Nonmyeloablative stem cell transplantation in adults with high-risk ALL may be effective in early but not in advanced disease

Diagnostic and treatment of adult Philadelphia chromosome-positive acute lymphoblastic leukemia

The outcome of adult patients with Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) has improved substantially with the introduction of tyrosine kinase inhibitors (TKIs). TKIs are now integral components of therapy for Ph+ ALL. The current consensus is that they improve patient outcomes compared with historical control patients treated with chemotherapy alone, and increase the number of patients able to receive stem cell transplant. New challenges have emerged with respect to induction of resistance mainly via Abelson tyrosine kinase mutations. Several novel kinase inhibitors with significantly more potent antileukemic activity are currently being developed. Furthermore novel immune therapies, which recruit or modify patient's own T cells to fight leukemic cells, are being developed and could find an important place in Ph+ ALL therapy by few years. In this article, we reviewed treatment approaches in adults with Ph+ ALL with a focus on TKIs and combined chemotherapy regimens.

Treatment of Philadelphia chromosome-positive acute lymphoblastic leukemia in adults: a broader range of options, improved outcomes, and more therapeutic dilemmas

The article addresses selected key areas of flux in the management of Philadelphia chromosome-positive acute lymphoblastic leukemia. There is no doubt that tyrosine kinase inhibitors (TKIs) have made a major contribution to higher rates of complete remission and that more patients are now surviving long term. Many patients tolerate TKIs well, and remission can be achieved with minimal toxicity. Because remissions can include a proportion of patients who become BCR-ABL1 transcript negative, the question of whether allogeneic hematopoietic stem cell transplantation can be avoided requires discussion. Despite the major progress that has been made and the relative profusion of therapeutic choice compared with 10 years ago, evidence is still lacking for many of the major possible interventions, and how to combine them is unclear. Because of the rarity of the condition and the enticing possibility of increasing traction to therapy, clinical trials and international cooperation remain paramount.

Pushing the envelope-nonmyeloablative and reduced intensity preparative regimens for allogeneic hematopoietic transplantation

Allogeneic hematopoietic cell transplantation (HCT) was originally developed to allow delivery of myeloablative doses of chemotherapy and radiotherapy. With better understanding of disease pathophysiology, the graft vs malignancy (GVM) effect of allogeneic hematopoietic transplantation and toxicities associated with myeloablative conditioning (MAC) regimens, the focus shifted to developing less toxic conditioning regimens to reduce treatment-related morbidity without compromising survival. Although HCT with MAC is preferred to reduced intensity conditioning (RIC) for most patients ⩽60 years with AML/myelodysplastic syndrome and ALL, RIC and nonmyeloablative (NMA) regimens allow HCT for many otherwise ineligible patients. Reduced intensity preparative regimens have produced high rates of PFS for diagnoses, which are highly sensitive to GVM. Relapse of the malignancy is the major cause of treatment failure with RIC/NMA HCT. Incorporation of novel agents like bortezomib or lenalidomide, addition of cellular immunotherapy and use of targeted radiation therapies could further improve outcome. In this review, we discuss commonly used RIC/NMA regimens and promising novel regimens.

Reduced-toxicity myeloablative conditioning consisting of 8-Gy total body irradiation, cyclophosphamide and fludarabine for pediatric hematological malignancies

Conventional myeloablative conditioning (MAC) regimens often cause severe regimen-related toxicity (RRT). Furthermore, many patients suffer from poor quality of life in accordance with the increase in long-term survivors. We therefore devised a reduced-toxicity myeloablative conditioning (RTMAC) regimen consisting of 8-Gy total body irradiation (TBI), fludarabine (FLU) and cyclophosphamide (CY) for pediatric hematological malignancies. A retrospective single-center analysis was performed on patients with leukemia or myelodysplastic syndrome (MDS), aged ≤20 years, who had received an 8-Gy TBI/FLU/CY RTMAC regimen followed by allogeneic hematopoietic stem cell transplantation (allo-HSCT). Thirty-one patients underwent first allo-HSCT after an RTMAC regimen. The diagnoses were acute lymphoblastic leukemia (n = 11), acute myeloid leukemia (n = 13), MDS (n = 4), juvenile myelomonocytic leukemia (n = 1) and acute leukemias of ambiguous lineage (n = 2). While 3 patients showed early hematological relapse, the remaining 28 patients achieved engraftments. None of the patients developed grade 4 or 5 toxicities during the study period. The 5-year overall survival and relapse-free survival were 80% [95% confidence interval: CI, 61-91%] and 71% [95% CI, 52-84%], respectively. Our RTMAC regimen would be less toxic and offers a high probability of survival for children with hematological malignancies.

