Imatinib mesylate (STI571) in preparation for allogeneic hematopoietic stem cell transplantation and donor lymphocyte infusions in patients with Philadelphia-positive acute leukemias

Effects of decitabine on allogeneic immune reactions of donor lymphocyte infusion via activation of dendritic cells

Background

Successful prevention of post-transplantation relapse after donor lymphocyte infusion (DLI) depends on its capability to mediate an effective graft-versus-leukemia (GVL) response while minimizing DLI-related toxicity, including graft-versus-host disease (GVHD).

Methods

We assessed the effects of decitabine (DEC), a hypomethylating agent, upon allogeneic immune reaction in a murine model of DLI.

Results

Significantly greater tumor growth retardation and survival prolongation occurred in mice administered with 1.0 mg/kg DEC for 5 days (DEC-1.0) than in control or DEC-0.1 mice. Upon prompt DEC and DLI co-administration, dendritic cells (DCs) were activated; DEC-1.0/DLI induced severe GVHD, and survival was significantly lower than with DLI alone or DEC-0.1/DLI treatments. IFN-γ and CD28 levels were higher in splenic DCs of DEC-1.0 mice than in those of control mice. Assessment of delayed DLI co-administration with DEC, when IFN-γ levels were normalized to control levels, revealed that DEC-1.0/DLI successfully facilitated tumor management without causing severe GVHD.

Conclusions

Our results suggest that DEC primes allogeneic immune reactions of DLI via DC activation, and GVHD and GVL effects are separable through optimal DLI timing based on DEC-induced increase in IFN-γ expression levels.

Immunological effects of nilotinib prophylaxis after allogeneic stem cell transplantation in patients with advanced chronic myeloid leukemia or philadelphia chromosome-positive acute lymphoblastic leukemia

Allogeneic stem cell transplantation remains the standard treatment for resistant advanced chronic myeloid leukemia and Philadelphia chromosome–positive acute lymphoblastic leukemia. Relapse is the major cause of treatment failure in both diseases. Post-allo-SCT administration of TKIs could potentially reduce relapse rates, but concerns regarding their effect on immune reconstitution have been raised. We aimed to assess immune functions of 12 advanced CML and Ph+ ALL patients who received post-allo-SCT nilotinib. Lymphocyte subpopulations and their functional activities including T-cell response to mitogens, NK cytotoxic activity and thymic function, determined by quantification of the T cell receptor (TCR) excision circles (TREC) and TCR repertoire, were evaluated at several time points, including pre-nilotib-post-allo-SCT, and up to 365 days on nilotinib treatment. NK cells were the first to recover post allo-SCT. Concomitant to nilotinib administration, total lymphocyte counts and subpopulations gradually increased. CD8 T cells were rapidly reconstituted and continued to increase until day 180 post SCT, while CD4 T cells counts were low until 180−270 days post nilotinib treatment. T-cell response to mitogenic stimulation was not inhibited by nilotinib administration. Thymic activity, measured by TREC copies and surface membrane expression of 24 different TCR Vβ families, was evident in all patients at the end of follow-up after allo-SCT and nilotinib treatment. Finally, nilotinib did not inhibit NK cytotoxic activity. In conclusion, administration of nilotinib post allo-SCT, in attempt to reduce relapse rates or progression of Ph+ ALL and CML, did not jeopardize immune reconstitution or function following transplantation.

Use of tyrosine kinase inhibitors to prevent relapse after allogeneic hematopoietic stem cell transplantation for patients with Philadelphia chromosome-positive acute lymphoblastic leukemia: A position statement of the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Allogeneic hematopoietic stem cell transplantation (alloHSCT) is a standard of care for patients with Philadelphia chromosome (Ph)-positive acute lymphoblastic leukemia (ALL). The introduction of tyrosine kinase inhibitors (TKIs) to first-line therapy has improved overall outcomes; however, a significant proportion of patients still relapse after alloHSCT. Posttransplant TKI maintenance was demonstrated to reduce the risk of relapse in a large retrospective study and, therefore, should be considered a valuable option. This consensus paper, written on behalf of the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation, presents an overview of clinical studies on the use of TKIs after alloHSCT and proposes practical recommendations regarding the choice of TKI, treatment timing, and dosage. It is hoped that these recommendations will become the state of art in this field and, more importantly, lead to a reduction of Ph-positive ALL relapse after alloHSCT. Cancer 2016;122:2941-2951. © 2016 American Cancer Society.

