens in patients with AML who underwent allo-HSCT at our tertiary transplantation center.

Results

We analyzed survival outcomes after MAC-HSCT versus RICHSCT among 107 adult patients with AML diagnosed from 2001 through 2017. Of those, 44 patients underwent a MAC regimen, whereas 63 patients received a RIC regimen. The median follow-up time was 37 months (range: 6-210) for the entire group. The 3-year overall survival (OS) for RIC and MAC patients was 67% and 60%, respectively (p>0.05). The 3-year progression-free survival (PFS) for RIC and MAC patients was 88% and 77%. In multivariate analysis, the type of conditioning regimen (RIC vs. MAC) did not influence PFS (p=0.24). Acute graft-versus-host disease (GVHD) was seen in five of the RIC patients and 9 of the MAC patients. Chronic GVHD was seen in 16 of the RIC patients and 6 of the MAC patients. There was no significant difference between the two groups in terms of acute GVHD (p=0.089), but there was a significant difference between the two groups in terms of chronic GVHD (p=0.03).

Conclusion

This retrospective analysis confirmed that MAC and RIC regimens had a consistently equivalent rate of OS and PFS in AML patients who underwent allo-HSCT. The choice of MAC versus RIC conditioning regimen might be decided on the basis of patient and disease characteristics.

Reduced intensity is preferred over myeloablative conditioning allogeneic HCT in chronic lymphocytic leukemia whenever indicated: A systematic review/meta-analysis

Despite availability of new and more effective therapies for chronic lymphocytic leukemia, presently this disease remains incurable unless eligible patients are offered an allogeneic hematopoietic cell transplant. Recent published clinical practice recommendations on behalf of the American Society for Blood and Marrow Transplantation relegated the role of for allogeneic hematopoietic cell transplantation to later stages of the disease. To our knowledge, no randomized controlled trial has been performed to date comparing myeloablative versus reduced intensity conditioning regimens in chronic lymphocytic leukemia patients eligible for the procedure. We performed a systematic review/meta-analysis to assess the efficacy of allogeneic hematopoietic cell transplantation when using myeloablative or reduced intensity conditioning regimens. We report the results in accordance to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Based on lower non-relapse mortality and slightly better overall survival rates, reduced intensity conditioning regimens appear to be the most desirable choice whenever the procedure is indicated for this disease. It appears highly unlikely that a RCT will be ever performed comparing reduced intensity vs. myeloablative allogeneic hematopoietic cell transplantation in chronic lymphocytic leukemia. In the absence of such a study, results of this systematic review/meta-analysis represent the best available evidence supporting this recommendation whenever indicated in patients with chronic lymphocytic leukemia.

Outcomes of Patients With Chronic Lymphocytic Leukemia and Richter's Transformation After Transplantation Failure

PURPOSE

Allogeneic stem-cell transplantation (SCT) induces long-term remission in a fraction of patients with high-risk chronic lymphocytic leukemia (CLL) or Richter's transformation (RT). Our purpose was to determine the outcomes of patients whose disease progressed after allogeneic SCT.

PATIENTS AND METHODS

We retrospectively analyzed the outcomes of 72 patients (52 with CLL and 20 with RT) who underwent allogeneic SCT between 1998 and 2011 and had documented progression after transplantation. Twenty-two (31%) never had a response, and 50 (69%) had a response but experienced relapse after a median of 7 months (range, 2 to 85 months). Forty-eight patients who were receiving or were candidates to receive post-SCT cell-based therapies were not included in this analysis.

RESULTS

The median age at time of transplantation was 58 years (range, 30 to 72 years). Sixty-two patients (86%) received more than two treatment regimens and 37 (51%) received more than three treatment regimens before SCT. Sixty-six patients (92%) had active disease at the time of transplantation. The 2- and 5-year survival rates were 67% and 38% (patients with CLL) and 36% and 0% (patients with RT). The patients who developed acute or chronic graft-versus-host disease had a longer overall survival (OS; P = .05). In a multivariable analysis, RT or low hemoglobin at the time of SCT predicted shorter OS. Chronic graft-versus-host disease and an initial response to SCT predicted longer OS.

CONCLUSION

Patients with CLL in whom allogeneic SCT fails may have a response to and benefit from salvage therapies, and their prognosis is relatively good.

Outcomes of human leukocyte antigen-matched sibling donor hematopoietic cell transplantation in chronic lymphocytic leukemia: myeloablative versus reduced-intensity conditioning regimens

Allogeneic hematopoietic cell transplantation (HCT) can cure some chronic lymphocytic leukemia (CLL) subjects. This study compared outcomes of myeloablative (MA) and reduced-intensity conditioning (RIC) transplants from HLA-matched sibling donors (MSD) for CLL. From 1995 to 2007, information regarding 297 CLL subjects was reported to the Center of International Blood and Marrow Transplant Research; of these, 163 underwent MA and 134 underwent RIC MSD HCT. The MA subjects underwent transplantation less often after 2000 and less commonly received antithymocyte globulin (4% versus 13%, P = .004) or prior antibody therapy (14% versus 53%; P < .001). RIC was associated with a greater likelihood of platelet recovery and less grade 2 to 4 acute graft-versus-host disease compared with MA conditioning. One- and 5-year treatment-related mortality (TRM) were 24% (95% confidence intervals [CI], 16% to 33%) versus 37% (95% CI, 30% to 45%; P = .023), and 40% (95% CI, 29% to 51%) versus 54% (95% CI, 46% to 62%; P = .036), respectively, and the relapse/progression rates at 1 and 5 years were 21% (95% CI, 14% to 29%) versus 10% (95% CI, 6% to 15%; P = .020), and 35% (95% CI, 26% to 46%) versus 17% (95% CI, 12% to 24%; P = .003), respectively. MA conditioning was associated with better progression-free (PFS) (relative risk, .60; 95% CI, .37 to .97; P = .038) and 3-year survival in transplantations before 2001, but for subsequent years, RIC was associated with better PFS and survival (relative risk, 1.49 [95% CI, .92 to 2.42]; P = .10; and relative risk, 1.86 [95% CI, 1.11 to 3.13]; P = .019). Pretransplantation disease status was the most important predictor of relapse (P = .003) and PFS (P = .0007) for both forms of transplantation conditioning. MA and RIC MSD transplantations are effective for CLL. Future strategies to decrease TRM and reduce relapses are warranted.

Autologous and Allogeneic Stem-Cell Transplantation for Transformed Chronic Lymphocytic Leukemia (Richter's Syndrome): A Retrospective Analysis From the Chronic Lymphocytic Leukemia Subcommittee of the Chronic Leukemia Working Party and Lymphoma Working Party of the European Group for Blood and Marrow Transplantation

Purpose

Patients with Richter's syndrome (RS) have a poor prognosis with conventional chemotherapy. The aim of this study was to evaluate the outcome after autologous stem-cell transplantation (autoSCT) or allogeneic stem-cell transplantation (alloSCT) in RS.