Role of allogeneic hematopoietic stem cell transplantation in adult patients with acute lymphoblastic leukemia

Adult acute lymphoblastic leukemia (ALL) is a heterogeneous disease, due to the expression of different biological and clinical risk factors, for which allogeneic stem cell transplantation (alloHSCT) is an effective consolidation therapy. The non-relapse mortality of alloHSCT remains significantly higher compared with that of conventional chemotherapy. Therefore, one of the main challenges in the care of ALL is to establish a more precise prognostic definition to select patients who could take advantage from an alloHSCT. Currently, the use of minimal residual disease following induction and early consolidation therapy has improved the prognostic accuracy in defining ALL risk class. In Philadelphia-positive ALL, the introduction of tyrosine kinase inhibitors pre and post alloHSCT appears to improve outcomes significantly and, in the absence of specially designed clinical trials, alloHSCT remains the most effective post-remission therapy. Nowadays, alloHSCT can be performed according to various modalities encompassing the use of different conditioning regimens, as well as distinct donors and stem cell source, with a significant accessibility to transplant.

Treatment of Philadelphia-positive acute lymphoid leukemia

SUMMARY Philadelphia-positive (Ph+) acute lymphoblastic leukemia (ALL) represents approximately 15–30% of ALL in adults and is characterized by the expression of the fusion protein BCR–ABL with oncogenic activity. Remission and survival rates were lower whereas relapse risk was increased in Ph+ compared with Philadelphia-negative ALL, until remarkable improvements in the management of Ph+ ALL were achieved through the introduction of tyrosine kinase inhibitors that reduce the activity of the BCR–ABL protein. However, in patients achieving complete remission, allogeneic hematopoietic stem cell transplantation is in most cases a mandatory therapeutic step because rate of relapses are still high. This review will illustrate the current therapeutic options for the management of Ph+ ALL and indicate how better curative options may stem from appropriate implementation of tyrosine kinase inhibitors and novel antitumoral agents.

Fludarabine and cyclophosphamide provides a nonmyeloablative alternative conditioning regimen with low transplant-related mortality and control of high risk disease

Non-myeloablative allogeneic transplant (NMAT) has a curative potential for patients who are not myeloablative allogeneic transplant (MAT) candidates. We report a phase II trial of a NMAT regimen with cyclophosphamide and fludarabine in 40 patients; 21 of whom had a prior MAT. Day +100 and 1-year transplant-related mortality (TRM) post-NMAT were 13% and 34%, respectively. Day +100 and 1-year Overall/Progression-Free Survival (OS/PFS) were 80%/65% and 43%/25%, respectively. OS was higher in patients with KPS≥90 and lower in recipient/donor CMV+/− vs. other combinations. FluCy has low TRM and is curative in about 20% of high-risk patients.

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We report a phase II trial of a NMAT regimen with cyclophosphamide and fludarabine in 40 patients.

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Transplant related mortality was low at Day+100 and 1-year.

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Fludarabine and cyclophosphamide as NMAT is curative in about 1/5 high risk patients.

Comparable long-term outcomes after reduced-intensity conditioning versus myeloablative conditioning allogeneic stem cell transplantation for adult high-risk acute lymphoblastic leukemia in complete remission

The role of reduced-intensity conditioning (RIC) in adult acute lymphoblastic leukemia (ALL) remains unclear because of the small sample size, short follow-up duration, various regimens for conditioning and graft-versus-host disease (GVHD) prophylaxis, and the heterogeneity of selection criteria for transplantation. We compared long-term outcomes of 60 consecutive RIC transplants (fludarabine plus melphalan) with 120 myeloablative conditioning (MAC) transplants (total body irradiation plus cyclophosphamide) for adult high-risk ALL in first or second complete remission. All transplants received a uniform strategy of pretransplant chemotherapy and GVHD prophylaxis. Compared to MAC transplants, RIC transplants had older age (46 years vs. 33 years, P < 0.001) and higher proportions of transplantation using peripheral blood (93.3% vs. 13.3%; P < 0.001) but otherwise showed similar characteristics. After a median follow-up of 67 months, RIC transplants showed comparable nonrelapse mortality (21.2% vs. 24.3%) and disease-free survival (50.8% vs. 54.9%) to MAC transplants, although relapse risk was higher (34.2% vs. 26.4%; HR, 2.07; P = 0.019) in multivariate analysis. Other independent factors associated with better outcomes were the presence of chronic GVHD and transplantation in first complete remission. Interestingly, the negative impact of RIC on relapse risk was seen only for Philadelphia-positive ALL transplants (32.7% vs. 19.6%; HR, 3.46; P = 0.020), while no difference was found between RIC and MAC for Philadelphia-negative ALL transplants (35.0% vs. 32.1%; HR, 1.39; P = 0.429). RIC can be considered as a reasonable choice for providing a sufficient long-term graft-versus-leukemia effect for adult high-risk ALL patients ineligible for MAC.