Tyrosine kinase inhibitors improve long-term outcome of allogeneic hematopoietic stem cell transplantation for adult patients with Philadelphia chromosome positive acute lymphoblastic leukemia

This study aimed to determine the impact of tyrosine kinase inhibitors given pre- and post-allogeneic stem cell transplantation on long-term outcome of patients allografted for Philadelphia chromosome-positive acute lymphoblastic leukemia. This retrospective analysis from the EBMT Acute Leukemia Working Party included 473 de novo Philadelphia chromosome-positive acute lymphoblastic leukemia patients in first complete remission who underwent an allogeneic stem cell transplantation using a human leukocyte antigen-identical sibling or human leukocyte antigen-matched unrelated donor between 2000 and 2010. Three hundred and ninety patients received tyrosine kinase inhibitors before transplant, 329 at induction and 274 at consolidation. Kaplan-Meier estimates of leukemia-free survival, overall survival, cumulative incidences of relapse incidence, and non-relapse mortality at five years were 38%, 46%, 36% and 26%, respectively. In multivariate analysis, tyrosine-kinase inhibitors given before allogeneic stem cell transplantation was associated with a better overall survival (HR=0.68; P=0.04) and was associated with lower relapse incidence (HR=0.5; P=0.01). In the post-transplant period, multivariate analysis identified prophylactic tyrosine-kinase inhibitor administration to be a significant factor for improved leukemia-free survival (HR=0.44; P=0.002) and overall survival (HR=0.42; P=0.004), and a lower relapse incidence (HR=0.40; P=0.01). Over the past decade, administration of tyrosine kinase inhibitors before allogeneic stem cell transplantation has significantly improved the long-term allogeneic stem cell transplantation outcome of adult Philadelphia chromosome-positive acute lymphoblastic leukemia. Prospective studies will be of great interest to further confirm the potential benefit of the prophylactic use of tyrosine kinase inhibitors in the post-transplant setting.

Phase 1/2 study of nilotinib prophylaxis after allogeneic stem cell transplantation in patients with advanced chronic myeloid leukemia or Philadelphia chromosome-positive acute lymphoblastic leukemia

BACKGROUND

Allogeneic stem cell transplantation (SCT) remains the standard treatment for advanced chronic myeloid leukemia (CML) and Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph(+) ALL). Relapsed disease is the major cause of treatment failure, especially when SCT is given in the setting of advanced disease. Tyrosine kinase inhibitors can be given after transplantation prophylactically or after the detection of minimal residual disease (MRD) to reduce the relapse risk.

METHODS

Posttransplant nilotinib was started after the achievement of sustained engraftment and the resolution of transplant-related toxicities. Nilotinib was continued until progression or unacceptable toxicity.

RESULTS

Twenty-two patients with advanced CML (n = 15) or Ph(+) ALL (n = 7) underwent SCT with human leukocyte antigen-matched siblings (n = 11), unrelated donors (n = 7), or alternative donors (n = 4). Sixteen patients were given prophylactic nilotinib maintenance, which was started at a median of 38 days after transplantation. Six patients stopped the treatment because of toxicities (mostly gastrointestinal and hepatic). After nilotinib maintenance, 11 patients achieved (n = 9) or maintained (n = 2) a complete molecular response (CMR), and only 1 of them later relapsed. Four of the 5 patients not achieving CMR relapsed. At a median follow-up of 46 months, 9 patients were alive, and 13 had died. The 2-year overall and progression-free survival rates were 55% (95% confidence interval [CI], 34%-75%) and 45% (95% CI, 25%-66%), respectively. Among the 16 nilotinib recipients, the rates were 69% (95% CI, 46%-92%) and 56% (95% CI, 32%-81%), respectively. The 2-year nonrelapse mortality and relapse rates for all patients were 32% (95% CI, 17%-58%) and 23% (95% CI, 11%-49%), respectively.

CONCLUSIONS

Nilotinib is relatively safe and effective prophylactic therapy for the prevention of relapse after SCT. It may control MRD and convert patients to CMR, which is associated with prolonged survival. These observations merit further study in larger scale studies.

Current status of hematopoietic stem cell transplant in chronic myeloid leukemia

Indications for hematopoietic stem cell transplant (HSCT) in chronic myeloid leukemia (CML) have changed over time. This change has largely been influenced by the advent of tyrosine kinase inhibitors, increased understanding of the mechanisms underlying disease phase progression as well as drug resistance, refinement of transplant techniques and exploitation of graft versus leukemia effect in this disease. Here, we have discussed the status of HSCT in CML in the present era with regards to the current indications, factors determining outcome and management strategies for posttransplant relapse.

Evidence-based guidelines for the use of tyrosine kinase inhibitors in adults with Philadelphia chromosome-positive or BCR-ABL-positive acute lymphoblastic leukemia: a Canadian consensus

Adult Philadelphia chromosome-positive (Ph+) or BCR-ABL-positive (BCR-ABL+) acute lymphoblastic leukemia (all) is an acute leukemia previously associated with a high relapse rate, short disease-free survival, and poor overall survival. In adults, allogeneic hematopoietic cell transplant in first remission remains the only proven curative strategy for transplant-eligible patients. The introduction of tyrosine kinase inhibitors (tkis) in the treatment of patients with Ph+ or BCR-ABL+ all has significantly improved the depth and duration of complete remission, allowing more patients to proceed to transplantation. Although tkis are now considered a standard of care in this setting, few randomized trials have examined the optimal use of tkis in patients with Ph+ all. Questions of major importance remain, including the best way to administer these medications, the choice of tki to administer, and the schedule and the duration to use. We present the results of a systematic review of the literature with consensus recommendations based on the available evidence.