Patients and Methods

A survey was sent to all European Group for Blood and Marrow Transplantation centers assessing transplantations performed for RS. Eligibility criteria included a diagnosis of RS or secondary lymphoma before SCT, age ≥ 18 years, and SCT performed from 1997 to 2007. Data were analyzed by descriptive statistics and methods from survival analysis.

Results

Fifty-nine patients were registered. Thirty-four patients had received autoSCT, mostly because of chemotherapy-sensitive disease, and 25 had received alloSCT, with 36% being refractory to chemotherapy at SCT. In 18 allograft recipients (72%), reduced-intensity conditioning (RIC) was used. Three-year estimates of the probabilities of overall survival and relapse-free survival (RFS) and the cumulative incidences of relapse and nonrelapse mortality were 36%, 27%, 47%, and 26% for alloSCT and 59%, 45%, 43%, and 12% for autoSCT, respectively. Taking into account the limitations set by the low number of events and age younger than 60 years, chemotherapy-sensitive disease and RIC were found to be associated with superior RFS after alloSCT in multivariate analysis. Factors with a significant impact on autoSCT could not be identified.

Conclusion

Patients with RS who are sensitive to induction chemotherapy appear to benefit from consolidation with transplantation strategies, and prolonged survival was observed in a proportion of patients.

Transplant in chronic lymphocytic leukemia: to do it or not and if so, when and how?

Most patients with chronic lymphocytic leukemia (CLL) have an indolent clinical course, but the disease remains incurable with standard therapy and the prognosis is dismal for those patients with disease refractory to available treatment options. The only potentially curative treatment is allogeneic hematopoietic stem cell transplantation (SCT), but since CLL is a disease of elderly patients, few patients are candidates for myeloablative allogeneic SCT. Although autologous SCT is feasible and has low treatment-related mortality, it is not curative. The widespread adoption of reduced-intensity conditioning (RIC) allogeneic SCT has made this approach applicable to the elderly patient population with CLL. This approach relies on the documented graft-versus-leukemia (GVL) effect and is strong in CLL. Steps to further decrease the morbidity and mortality of the RIC SCT and in particular to reduce the incidence of chronic extensive graft-versus-host disease (GVHD) remain a major focus. Many potential treatments are available for CLL, and appropriate patient selection and SCT timing remain controversial and the focus of ongoing clinical trials. The use of SCT must always be weighed against the risk of the underlying disease, particularly in a setting where improvements in treatment are leading to improved outcome. The major challenge remains how to identify which patients with CLL merit this approach and where in the treatment course this treatment can be applied optimally.

Stem cell transplantation for indolent lymphoma and chronic lymphocytic leukemia

The indolent lymphomas, including chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) remain incurable with standard therapy. Autologous hematopoietic stem cell transplantation (HSCT) is feasible and has low treatment-related mortality in follicular lymphoma, but there are questions relating to optimal timing of the procedure, conditioning regimen, and late effects. Myeloablative allogeneic HSCT is associated with high treatment-related morbidity and mortality, few late relapses, but is applicable to only a small number of patients. The major focus of HSCT in these lymphomas has been with reduced-intensity conditioning (RIC) allogeneic HSCT, which is applicable to the age distribution of these diseases and which exploits the graft-versus-lymphoma effect in these diseases. Steps to further decrease the morbidity and mortality of the RIC HSCT and in particular to reduce the incidence of chronic extensive graft-versus-host disease (GVHD) while maintaining tumor control remain the major focus. Many potential treatments are available for indolent lymphomas and CLL, and appropriate patient selection and the timing of HSCT remain controversial. The use of HSCT must always be weighed against the risk of the underlying disease, particularly in a setting where improvements in treatment are leading to improved outcome.

Stem cell transplantation in chronic lymphocytic leukaemia - steering a safe course over shifting sands

There is no clear consensus regarding the optimal management of chronic lymphocytic leukaemia. Many patients are diagnosed at an advanced age and will die with chronic lymphocytic leukaemia, but of other unrelated causes. A significant minority are diagnosed at an earlier age, or with more aggressive disease, and despite chemotherapy, are likely to die of chronic lymphocytic leukaemia. The infusion of autologous or allogeneic haemopoietic stem cells, following a variety of conditioning regimes, offers the possibility of longer remissions or even cure. We explore the key questions facing clinicians in this field: Who is it best to transplant? When is it best to transplant? How is it best to transplant?

Allogeneic transplantation for chronic lymphocytic leukemia

Even if Chronic lymphocytic leukemia (CLL) often has an indolent behavior with good responsiveness to cytoreductive treatment, about 20% of the patients, so called “poor-risk” patients, show an aggressive course and die within a few years despite early intensive therapies. Criteria for poor-risk disease according to the European Bone Marrow Transplantation (EBMT) CLL Transplant Consensus are: purine analogue refractoriness, early relapse after purine analogue combination therapy, CLL with p53 lesion requiring treatment.

Allogeneic transplant has potential curative role in CLL, however burden with very high transplant related mortality (TRM) rates of 38–50%. A major advance in reducing the short-term morbidity and mortality of allogeneic stem cell transplantation (SCT) has been the introduction of non-myeloablative or reduced intensity conditioning (RIC) regimens to allow engraftment of allogeneic stem cells. There is no doubt that the crucial therapeutic principle of allo-SCT in CLL is graft versus leukemia (GVL) activity.

The major complications of allogeneic SCT in CLL are: chronic graft-versus-host-disease (GVHD) affecting quality of life, high graft rejection and infection rates correlated with preexisting immunosuppression. Disease relapse remains the major cause of failure after RIC allo-HCT in CLL patients.

Sensitive minimal residual disease (MRD) quantification has strong prognostic impact after transplant.

Transplantation in chronic lymphocytic leukemia: timing and expectations

Stem cell transplantation in chronic lymphocytic leukemia (CLL) is an evolving field. Younger patients with high-risk disease might derive the greatest benefit from this approach and the availability of reduced-intensity conditioning regimens has made allogeneic stem cell transplantation more relevant to patients with CLL. Patient selection, timing of transplantation, and method of conditioning, stem cell delivery and immunosuppression appear to influence outcomes. We collect and review the available data to assist clinical decision-making in this field.

Allogeneic hematopoietic cell transplantation for chronic lymphocytic leukemia: ready for prime time?

The development of reduced intensity conditioning regimens has increased the number of patients diagnosed with chronic lymphocytic leukemia that are referred for allogeneic hematopoietic cell transplantation (allo-HCT). However, given the toxicity of allo-HCT, it should only be offered to eligible patients whose life expectancy is significantly reduced by the disease. Accordingly, the European Group of Blood and Marrow Transplantation has recently identified those patients in whom allo-HCT could be a reasonable therapeutic approach. In this review, we have evaluated the outcome of chronic lymphocytic leukemia patients undergoing allo-HCT, either after conventional or reduced intensity conditioning regimens, in the context of current nontransplantation strategies. We have also analyzed the most important predisposing factors that might interfere with the procedure as well as posttransplantation complications that are particularly common in these patients. Finally, we have addressed the most relevant factors when deciding what patients should be considered for allo-HCT and the timing of the procedure.

