New strategies of antifungal therapy in hematopoietic stem cell transplant recipients and patients with hematological malignancies

Invasive fungal infections (IFIs) are associated with considerable morbidity and mortality among high-risk individuals. Outcomes for IFI historically have been suboptimal and associated with a high mortality rate, hence global prophylaxis strategies have been applied to at-risk populations. Among certain populations, fluconazole prophylaxis has reduced systemic and superficial infections caused by Candida species. Newer azoles are currently being evaluated as prophylaxis and have the potential to provide protection against mould pathogens that are more troublesome to treat once they occur. Global prophylaxis strategies have the shortcoming of subjecting patients to therapy that ultimately will not need it. Targeted prophylaxis has the advantage of treating only patients at highest risk using some parameter of greater host susceptibility. Prophylaxis strategies are most suitable in patients at the highest risk for IFI. For patient groups whose risk is somewhat lower or when suspicion of IFI occurs in patients receiving prophylaxis, empirical antifungal therapy is often employed following a predefined period of fever. Again this approach subjects many non-infected patients to unnecessary and toxic therapy. A more refined approach such as presumptive or pre-emptive therapy whereby treatment is only initiated upon positive identification of a surrogate marker of infection in combination with clinical and radiological signs will subject fewer patients to toxic and expensive treatments.     

Prolonged viremia in dengue virus infection in hematopoietic stem cell transplant recipients and patients with hematological malignancies

Fever, skin rash, headache, and thrombocytopenia are considered hallmarks of dengue infection. However, these symptoms are frequently observed in infectious and non‐infectious complications of hematopoietic stem cell transplant recipients and oncohematological patients. Thus, laboratory confirmation of dengue is relevant for prompt intervention and proper management of dengue in endemic and non‐endemic regions. Because no prospective study of dengue has been conducted in these populations, the actual morbidity and mortality of dengue is unknown. In the present series, we describe five cases of dengue in patients living in endemic areas, emphasizing the prolonged course of the disease and the occurrence of prolonged viremia.     

Risk factors for invasive pulmonary fungal infection in patients with hematological malignancies not receiving hematopoietic stem cell transplant

We investigated the incidence, pathogens and risk factors of invasive pulmonary fungal infection (IPFI) in patients with hematological malignancies who did not receive hematopoietic stem cell transplantation (HSCT). Of the 323 patients included, 106 had confirmed IPFI, 111 had pulmonary bacterial infections, and 106 did not have pulmonary infections. The risk factors for IPFI were explored through logistic univariate and multivariate analysis. The incidence of IPFI in patients with hematological malignancies but without HSCT was 3.5%. The leading pathogen was Candida albicans which accounted for 50.7% of the infections, and the second one was Aspergillus which accounted for 37.3% of the infections. The main risk factors for these patients were days of hospitalization, history of IPFI, agranulocytosis, concomitant hypoproteinemia, number of antibiotics being used, concomitant bacterial sepsis, and age. Furthermore, Nystatin mouthwash was protective against IPFI. Among patients with hematological malignancies, IPFI causes the highest proportion of deaths. We have identified two important pathogens and several risk factors as well as one factor protective against IPFI. Awareness of risk factors and reduction of pathogens can decrease the incidence of IPFI. Keywords: fungemia, mycoses/prevention and control, epidemiology, Nystatin, hematologic neoplasms/complications.     

Conventional versus reduced-intensity conditioning regimen for allogeneic stem cell transplantation in patients with hematological malignancies