How I treat older patients with ALL

The treatment of older patients with acute lymphoblastic leukemia (ALL) is an unmet medical need. In Western countries, the population is aging, which means there will be an increasing number of older patients. However, in the past few decades, there has been little improvement in treating them, and few clinical trials specifically designed for older patients with ALL have been reported. Older patients with ALL have a significantly lower complete response rate, higher early mortality, higher relapse rate, and poorer survival compared with younger patients. This is partly explained by a higher incidence of poor prognostic factors. Most importantly, intensive chemotherapy with or without stem cell transplantation, both of which are successful in younger patients, is less well tolerated in older patients. For the future, the most promising approaches are optimized supportive care, targeted therapies, moderately intensified consolidation, and reduced-intensity stem cell transplantation. One of the most important challenges for physicians is to differentiate between fit and unfit older patients in order to offer both groups optimal treatment regarding toxicity and mortality risks, quality of life, and long-term outcome. Prospective trials for older patients with ALL are urgently needed.

Promising role of reduced-toxicity hematopoietic stem cell transplantation (PART-I)

Allogeneic hematopoietic stem cell transplantation (HSCT) remains a potential curative option for many patients with hematological malignancies (HM). However, the high rate of transplantation-related mortality (TRM) restricted the use of standard myeloablative HSCT to a minority of young and fit patients. Over the past few years, it has become evident that the alloreactivity of the immunocompetent donor cells mediated anti-malignancy effects independent of the action of high dose chemoradiotherapy. The use of reduced intensity conditioning (RIC) regimens has allowed a graft-versus-malignancy (GvM) effect to be exploited in patients who were previously ineligible for HSCT on the grounds of age and comorbidity. Retrospective analysis showed that RIC has been associated with lower TRM but a higher relapse rate leading to similar intermediate term overall and progression-free survivals when compared to standard myeloablative HSCT. However, the long term antitumor effect of this approach is less well established. Prospective studies are ongoing to define which patients might most benefit from reduced toxicity stem cell transplant (RT-SCT) and which transplant protocols are suitable for the different types of HM. The advent of RT-SCT permits the delivery of a potentially curative GvM effect to the majority of patients with HM whose outcome with conventional chemotherapy would be dismal. Remaining challenges include development of effective strategies to reduce relapse rates by augmenting GvM effects without increasing toxicity.

Criteria for and outcomes of allogeneic haematopoietic stem cell transplant in children, adolescents and young adults with acute lymphoblastic leukaemia in first complete remission

Most children, adolescents and young adults with acute lymphoblastic leukaemia (ALL) in first complete remission (CR1) have an excellent prognosis with multi-agent chemotherapy in induction, consolidation, re-induction and maintenance therapy. However, there is a subset of patients with a more guarded prognosis using this approach, who may benefit from haematopoietic allogeneic stem cell transplantation (alloHSCT). Commonly used criteria for alloHSCT in children, adolescents and young adults with ALL in CR1 include: induction failure, poor cytogenetics, persistent minimal residual disease (MRD), age, immunophenotype, white blood cell count at diagnosis and rapidity of induction response. Two-year event-free survival following alloHSCT in patients with ALL in CR1 ranges from 50 to 80% depending on disease status, donor source, conditioning therapy, age and other risk factors. Future studies should focus on more precisely identifying poor-risk features, such as disease genomics and host pharmacogenomics, refining MRD measurements, improving unrelated donor matching, reducing MRD prior to alloHSCT, and developing post-alloHSCT humoral and cellular therapy approaches.

Evidence for a GVL effect following reduced-intensity allo-SCT in ALL: a British Society of Blood and Marrow Transplantation study

Myeloablative allo-SCT decreases relapse incidence (RI) in ALL. Reduced intensity conditioning (RIC) may extend allo-SCT to older and less fit patients. Sixty-nine ALL patients reported to the BSBMT underwent fludarabine-based RIC allo-SCT, 38 from unrelated donors (UD). Forty-four patients received alemtuzumab. ALL was in CR in 64 patients (93%). This was a second or third SCT in 23 patients. Two-year OS and PFS were 36% and 32%, respectively. In multivariate analysis male recipients demonstrated better OS and PFS (hazard ratio (HR) = 0.42, P = 0.008 and HR = 0.45, P = 0.012, respectively). Two-year TRM was 29%: higher with younger age (HR = 0.97/year, P = 0.041), female recipient (HR = 2.55, P = 0.049) and increasing grade of acute GVHD (HR = 1.87, P = 0.001). Two-year RI was 38% and was lower in patients with acute and chronic GVHD (HR = 0.62 per increasing grade, P = 0.035 and HR = 0.52, P = 0.025, respectively). Long-term ALL-free survival is achievable following fludarabine-based RIC allo-SCT. The association between GVHD and decreased RI suggests the presence of a GVL effect.

