Reduced-intensity stem cell transplantation from an HLA-identical sibling donor in patients with myeloid malignancies

Reduced intensity conditioning of allogeneic hematopoietic stem cell transplantation for myelodysplastic syndrome and acute myeloid leukemia in patients older than 50 years of age: a systematic review and meta-analysis

PURPOSE

A systematic review and meta-analysis were performed to explore the efficacy and safety of allogeneic hematopoietic stem cell transplantation with a reduced intensity conditioning regimen in elderly patients with myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML).

METHODS

Overall survival (OS) and event-free survival (EFS) were established as the primary endpoints for directly assessing the efficacy, and non-relapse mortality (NRM) for safety. The eligible patients were at or above 50 years of age, and the outcomes of the typical elderly patients (≥60 years) were analyzed individually.

RESULTS

The pooled estimates (95% confidence interval (CI)) for 1-year OS, EFS and NRM were 65 (55-74)  %, 50 (44-55)  % and 26 (21-30)  %, respectively; as for the patients ≥60 years of age, these were 63 (53-72) %, 46 (41-50)  % and 28 (23-32) %, respectively. No significantly statistical difference achieved between MDS and AML patients in 1-year EFS and NRM [relative risk (RR) 0.91, 95% CI 0.80-1.04; P = 0.172 and RR 1.18, 95% CI 0.82-1.69; P = 0.365]. The patients with lower diseases risk had the possibility of higher OS rate at ≥ 3 years than those with higher diseases risk (RR 1.37, 95% CI 0.95-1.97; P = 0.088). The patients had significantly higher 2-year OS and EFS rates in complete remission (CR, CR1 and CR2) at transplantation compared to those with advanced diseases (P < 0.05).

CONCLUSIONS

RIC-alloHSCT is a feasible treatment option for the patients older than 50 year of age with MDS and AML. Advanced diseases status and higher diseases risk may be the poor factors for prognosis.

Comparison of the cytotoxicity of cladribine and clofarabine when combined with fludarabine and busulfan in AML cells: Enhancement of cytotoxicity with epigenetic modulators

Clofarabine (Clo), fludarabine (Flu), and busulfan (Bu) combinations are efficacious in hematopoietic stem cell transplantation for myeloid leukemia. We sought to determine whether the more affordable drug cladribine (Clad) can provide a viable alternative to Clo, with or without panobinostat (Pano) and 5-aza-2'-deoxycytidine (DAC). Both Clad+Flu+Bu and Clo+Flu+Bu combinations showed synergistic cytotoxicity in KBM3/Bu250(6), HL60, and OCI-AML3 cell lines. Cell exposure to these drug combinations resulted in 60%-80% inhibition of proliferation; activation of the ATM pathway; increase in histone modifications; decrease in HDAC3, HDAC4, HDAC5 and SirT7 proteins; decrease in mitochondrial membrane potential; activation of apoptosis and stress signaling pathways; and downregulation of the AKT pathway. These drug combinations activated DNA-damage response and apoptosis in primary cell samples from AML patients. At lower concentrations of Clad/Clo, Flu, and Bu, inclusion of Pano and DAC enhanced cell killing, increased histone modifications and DNA demethylation, and increased the levels of P16/INK4a, P15/INK4b and P21/Waf1/Cip1 proteins. The observed DNA demethylating activity of Clad and Clo may complement DAC activity; increase demethylation of the gene promoters for SFRP1, DKK3, and WIF1; and cause degradation of β-catenin in cells exposed to Clad/Clo+Flu+Bu+DAC+Pano. The overlapping activities of Clad/Clo+Flu+Bu, Pano, and DAC in DNA-damage formation and repair, histone modifications, DNA demethylation, and apoptosis may underlie their synergism. Our results provide a basis for supplanting Clo with Clad and for including epigenetic modifiers in the pre-hematopoietic stem cell transplantation conditioning regimen for myeloid leukemia patients.