BACKGROUND: Allogeneic hematopoietic stem cell transplantation (HSCT) from human leukocyte antigen (HLA)-compatible sibling donors is a potential curative treatment for hematological and non-hematological malignancies. Nevertheless, high mortality rates may be associated with this therapy, especially in older patients, those with other comorbidities or who receive a second HSCT. PATIENTS AND METHODS: We analyzed the factors associated with transplant-related mortality (TRM) and overall survival in 157 consecutive adult patients (104 males and 53 females) who received a HSCT [29 bone marrow (BM) transplantation and 128 peripheral blood (PB) transplantation] from a HLA-identical sibling between January 1995 and March 2002 in our institution. One hundred patients received a standard conditioning prior to HSCT (STAND) and 57 patients received a reduced-intensity conditioning (RIC) HSCT. Fifty-eight patients were in an early phase at transplant and 99 in a non-early phase. Median age was 46 yr (16-66), and 90 patients (57%) were >45 yr of age. RESULTS: Patients in the RIC group were older than those in the STAND group, and had a higher proportion of non-early disease phases including a prior autologous HSCT in 39%. Median follow-up for survivors was 28 and 15 months in the STAND and RIC groups (P < 0,001), respectively. Cumulative incidence of TRM at 2 yr was 30% [95% confidence interval (CI) 22-41%] for the STAND group and 22% (95% CI 13-37%) for the RIC group [non-significant (NS)]. Factors associated with a higher TRM in multivariate analysis were: STAND vs. RIC conditioning regimen [relative risk (RR) 5.4; 95% CI 2.3-12.8; P < 0.001]; age > or =45 yr vs. <45 yr (RR 5; 95% CI 2.4-10.8, P < 0.001); second vs. first HSCT (RR 2.8, 95% CI 1.3-6.3, P = 0.01) and non-T-cell-depleted vs. T-cell-depleted graft (RR 2.7, 95% CI 1.3-5.8, P = 0.009). Overall survival (OS) at 2 yr was 52.5 +/- 10.4% for STAND group and 59 +/- 16.8% in RIC group. Factors associated with poorer OS in multivariate analysis were: STAND vs. RIC conditioning regimen (RR 3.4, 95% CI 1.7-6.9, P = 0.001); age > or =45 vs <45 yr (RR 2.5, 95% CI 1.4-4.5, P = 0.002) and diagnosis [other than chronic myeloid leukemia (CML) vs. CML] (RR 2.6, 95% CI 1.2-5.7 P = 0.02). CONCLUSIONS: Our results indicate that the introduction of RIC allogeneic HSCT for patients at high risk for TRM (advanced age, prior HSCT and non-T-cell depletion) leads to a reduction in the TRM and improvement in the OS.     

Colistin is relatively safe in hematological malignancies and hematopoietic stem cell transplantation patients

Purpose

Colistin is increasingly used as the last-resort treatment option against infections caused by multidrug-resistant (MDR) Gram-negative pathogens, but its nephrotoxicity is of concern, especially in severely ill patients. The aim of this study was to analyze the toxicity of colistin therapy in adults and children with hematological malignancies (HM) and hematopoietic stem cell transplantation (HSCT) recipients.

Methods

Data on HSCT recipients and HM patients, treated with intravenous colistin (2.5–5 mg/kg/day in children and 3–6 million international units (IU) in adults, adjusted to renal function) during the period 2008–2011 in our center, were retrospectively collected and analyzed. Nephrotoxicity was defined according to the RIFLE criteria (Risk, Injury, Failure, Loss, and End-stage kidney disease).

Results

Twenty-nine children and adults received 38 courses of intravenous colistin (2.5–5 mg/kg/day in children and 3–6 × 10⁶ IU in adults, adjusted to renal function) [allogeneic HSCT (22 courses) and HM (16 courses)] for 3–28 days (median 10 days) for empirical therapy for nosocomial clinical sepsis (28) or local infection (6), and bacteremia with MDR Gram-negative rods (4). Nephrotoxicity was observed at the end of 4 (10.5 %) courses. In 32 (84 %) courses, nephrotoxic medications were concomitantly administered. Two patients had convulsions, probably unrelated to colistin. Seven patients (18 %) died while on colistin therapy. No death was attributed to an adverse effect of colistin.

Conclusions

Treatment with intravenous colistin, with dosage adjusted to renal function, was relatively safe for HM/HSCT patients, even with concomitantly administered nephrotoxic medications. Concern about nephrotoxicity should not justify a delay in initiating empirical colistin treatment in situations where infection with MDR Gram-negative rods is likely.     

Indications and outcomes of reduced-toxicity hematopoietic stem cell transplantation in adult patients with hematological malignancies

Hematopoietic stem cell transplantation (HCT) utilizing non-myeloablative (NMA) and reduced-intensity conditioning (RIC) regimens (collectively referred to as reduced-toxicity HCT, RT-HCT) has become a viable therapeutic option for patients with hematological malignancies who are ineligible for standard myeloablative conditioning transplantation (MA-HCT). RT-HCT has been shown to induce stable engraftment with low toxicity, and to produce similar overall and progression-free survival (PFS) when compared to MA-HCT in acute myeloid leukemia and myelodysplastic syndrome. The best results for RT-HCT have been reported for patients with disease that is in remission, indolent and chemosensitive, and with a strong graft-versus-malignancy effect. Chronic graft-versus-host disease seems to correlate with a lower relapse rate and better PFS. RT-HCT is inferior when performed in poor risk or advanced disease, due to high relapse rates. A search for novel strategies that includes the most appropriate conditioning regimens and post-transplant immunomodulation protocols with more intensive anti-malignancy activity but limited toxicity is in progress. This review provides an update on the results of clinical studies of RT-HCT, and discusses possible indications and investigative strategies for improving the clinical outcomes of RT-HCT for the major hematological malignancies.     