Philadelphia-positive acute lymphoblastic leukemia: current treatment options

The Philadelphia chromosome (Ph), t(9;22), is seen in about 20 % to 30 % of adults diagnosed with acute lymphoblastic leukemia (ALL). It has been associated with poorer prognosis compared with Ph-negative ALL. Tyrosine kinase inhibitors (TKIs) targeting the BCR-ABL oncogenic protein from this translocation have been incorporated into treatment regimens used to treat patients with Ph-positive ALL. Imatinib has been the most widely used TKI with several published trials showing it produced better outcomes when combined with chemotherapy. Dasatinib, a more potent inhibitor than imatinib, has also been evaluated with promising results. However, relapses still occur at a high rate, and allogeneic stem cell transplant is considered, so far, a better curative option in first remission. Additional strategies have also included incorporation of TKIs in the post-transplant setting and the use of newer third generation TKIs. This review provides an update on emerging therapies for adults with Ph-positive ALL.

Optimal approach to treatment of patients with Philadelphia chromosome-positive acute lymphoblastic leukemia: how to best use all the available tools

Approximately 20% of adult and 50% of elderly patients with acute lymphoblastic leukemia (ALL) express the t(9;22) chromosome translocation with BCR-ABL rearrangement. The use of tyrosine kinase inhibitors (TKIs) has resulted in higher rates of complete remission (95-100%), and many fit patients are able to receive allogeneic hematopoietic stem cell transplant (HSCT). TKI-containing induction followed by myeloablative allogeneic HSCT has resulted in long-term survival between 50 and 60% in young adults, and recent reports show promising results in patients submitted to non-myeloablative HSCT. The prognosis of elderly patients with Philadelphia chromosome-positive (Ph+) ALL is poor despite a high complete remission (CR) rate with TKIs and minimal chemotherapy, and improvements are clearly needed in this subgroup of patients. This review summarizes and discusses current challenges in the treatment of patients with Ph+ ALL, such as selection of the appropriate induction therapy, minimization of transplant toxicity, correct use of TKIs after transplant, BCR-ABL monitoring, the study of mutations which confer resistance to TKIs and new drugs to overcome this resistance.

The role of allogeneic hematopoietic stem cell transplantation in the therapy of patients with acute lymphoblastic leukemia

Allogeneic hematopoietic stem cell transplantation (alloHSCT) is an effective post-remission therapy in patients with acute lymphoblastic leukemia (ALL), but is associated with significant toxicity, so the optimal timing and use of this modality remains an issue of debate. Increased advances in reduced-intensity transplant preparative regimens and alternative donors has increased the accessibility of allogeneic transplantation. A risk adapted paradigm, using minimal residual disease analysis, may help in the selection of patients at highest risk for relapse, who may benefit most from alloHSCT. In this review, we summarize the indications for allogeneic transplantation within the risk-oriented paradigm, and also explore the latest literature on reduced intensity transplant regimens, as well as alternative donor transplantation for patients with ALL.

Cellular therapies in acute lymphoblastic leukemia

ALL remains a difficult disease to treat. In the adult setting, most patients will ultimately die of their disease, whereas in the pediatric setting, relapsed and refractory disease remains a therapeutic challenge. Cellular therapy through allo-HSCT remains an option for these patients, and recent advances in alternative forms of allo-HSCT, including unrelated donor transplants, UCB transplants, and haploidentical transplants, have expanded the numbers of patients eligible for allo-HSCT but have not improved outcomes when compared with HLA-matched related allo-HSCTs. In light of this persistent failure, several novel adoptive cellular approaches are being investigated to treat patients with ALL. The use of enriched WT-1–specific donor T cells to treat patients with ALL is currently under investigation in phase I trials at several centers. Treatment of ALL with genetically modified T cells targeted to the CD19 antigen through the expression of a CD19-specific CAR also have entered phase I clinical trials at several centers. Similarly, a clinical trial treating patients with ALL with genetically modified NK cells targeted to the CD19 antigen has recently opened for accrual. Collectively, these ongoing and anticipated trials provide a promising role for adoptive cellular therapies in the treatment of ALL. What remains to be seen is whether this promise will either translate into improved outcomes for these patients or provide significant insights on which to design second-generation adoptive cell therapeutic clinical trials for ALL in the future.