Interstrand crosslink inducing agents in pretransplant conditioning therapy for hematologic malignancies

Despite successful molecularly targeted, highly specific, therapies for hematologic malignancies, the DNA interstrand crosslinking agents, which are among the oldest and least specific cytotoxic drugs, still have an important role. This is particularly true in stem cell transplantation, where virtually every patient receives conditioning therapy with a DNA-alkylating agent-based program. However, due to concern about serious additive toxicities with combinations of different alkylating drugs, the last several years have seen nucleoside analogs, whose cytotoxic action follows vastly different molecular pathways, introduced in combination with alkylating agents. The mechanistic differences paired with different metabolic pathways for the respective drugs have clinically translated into increased safety without appreciable loss of antileukemic activity. In this report, we review pre-clinical evidence for synergistic antileukemic activity when nucleoside analog(s) and DNA-alkylating agent(s) are combined in the most appropriate manner(s), without a measurable decrease in clinical efficacy compared with the more established alkylating agent combinations. Data from our own laboratory using combinations of fludarabine, clofarabine, and busulfan as prototype representatives for these respective classes of cytotoxic agents are combined with information from other investigators to explain how the observed molecular events will result in greatly enhanced synergistic cytotoxicity. We further present possible mechanistic pathways for such desirable cytotoxic synergism. Finally, we propose how this information-backed hypothesis can be incorporated in the design of the next generation conditioning therapy programs in stem cell transplantation to optimize antileukemic efficacy while still safeguarding patient safety.

Successful treatment of acute myelogenous leukemia with favorable cytogenetics by reduced-intensity stem cell transplantation

Acute myelogenous leukemia (AML) with favorable cytogenetics responds well to chemotherapy. If the leukemia relapses, allogenic hematopoietic stem transplantation (allo-HSCT) is considered as a treatment option. Since the efficacy of reduced-intensity stem cell transplantation (RIST) for AML with favorable cytogenetics has not been established, we retrospectively analyzed the outcomes of allo-HSCT in AML patients according to cytogenetic risks. The outcome of allo-HSCT for AML patients with favorable cytogenetics seemed to be superior to that for AML patients with intermediate cytogenetics. In AML patients with favorable cytogenetics, the 3-year overall survival (OS) and relapse-free survival (RFS) rates were 88 and 76%, respectively, in the RIST group. Both the 3-year OS and RFS rates were 81% in the conventional stem cell transplantation (CST) group. The outcome of RIST for AML patients with favorable cytogenetics was comparable to that for patients who received CST despite the more advanced age and greater organ dysfunction in RIST group than in CST group. None of the patients died within 90 days after RIST. Moreover, there was no relapse in patients with favorable cytogenetics who were in hematological remission prior to RIST. Thus, RIST for AML patients with favorable cytogenetics in remission is safe and effective.

Reduced-intensity conditioning using fludarabine with either antithymocyte globulin and BU, or low-dose TBI allowing allogeneic hematopoietic SCT

In a single-center study, we analyzed the outcomes of 66 patients with advanced hematological malignancies receiving two reduced-intensity conditioning regimens for allogeneic transplantation: fludarabine and low-dose TBI (flu/TBI, n=25), or fludarabine, antithymocyte globulin and BU (flu/ATG/BU, n=41). The selection criteria were based on the hypothesis that flu/TBI patients were expected to achieve autologous recovery in the event of non-engraftment. Sixty-three patients (95%) engrafted. Regimen-related mortality at day 100 and 1 year was 6 and 15%, respectively. With median follow-up of 50.4 months, survival did not differ by regimen. Multivariate analysis confirmed that the type of regimen did not affect relapse. In patients achieving full donor chimerism by day 30, those conditioned with flu/TBI showed greater overall survival (P=0.02). Engraftment failure occurred in two patients (3%), both of whom received flu/TBI. We conclude that conditioning with flu/TBI or flu/ATG/BU yields comparable survival and remission outcomes. By contrast to our hypothesis, patients receiving flu/TBI who subsequently failed engraftment did not achieve autologous recovery. Yet, rapid attainment of full donor chimerism after flu/TBI is associated with greater survival than after flu/ATG/BU. Further, larger prospective randomized studies are required to define the advantage of one regimen over the other.