Current and future management of Ph/BCR-ABL positive ALL

Following the introduction of targeted therapy with tyrosine kinase inhibitors (TKI) at the beginning of the past decade, the outcome of patients with Philadelphia-chromosome positive acute lymphoblastic leukemia (Ph+ ALL) has dramatically improved. Presently, the use of refined programs with first/second generation TKI's and chemotherapy together with allogeneic stem cell transplantation allow up to 50% of all patients to be cured. Further progress is expected with the new TKI ponatinib, overcoming resistance caused by T315I point mutation, other targeted therapies, autologous transplantation in molecularly negative patients, therapeutic monoclonal antibodies like inotuzumab ozogamicin and blinatumomab, and chimeric antigen receptor-modified T cells. Ph+ ALL could become curable in the near future even without allogeneic stem cell transplantation, minimizing the risk of therapy-related death and improving greatly the quality of patients' life.

Allogeneic transplant for chronic myeloid leukemia in 2010

Tyrosine kinase inhibitor (TKI) therapy has revolutionized the therapy of chronic myeloid Leukemia (CML). Thus, while in the near past allogeneic transplantation was the curative option for CML, imatinib, nilotinib, and dasatinib have pushed transplantation to the role of salvage therapy in CML. Still, TKI therapy still fails some patients, and so the clinical challenge is to integrate transplantation in a safe and sane manner. This manuscript reviews the data on the variables that have an influence on outcome following transplantation, and discusses the variables to consider in determining who and when patients should receive transplantation.

Chronic myelogenous leukemia: role of stem cell transplant in the imatinib era

In the pre-tyrosine kinase (TKI) era, allogeneic stem cell transplant (allo-SCT) was the front-line treatment of choice for young patients with chronic myelogenous leukemia (CML). Today, imatinib is well established as front-line therapy for CML, with excellent long-term outcomes. This has changed the role of allo-SCT and the number of patients undergoing allo-SCT has declined dramatically. Allo-SCT is currently recommended for patients in accelerated/blast phase disease, those who have failed a second-generation TKI and those with TKI-resistant mutations such as T315I. The role of allo-SCT in the management of CML will require continual reappraisal as medical therapies continue to evolve.

Prognostic factors for outcomes in allogeneic transplantation for CML in the imatinib era: a CIBMTR analysis

Allogeneic hematopoietic stem cell transplantation (HSCT) is curative treatment, albeit in a minority of patients with accelerated (AP) or blast phase (BP) chronic myeloid leukemia (CML). Imatinib (IM) has transient but significant activity in advanced phases of CML, which may permit early allografting for responding patients. To identify prognostic factors in allograft recipients previously treated with IM, we analyzed 449 allogeneic HSCT performed between 1999–2004 in advanced phase CML using data reported to the Center for International Blood and Marrow Transplant Research. CML patients in second chronic phase (CP2, n=184), AP (n=185), and BP (n=80) received HLA-identical sibling (27%), related (3%), or matched or mismatched unrelated donor (70%), peripheral blood (47%) or bone marrow (53%) HSCT after myeloablative (78%) or non-myeloablative (22%) conditioning. 52% in CP2, 49% in AP, and 46% in BP received IM pre-HSCT. Disease-free survival was 35–40% for CP2, 26–27% for AP and 8–11% for BP. Cumulative incidence of acute and chronic GVHD and TRM were not affected by stages of CML or pre-HSCT IM exposure. Multivariate analyses showed that conventional prognostic indicators remain the strongest determinants of transplant outcomes. In conclusion, there are no new prognostic indicators of outcomes of allogeneic HSCT for advanced phase CML in the IM era.

Stem cell transplant for chronic myeloid leukemia in the imatinib era

Tyrosine kinase inhibitor (TKI) therapy has revolutionized the therapy of chronic myeloid leukemia (CML). Thus, while in the near past allogeneic transplantation was the curative option for CML, imatinib, nilotinib, and dasatinib have pushed transplantation to the role of salvage therapy in CML. Still, TKI therapy still fails some patients, and so the clinical challenge is to integrate transplantation in a safe and sane manner. This article reviews the data on the variables that influence outcome following transplantation, and discusses the variables to consider in determining which patients should receive transplantation and when.

Update on practical aspects of the treatment of chronic myeloid leukemia with imatinib mesylate

Imatinib (imatinib mesylate, Gleevec(R) [formerly known as STI571], Novartis Pharmaceuticals, Basel, Switzerland) is a protein tyrosine kinase inhibitor that is approved by the US Food and Drug Administration for patients with all phases of chronic myeloid leukemia (CML). Imatinib is remarkably effective as treatment for CML in the chronic phase (at a dosage of 400 mg/d) and the accelerated phase (at 600 mg/d). At this time, it remains to be seen whether the chronic phase of CML can be extended sufficiently in some patients so that they are functionally "cured," and also whether the increased rate of major molecular response induced by doses of imatinib higher than 400 mg/d will further improve overall survival of patients with CML in the chronic phase. The value of molecular monitoring of response in patients with CML in the chronic phase is examined. Although imatinib 800 mg/d can induce dramatic responses in patients with myeloid blast crisis, lymphoid blast crisis, and Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL), the responses are usually incomplete and of short duration. We discuss the role of imatinib in relation to allogeneic stem cell transplantation (particularly in younger patients), recognizing that the data upon which any decisions can be made are relatively immature. Finally, recent data on new tyrosine kinase inhibitors capable of overcoming primary or acquired resistance to imatinib are reviewed.