Current Treatment of Philadelphia Chromosome–Positive Acute Lymphoblastic Leukemia

The author discusses both the standards of care and more controversial areas in the treatment of Philadelphia chromosome–positive acute lymphoblastic leukemia.

Current Treatment of Philadelphia Chromosome–Positive Acute Lymphoblastic Leukemia

The author discusses both the standards of care and more controversial areas in the treatment of Philadelphia chromosome–positive acute lymphoblastic leukemia.

Cancer immunotherapy

Cancer immunotherapy consists of approaches that modify the host immune system, and/or the utilization of components of the immune system, as cancer treatment. During the past 25 years, 17 immunologic products have received regulatory approval based on anticancer activity as single agents and/or in combination with chemotherapy. These include the nonspecific immune stimulants BCG and levamisole; the cytokines interferon-α and interleukin-2; the monoclonal antibodies rituximab, ofatumumab, alemtuzumab, trastuzumab, bevacizumab, cetuximab, and panitumumab; the radiolabeled antibodies Y-90 ibritumomab tiuxetan and I-131 tositumomab; the immunotoxins denileukin diftitox and gemtuzumab ozogamicin; nonmyeloablative allogeneic transplants with donor lymphocyte infusions; and the anti-prostate cancer cell-based therapy sipuleucel-T. All but two of these products are still regularly used to treat various B- and T-cell malignancies, and numerous solid tumors, including breast, lung, colorectal, prostate, melanoma, kidney, glioblastoma, bladder, and head and neck. Positive randomized trials have recently been reported for idiotype vaccines in lymphoma and a peptide vaccine in melanoma. The anti-CTLA-4 monoclonal antibody ipilumumab, which blocks regulatory T-cells, is expected to receive regulatory approval in the near future, based on a randomized trial in melanoma. As the fourth modality of cancer treatment, biotherapy/immunotherapy is an increasingly important component of the anticancer armamentarium.

How I treat Philadelphia chromosome–positive acute lymphoblastic leukemia

The Philadelphia chromosome is present in approximately 20% to 30% of adults with acute lymphoblastic leukemia (ALL). The poor prognosis of this relatively uncommon acute leukemia has led to the rapid adoption of treatment strategies such as unrelated donor hematopoietic stem cell transplant and tyrosine kinase inhibitors into clinical practice, despite a relative paucity of randomized clinical trials. Recently, there has been a surge of interest in the underlying biology of ALL. In combination with an accumulation of more mature clinical study data in Philadelphia-positive ALL, it is increasingly possible to make more rational and informed treatment choices for patients of all ages. In this article, I review available data and indicate how I personally interpret current evidence to make pragmatic treatment choices with my patients, outside of clinical trials. My strongest recommendation is that all physicians who are treating this rare disease actively seek appropriate clinical trials for their patients wherever possible.

Allogeneic hematopoietic stem cell transplantation for adult acute lymphocytic leukemia

Allogeneic hematopoietic stem cell transplantation (alloHCT) is the single most potent treatment modality to prevent relapse in adults with acute lymphocytic leukemia, but its optimal use and timing remains a matter of intense debate and research. There is general agreement that patients with clinical features of high risk for relapse should undergo alloHCT in first complete remission. However, newer studies suggest that even patients without these risk factors may benefit. Monitoring of minimal residual disease may improve risk stratification and may complement or replace conventional risk features. Prognosis in relapsed and refractory patients is dismal, and alloHCT should be performed as soon as possible. AlloHCT also offers the only reasonable chance for cure in Philadelphia chromosome-positive acute lymphocytic leukemia; the role of imatinib is not yet clearly defined. Recent developments in unrelated-donor transplantation and reduced-intensity conditioning allow the beneficial effects of alloHCT to reach a considerably wider patient population.

Allogeneic hematopoietic cell transplantation: the state of the art

Allogeneic hematopoietic cell transplantation (HCT) is a potentially curative procedure for a variety of hematologic malignancies. The field has evolved substantially over the past decade, with advances in patient and donor selection, stem cell sources, supportive care, prevention of complications and reduced-toxicity preparative regimens. As a result, the indications for HCT and the pool of eligible patients have expanded significantly. In this article, we provide an overview of the major aspects of allogeneic HCT, and focus specifically on areas of active research and on novel approaches to challenges in the field. Specifically, we will discuss approaches to reduce the toxicity of the preparative regimen, with the goal of increasing the safety and applicability of HCT. The availability of suitable donors may be an obstacle to wider application of HCT. We review three major approaches to broadening the donor pool: the use of HLA-mismatched unrelated donors, umbilical cord blood and HLA-haploidentical family donors. Graft-versus-host disease remains a major cause of morbidity and mortality after HCT. We review recent advances in the understanding of this phenomenon, and novel prophylactic and therapeutic approaches that hold the promise of further improving the safety of the procedure. We conclude with a speculative outline of the next 5 years of research in the field of HCT.