HLA-matched unrelated donor hematopoietic cell transplantation after nonmyeloablative conditioning for patients with hematologic malignancies

A hematopoietic cell transplantation (HCT) approach was developed for elderly or ill patients with hematologic malignancies that employed nonmyeloablative conditioning to avoid common regimen-related toxicities and relied on graft-versus-tumor effects for control of malignancy. Eighty-nine patients, median age 53 years, were given fludarabine (90 mg/m2) and 2 Gy total body irradiation. Marrow (n = 18) or granulocyte colony-stimulating factor (G-CSF)-stimulated peripheral blood mononuclear cells (G-PBMCs; n = 71) were transplanted from unrelated donors matched for human leukocyte antigen A (HLA-A), -B, -C antigens and -DRB1 and -DQB1 alleles. Postgrafting immunosuppression included mycophenolate mofetil and cyclosporine. Donor T-cell chimerism was higher for G-PBMCs compared with marrow recipients. Durable engraftment was observed in 85% of G-PBMCs and 56% of marrow recipients. Cumulative probabilities of grade II, III, and IV acute graft-versus-host disease (GVHD) were 42%, 8%, and 2%, respectively. Nonrelapse mortality at day 100 and at 1 year was 11% and 16%, respectively. One-year overall survivals and progression-free survivals were 52% and 38%, respectively. G-PBMC recipients had improved survival (57% vs 33%) and progression-free survival (44% vs 17%) compared with marrow recipients. HLA-matched unrelated donor HCT after nonmyeloablative conditioning is feasible in patients ineligible for conventional HCT. G-PBMCs conferred higher donor T-cell chimerism, greater durable engraftment, and better progression-free and overall survivals compared with marrow.     

用低强度Bu/Cy预处理方案进行异基因造血干细胞移植治疗恶性血液病的疗效观察

目的探讨使用低强度Bu/Cy预处理方案进行异基因造血干细胞移植治疗恶性血液病的疗效。方法在哈尔滨医科大学附属第二医院采用低强度的Bu/Cy方案,进行异基因造血干细胞移植,治疗5例恶性血液病,预处理方案是:马利兰3~4mg/(kg·d)×3,环磷酰胺50mg/(kg·d)×2,阿糖胞苷2g/(m2·d)×1~2d,移植前7d开始环孢素A(CsA)3mg/(kg·d),霉酚酸酯(MMF)1g/d。结果5例病人均重建造血,未发生预处理相关严重并发症,5例病人已无病存活3~22个月(中位时间10·5个月)。结论低强度的Bu/Cy预处理方案,移植相关毒性减小,该方法治疗恶性血液病是安全可行的。     

Hematopoietic reconstitution on the prognosis of hematological malignancies after allogenceic hematopoietic stem cell transplantation

Objective To analyze the impact of the time to hematopoietic reconstitution on the prognosis of hematological malignancies after allogeneic hematopoietic stem cell transplantation(allo-HSCT) . Methods 173 patients with hematological malignancies treated with allo-HSCT (excluding umbilical cord blood transplantation)     

Secondary malignancies after allogeneic hematopoietic stem cell transplantation using reduced-intensity conditioning and outpatient conduction

Background

Patients given allogeneic hematopoietic stem cell transplants (HSCT) may develop secondary malignant neoplasms (SMN). Several variables have been identified but there are no data about the incidence of this complication in individuals given HSCT using reduced-intensity conditioning (RIC) methods.

Objective

Define the incidence of SMN in patients given HSCT using a RIC preparative regimen conducted on an outpatient basis.

Materials and methods

Patients given HSCT in two institutions between October 1998 and 2012 were analyzed. To appraise the SMN appearance, those patients dead were also regarded as censored at that moment, as well as those lost to follow up and those alive at the closing of the study. 95% Confidence intervals (CI) for the survival or failure estimate were calculated with the Greenwood's method.