Stem cell transplantation in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) remains incurable with standard therapy. Most patients with CLL have an indolent clinical course, but it is possible to identify patients with high-risk disease. Younger patients with adverse risk factors will die from their disease, and are therefore candidates for clinical trials exploring hematopoietic stem cell transplantation (HSCT). Autologous SCT is feasible and has low treatment-related mortality (TRM); but it is not curative. Myeloablative allogeneic SCT is associated with high treatment-related mortality and, TRM few late relapses, but is applicable to only a small number of CLL patients. The major focus of SCT in CLL has been with reduced-intensity conditioning (RIC) allogeneic SCT, which is applicable to the more elderly patient population with this disease and which attempts to exploit the graft-versus-leukemia (GVL) effect that exists in CLL. Steps to further decrease the morbidity and mortality of the RIC SCT, and, in particular, to reduce the incidence of extensive chronic graft-versus-host disease (cGVHD) remain the major focus. Many potential treatments are available for CLL, and appropriate patient selection and the timing of SCT remain controversial and the focus of ongoing clinical trials. The use of SCT must always be weighed against the risk of the underlying disease, particularly in a setting where improvements in treatment are leading to improved outcome.

Long-term outcome of allogeneic stem cell transplantation in chronic lymphocytic leukemia: analysis after a minimum follow-up of 5 years

In order to evaluate the long-term results of allogeneic stem cell transplantation (ASCT) in B-cell chronic lymphocytic leukemia (CLL), we reviewed the outcome of 12 consecutive CLL patients, who underwent ASCT at the Mayo Clinic prior to July, 2004. Median age was 44 years (range 18-55) and median time from diagnosis to transplant 58.5 months. All patients had failed prior fludarabine-based chemotherapy and all but two patients had chemo-resistant refractory disease at time of transplant. A 'myeloablative' conditioning regimen was used in 11 patients and 'reduced intensity' in one. Bone marrow was the source of hematopoietic stem cells in 10 patients and peripheral blood in two. Donors were matched sibling in nine patients, unrelated in two and partial phenotypic match father in one. Grade II-IV acute and chronic graft versus host disease was documented in five and four patients, respectively. To date, six patients (50%) have died including four early deaths from infection. Complete remission (CR) was documented in eight patients (66.7%) post-transplant; six are currently alive whereas one died at 7 months from infection while still in CR and one relapsed 7 months post-transplant and died later. One CR patient relapsed after 4.5 years but was successfully re-transplanted and remains in second CR for 6.5+ years. Another patient recently relapsed after 10.5 years of CR. Duration of ASCT-induced CR in the remaining four patients was 6.5+, 8.5+, 9+ and 10+ years. All surviving patients displayed excellent performance status without ongoing chronic graft versus host disease. We conclude that ASCT is an effective salvage therapy for fludarabine-refractory CLL but late relapses can occur.

Stem-cell transplantation in chronic lympocytic leukaemia

Excellent response rates are now achieved with modern chemoimmunotherapeutic approaches in chronic lymphocytic leukaemia (CLL), but the disease remains incurable. Younger patients and those with adverse prognostic factors will die from their disease, and are therefore candidates for clinical trials investigating the potential role of haematopoietic stem-cell transplantation (SCT) in the management of their disease. Autologous SCT is feasible and safe, but there is a high incidence of subsequent relapse. Myeloablative allogeneic SCT is associated with high treatment-related morbidity and mortality but few late relapses. Attempts to exploit the graft-versus-leukaemia effect of allogeneic donor cells but to reduce the toxicity are being explored in studies of reduced-intensity conditioning allogeneic SCT in CLL. With many potential treatments available, appropriate patient selection and the timing of SCT in the management of CLL remain controversial and the focus of ongoing clinical trials.

Graft-versus-leukemia in chronic lymphocytic leukemia

Immune-mediated anti-leukemia effects, often termed graft-versus-leukemia (GvL), operate after bone marrow or blood cell transplants for acute lymphoblastic leukemia, acute myelogenous leukemia and chronic myelogenous leukemia. Sometimes the magnitude of this anti-leukemia effect exceeds that of high-dose anti-leukemia drugs and radiation and can result in leukemia cure. We analyzed leukemia relapse data after transplants for chronic lymphocytic leukemia (CLL) in this context. These data support the notion of a strong GvL effect in CLL. However, as most of these data are from studies of allotransplants, it is uncertain whether GvL operates in settings where the anti-leukemia effector cells and target CLL cells are genetically identical except for leukemia-related mutations. It is also uncertain whether GvL is distinct from GvHD. These potential limitations have important implications on whether immune therapy of CLL will work in non-allotransplant settings.

Transplantation in chronic lymphocytic leukemia

Although there have been no randomized trials comparing the outcome of stem cell transplantation (SCT) with standard chemotherapy for patients with chronic lymphocytic leukemia (CLL), increasingly, both autologous and allogeneic SCT approaches are being explored in this disease. Clinical trials have demonstrated that these approaches are feasible, but current data suggest that autologous transplantation is not curative and myeloablative SCT, although offering the potential for cure, is associated with high treatment-related mortality. There is a clear demonstration of a graft-versus-leukemia effect in CLL, with encouraging results seen after SCT with reduced-intensity conditioning. Because no other treatment modalities are currently capable of improving survival in this disease, the treatment of choice for younger patients with poor-risk CLL may well be SCT, but continued enrollment of appropriate patients into well-designed clinical trials is vital to compare advances in SCT with the advances occurring in chemoimmunotherapy in CLL.

Pentostatin - pharmacology, immunology, and clinical effects in graft-versus-host disease

Pentostatin (deoxycoformycin), is one of a number of purine analogues. The drug was originally designed to mimic a form of severe combined immune deficiency, characterised by marked T lymphopenia but variable B cell function. Clinically, the drug has been used primarily to treat a rare type of leukaemia - hairy cell leukaemia. Recently, the drug has seen increasing attention as an immunosuppressant. This review will cover the basic pharmacology and immunological effects of pentostatin. The clinical use of this agent in prevention and treatment of graft-versus-host disease will be examined. Although many of these studies are ongoing, this agent has promise as a novel immunosuppressive agent with a new mechanism of action.

Allogeneic Transplant with Reduced Intensity Conditioning Regimens may Overcome the Poor Prognosis of B-Cell Chronic Lymphocytic Leukemia with Unmutated Immunoglobulin Variable Heavy-Chain Gene and Chromosomal Abnormalities (11q− and 17p−)

PURPOSE

To evaluate the efficacy of reduced intensity conditioning (RIC) allogeneic transplant in 30 patients with poor-prognosis chronic lymphocytic leukemia (CLL) and/or high-risk molecular/cytogenetic characteristics.