NCI First International Workshop on the Biology, Prevention, and Treatment of Relapse after Allogeneic Hematopoietic Stem Cell Transplantation: report from the Committee on the Epidemiology and Natural History of Relapse following Allogeneic Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (alloHSCT) is increasingly being used for treatment of hematologic malignancies, and the immunologic graft-versus-tumor effect (GVT) provides its therapeutic effectiveness. Disease relapse remains a cause of treatment failure in a significant proportion of patients undergoing alloHSCT without improvements over the last 2-3 decades. We summarize here current data and outline future research regarding the epidemiology, risk factors, and outcomes of relapse after alloHSCT. Although some factors (eg, disease status at alloHSCT or graft-versus-host disease [GVHD] effects) are common, other disease-specific factors may be unique. The impact of reduced-intensity regimens on relapse and survival still need to be assessed using contemporary supportive care and comparable patient populations. The outcome of patients relapsing after an alloHSCT generally remains poor even though interventions including donor leukocyte infusions can benefit some patients. Trials examining targeted therapies along with improved safety of alloHSCT may result in improved outcomes, yet selection bias necessitates prospective assessment to gauge the real contribution of any new therapies. Ongoing chronic GVHD (cGVHD) or other residual post-alloHSCT morbidities may limit the applicability of new therapies. Developing strategies to promptly identify patients as alloHSCT candidates, while malignancy is in a more treatable stage, could decrease relapses rates after alloHSCT. Better understanding and monitoring of minimal residual disease posttransplant could lead to novel preemptive treatments of relapse. Analyses of larger cohorts through multicenter collaborations or registries remain essential to probe questions not amenable to single center or prospective studies. Studies need to provide data with detail on disease status, prior treatments, biologic markers, and posttransplant events. Stringent statistical methods to study relapse remain an important area of research. The opportunities for improvement in prevention and management of post-alloHSCT relapse are apparent, but clinical discipline in their careful study remains important.

Role of reduced intensity transplant in adult patients with acute lymphoblastic leukemia: If and when?

Although allogeneic transplantation is a potentially curative therapy for adults with acute lymphoblastic leukemia (ALL), the high risk of the ablative regimen limits its use, especially in older patients where the need for better therapy is greatest. Recent observations suggesting that a donor derived graft vs leukemia effect is important is facilitating cure after an allogeneic transplant has kindled interest in utilizing a reduced-intensity approach, which relies in large part on this effect to control and cure the disease. Several trials have now been reported that suggest that a reduced-intensity conditioning (RIC) approach might be very effective, especially in patients who are in the first remission of the disease from either related, unrelated, or cord blood transplant donors, with approximately 50% of patients alive and in remission two years after transplant. These studies suggest that prospective studies of RIC should be conducted in patients with ALL in first remission who are at high risk for relapse based on age or comorbidity to determine its role in the overall management of adult patients with this disease.

Reduced-intensity conditioning regimens for allogeneic transplantation in children with acute lymphoblastic leukemia

Reduced-intensity conditioning regimens have been used extensively in adults with hematologic malignancies. To address whether this is a feasible approach for children with acute lymphoblastic leukemia, we evaluated transplant outcomes in 38 recipients transplanted from 1995-2005 for whom this was their first transplant. The median age at transplant was 12 years, and 47% had performance scores <90%. Disease status was first complete remission (CR) in 13%, > or =CR2 in 60% of patients, and 22% had active disease at transplantation. Matched related donors were available for a third of patients, about half of whom received bone marrow (BM) and the others, peripheral blood progenitor cells. Sixty percent of unrelated donor transplant recipients received peripheral blood progenitor cells. The day-100 probability of grade II-IV acute graft-versus-host disease was 37% and the 3-year probability of chronic graft-versus-host disease, 26%. At 3 years, the probability of treatment-related mortality was 40%, relapse 37%, and disease-free survival 30%. These data indicate long-term DFS can be achieved using reduced-intensity conditioning regimens in children with acute lymphoblastic leukemia. Given the relatively small cohort, these findings must be validated in a larger population.