TLI and ATG conditioning with low risk of graft-versus-host disease retains antitumor reactions after allogeneic hematopoietic cell transplantation from related and unrelated donors

A hematopoietic cell transplantation regimen was adapted from a preclinical model that used reduced-intensity conditioning (RIC) and protected against graft-versus-host disease (GVHD) by skewing residual host T-cell subsets to favor regulatory natural killer T cells. One hundred eleven patients with lymphoid (64) and myeloid (47) malignancies received RIC using total lymphoid irradiation (TLI) and antithymocyte globulin (ATG) followed by the infusion of granulocyte colony-stimulating factor-mobilized grafts. Included were 34 patients at least 60 years of age, 32 patients at high risk of lymphoma relapse after disease recurrence following prior autologous transplantation, and 51 patients at high risk of developing GVHD due to lack of a fully human leukocyte antigen (HLA)-matched related donor. Durable chimerism was achieved in 97% of patients. Cumulative probabilities of acute GVHD (grades II-IV) were 2 and 10% of patients receiving related and unrelated donor grafts. Nonrelapse mortality (NRM) at 1 year was less than 4%. Cumulative incidence of chronic GVHD was 27%. The 36-month probability of overall and event-free survival was 60% and 40%, respectively. Disease status at start of conditioning and the level of chimerism achieved after transplantation significantly impacted clinical outcome. The high incidence of sustained remission among patients with active disease at time of transplantation suggests retained graft-versus-tumor reactions. Active trial registration currently at clinicaltrials.gov under IDs of NCT00185640 and NCT00186615.

Reduced-intensity conditioning and allogeneic hematopoietic stem cell transplantation for acute myeloid leukemia

Acute myeloid leukemia (AML) is a hematologic malignancy with a peak incidence over the age of 55 years. AML of older patients is less curable with conventional chemotherapy, and, when it relapses, is almost uniformly fatal. Novel treatments hold the promise of improving the results of therapy, but have failed so far to show dramatic change in the prognosis. Allogeneic stem cell transplantation using traditional myeloablative preparative regimens is not easily tolerated by the elderly and/or frailer patient, and may lead to prohibitive treatment-related mortality rates. Most patients treated in the past were younger and devoid of comorbid clinical conditions. Novel reduced-intensity regimens made allogeneic transplants applicable to the elderly, providing the benefit of the graft-versus-leukemia effect to a larger number of patients in need. Here we review the indications for allogeneic transplants in AML and discuss reduced-intensity conditioning regimens.

Reduced intensity conditioning for allogeneic hematopoietic stem cell transplantation in myelodysplastic syndromes and acute myelogenous leukemia

PURPOSE OF REVIEW

The aim of this article is to summarize the outcome in recent studies of patients with acute myelogenous leukemia/myelodysplastic syndromes after reduced intensity conditioning for allogeneic stem cell transplantation.

RECENT FINDINGS

Reduced intensity conditioning has demonstrated the capability to achieve engraftment and to decrease early nonrelapse mortality in older and unfit patients. Most large retrospective studies have demonstrated that reduced intensity conditioning regimens lead to a reduction of nonrelapse mortality in patients with acute myelogenous leukemia and myelodysplastic syndromes, but disease relapse is higher than with standard myeloablative conditioning regimens. Chronic graft-versus-host disease has emerged as one of the more powerful variables reducing relapses and improving overall and disease-free survival. The use of in-vivo T-cell depletion with alemtuzumab or antithymocyte globulin reduces acute graft-versus-host disease but appears to have no impact on survival. Hopefully, a new second generation of reduced intensity conditioning will study new strategies for reducing disease relapse with low nonrelapse mortality.

SUMMARY

Allogeneic stem cell transplantation with reduced intensity conditioning allows many patients considered ineligible for standard myeloablative conditioning to benefit from this therapy. Research must now focus on designing new strategies for reducing the increased risk of disease relapse.

Prospective phase II trial to evaluate the complications and kinetics of chimerism induction following allogeneic hematopoietic stem cell transplantation with fludarabine and busulfan