Results

A total of 416 allografted patients with a Karnofsky performance index of 100% were included in the study. All patients received peripheral blood stem cells allografts. The conditioning regimen was delivered as an outpatient procedure in all individuals. No patient was given radiotherapy nor antithymocyte globulin during the conditioning. Three hundred and sixty five patients (88%) were never admitted to the hospital, whereas 12% were admitted because of grade III–IV acute graft versus host disease (aGVHD), fever, or mucositis. Median survival time was 15.7 months. Survival at 6 months (95% CI): 66.4% (61.5–70.8%), at 12 months: 53.3% (48.1–58.1%), at 60 months: 30.6% (30.5–41.5%). Eight patients with a SMN were identified in the group of 416 allografted patients, SMN rates (95% CI) were: one year post graft: 1.9% (0.7–4.9%), 5 years: 3.8% (1.6–9.2%), 10 years: 6.8% (2.6–17.7%) and 13 years post-graft: 20.2% (5.5–59.2%), the cumulative probability of SMN being 6.8 at 10 years. Since the number of expected cases in the general population is 0.62, the ratio of observed to expected cases is 12.9 (P < 0.001). This figure means that the risk of developing a malignant neoplasm in allografted individuals using our method is 12.9 times higher than that in the general population. There were three non-Hodgkin's lymphomas, two M2 acute myelogenous leukemias, one hairy cell leukemia, one tongue epidermoid carcinoma, and one breast carcinoma.

Conclusions

We have found a low incidence of SMN in this group of Mexican patients allografted with the Mexican RIC method. Possible explanations for this difference are discussed, focusing on the RIC preparative regimen.     

Secondary malignancies after hematopoietic stem cell transplantation

Advances in the field of hematopoietic stem cell transplantation have led to an increasing number of cures of malignant and non-malignant diseases with this therapeutic approach. Long-term survivorship may, however, be associated with secondary malignancies, the result of a complex interaction of treatment-, recipient- and immunosuppression-related factors. Furthermore, the increasing use of donors other than human leukocyte antigen-identical siblings is associated with more intense immunosuppression, delayed immune recovery and higher incidence of B-cell post-transplantation lymphoproliferative disorders. Here, we review the incidence and the risk factors associated with these complications of hematopoietic stem cell transplants.     

Secondary malignancies after hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation (HSCT) offers patients with malignant and nonmalignant diseases the oportunity to pursue life-prolonging therapy. The number of survivors after successful HSCT is continually increasing. However, HSCT can induce tissue and organ damage that occurs not only "on treatment" , but long after completing therapy. Secondary malignancies belong to serious late complications after HSCT. A significant association of certain risk factors with increased likelihood of secondary malignancies after HSCT has been published over the last ten years. Better knowledge of pathogenesis of these complications, their early identification and treatment may contribute to better health outcomes of allogeneic and autologous hematopoietic stem cell transplantation recipients. We review here the incidence and risk factors of secondary malignancies after hematopoietic stem cell transplantation.     

异基因造血干细胞移植治疗恶性血液病

目的：探讨异基因造血干细胞移植(Allo—HSCT)治疗恶性血液病的疗效、造血重建、免疫重建及长期生存的情况。方法：血液系统恶性疾病患者12例，其中同胞HLA相合异基因骨髓移植(Allo-BMT)及外周血干细胞移植(Allo—PBSCT)7例；无亲缘关系HLA不全相合脐血移植(UCBT)5例。结果：11／12例受者获造血重建，UCBT患者造血重建速度较同胞PBSCT或BMT慢，1例UCBT移植后46d造血功能未重建，回输自体骨髓后恢复自体造血。11例Allo—HSCT受者免疫功能重建开始于移植后30d，死亡2例，均为移植后复发病例。结论：Allo—HSCT是目前治愈恶性血液病的最佳方法，对于无同胞HLA相合的供者，选择较高细胞数量、HLA1～2个位点不合的UCBT仍然安全有效。     

Long-term outcomes after allogeneic stem cell transplantation for children with hematological malignancies