Impact of genomic risk factors on outcome after hematopoietic stem cell transplantation for patients with chronic myeloid leukemia

BACKGROUND

Non-HLA gene polymorphisms have been shown to influence outcome after allogeneic hematopoietic stem cell transplantation. Results were derived from heterogeneous, small populations and their value remains a matter of debate.

DESIGN AND METHODS

In this study, we assessed the effect of single nucleotide polymorphisms in genes for interleukin 1 receptor antagonist (IL1RN), interleukin 4 (IL4), interleukin 6 (IL6), interleukin 10 (IL10), interferon (IFNG), tumor necrosis factor (TNF) and the cell surface receptors tumor necrosis factor receptor II (TNFRSFIB), vitamin D receptor (VDR) and estrogen receptor alpha (ESR1) in a homogeneous cohort of 228 HLA identical sibling transplants for chronic myeloid leukemia. Three good predictors of overall survival, identified via statistical methods including Cox regression analysis, were investigated for their effects on transplant-related mortality and relapse. Predictive power was assessed after integration into the established European Group for Blood and Marrow Transplantation (EBMT) risk score.

RESULTS

Absence of patient TNFRSFIB 196R, absence of donor IL10 ATA/ACC and presence of donor IL1RN allele 2 genotypes were associated with increased transplantation-related mortality and decreased survival. Application of prediction error and concordance index statistics gave evidence that integration improved the EBMT risk score.

CONCLUSIONS

Non-HLA genotypes were associated with survival after allogeneic hematopoietic stem cell transplantation. When three genetic polymorphisms were added into the EBMT risk model they improved the goodness of fit. Non-HLA genotyping could, therefore, be used to improve donor selection algorithms and risk assessment prior to allogeneic hematopoietic stem cell transplantation.

Philadelphia chromosome-positive acute lymphoblastic leukemia

The Philadelphia (Ph) chromosome, a short chromosome 22, is the most frequent cytogenetic abnormality in adult patients with acute lymphoblastic leukemia (ALL). It occurs in approximately 20% to 30% of adults and in about 5% of children with this disease. The incidence rises with age and occurs in approximately 50% of patients older than 50 years. This article reviews the treatment regimens for Ph+ ALL, including imatinib and second generation tyrosine kinase inhibitors (TKIs). The introduction of effective TKIs in the treatment of Ph+ ALL has introduced several avenues of research in a disease that was hitherto difficult to treat.

Allogeneic stem-cell transplantation provides excellent results in advanced stage chronic myeloid leukemia with major cytogenetic response to pre-transplant imatinib therapy

To determine the impact of imatinib therapy prior to allogeneic stem-cell transplantation in advanced stage chronic myelogenous leukaemia (CML), 30 CML patients who had received imatinib as part of pre-transplant treatment were analysed, with special emphasis on the cytogenetic response to imatinib therapy shortly before transplantation. Median patient age was 51 years (range, 24 - 64). At the time of transplantation all patients were in second or higher chronic phase (CP). The median follow-up after allogeneic transplantation was 360 days (range, 24 - 1524). Cox regression analysis revealed that the quality of cytogenetic response was a prognostic factor for transplant-related mortality (p = 0.050), relapse incidence (p = 0.015), leukaemia-free survival (p = 0.002) and overall survival (p = 0.006). A cytogenetic response with <35%BCR-ABL-positive interphase nuclei in FISH analysis from bone marrow was associated with a probability of overall survival of 81% at 3 years. In conclusion, our data suggest that advanced stage CML has an excellent outcome after allogeneic haematopoietic stem-cell transplantation when transplanted in the phase of cytogenetic response to imatinib.

Immunomodulatory effects of imatinib and second-generation tyrosine kinase inhibitors on T cells and dendritic cells: an update

The discovery of new drugs has occasionally led to a better understanding of biologic processes and unforeseen therapeutic applications. One such example is the new group of tyrosine kinase inhibitors, exemplified by the Bcr-Abl inhibitor imatinib (Glivec). In the last 10 years, these so-called 'small molecules' have started to enter the clinic with the promise of cancer treatments targeted at the underlying molecular changes that are responsible for specific malignant phenotypes. The aim of these small molecules has been to avoid the side-effects of systemic chemotherapies and the high morbidity/mortality risks associated with hematopoietic stem cell transplantation. Concurrently, however, increasing evidence has emerged to indicate that these drugs exert profound immunomodulatory effects on T cells and antigen-presenting cells, such as dendritic cells, which play major roles in immune tumor surveillance and the outcome of hematopoietic stem cell transplantation. Targeted tyrosine kinase inhibitor therapy may thus control cancer cell growth both directly and indirectly by changing the immunologic microenvironment. Furthermore, such molecules might help to unravel the complexities of the human immune system and could find therapeutic application in conditions as diverse as autoimmune diseases and certain infectious processes. In this brief review, we discuss recent developments in this fast evolving field.