EXPERIMENTAL DESIGN

Eighty-three percent of patients had active disease at the moment of transplant. That is, 14 of the 23 patients analyzed (60%) had unmutated immunoglobulin variable heavy-chain gene (IgV(H)) status; 8 of 25 patients (32%) had 11q-, with four of them also displaying unmutated IgV(H); and six (24%) had 17p- (five were also unmutated).

RESULTS

After a median follow-up of 47.3 months, all 22 patients alive are disease free; overall survival and event-free survival (EFS) at 6 years were 70% and 72%, respectively. According to molecular/cytogenetic characteristics, overall survival and EFS for unmutated CLL and/or with 11q- aberration (n = 13) were 90% and 92%, respectively, not significantly different to those with normal in situ hybridization, 13q- and +12, or mutated CLL (n = 7). All six patients with 17p deletion were transplanted with active disease, including three with refractory disease; all except one reached complete remission after the transplant and two are alive and disease free. Nonrelapse mortality (NRM) was 20%; more than two lines before transplant is an independent prognostic factor for NRM (P = 0,02), EFS (P = 0.02), and overall survival (P = 0.01). Patients older than 55 years have a higher risk of NRM (hazard ratio, 12.8; 95% confidence interval, 1.5-111). Minimal residual disease was monitored by multiparametric flow cytometry in 21 patients. Clearance of CD79/CD5/CD19/CD23 cells in bone marrow was achieved in 68% and 94% of the patients at days 100 and 360, respectively.

CONCLUSION

According to these results, RIC allogeneic transplant could overcome the adverse prognosis of patients with unmutated CLL as well as those with 11q- or 17p-.

Revisiting the role of hematopoietic stem cell transplantation in chronic lymphocytic leukemia

Since the advent of hematopoietic stem cell transplantation more than 40 years ago, numerous methods of transplantation have been developed, modified and improved upon. Although hematopoietic stem cell transplantation has been used in a variety of malignant diseases since then, its use in the treatment of chronic lymphocytic leukemia has recently started to gain interest. Patients with chronic lymphocytic leukemia are generally elderly, and because of its relatively benign course, they were not considered suitable candidates for hematopoietic stem cell transplantation. Nonetheless, there have been marked improvements in transplantation techniques, including better conditioning regimens that have decreased treatment-related morbidity and mortality. In this article, the authors review the most recent data on hematopoietic stem cell transplantation in chronic lymphocytic leukemia as well as the change in risk stratification based on newer prognostic factors and its impact on treatment decisions in chronic lymphocytic leukemia.

Myeloablative allografting for chronic lymphocytic leukemia: evidence for a potent graft-versus-leukemia effect associated with graft-versus-host disease

In all, 30 patients with CLL proceeded to myeloablative allogeneic BMT using related (n=20, 67%) or unrelated (n=10) donors, at the Princess Margaret Hospital (Toronto) (n=20) or the Leukemia/BMT Program of BC (Vancouver) (n=10), from 1989 to 2001. Median (range) interval from diagnosis to BMT was 4.8 (0.3-13) years, median number of prior therapies was three and median age 48 years. The preparative regimen included total body irradiation in 15 (50%). In all, 14 of 30 patients (47%) are alive, with median (range) follow up of 4.3 (2.4-10.5) years. All are in complete remission, two following therapy for post-BMT progression. Actuarial overall (OS) and event-free survival (EFS) at 5 years is 39% (OS 48% for related donor and 20% for unrelated donor BMT); cumulative incidence of nonrelapse mortality (NRM) and relapse is 47 and 19%, respectively. Both acute (RR=0.008, P=0.01) and chronic (RR=0.006, P=0.02) Graft-versus-host disease (GVHD) were associated with markedly decreased risk of relapse. Patients receiving grafts from unrelated donors had increased NRM (RR=3.6, P=0.02) and decreased OS (RR of death=3.4, P=0.002). Allogeneic BMT has resulted in long-term EFS in approximately 40% of patients with CLL. There is evidence for a strong graft-versus-leukemia effect associated with acute and chronic GVHD, resulting in near complete protection from relapse.

Unrelated Donor Marrow Transplantation for B-Cell Chronic Lymphocytic Leukemia After Using Myeloablative Conditioning: Results From the Center for International Blood and Marrow Transplant Research

Purpose

To determine the role of myeloablative conditioning and unrelated donor (URD) bone marrow transplantation in the treatment of patients with advanced B-cell chronic lymphocytic leukemia (CLL).

Patients and Methods

A total of 38 CLL patients received a matched URD transplant using bone marrow procured by the National Marrow Donor Program. The median age was 45 years (range, 26 to 57 years), the median time from diagnosis was 51 months, and the median number of prior chemotherapy regimens was three. Fifty-five percent of patients were chemotherapy refractory and 89% had received fludarabine. Conditioning included total-body irradiation in 92% of patients. Graft-versus-host disease (GVHD) prophylaxis consisted of methotrexate with cyclosporine or tacrolimus for 82% of patients.

Results

Twenty-one patients (58%) achieved complete response and six (17%) achieved partial response. Incidences of grades 2 to 4 acute GVHD were 45% at 100 days and incidences of chronic GVHD were 85% at 5 years. Eleven patients are alive and disease free at a median of 6 years (range, 3.0 to 9.0 years). Five-year overall survival, failure-free survival, disease progression rates, and treatment-related mortality (TRM) were 33%, 30%, 32%, and 38% respectively.

Conclusion

These data demonstrate that lasting remissions can be achieved after URD transplantation in patients with advanced CLL. High TRM suggest that myeloablative conditioning and HLA-mismatched donors should be avoided in future protocols, and it is mandatory to investigate transplant strategies with a lower morbidity and mortality, including the use of nonmyeloablative regimens.

Reduced-intensity conditioning lowers treatment-related mortality of allogeneic stem cell transplantation for chronic lymphocytic leukemia: a population-matched analysis

To elucidate whether reduced-intensity conditioning (RIC) decreases treatment-related mortality (TRM) after allogeneic stem cell transplantation (allo-SCT) for chronic lymphocytic leukemia (CLL), we retrospectively compared 73 RIC cases from a recent EBMT survey with 82 patients from the EBMT database who had undergone standard myeloablative conditioning (MC) for CLL during the same time period. The two populations were matched by adjusting the primary risk factor, the conditioning regimen, in a series of Cox models for age, sex, donor type, remission status at transplant and analyzed for its effect on TRM, relapse incidence, event-free (EFS) and overall survival (OS). After adjustment, a significant reduction of TRM became evident for the RIC population (hazard ratio (HR) 0.4 (95% confidence interval 0.18-0.9); P=0.03). On the other hand, RIC was associated with an increased relapse incidence (HR 2.65 (0.98-7.12); P=0.054). There was no significant difference between RIC and MC in terms of EFS (HR 0.69 (0.38-1.25); P=0.22) and OS (HR 0.65 (0.33-1.28); P=0.21). We conclude that RIC appears to favorably influence TRM after allo-SCT for CLL. This observation, as well as possible detrimental effects of RIC on relapse risk, should be confirmed by prospective studies.