We analyzed long-term outcomes and psycho-social aspects in 112 children with malignancies surviving 1 year after hematopoietic stem cell transplantation. At 10 years, overall survival was 75+/-5%, TRM 18+/-4% and relapse 14+/-3%; 10-year cumulative incidence of infections was 31+/-4%, cataract 44+/-4%, pulmonary dysfunction 20+/-4%, bone and joint complications 29+/-5%, hypothyroidism 36+/-4%, cardiac complications 11+/-3% and secondary malignancies 7+/-3%. Total body irradiation (TBI) was the most significant risk factor associated with cataract, pulmonary impairment, osteoarticular complications and hypothyroidism. Chronic graft-versus-host disease was associated with higher incidence of pulmonary dysfunction. The number of complications per patient increased with time. Half of the patients had psychological disturbance, 13 signs of depression and 16 a history of eating behavior disorders; 54% of patients with one or more long-term complications had psychological problems. Sixty-nine patients had learning difficulties and 36 achieved normal scholarship. With increased follow-up, development of late effects and of psycho-social disturbance are of major concern. While the use of single-dose TBI has now been abandoned, other risk factors are still of concern in the early 2000s.     

Unrelated stem cell transplantation after reduced intensity conditioning for patients with multiple myeloma relapsing after autologous transplantation

From 2002 to 2007, 49 myeloma patients who relapsed following autologous SCT were included in a prospective multicenter trial to determine the efficacy of a reduced melphalan/fludarabine regimen followed by allogeneic SCT from unrelated donors. All patients showed leucocyte and platelet engraftment after a median of 15 and 19 d, respectively. Grade II–IV acute graft- versus -host disease (GvHD) occurred in 25% of patients and 35% had chronic GvHD. Overall response rate at day 100 was 95% including 46% complete remission (CR). Cumulative incidence of non-relapse mortality at 1 year was 25% [95% confidence interval (CI): 13–37%] and was significantly lower for human leucocyte antigen (HLA)-matched compared to -mismatched SCT (10% vs. 53%, P  = 0·001). The cumulative incidence of relapse at 3 years was 55% (95% CI: 40–70%). After a median follow up of 43 months, the estimated 5-year progression-free and overall survival rates were 20% and 26% respectively and were significantly better for matched in CR at day 100 (41% vs. 7%, P  = 0·04 and 56% vs. 16%, P  = 0·02). We conclude that optimal donor selection is mandatory for a low non-relapse mortality and high relapse incidence, which remains a major concern, should be improved by including post-transplant strategies to upgrade remission status.     

Fludarabine with cytarabine followed by reduced-intensity conditioning and allogeneic hematopoietic stem cell transplantation in patients with poor-risk chronic lymphocytic leukemia

Allogeneic stem cell transplantation (SCT) is a treatment option for patients with poor-risk chronic lymphocytic leukemia (CLL). Sequential use of chemotherapy and reduced-intensity conditioning has been proposed to improve the treatment outcomes. Fludarabine (30 mg/m²/day) and cytarabine (2 g/m²/day) for 4 days (combination of fludarabine with cytarabine; FAraC) were used for cytoreduction. After 3 days of rest, reduced intensity conditioning (RIC) was carried out consisting of 4 Gy total body irradiation, 10–20 mg/kg/day antithymocyte globulin for 3 days, and 40–60 mg/kg/day cyclophosphamide for 2 days. The median time of neutrophil engraftment was 16 days. The most frequent toxicities were grades III/IV infections in 12 of 15 cases and gastrointestinal toxicities in 8 of 15 cases. Remission (complete remission?+?partial remission) was achieved in 14 of 15 patients (93 %), minimal residual disease negativity according to flowcytometric analysis was observed in 10 patients. Nonrelapse mortality after 1 and 2 years was 7 and 13 %, respectively. After the median follow-up from SCT of 30 months, 80 % of patients were alive (12/15), three patients have died, and three relapses occurred. The FAraC–RIC protocol seems to be a promising approach to the treatment of poor-risk CLL with a high response rate of 93 % and favorable progression-free survival and overall survival of 70 and 85 % at 2 years after SCT, respectively. Other prospective clinical trials are needed to confirm the results of this novel therapeutic strategy.     