Allogeneic transplantation for pediatric acute lymphoblastic leukemia: the emerging role of peritransplantation minimal residual disease/chimerism monitoring and novel chemotherapeutic, molecular, and immune approaches aimed at preventing relapse

Although improved donor sources and supportive care have decreased transplantation-related mortality over the past decade, relapse remains the principal cause of failure after allogeneic transplantation for high-risk pediatric acute lymphoblastic leukemia (ALL). Emerging tools of minimal residual disease (MRD) and chimerism monitoring before and after transplantation have defined those children at highest risk for relapse and provide the opportunity for intervention to prevent relapse. Specific methods aimed at decreasing relapse include the use of intensive treatment before transplantation to increase the percentage of patients undergoing the procedure with negative MRD, optimal transplantation preparative regimens, and posttransplantation interventions with targeted or immunologic therapy. Early data demonstrate decreased relapse with the use of sirolimus for all types of ALL and imatinib for ALL with the Philadelphia chromosome (Ph(+) ALL) after transplantation. Patients with increasing chimerism or MRD have been shown to benefit from early withdrawal of immune suppression or donor lymphocyte infusion. Finally, various targeted immunologic therapies, including monoclonal antibodies, killer cell immunoglobulin-like receptor mismatching, natural killer cell therapy, and targeted T cell therapies, are emerging that also could have an affect on relapse and improve survival after transplantation for pediatric ALL.

Allo-hematopoietic cell transplantation for Ph chromosome-positive ALL: impact of imatinib on relapse and survival

The utility of imatinib in either the pre- or post-transplant period for Ph chromosome-positive (Ph+) ALL is uncertain. In addition, there have been recent concerns regarding imatinib and cardiac toxicity. We investigated the outcome of 32 patients with Ph+ ALL who received an allo-hematopoietic cell transplant (HCT) at the University of Minnesota between 1999 and 2006. The median age at HCT was 21.9 years (range: 2.8-55.2). All patients were conditioned with CY and TBI. GVHD prophylaxis was CsA based. Of the 32 patients, 15 received imatinib therapy pre- or post-HCT (imatinib group) and 17 patients received either no imatinib (n=11) or only after relapse (n=6) (non-imatinib group). Overall survival, relapse-free survival and relapse at 2 years was 61, 67 and 13% for the imatinib group as compared with 41, 35 and 35% for the non-imatinib group (P=0.19, 0.12 and 0.20, respectively). Cardiac toxicity and TRM at 2 years were similar between groups. Thus, patients treated with imatinib in either the pre- or post-transplant setting had trends toward improved outcomes and no increase in cardiac toxicity. We suggest that imatinib be included in the peri-transplant management of all patients with Ph+ ALL.

Impact of prior imatinib mesylate on the outcome of hematopoietic cell transplantation for chronic myeloid leukemia

Imatinib mesylate (IM, Gleevec) has largely supplanted allogeneic hematopoietic cell transplantation (HCT) as first line therapy for chronic myeloid leukemia (CML). Nevertheless, many people with CML eventually undergo HCT, raising the question of whether prior IM therapy impacts HCT success. Data from the Center for International Blood and Marrow Transplant Research on 409 subjects treated with IM before HCT (IM(+)) and 900 subjects who did not receive IM before HCT (IM(-)) were analyzed. Among patients in first chronic phase, IM therapy before HCT was associated with better survival but no statistically significant differences in treatment-related mortality, relapse, and leukemia-free survival. Better HLA-matched donors, use of bone marrow, and transplantation within one year of diagnosis were also associated with better survival. A matched-pairs analysis was performed and confirmed a higher survival rate among first chronic phase patients receiving IM. Among patients transplanted with advanced CML, use of IM before HCT was not associated with treatment-related mortality, relapse, leukemia-free survival, or survival. Acute graft-versus-host disease rates were similar between IM(+) and IM(-) groups regardless of leukemia phase. These results should be reassuring to patients receiving IM before HCT.

Allogeneic hematopoietic cell transplantation for adult Philadelphia-positive acute lymphoblastic leukemia in the era of tyrosine kinase inhibitors

Allogeneic hematopoietic cell transplantation in first complete remission (CR1) is considered the standard of care, and the only established therapy that offers a possibility of cure for patients with Philadelphia-positive acute lymphoblastic leukemia (Ph+ ALL). Unfortunately, a number of patients, with suitable HLA-matched donors, are unable to receive an allograft because they fail to respond, or relapse shortly after induction chemotherapy. Incorporating imatinib during the induction/consolidation phase is facilitating a higher number of potentially curative allografts by improving both remission rates and/or the durability of responses in patients with Ph+ ALL. Imatinib and other tyrosine kinase inhibitors are also improving outcomes in elderly patients with Ph+ ALL, ineligible for allografting, when combined with glucocorticoids, and/or conventional chemotherapy. The addition of imatinib or other tyrosine kinase inhibitors to the therapeutic armamentarium of Ph+ ALL is reshaping the treatment algorithm and improving prognosis of this dreadful disease.