Remission induction using alemtuzumab can permit chemotherapy-refractory chronic lymphocytic leukemia (CLL) patients to undergo allogeneic stem cell transplantation

The outcome of allogeneic stem cell transplantation depends upon the disease status before transplantation. Patients with refractory disease are at high risk for relapse. To improve the curative potential of the transplant procedure, we treated 3 chemotherapy-refractory CLL patients with alemtuzumab before allogeneic stem cell transplantation. Prior to therapy, all patients suffered from B-symptoms, and had massive adenopathy, splenomegaly, thrombocytopenia, and anemia; two patients had hepatomegaly. Alemtuzumab greatly reduced tumor mass in blood and bone marrow, B-symptoms resolved, and organomegaly improved. Two patients became blood product independent. All patients proceeded to transplantation after conditioning with TBI 2 Gy (n=1) or Treosulfan (n=2) in combination with Fludarabine either from an HLA-matched sibling (n=2) or from an HLA-matched unrelated donor (n=1). All patients engrafted, and are alive and well. Two patients reached complete remission (CR); one patient attained stable partial remission (PR). These heavily pre-treated refractory patients gained substantial clinical benefit from alemtuzumab, and received successful allografts.

Stem cell transplantation for chronic lymphocytic leukaemia

Early results of autologous stem cell transplantation (ASCT) in chronic lymphocytic leukaemia (CLL) suggested a significant proportion of patients remained disease-free for years, raising the possibility of cure. More recent studies have shown no evidence of a plateau in the survival curves indicating that, at best, ASCT may only prolong disease-free survival. Problems remain over progenitor cell mobilization and one study has raised anxieties about post-transplant myelodysplasia. The impact of ASCT in CLL will only be properly ascertained in a randomized clinical trial and this in underway in Europe. Initial results of conventional allogeneic transplantation (allo-SCT) were very disappointing, with an unacceptably high mortality, but did show that cure was possible in some patients. The introduction of reduced intensity conditioning has limited the early transplant-related mortality but it remains too early to determine what proportion of patients will be cured. In view of these uncertainties, is important that reduced intensity allo-SCT for CLL is conducted in the context of a clinical trial. Finally, CLL is very heterogeneous condition and great deal more is becoming understood about the prognostic factors. These will become important in allowing patients and their physicians a choice in balancing the risks of various treatment options.

Salvage Therapy for CLL and the Role of Stem Cell Transplantation

Chronic lymphocytic leukaemia (CLL) remains an incurable disease and, notwithstanding the excellent remission rates now achieved with purine analogs and monoclonal antibodies, the vast majority of patients with CLL are destined to relapse after primary treatment. The management of relapsed CLL patients is then dependent upon a number of factors, most importantly age, performance status, previous therapy administered, the response and duration of response to such therapy, and time from last therapy. Although prior therapy and response to such therapy are important factors in determining next therapy, it is often difficult to determine their importance from published studies. Furthermore, the goal of therapy, whether palliative or aggressive, must also be weighed into the decision when deciding on the next line of treatment. With many potential treatments available, the sequence of treatments and the timing of procedures such as stem cell transplantation remain controversial and are the focus of ongoing clinical trials.

Graft-versus-leukemia activity may overcome therapeutic resistance of chronic lymphocytic leukemia with unmutated immunoglobulin variable heavy-chain gene status: implications of minimal residual disease measurement with quantitative PCR

The aim of this study was to investigate if graft-versus-leukemia (GVL) activity conferred by allogeneic stem cell transplantation (allo-SCT) is effective in chronic lymphocytic leukemia (CLL) with unmutated VH gene status. The kinetics of residual disease (MRD) were measured by quantitative allele-specific immunoglobulin heavy chain (IgH) polymerase chain reaction (PCR) in 9 patients after nonmyeloablative allo-SCT for unmutated CLL. Despite an only modest decrease in the early posttransplantation phase, MRD became undetectable in 7 of 9 patients (78%) from day +100 onwards subsequent to chronic graft-versus-host disease or donor lymphocyte infusions. With a median follow-up of 25 months (range, 14-37 months), these 7 patients remain in continuous clinical and molecular remission. In contrast, PCR negativity was achieved in only 6 of 26 control patients (23%) after autologous SCT for unmutated CLL and it was not durable. Taken together, this study shows for the first time that GVL-mediated immunotherapy might be effective in CLL with unmutated VH.

Long-term disease-free survival of patients with advanced follicular lymphoma after allogeneic bone marrow transplantation

Myeloablative allogeneic bone marrow transplantation (BMT) may be curative in patients with follicular non-Hodgkin's lymphoma, however, the impact of this therapy on long-term survival, disease progression and functional status is less clear. Twenty-nine patients (median age 42 years, range: 20-53) with advanced stage follicular lymphoma proceeded to allogeneic BMT a median of 25 (range: 8-154) months postdiagnosis, between 1985 and 2001, and have been followed for a minimum of 2 years. Eleven of 29 (38%) had refractory disease (n = 5 induction failure, n = 6 resistant relapse). Most (27 of 29, 93%) received total body irradiation-based conditioning; stem cell source was marrow from a related donor (n = 20) or unrelated donor (n = 9). Seventeen of 29 patients (59%) were alive a median of 5 years (range: 2-11) post-BMT with a median Karnofsky Performance Score of 100%. Death occurred because of transplant complications in seven patients (cumulative incidence of non-relapse mortality 24%), and progressive lymphoma in five patients (cumulative incidence of refractory/recurrent lymphoma 23%). The 5-year probability of overall and event-free survival was 58% and 53% respectively. Allogeneic BMT has resulted in long-term disease-free survival for approximately 50% of this cohort of patients with advanced follicular lymphoma and most of them now enjoy robust health.

Role of auto- and allotransplantation in B-cell chronic lymphocytic leukemia

Although important progress has been made in its management, B-cell chronic lymphocytic leukemia (CLL) remains incurable with standard therapies. Hematopoietic stem-cell transplants (HSCT) are frequently being offered to individuals with CLL, the hope being that, as in other hematologic malignancies, they can prolong survival in or even cure some patients. This article analyzes which patients with CLL are appropriate candidates for HSCT, current transplant procedures, results with autologous and allogeneic HSCT, and future trends in transplantation in this form of leukemia.

The role of stem cell transplantation in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) generally follows an indolent clinical course and usually occurs in the elderly. However, the disease is heterogeneous with some patients having a more aggressive clinical course and short survival. Although the role of fludarabine in combination with other chemotherapy drugs and/or monoclonal antibody therapy appears promising, to date chemotherapy has not been curative in this disease. At present, the only potential cure for CLL appears to be stem cell transplantation (SCT), but its role in the management of CLL has not been established. In particular, patient selection for consideration of SCT, timing of SCT in the clinical course of CLL, selection of autologous versus allogeneic SCT, use of nonmyeloablative regimens, and exploitation of the graft-versus-leukemia (GVL) effect are currently under investigation.

Stem cell transplantation for chronic lymphocytic leukemia: should not more patients get a transplant?