This prospective trial assessed the safety and efficacy of allogeneic hematopoietic stem cell transplantation from a HLA-matched donor with a reduced-intensity regimen (RIST) consisting of iv fludarabine 30 mg/m(2) for 6 days and oral busulfan 4 mg/kg/day for 2 days in patients older than 50 years with hematological malignancies. Cyclosporine alone or cyclosporine with short-term methotrexate was randomized for graft-versus-host disease prophylaxis. After 30 patients had been enrolled, an interim analysis was performed, and this report focuses on a precise evaluation of the toxicity profile and chimerism kinetics. Sustained engraftment in all patients, no severe regimen-related toxicity (RRT) within 20 days, and no transplant-related mortality through Day 100 were observed. T-cell (CD3+) full-donor (over 90%) chimerism was observed in 22 of the 30 patients, while the remaining eight had mixed-donor chimerism over 77% on Day 90. Thereafter, five subsequently converted to full-donor chimerism without donor lymphocyte infusion by day 120 (n = 4) or Day 180 (n = 1). Two showed persistent mixed chimerism without relapse through Day 180. Grade III-IV acute graft-versus-host disease and extensive chronic graft-versus-host disease occurred in 10% and 73%, respectively. With a median follow-up of 1.5 years, overall survival and disease-free survival at 1 year was 83% and 62%, respectively. Seven patients hematologically relapsed overall, and five of them had myelodysplastic syndrome with poor prognostic factors. In older patients, RIST with fludarabine and busulfan was associated with acceptable toxicities and a satisfactory antileukemia effect, regardless of the early chimerism status.

The Beneficial Effect of Chronic Graft-versus-Host Disease on the Clinical Outcome of Transplantation with Fludarabine/Busulfan-Based Reduced-Intensity Conditioning for Patients with De Novo Myelodysplastic Syndrome

Allogeneic hematopoietic stem cell transplantation following reduced-intensity stem cell transplantation (RIST) has enabled the treatment of older or medically infirm patients with myeloid malignancies; however, determining the value of RIST outcomes for myelodysplastic syndrome (MDS) is difficult because of the heterogeneity of the diseases included in most trials. To define the role of RIST in MDS, we performed RIST for 22 consecutive patients who had de novo MDS as classified by World Health Organization (WHO) criteria and who received an allograft with fludarabine/busulfan (Busulfex) or fludarabine/Busulfex/antithymocyte globulin (ATG) conditioning. Nineteen patients (86.4%) achieved engraftment. At a median follow-up of 18.9 months (range, 13.1-24.8 months), the estimated 2-year rates of overall survival, event-free survival (EFS), transplantation-related mortality, and relapse were 78.7%, 67.7%, 12.6%, and 22.5%, respectively. Acute graft-versus-host disease (GVHD) greater than grade II developed in 3 patients (15.8%). Chronic GVHD developed in 10 patients (55.6%), none of whom received ATG as a conditioning regimen. Variables influencing EFS were chronic GVHD, marrow blasts before transplantation, and the WHO criteria. The present study clarifies the benefits of the fludarabine/Busulfex-based conditioning regimen for de novo MDS diagnosed according to the WHO criteria and shows that chronic GVHD appears to have a beneficial effect on survival rates, which are strongly associated with graft-versus-tumor effects.

Performance status and comorbidity predict transplant-related mortality after allogeneic hematopoietic cell transplantation

Comorbidity measurements have recently been used to improve estimation of tolerance to allogeneic hematopoietic cell transplantation (HCT). We sought to determine the independent effect of comorbidity and performance status on HCT outcome and to devise a simple risk classification system for transplant-related mortality. We analyzed 105 consecutively enrolled patients who underwent HCT and received reduced intensity conditioning with fludarabine, melphalan, and alemtuzumab. Comorbid conditions were tabulated using 2 scales, the Charlson Comorbidity Index (CCI) and the Kaplan-Feinstein Scale (KFS). Comorbid conditions were found in 47% of patients by the KFS and in 27% by the CCI (P < .001). Using the Eastern Cooperative Oncology Group Performance Status (PS) scale, 34% had a PS score >0 (range, 0-2). A simple scale combining the KFS and PS enabled separation of high- from low-risk patients, with 6-month cumulative incidences 50% and 15%, respectively for transplant-related mortality (P = .001) and enhanced prognostic power over the CCI alone (P = .018). Prospective studies evaluating more comprehensive functional and comorbidity measurements are warranted.