Reduced-intensity conditioning followed by peripheral blood stem cell transplantation for adult patients with high-risk acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) with high-risk features has a poor prognosis in adults despite aggressive chemotherapy. Reduced-intensity conditioning (RIC) is a lower toxicity alternative for high-risk patients requiring hematopoietic cell transplantation (HCT); however, it has not been widely used for ALL. We conducted a retrospective study of 24 high-risk adult ALL patients who received an RIC regimen of fludarabine (Flu)/melphalan (Mel) prior to allogeneic peripheral blood stem cell transplantation (PBSCT) between 6/14/02 and 6/15/07 at the City of Hope. Indications for the RIC regimen were: (1) aged 50 years or older (42%), (2) compromised organ function (54%), or (3) recipient of a previous HCT (37.5%). Patients had a median age of 47.5 years and the median follow-up was 28.5 months for living patients. Both overall survival (OS) and disease-free survival (DFS) at 2 years was 61.5%. Relapse incidence was 21.1% and nonrelapse mortality (NRM) was 21.5% at 2 years. Chronic graft-versus-host (cGVHD) developed in 86% of evaluable patients. In this series, no significant correlations were made between outcomes and patient age, presence of Philadelphia chromosome, relatedness of donor source, or prior HCT. These high survival rates for high-risk ALL patients following RIC HCT may offer a promising option for patients not eligible for a standard myeloablative transplant.

Prolonged survival in adults with acute lymphoblastic leukemia after reduced-intensity conditioning with cord blood or sibling donor transplantation

Twenty-two adult acute lymphoblastic leukemia (ALL) patients (21 of 22 in complete remission [CR]) received reduced-intensity conditioning followed by allogeneic transplantation. All patients were high risk. After a uniform preparative regimen (fludarabine 40 mg/m(2) x 5, cyclophosphamide 50 mg/kg, 200 cGy total body irradiation), patients received either matched related (n=4) or umbilical cord (n=18) donor grafts. All patients reached neutrophil engraftment and 100% donor chimerism (median, days 10 and 23, respectively). Overall survival, treatment-related mortality (TRM) and relapse were 50% (95% confidence interval [CI], 27%-73%), 27% (95% CI, 9%-45%), and 36% (95% CI, 14%-58%) at 3 years, respectively. There were no relapses beyond 2 years. The cumulative incidence of acute and chronic graft-versus-host disease was 55% and 45%. Hematopoietic cell transplantation in CR1 (n=14) led to significantly less TRM (8%, P< .04) and improved overall survival (81%, P< .01). For adults with ALL in CR, reduced intensity conditioning allografting results in modest TRM, limited risk of relapse, and promising leukemia-free survival. Clinical trial numbers are NCT00365287, NCT00305682, and NCT00303719.

Management of Philadelphia chromosome–positive acute lymphoblastic leukemia (Ph+ ALL)

The tyrosine kinase inhibitor (TKI) imatinib has become an integral part of front-line therapy for Ph+ ALL, with remission rates exceeding 90% irrespective of whether imatinib is given alone or combined with chemotherapy. Treatment outcome with imatinib-based regimens has improved compared with historic controls, but most patients who do not undergo allogeneic stem cell transplantation (SCT) eventually relapse. Acquired resistance on TKI treatment is associated with mutations in the bcr-abl tyrosine kinase domain in the majority of patients, and may be detected at low frequency prior to TKI treatment in a subset of patients. Second generation TKIs, eg, dasatinib and nilotinib, show activity against most of the bcr-abl tyrosine kinase domain (TKD) mutations involved in acquired imatinib resistance, but clinical benefit is generally short-lived. Accordingly, SCT in first complete remission (CR) is considered to be the best curative option. Molecular monitoring of minimal residual disease levels appears to have prognostic relevance and should be used to guide treatment. International standardization and quality control efforts are ongoing to ensure comparability of results. Mutation analysis during treatment relies increasingly on highly sensitive PCR techniques or denaturing HPLC and may assist in treatment decisions, eg, in case of molecular relapse. Results from current studies of second-generation TKI as front-line treatment for Ph+ ALL are promising and show high molecular response rates, but follow-up is still too short to determine their impact on remission duration and long-term survival. Strategies to improve outcome after SCT include the pre-emptive use of imatinib, which appears to reduce the relapse rate. In patients ineligible for transplantation, novel concepts for maintenance therapy are needed. These could involve novel immunotherapeutic interventions and combinations of TKI.