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.

Philadelphia chromosome-positive acute lymphoblastic leukemia: impact of imatinib treatment on remission induction and allogeneic stem cell transplantation

Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) has been associated with the worst patient survival rates of the various acute leukemias. Imatinib mesylate is a novel therapeutic agent that targets the BCR-ABL tyrosine kinase, the molecular abnormality associated with Ph+ ALL. The combination of imatinib with chemotherapy has led to improved and durable treatment responses in adult patients with Ph+ ALL, including the elderly population. Hematopoietic stem cell transplantation has also integrated imatinib into its transplant strategies, with early data suggesting improved progression-free survival without clearly identifiable augmented toxicity. Second-generation tyrosine kinase inhibitors offer potentially even greater improvements on these excellent imatinib-associated outcomes. This review addresses the evolution of the management of Ph+ ALL and is intended to assist in the description of its new natural history.

Donor leukocyte infusions in myeloid malignancies: new strategies

Donor leukocyte infusion (DLI) provides direct and potent graft-versus-leukemia (GVL) activity to treat relapse after allogeneic stem-cell transplantation. DLI is dramatically effective for relapsed chronic myelogenous leukemia (CML), but has been less effective for relapse of other myeloid malignancies. Nevertheless, most recipients of DLI for relapsed CML, and many patients with relapsed acute myelogenous leukemia (AML) and myelodysplastic syndrome (MDS), will experience prolonged remissions and probable cure. Graft-versus-host disease remains the major complication of DLI. New strategies for GVL induction explore novel dosing regimens and both methods of enhancing GVL activity of donor T cells and of minimizing toxicity from graft-versus-host disease. Ultimately, the identification of the effector cells and target antigens for GVL induction will lead to the use of tumor-specific adoptive immunotherapy to both prevent and treat relapse with minimal toxicity. Although many issues remain unsettled, the potential to harness the graft-versus-leukemia activity of allogeneic donor cells provides a powerful new paradigm for the immunotherapy of cancer.

Imatinib combined chemotherapy for Philadelphia chromosome-positive acute lymphoblastic leukemia: major challenges in current practice

The prognosis of Philadelphia chromosome-positive (Ph+) and/or BCR-ABL-positive acute lymphoblastic leukemia (ALL) is extremely poor, and for decades allogeneic hematopoietic stem cell transplantation (HSCT) has been considered the only option for a cure. However, the treatment for Ph+ ALL has been rapidly changing since imatinib, a selective inhibitor of the ABL tyrosine kinase, was introduced. Earlier clinical trials in which a moderate anti-leukemic effect of imatinib monotherapy was demonstrated have prompted investigators to explore the combination of imatinib and chemotherapy. The results of multiple studies indicate that chemotherapy combined with imatinib is well tolerated, induces complete hematological remission in almost every patient with newly diagnosed Ph+ ALL, and molecular remission in more than half of the cases. Future clinical studies need to focus on how imatinib can be incorporated into chemotherapy more effectively by determining the optimal dosage of imatinib, the optimal combinational schedule, and the role of allogeneic HSCT.

The effects of imatinib mesylate treatment before allogeneic transplantation for chronic myeloid leukemia

The impact of imatinib mesylate (IM) treatment for chronic myeloid leukemia (CML) on subsequent allogeneic transplantation is uncertain. To better understand this relationship, we retrospectively compared 145 patients with CML receiving IM for a minimum of 3 months before allogeneic hematopoietic cell transplantation (HCT) to 231 patients with CML who did not. IM treatment was associated with no increase in early hepatotoxicity or engraftment delay after HCT compared with the historical cohort. In addition, there was no statistically significant difference in the IM-treated cohort compared with the historical cohort with regard to overall survival, disease-free survival, relapse, and nonrelapse mortality. For chronic-phase (CP) patients, IM response prior to HCT was associated with post-HCT outcome. Patients who underwent transplantation in CP with a suboptimal response or a loss of response on IM had a statistically significant higher hazard of mortality when compared with CP patients who achieved a complete cytogenetic response (CCR) or major cytogenetic response (MCR) on IM (HR=5.31, 95% confidence interval [CI] 1.13-25.05, P=.03). These data indicate that pre-HCT IM is not associated with increased transplant-related morbidity (TRM) or poorer outcomes. However, patients with a suboptimal or loss of IM response before HCT do worse, suggesting a more aggressive disease course for these patients.