Reduced intensity conditioning (RIC) haematopoietic cell transplants in elderly patients with AML

Reduced intensity conditioning (RIC) transplants were first developed almost a decade ago to reduce the transplant-related mortality (TRM) of allogeneic haematopoietic cell transplantation (HCT) and to make the graft-versus-leukaemia effect accessible to patients otherwise ineligible for HCT. Acute myelogenous leukaemia (AML) in elderly patients is now a frequent indication for RIC-HCT. The major reasons for these rapid developments have been on the one hand the high median age of patients with AML coupled with the unsatisfactory results with conventional chemotherapy, and on the other hand with the promising results already reported for RIC-HCT. Using RIC-HCT, overall survival rates at 2 years of 45-50% have been observed in patients with AML. This compares favourably with overall survival rates of 10-15% under chemotherapy in AML CR1, or no long-term survivors in patients >CR2. From the available data we conclude that RIC-HCT is a promising treatment for elderly patients with AML. However, phase-III studies with unrelated donors will have to be done in order to formally prove its superiority in comparison to conventional chemotherapy.

Reduced-intensity conditioning for acute myeloid leukemia: is this strategy correct

Allogeneic stem cell transplantation for acute myeloid leukemia (AML) using reduced-intensity conditioning (RIC) is based on the strategy of attaining donor cell engraftment with immunosuppressive agents. This approach, which relies predominantly on donor effector cells for anti-leukemic or graft-versus-leukemia effect, is being used with increased frequency. Treatment-related mortality appears less with RIC than that observed with conventional myeloablative regimens. Available data support the fact that a myeloablative regimen is not required for successful engraftment and some patients appear to be cured of their disease. Despite the plethora of clinical reports, however, no prospective studies have been conducted that establish this procedure as the preferred option in AML. On the other hand, patients formerly excluded from a myeloablative procedure such as the 'elderly' and those with significant comorbid conditions, often may be RIC transplant candidates. By using prospective controlled clinical trials, we will determine whether these encouraging RIC data are applicable to a nonselect population of AML. The transplant community now is poised to design and complete investigations to ascertain the true role of RIC in the treatment of AML.

Myeloablative conditioning is well tolerated by older patients receiving T-cell-depleted grafts

Older age has been linked to increased transplant-related mortality from graft-versus-host disease (GvHD). Depletion of T cells from stem cell grafts seems to protect from complications of GvHD particularly in older patients. After myeloablative conditioning, patients with haematological malignancies received allogeneic grafts from HLA identical siblings. For GvHD prophylaxis, PBPC grafts were treated ex vivo with anti-CD52, and therapeutic doses of cyclosporin until day +90. Survival of patients younger or older than the population age median was analysed. In all, 62 consecutive patients with a median age of 42.5 years were studied. Death was procedure related in 17% and from relapse of malignancy in five. At a median, follow-up is 662 (7-2316) days, 74% survive disease free. The rate of haematopoietic recovery and treatment-related mortality was similar in both groups. A total of 73% of 30 individuals in the younger group and 75% (P=0.8) in the older cohort survive at a median follow-up of 444 and 806 days (P=0.4). GvHD occurred in 13% and was the only adverse factor for survival (P<0.04). Myeloablative conditioning is well tolerated up to the age of 59 in patients receiving T-cell-depleted grafts. This information is useful to more precisely select patients who would benefit most from reduced intensity conditioning schedules.

Nonmyeloablative Stem Cell Transplantation for Myelodysplastic Syndrome or Acute Myeloid Leukemia in Patients 60 Years or Older

We analyzed the outcomes of 24 consecutive patients aged >or=60 years with poor-prognosis myelodysplastic syndrome or acute myeloid leukemia undergoing transplantation with nonmyeloablative conditioning using fludarabine (125 mg/m2) and low-dose total body irradiation (2 Gy) followed by allogeneic peripheral blood stem cell grafts from HLA-identical sibling donors. Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporine and mycophenolate mofetil. The median age of the patients was 64 years (range, 60-71 years). In addition to age, 88% of patients had 1 or more adverse biological features of the disease. With a median follow-up of 21 months, 12 patients are alive, 11 of whom are disease free. The probabilities of 2-year overall and progression-free survival were 52% and 44%, respectively. The cumulative probabilities of relapse and of acute and chronic GVHD were 27%, 45%, and 74%, respectively. Nonrelapse mortality at 100 days and 2 years was 8% and 25%, respectively. Of the 15 patients with extensive chronic GVHD, 1 patient relapsed. These data suggest that nonmyeloablative stem cell transplantation is a feasible treatment option in patients aged >or=60 years with poor-prognosis myelodysplastic syndrome or acute myeloid leukemia. The reasonable disease control with nonmyeloablative transplantation in this high-risk group of patients merits further investigation.