Novel therapeutic approaches with conventional chemotherapy and monoclonal antibody combinations have improved the complete remission rates in chronic lymphocytic leukemia. However, cure remains elusive, particularly in fludarabine-refractory patients, whose prognosis remains poor. Autologous stem cell transplantation (SCT) has been explored for such patients, lengthening the time to treatment failure in selected patients, but there is little hope that it will improve the cure rate. The strategy is particularly ineffective in patients with poor biological prognostic factors, such as abnormal cytogenetics and unmutated immunoglobulin heavy-chain variable region. Allogeneic SCT remains the only curative approach, producing an extended disease-free survival in 25-60%, mainly via the graft-versus-leukemia effect. The treatment-related mortality with such an approach has been significant, however, with a 30-40% risk of death within 100 days of the transplant. Nonmyeloablative (NMA) conditioning regimens may produce high response rates and lower morbidity, especially for patients with chemosensitive disease. Randomized trials designed according to the new biologic prognostic parameters described in chronic lymphocytic leukemia are required to better define the role of NMA SCT in the near future.

Nonablative allogeneic stem cell transplantation for chronic lymphocytic leukemia: impact of rituximab on immunomodulation and survival

OBJECTIVE

To investigate the graft-vs-leukemia effect of allogeneic stem cell transplantation after a nonablative conditioning regimen as treatment for patients with chronic lymphocytic leukemia.

PATIENTS AND METHODS

Patients were eligible to treatment if they were refractory or recurred after a prior response to fludarabine. Seventeen patients were treated. All patients received a preparative regimen of fludarabine (30 mg/m(2) daily for 3 days) and intravenous cyclophosphamide (750 mg/m(2) daily for 3 days). Ten patients received rituximab in addition to chemotherapy. The median time from diagnosis to transplant was 67 months. Nine of 17 patients had refractory disease.

RESULTS

All patients had engraftment of donor cells. Eleven (65%) did not require platelet transfusions. Ten patients with persistent disease underwent immunomanipulation to augment GVL effects including immunosuppression withdrawal and donor lymphocyte infusion with or without rituximab treatment. Seven of these 10 patients had a complete response and 2 had a partial response; 8 of these 9 responders had received rituximab with their immunomanipulation process. The final response was complete remission in 12 and partial remission in 4 patients for an overall response rate of 94%. Overall survival was 100% for patients who received the combined chemo-rituximab conditioning regimen, vs 14% for those who received chemotherapy alone (p=0.03).

CONCLUSION

Our results indicate that a pronounced GVL effect occurs after nonmyeloablative allogeneic hematopoietic transplantation for advanced CLL. This activity might be facilitated by rituximab. Prospective controlled trials are needed to define the role of nonablative allogeneic hematopoietic transplantation for treatment of this disease.

Rapid induction of complete donor chimerism by the use of a reduced-intensity conditioning regimen composed of fludarabine and melphalan in allogeneic stem cell transplantation for metastatic solid tumors

We evaluated the feasibility and efficacy of a reduced-intensity conditioning (RIC) regimen of fludarabine and melphalan to achieve rapid complete donor chimerism after allogeneic stem cell transplantation (SCT) in patients with metastatic solid tumors. Between January 1999 and January 2003, 8 patients with metastatic breast cancer (BC) and 15 with metastatic renal cell carcinoma (RCC) underwent allogeneic SCT after an RIC regimen of 5 days of fludarabine and 2 days of melphalan. Filgrastim-mobilized stem cells from HLA-identical related or unrelated donors were infused. Prophylaxis for graft-versus-host disease (GVHD) consisted of tacrolimus and methotrexate. All 22 evaluable patients had 100% donor chimerism at day 30 and at all measurement times thereafter. One patient died 19 days after SCT. Nine patients (39%) had grades II to IV acute GVHD and 10 patients (43%) had chronic GVHD. Five patients (22%) died of nonrelapse treatment-related complications. Treatment-related disease response was seen in 10 patients (45%), with 3 complete responses, 2 partial responses, and 5 minor responses. Fludarabine-melphalan is a feasible and effective RIC regimen for allogeneic SCT in metastatic BC and RCC. It induces rapid complete donor chimerism without the need for donor lymphocyte infusion. Tumor regression associated with GVHD is consistent with graft-versus-tumor effect.

Treatment-related mortality and graft-versus-leukemia activity after allogeneic stem cell transplantation for chronic lymphocytic leukemia using intensity-reduced conditioning

Allogeneic stem cell transplantation (SCT) using reduced-intensity conditioning (RIC) has potential to be a promising treatment of aggressive chronic lymphocytic leukemia (CLL). Since available clinical data obtained with this novel approach are very limited, we have performed a survey on this issue. Data of 77 patients were collected from 29 European Group for Blood and Marrow Transplantation centers. Median age was 54 (30-66) years, and the median number of previous chemotherapy regimens was 3 (0-8). HLA-identical sibling donors were used in 81% of the cases. Moderate conditioning regimens (mainly low-dose total body irradiation (TBI) or fludarabine-cyclophosphamide combinations) were administered to 56% of the patients, whereas the remainder received more intense conditioning consisting of fludarabine-busulfan or high-dose melphalan combinations. In 40% of the patients, in vivo T-cell depletion (TCD) with anti-thymocyte globulin or CAMPATH-1H was part of the conditioning regimen. Cumulative treatment-related mortality (TRM) was 18% (95% CI 9; 27) after 12 months. Complete chimerism as well as best response was not achieved immediately post-transplant but took a median of 3 months to develop. The 2-year probability of relapse was 31% (95% CI 18; 44), with no event occurring later than 12 months post transplant in the absence of TCD. With one exception, relapses were not observed after onset of chronic graft-versus-host disease. Event-free and overall survival at 24 months were 56% (95% CI 43; 69) and 72% (95% CI 61; 83), respectively. The median follow-up was 18 (1-44) months. Donor lymphocyte infusions or secondary transplants were performed in 19 patients with insufficient disease control and/or incomplete donor chimerism post-transplant, leading to a response in seven patients (37%). Preliminary multivariate analysis identified less than PR at transplant (hazard ratio (HR) 3.5; P&<0.01) and alternative donor (HR 3.1; P=0.02) as significant risk factors for relapse, whereas number of previous regimens >2 (HR 5.4; P=0.03), TBI (HR 2.5; P=0.05), and alternative donor (HR 2.3; P=0.08) were risk factors for survival. We conclude that RIC might favorably influence the outcome after allogeneic SCT for CLL by reducing TRM while preserving graft-versus leukemia activity.

Long-term follow-up of patients with CLL treated with allogeneic hematopoietic transplantation

BACKGROUND

We investigated the long-term outcome of allogeneic stem-cell transplantation after myeloablative conditioning regimen as treatment for patients with chronic lymphocytic leukemia.