Effects of imatinib on normal hematopoiesis and immune activation

The selective tyrosine kinase inhibitor imatinib (Glivec; Novartis International, Basel, Switzerland, http://www.glivec.com/content/home.jsp) is increasingly used for the treatment of Philadelphia chromosome-positive leukemias and other malignancies. In principle, the drug is well tolerated and clinical side effects are mostly moderate. However, it was shown that imatinib can affect the function of normal, nonmalignant cells, resulting in myelosuppression in treated patients. Recently, it has been demonstrated that imatinib might affect mobilization, proliferation, and differentiation of hematopoietic progenitor cells while leaving hematopoietic stem cells unaffected. Furthermore, in several in vitro studies and animal models, it was demonstrated that imatinib can affect the function and differentiation of antigen-presenting cells and inhibit the effector functions of T lymphocytes. Moreover, the induction of specific cytotoxic T cells seems to be impaired in chronic myeloid leukemia (CML) patients treated with imatinib compared with patients receiving interferon-alpha. This is of importance because some of the therapeutic effects in the treatment of patients with CML are mediated by the induction of leukemia-specific T-cell responses. Further studies investigating the effects of imatinib on normal hematopoiesis are of interest as they might lead to a better understanding of the clinically observed side effects and also might help identify new therapeutic applications of the drug, possibly in Bcr-Abl-negative myeloproliferative disorders and potentially as an immunomodulatory agent.

Allogeneic haematopoietic cell transplantation for chronic myelogenous leukaemia in the era of imatinib: a retrospective multicentre study

OBJECTIVE

To analyse the results of allogeneic haematopoietic cell transplantation (HCT) in patients with advanced stages of Philadelphia chromosome-positive chronic myelogenous leukaemia (CML) who had previously been treated with imatinib mesylate (IM).

METHODS

We analysed the outcome of 61 patients with CML who had received allogeneic HCT from sibling (n = 18) or unrelated (n = 43) donors after having been treated with IM. Forty-one patients had received IM because of accelerated or blast phase CML. Conditioning therapy contained standard doses of busulfan (n = 25) or total-body irradiation (n = 20) in conjunction with cyclophosphamide in the majority of cases. Sixteen patients received dose-reduced conditioning with fludarabine-based regimens.

RESULTS

The incidence of grades II-IV and III-IV graft-versus-host disease was 66% and 38% respectively. The probability of overall survival (OS), disease-free survival (DFS) and relapse at 18 months for the whole patient cohort were 37%, 33% and 24% respectively. The probability of non-relapse mortality (NRM) at 100 d and 12 months was 30% and 46% respectively. Univariate analysis showed that fludarabine-based conditioning therapy, age > or = 40 yr and >12 months interval between diagnosis and transplantation were associated with a significantly lower OS and DFS and a higher NRM.

CONCLUSION

These data suggest that although pretreatment with IM is not an independent negative prognostic factor, it cannot improve the dismal prognosis of CML patients at high risk for transplant-related mortality.

Effect of Tyrosine Kinase Inhibition Using Imatinib on Normal Lymphohematopoietic Cells

Imatinib is a selective tyrosine kinase inhibitor used for the treatment of Philadelphia chromosome-positive leukemias and other malignancies. An important clinical observation is that imatinib can affect the function of normal nonmalignant cells resulting in myelosuppression in treated patients. This observation is supported by the recent findings suggesting that imatinib might affect mobilization, proliferation, and differentiation of hematopoietic progenitor cells while leaving hematopoietic stem cells unaffected. Furthermore, the induction of a specific T cell response seems to be impaired in chronic myeloid leukemia (CML) patients treated with imatinib in contrast to patients receiving interferon-alpha. Recent studies demonstrate that in vitro exposure of mobilized human CD34(+) progenitors to imatinib inhibits their differentiation into dendritic cells. This is of importance as some of the therapeutic effects in the treatment of patients with CML are mediated by the induction of leukemia-specific T cell responses. Studies investigating the effects of imatinib on normal hematopoiesis are of interest because they might help us better understand the side effects observed clinically and might lead to the identification of novel therapeutic applications of the drug (e.g., in Bcr-Abl(-) myeloproliferative disorders and potentially as an immunomodulatory agent).

Imatinib therapy prior to myeloablative allogeneic stem cell transplantation

It is unknown whether imatinib prior to myeloablative haematopoietic stem cell transplantation (HSCT) increases transplant-related toxicity. Among the side effects induced by imatinib, myelosuppression and liver injury might worsen HSCT outcomes. We retrospectively analysed engraftment, liver toxicity, acute graft-versus-host disease (aGVHD) incidence and 100-day mortality in 30 patients with BCR/ABL-positive leukaemias who received imatinib before HSCT and compared results of 48 age-matched controls who did not receive preceding imatinib. Both neutrophil and platelet engraftment occurred more rapidly among imatinib patients but the differences adjusted for Gratwohl scale were not statistically significant (P = 0.18 and 0.22, respectively). The adjusted hazards of having liver function tests (LFTs) >1.5 normal increased and the adjusted durations of elevated LFTs were not significantly different. The estimated adjusted difference in mean peak bilirubin values was also not significantly different (P = 0.48). However, the adjusted hazard of increased creatinine >1.5 normal was significantly higher in the imatinib group (HR = 4.09, P = 0.02). The adjusted odds of grades II-IV aGVHD were similar in both groups (OR = 0.86, P = 0.78), and while the adjusted odds of 100-day mortality were lower among imatinib patients, the difference was not significant (OR = 0.65, P = 0.60). These data do not provide any evidence that imatinib preceding HSCT increases acute transplant-related toxicities.