Reduced-intensity allogeneic hematopoietic stem cell transplantation for acute leukemias: ‘what is the best recipe?’

Reduced-intensity stem cell transplantation (RIST) has been shown to be a safe and useful alternative transplant method for patients including elderly and medically unfit patients. RIST conditioning regimens vary widely in the intensity of myeloablation, immunoablation, and antileukemia effects, and thus optimal regimen for each disease entity is yet to be determined. Most reports on RIST to date are small, single-institution experiences or retrospective studies with heterogeneous patient populations and primary diseases, complicating any direct comparison between studies. In acute myeloid leukemia (AML), moderate-intensity regimens may be effective, achieving 30-70% 1-year disease-free survival in various series, but minimal-intensity regimens are associated with high relapse rates. In acute lymphoblastic leukemia (ALL), not even moderate-intensity regimens are effective and most patients with advanced ALL relapse post transplant. Thus, the risk/benefit ratios of graft-versus-host disease/graft-versus-leukemia effect differ among diseases. Larger, prospective, multi-center clinical trials are needed to determine the best use of RIST in hematologic malignancies.

Reduced-intensity hematopoietic stem-cell transplantation for malignant lymphoma: a retrospective survey of 112 adult patients in Japan

We conducted a nation-wide survey of 112 adult Japanese patients who underwent reduced-intensity stem cell transplantation (RIST) from 1999 to 2002. Underlying diseases included indolent (n=45), aggressive (n=58) and highly aggressive lymphomas (n=9). Median age of the patients was 49 years. A total of 40 patients (36%) had relapsed diseases after autologous stem cell transplantation and 36 patients (32%) had received radiotherapy. RIST regimens were fludarabine-based (n=95), low-dose total body irradiation-based (n=6) and others (n=11). Cumulative incidences of grade II-IV acute graft-versus-host disease (GVHD) and chronic GVHD were, respectively, 49 and 59%. Cumulative incidences of progression and progression-free mortality were 18 and 25%, respectively. With a median follow-up of 23.9 months, 3-year overall survival rates were 59%. A multivariate analysis identified three significant factors for progression, which are history of radiation (relative risk (RR) 3.45, confidential interval (CI) 1.12-10.0, P=0.03), central nervous system involvement (RR 6.25, CI 2.08-20.0, P=0.001) and development of GVHD (RR 0.28, CI 0.090-0.86, P=0.026). RIST may have decreased the rate of transplant-related mortality, and GVHD may have induced a graft-versus-lymphoma effect. However, whether or not these potential benefits can be directly translated into improved patient survival should be evaluated in further studies.

Outcomes of patients with acute leukaemia who relapsed after reduced-intensity stem cell transplantation from HLA-identical or one antigen-mismatched related donors

The characteristics of relapse following reduced-intensity stem-cell transplantation (RIST) remain to be clarified. We reviewed the medical records of 19 patients with acute leukaemia [acute myeloid leukaemia (AML), 16; acute lymphoblastic leukaemia (ALL), 3] who relapsed after RIST from related donors using purine-analogue-based regimens. Their median age was 55 years (range, 29-65 years). Median interval between RIST and relapse was 4.9 months (range, 1.8-24.9 months). Three chose not to receive interventions. The remaining 16 patients received withdrawal of immunosuppression (n = 3), chemotherapy (n = 2), donor lymphocyte infusion (n = 10) and second transplantation (n = 7), alone (n = 9) or in combination (n = 7). Four are alive with a median follow-up of 27.6 months (range, 16.0-28.9 months); three in remission and one in relapse. The 2-year overall survival after relapse was 28.9%. Causes of death in 15 patients included progressive disease (n = 7), graft-versus-host disease (n = 5) and infections (n = 3). Cumulative incidences of relapse-related and non-relapse-related deaths at 2 years after relapse were 37% and 32% respectively. Two prognostic factors were identified on univariate analysis: age [P = 0.017; hazard ratio (HR), 1.16; 95% confidence interval (CI), 1.03-1.32], and ALL as underlying disease (P = 0.011; HR, 10.4; 95% CI, 1.73-62.4). Some AML patients who relapse after RIST achieve durable remission with allogeneic immunotherapy-based interventions; however they carry a significant risk of non-relapse mortality.