METHODS

Patients were eligible for our study if they were refractory or failed a prior response to fludarabine. The conditioning regimen consisted of high-dose CY 60 mg/kg daily for 2 days and fractionated TBI. One patient received BEAM because of prior radiation. GvHD prophylaxis consisted of CYA or tacrolimus and MTX in the majority of patients.

RESULTS

Twenty eight patients were treated. nineteen had disease that was refractory to fludarabine. The median number of prior chemotherapy regimens per patient was 3. Twenty had HLA-identical donors and one had a one-Ag mismatched sibling donor. Seven patients had a matched unrelated transplant. The median follow-up time for the surviving patients was 66 months. By univariate analysis, chemosensitivity was the only factor that predicted a better outcome. For the chemosensitive patients, the overall survival was 78%, compared with 31% for those with refractory disease (P = 0.05). Progression-free survival at 5 years was 78% for the chemosensitive and 26% for those who were refractory to conventional chemotherapy at the time of transplantation (P = 0.03). Three patients (11%) died within 100 days of transplant. The actuarial risk of acute Grade II-IV GvHD was 49%. Only one patient developed acute Grade III GvHD.

CONCLUSION

Allogeneic transplantation is probably curative for a subset of patients with chronic lymphocytic leukemia. Patients should be considered for clinical trials involving allogeneic transplantation at an earlier stage prior acquiring chemorefractoriness.

Nonmyeloablative transplantation with or without alemtuzumab: comparison between 2 prospective studies in patients with lymphoproliferative disorders

Although nonmyeloablative conditioning regimen transplantations (NMTs) induce engraftment of allogeneic stem cells with a low spectrum of toxicity, graft-versus-host disease (GVHD) remains a significant cause of morbidity and mortality. In vivo T-cell depletion, using alemtuzumab, has been shown to reduce the incidence of GVHD. However, this type of maneuver, although reducing GVHD, may have an adverse impact on disease response, because NMTs exhibit their antitumor activity by relying on a graft-versus-malignancy effect. To explore the efficacy of alemtuzumab compared with methotrexate (MTX) for GVHD prophylaxis, we have compared the results in 129 recipients of a sibling NMT enrolled in 2 prospective studies for chronic lymphoproliferative disorders. Both NMTs were based on the same combination of fludarabine and melphalan, but the United Kingdom regimen (group A) used cyclosporin A plus alemtuzumab, whereas the Spanish regimen (group B) used cyclosporin A plus MTX for GVHD prophylaxis. Patients receiving alemtuzumab had a higher incidence of cytomegalovirus (CMV) reactivation (85% versus 24%, P <.001) and a significantly lower incidence of acute GVHD (21.7% versus 45.1%, P =.006) and chronic GVHD (5% versus 66.7%, P <.001). Twenty-one percent of patients in group A and 67.5% in group B had complete or partial responses 3 months after transplantation (P <.001). Eighteen patients in group A received donor lymphocyte infusions (DLIs) to achieve disease control. At last follow-up there was no difference in disease status between the groups with 71% versus 67.5% (P =.43) of patients showing complete or partial responses in groups A and B, respectively. No significant differences were observed in event-free or overall survival between the 2 groups. In conclusion, alemtuzumab significantly reduced GVHD but its use was associated with a higher incidence of CMV reactivation. Patients receiving alemtuzumab often required DLIs to achieve similar tumor control but the incidence of GVHD was not significantly increased after DLI.

B-chronic lymphocytic leukemia: practical aspects

B-CLL is the most common adult leukemia in the Western world. It is a neoplasia of mature looking B-monoclonal lymphocytes co-expressing the CD5 antigen (involving the blood, the bone marrow, the lymph nodes and related organs). Much new information about the nature of the neoplastic cells, including chromosomal and molecular changes as well as mechanisms participating in the survival of the leukemic clone have been published recently, in an attempt to elucidate the biology of the disease and identify prognostic subgroups. For the time being, clinical stage based on Rai and Binet staging systems remains the strongest predictor of prognosis and patients' survival, and therefore it affects treatment decisions. In the early stages treatment may be delayed until progression. When treatment is necessary according to well-established criteria, there are nowadays many different options. Chlorambucil has been the standard regimen for many years. During the last decade novel modalities have been tried with the emphasis on fludarabine and 2-chlorodeoxyadenosine and their combinations with other drugs. Such an approach offers greater probability of a durable complete remission but no effect on overall survival has been clearly proven so far. Other modalities, included in the therapeutic armamentarium, are monoclonal antibodies, stem cell transplantation (autologous or allogeneic) and new experimental drugs. Supportive care is an important part of patient management and it involves restoring hypogammaglobulinemia and disease-related anemia by polyvalent immunoglobulin administration and erythropoietin respectively.

Results of first salvage therapy for patients refractory to a fludarabine regimen in chronic lymphocytic leukemia

Resistance to purine analogs is emerging as a major problem in the management of patients with chronic lymphocytic leukemia (CLL). Most of these patients have already been exposed to and have become refractory to alkylating agents. To define the natural history of fludarabine (Fludara) refractory patients with CLL, we reviewed the response to first salvage therapy of 147 patients who were refractory to Fludara or had a remission less than six months in duration after a Fludara-containing regimen. Thirty-three (22%) patients responded to their first salvage attempt. However, the median survival was only 10 months. Responders survived significantly longer than non-responders. The most effective salvage regimens were combinations of purine analogs and cyclophosphamide. Patients still possibly sensitive to alkylating agents had a superior response than alkylating agent resistant or naive patients. Subsequent salvage therapy was administered to 61 patients. The most promising results noted in the group were transplantation and the use of Campath-1H antibody. The major morbidity and cause of death were associated with infections. The probability of infection was most strongly associated with the response to salvage therapy. Gram-positive organisms were most commonly associated with infection. However, gram-negative bacilli or opportunistic infection such as fungi, Pneumocystis carinii, acid-fast bacilli and legionella were prominent causes of infection. Fludara-refractory patients are a poor prognosis group and need more effective therapeutic regimens and well-designed infection prophylactic regimens.

Autologous and allogeneic stem cell transplantation for chronic lymphocytic leukemia

Allogeneic and autologous stem cell transplantation (SCT) are increasingly considered for treatment of patients with chronic lymphocytic leukemia (CLL). In order to assess the potential therapeutic value of SCT for CLL, the present article aims at answering the following crucial questions: (1) Is SCT a curative treatment? (2) Does SCT improve the prognosis of poor-risk CLL? (3) Do risk factors exist which are useful for defining prognostic groups in terms of feasibility and post-transplant outcome? The efficacy of auto-SCT relies exclusively on the cytotoxic therapy administered. To date, there is only limited hope that autotransplantation can cure the disease. Nevertheless, the results of the published series suggest that auto-SCT is capable of improving the prognosis of CLL with poor-risk features. Well defined favorable conditions for successful autografting are the status of the disease (CR or VGPR) and the number of lines of therapy (<2) before transplantation. The crucial anti-leukemic principle of allo-SCT consists in the immune-mediated GVL effects conferred with the graft. The GVL activity explains that allografting seems to be curative for at least a subset of patients. However, as long as allo-SCT in CLL is still associated with an excessively high treatment-related mortality, only selected patients with advanced poor-risk disease should be considered for allografting. The development of conditioning regimens with reduced intensity may allow extending the indications of allogeneic SCT for CLL in the near future.