A myeloablative conditioning regimen for patients with impaired cardiac function undergoing allogeneic stem cell transplantation: reduced cyclophosphamide combined with etoposide and total body irradiation

To circumvent the cardiac toxicity of high-dose cyclophosphamide (CY) in the myeloablative conditioning for those with cardiac comorbidity, we developed a new cardiac sparing conditioning regimen (VP/rCY/TBI) composed of 12 Gy of total body irradiation (TBI), etoposide (VP-16) (40 mg/kg), and reduced CY (40 mg/kg). We assessed the feasibility of this regimen by retrospectively comparing the outcome of VP/rCY/TBI recipients (n = 18) with that of CY/TBI recipients (n = 140). VP/rCY/TBI recipients had significantly higher cumulative dose of anthracyclines, lower ejection fraction (EF), and poorer Karnofsky performance scales (KPS) than CY/TBI recipients. The cumulative incidences of disease progression were 34.9% in VP/rCY/TBI recipients and 19.0% in CY/TBI recipients (P = 0.33). Despite poorer KPS and more cardiac comorbidity in the VP/rCY/TBI recipients, no difference in the nonprogression mortality rates was observed among recipients of the two regimens (17.5 and 14.3%, respectively, P = 0.96). Severe cardiac toxicity within 28 days after transplantation occurred in 5.9 and 3.6% of VP/rCY/TBI and CY/TBI recipients, respectively (P = 0.64). Graft rejection was not observed in VP/rCY/TBI recipients. There is a possibility that VP/rCY/TBI regimen can be safely administered for patients with pretransplantation cardiac comorbidity while preserving antineoplastic effects. These observations merit further prospective study.

Transplant-finalized salvage of adult acute lymphoblastic leukemia: results of a mitoxantrone- and methotrexate-based regimen in 36 patients

Idarubicin-based induction programs in acute lymphoblastic leukemia (ALL) account for 75?-?85% of complete remission rate. A small amount of patients exhibit primary refractoriness, and approximately 60% of those achieving a remission eventually relapse. The present study aimed to review the outcome of patients relapsing after or resistant to an idarubicin-based, induction-consolidation regimen (with/without additional high dose cytarabine). The 'ABC' phase II trial consisted of mitoxantrone (50 mg/m(2) over 5 days) associated with high-dose methotrexate (1.5 g/m(2) over 24 h, followed by folinic acid rescue), high-dose methyl-prednisolone (125 mg b.i.d.) and vincristine, plus granulocyte colony-stimulating factor. Eligible patients were treated with two courses ('A' and 'B', the latter with reduced drug dosages), followed by allogeneic or autologous haematopoietic stem cell transplantation (HSCT, 'C'). Thirty-six patients (3 primary resistant, 33 at first marrow relapse) were evaluated. With 'A', 21 achieved a complete remission (CR), 10 were refractory and 5 died early. Eighteen patients received 'B' (with one more CR, for an overall CR rate of 61%) and, eventually, 12 patients had 'C' procedures (7 autologous, 5 allogeneic HSCT). WHO grade >or=3 treatment-related toxicity developed in 50% and 34% of 'A' and 'B' courses, respectively. The median duration of CR was 5.2 (range 0.5-19.7) months and median overall survival was 7.6 (range 0.5-20) months. In spite of 12 HSCTs, there was no long-term survivor. 'ABC' salvage proved feasible and comparable to reported rescue chemotherapic regimens, but the achievement of cure in refractory/relapsing ALL remains an outstanding clinical task.

Allogeneic transplantation for ALL in adults

Allogeneic transplantation is an effective treatment for adult patients with high-risk ALL, including patients in first or second remission. Although only a few studies have evaluated the optimal transplant regimens, the data would suggest that a TBI-based regimen results in better disease control. Although not as potent as it is in other hematologic malignancies, the GVL effect is an important component of achieving cure of ALL. Because of the toxicity of the fully ablative regimen, reduced-intensity transplants are being explored in older patients with ALL when the prognosis is especially poor with standard chemotherapy.

The treatment of adults with acute lymphoblastic leukemia

Despite the relatively low incidence of acute lymphoblastic leukemia (ALL) in adults, large national and international collaborations have recently improved our understanding of how to treat ALL in adults. This article documents and examines the current evidence base for a "state of the art" therapy in both Philadelphia chromosome-negative and -positive adult ALL. The article comments upon areas of therapeutic debate, such as the role of bone marrow transplantation. In particular, the controversial subject of whether the superior outcome seen in younger patients is predicated on disease biology or therapeutic strategy is examined closely. Promising approaches under development are also discussed.

Allogeneic haematopoietic stem cell transplant in Philadelphia-positive acute lymphoblastic leukaemia

ALL in which the Philadelphia (Ph) chromosome is detected is one of the few diseases in which there is almost unequivocal agreement that a matched sibling allogeneic haematopoietic stem cell transplant in first CR is the most appropriate therapy for patients within certain age limits. Extension of allogeneic stem cell transplant to patients without matched sibling donors or to older individuals is increasingly possible due to unrelated donors, umbilical cord blood and reduced-intensity conditioning regimens. Here, we carefully review evidence supporting current practice and examine recent evidence relating to the use of newer allogeneic transplant technologies in Ph-pos ALL. We explore the burgeoning literature on the role of tyrosine kinase inhibitors in this disease and summarize their impact on the transplant practice.