Second allogeneic hematopoietic stem cell transplantation as treatment for leukemia relapsing following a first transplant

We report 27 patients with relapsed acute or chronic leukemia who underwent a second hematopoietic stem cell transplant (HSCT) from a related or unrelated donor. Seventeen patients were diagnosed with acute myelogenous leukemia (AML), six with acute lymphocytic leukemia (ALL) and four with chronic myeloid leukemia (CML). Ages ranged from 22 to 49 years (median 37); 13 patients were female and 14 male. Relapse was diagnosed between 1 and 45 months after the first HSCT. Sixteen patients who relapsed had received an autologous transplant initially and 11 an allogeneic transplant. Ten patients relapsed within 6 months and 17 patients later than 6 months. Chemotherapy was used as reinduction for relapse after HSCT in 16 patients who had received an autologous transplant and in three who had received an allogeneic transplant, since the latter did not respond to reduction of immunosuppression to induce a graft-versus-leukemia (GVL) reaction. Five of these 19 patients (26%) achieved complete remission (CR), seven patients did not respond to chemotherapy and seven achieved a partial remission (PR). The stem cell source for the second HSCT included bone marrow (n = 12) and PBSC (n = 4) from genotypically identical unrelated donors, PBSC (n = 7) and bone marrow (n = 3) from related donors. Currently eight of the 27 patients are alive and disease-free after the second HSCT. One patient is alive and disease-free after two allogeneic transplants (day +1538), eight patients, who relapsed after an autologous transplant followed by an allogeneic transplant (days +248 to +1140), acute myeloid leukaemia (n = 6) and chronic myeloid leukemia (n = 2) are alive and disease-free. The overall disease-free survival is 30% (8/27). The overall disease-free survival of autologous transplant patients subsequently undergoing an allogeneic transplant is 43% (P = 0.049). It is suggested that a second HSCT is possible for patients with leukemia relapse following the first autologous transplant. A second transplant might also be offered to patients relapsing after the first allogeneic HSCT. Bone Marrow Transplantation (2000) 25, 41-45.     

Treosulfan/fludarabine as an allogeneic hematopoietic stem cell transplant conditioning regimen for high-risk patients

In recent years, new conditioning regimens have been explored in patients not eligible for conventional transplant with the aim to reduce transplant-related mortality. In a phase II multicentric prospective trial, we investigated the safety and feasibility of the treosulfan-fludarabine combination prior to allogeneic hematopoietic stem cell transplant in patients with various hematological malignancies not eligible for conventional regimens because of previous intensive treatment, older age, and comorbidities. Forty-six consecutive patients, median age 48 years (range 17-69), were enrolled. Sixteen of them were in complete remission, and 20 had a HSCT comorbidity index > or = 1. Forty-four patients had regular and sustained engraftment, and 39 out of 40 evaluable patients developed complete chimerism. Nonhematological toxicity was limited. Risk of transplant-related mortality was 9% (95% CI, 2-17%) at day +100 and plotted at 15% (95% CI, 7-22%) after 7 months. The estimated overall survival and progression-free survival with a median follow-up of 20 months were 51% and 38%, respectively. The estimated 30 months progression-free survival for patients transplanted in remission was 56%. The treosulfan-fludarabine combination is a reduced-toxicity but myeloablative regimen that can be proposed to patients not fitting criteria for conventional transplant regimens. Longer follow-up and further prospective studies are necessary to evaluate this regimen.     

Treatment of hematological malignancies with allogeneic nonmyeloablative stem cell transplantation: conditioning regimens with fludarabine

Allogeneic stem cell transplantation (alloSCT) is an accepted therapeutic option for various hematological malignancies. For many years, alloSCT was based on the concept that a myeloablative dose of chemoradiotherapy was necessary to allow successful donor stem cell engraftment. These high-dose regimens cause considerable toxicity in graft recipients and even the most intensive conditioning regimens do not reliably eliminate all malignant cells. During the last decade, it became clear that the curative potential of alloSCT was not solely due to the conditioning regimen but also to an immune response of donor cells against the malignancy, termed the graft-versus-leukemia (GVL) effect. The increasing evidence that the GVL effect is essential for the eradication of host tumor cells has led to the development of a new concept in alloSCT: the use of reduced intensity, nonmyeloablative conditioning regimens that allow exploitation of the GVL effect without the toxicity of myeloablative therapy. The purine analog fludarabine is immunosuppressive and has activity against many hematological malignancies. The introduction of nonmyeloablative fludarabine-based conditioning regimens has facilitated alloSCT, while limiting regimen-related morbidity and mortality in patients with susceptible hematological malignancies. This potentially curative approach extends the use of alloSCT to older patients and to those with comorbidities that preclude high-dose chemoradiotherapy. The purpose of this review is to summarize the results obtained with fludarabine-based nonmyeloablative conditioning regimens and alloSCT in patients with malignant hematological disorders.