Allogeneic peripheral blood stem cell transplantation with reduced intensity conditioning in primary refractory prolymphocytic leukemia: graft-versus-leukemia effect without graft-versus-host disease

A patient with progressive prolymphocytic leukemia (PLL) received an allogeneic stem cell transplant using a reduced intensity conditioning regimen to avoid prohibitive toxicities. Early in the post-transplant period, a high donor-derived CD8+ count was observed. One year from transplantation, the patient was in complete remission, fully donor chimeric and with a normal performance status, suggesting that this approach may represent a useful treatment option in patients with refractory PLL.

Progress in CLL, chemotherapy, antibodies and transplantation

Over the last decade, major advancements in our understanding of chronic lymphocytic leukemia (CLL) and its variants have occurred. It has become apparent that there is diversity in types of CLL including those patients that do or do not have hyper-mutation of their immunoglobulin genes. Mutated genes confer a favorable prognosis. One of the major advances in our therapy has been the discovery of the activity of purine analogs, which have been demonstrated to be more active than conventional therapy in achieving complete remission, prolonged remission duration, and a suggestion of improved survival. More recently, based on information that purine analogs inhibit DNA repair, rational combinations have been developed. In particular, fludarabine plus cyclophosphamide appeared to have added activity compared to either drug given alone or in sequence. This has led to a higher response rate, longer time to progression, and an improvement in survival in patients treated following prior alkylating agents. Two monoclonal antibodies, Rituximab and Campath-1H, have become available for clinical use and research. Rituximab has modest activity as a single agent, with higher response rates being noted in patients who receive more intensive regimens. Rituximab has been successfully combined with chemotherapy, and in association with fludarabine plus cyclophosphamide (FCR) has a very high response rate and the ability to obtain polymerase chain reaction (PCR) negativity for the immunoglobulin heavy chain region. Campath-1H is very active as a single agent and is being recommended for treatment for patients with fludarabine refractory disease and will receive increased attention as a research agent in earlier-stage patients. Autologous and allogeneic bone marrow transplantation have emerged as significant treatments in CLL. The ability to achieve responses in bone marrow and peripheral blood with newer regimens has given the opportunity to collect stem cells from patients. There is a suggestion that intensification of remissions with autologous transplant can lead to PCR negativity and prolonged remissions. Allogeneic transplantation has been demonstrated to be effective with a strong suggestion of graph versus leukemia effect. This has been utilized in the development of non-ablative marrow allogenaic bone marrow transplant programs. Non-ablative transplants appear to be as effective as ablative transplants in the most recent analysis. Thus, multiple modalities have been brought together to achieve high-quality complete remissions in CLL, giving the prospect of improved survival.

Pediatric hematopoietic stem cell transplantation

The successful use of allogeneic HSCT for children with malignant and nonmalignant diseases continues to be limited by the development of acute and chronic GVHD, infectious complications, delayed recovery of the immune system, acute and long-term toxicity, and relapse of disease. Significant advances have been made, particularly in the ability to identify suitable sources of HSC. Future advances will depend on a better understanding of the biology of HSC sources, GVHD, immune reconstitution, and common complications. Improved therapies are dependent on participation of children in well-designed, translational and clinical transplant studies.

Allogeneic and autologous transplantation for chronic lymphocytic leukemia

Autologous and allogeneic transplantation are increasingly used in the management of patients with chronic lymphocytic leukemia. Many questions regarding patient selection, efficacy and outcome are unresolved, hence a review of the literature through Medline search. Autologous transplantation for CLL has been used mainly in selected patients under the age of 60. Conditioning typically involves total body irradiation (TBI). Bone marrow and more recently peripheral blood stem cells are used. Treatment-related mortality in most series is less than 10%. Molecular remissions after autologous transplantation are common, and clinical remissions can be prolonged in some patients. Randomized studies are needed to establish whether autologous transplantation confers a survival benefit over standard chemotherapy approaches. Allogeneic transplantation has a considerable treatment-related mortality, but durable remissions sometimes occur in patients with advanced disease. The use of non-myeloablative 'mini-transplants' has been investigated as a method to reduce treatment-related mortality, but prolonged follow-up will be required to establish the cure rate obtained with this procedure. Autologous and allogeneic transplantation are promising treatment modalities. Further refinements of transplant techniques and properly designed prospective studies are necessary to establish the role of stem cell transplantation in the overall management of CLL.

Stem Cell Transplantation for Chronic Lymphocytic Leukaemia: Is this the Way Forward in the New Millennium?; Malignancy; Current Clinical Practice

The failure of conventional chemotherapy to eradicate chronic lymphocytic leukaemia cells and induce cure has led many clinicians to investigate the use of high dose chemotherapy and haemopoietic stem cell rescue in this disease. The selection of patients remains a major problem because this is a disease of elderly patients with a median overall survival of 7 years and will only therefore be applicable to a minority of patients. However transplantation is the most likely therapeutic option at this time to lead to cure in this condition. The best type of transplant is not known and not all patients will be able to mobilise adequate numbers of stem cells or have a suitable donor identified. Autologous transplantation relies on the ability of high doses of chemotherapy to eradicate disease whilst allogeneic transplantation attempts to harvest the graft versus leukaemia effect that has been identified in chronic granulocytic leukaemia. However, the high treatment related mortality and morbidity of allogeneic transplants has led to interest in the use of non-myeloablative allografts which hope to maximise the immunological effects of transplantation to achieve durable remissions. To date there have been no randomised clinical trials to compare the efficacy of combination chemotherapy, autologous or allogeneic transplants and this is unlikely to happen in the near future. Other issues that need to be addressed include the timing of transplantation, the source of stem cells, the optimal conditioning regimen and the role of immunomodulation post transplantation. This review attempts to answer some of these questions.

Nonmyeloablative preparative regimens for allogeneic hematopoietic transplantation

Allogeneic hematopoietic transplantation is an effective therapy for a range of malignancies. High doses of myelosuppressive chemotherapy or radiation have been used in preparative regimens with the goal of preventing graft rejection and eradicating malignancy. Much of the benefit of transplantation, however, results from graft-versus-malignancy effects, mediated by donor immunocompetent cells. An alternative approach is to utilize less toxic, nonmyeloablative preparative regimens to achieve engraftment and allow graft-versus-malignancy effects to develop. This strategy reduces the risk of treatment-related mortality and allows transplantation for elderly or medically infirm patients not eligible for myeloablative therapy. Nonmyeloablative preparative regimens appear promising in diagnoses sensitive to graft-versus-malignancy effects and provide a platform for further development of cellular immunotherapy. Controlled clinical trials are warranted to define the role of nonmyeloablative allogeneic transplants in a range of hematologic malignancies and selected solid tumors.