Imatinib mesylate in conjunction with allogeneic hematopoietic stem cell transplantation in patients with Philadelphia chromosome positive leukemias: report of 4 cases

We described here four patients diagnosed with Philadelphia chromosome positive (Ph+) leukemia, consisting of chronic myeloid leukemia (CML) (n=2) and Ph+ acute lymphoblastic leukemia (ALL) (n=2). All patients were treated with imatinib mesylate (300-400 mg/day) for the treatment of relapsed CML after allogeneic hematopoietic stem cell transplantation (SCT) (n=2), relapsed Ph+ ALL after SCT (n=1), and Ph+ ALL preceding SCT (n=1). Significant clinical and molecular responses were observed in all patients and three of them achieved sustained molecular remission. Imatinib was well tolerated and did not induce noticeable graft versus host disease although one patient presented severe skin rash (Grade III). Notably, serum cyclosporine A concentration increased after the initiation of imatinib treatment, probably through competitive inhibition of P450 3A4 isoenzyme. Our data suggest that imatinib in conjunction with SCT for the Ph+ leukemia may be a promising treatment strategy.

Philadelphia positive acute lymphoblastic leukaemia of childhood

On current chemotherapeutic regimens, children with Philadelphia positive acute lymphoblastic leukaemia show a heterogeneous response to treatment. A few respond quickly to treatment and achieve long-term remission. Some fail to achieve remission after induction and the majority respond slowly to treatment. Relapse on treatment is common and remission is sustained in a proportion of cases only after allogeneic stem cell transplantation (allo-SCT). The use of imatinib along with conventional cytoreductive therapy, prior to allo-SCT appears to be the most promising strategy. The future lies in the molecular evaluation of response to treatment and combination targeted chemotherapy.

Outcome and long-term follow-up of alloreactive donor lymphocyte infusions given for relapse after myeloablative allogeneic hematopoietic stem cell transplantations (HSCT)

In order to study efficacy, toxicity and the long-term results of donor lymphocyte infusions (DLI), we retrospectively analyzed DLI given for relapse after conventional allogeneic hematopoietic stem cell transplantation (HSCT) in 30 patients with a median delay of 107.5 months after transplant and 58 months after DLI. After DLI, 15 patients established full donor chimerism, three patients developed grade III and one grade IV acute GVHD. A total of 15 patients achieved a disease response. Among the 14 patients with chronic myeloid leukemia (CML), 11 are alive at the last follow-up: five are in complete molecular response (CMR) and two in complete cytogenetic response (CCR) with no other intervention after DLI, three in CMR after imatinib mesylate given after DLI and one in complete hematological response after imatinib mesylate and reduced-intensity conditioning allogeneic SCT performed after DLI. At the time of the last follow-up, 19 (63%) patients died and 11 (37%) remain alive. The 3-year probability of survival for the entire population, CML patients and non-CML patients, was 60, 93, 62% after transplantation, and 48, 80 and 48% after DLI, respectively. A multivariate analysis demonstrated a significantly worse survival rate after transplantation for female recipients, advanced disease and acute leukemia before transplantation.

The effect of first-line imatinib interim therapy on the outcome of allogeneic stem cell transplantation in adults with newly diagnosed Philadelphia chromosome-positive acute lymphoblastic leukemia

Previously, we suggested that imatinib incorporation into conventional chemotherapy as an alternative (imatinib interim therapy) might be a useful strategy for bridging the time to allogeneic stem cell transplantation (SCT) for newly diagnosed Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph(+) ALL). Here, we provide an updated report on this strategy in 29 patients. At the time of enrollment, 23 patients (79.3%) achieved complete remission (CR). After the first imatinib cycle, the median breakpoint cluster region-Abelson oncogene locus (BCR-ABL)/ABL ratios decreased by 0.77 log in 25 (86.2%) responders, and their BCR-ABL/ABL ratios decreased further by 0.34 log after the second imatinib cycle, which included 7 molecular CR. One patient (4.3%) relapsed during the imatinib therapy. The remaining 3 patients were primarily refractory to both imatinib and chemotherapy. Twenty-five (86.2%) of the 29 patients received transplants in first CR. With a median follow-up duration of 25 months after SCT, the 3-year estimated probabilities of relapse, nonrelapse mortality, disease-free survival, and overall survival were 3.8%, 18.7%, 78.1%, and 78.1%, respectively. In comparison to our historical control data, first-line imatinib interim therapy appears to provide a good quality of CR and a survival advantage for patients with Ph(+) ALL. Further long-term follow-up is needed to validate the results of this study.

Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia Rescued with a Second Allogeneic Stem Cell Transplantation from a Haploidentical Mother after Relapse following Cord Blood Transplantation

A 32-year-old female patient who had Philadelphia chromosome-positive acute lymphoblastic leukemia underwent cord blood transplantation while in her second remission. However, she had a hematological and central nervous system relapse 3 months later. After reinduction with imatinib mesylate, unmanipulated peripheral blood stem cell transplantation was performed from the patient's haploidentical mother with a reduced-intensity conditioning regimen. Rabbit antithymocyte globulin, tacrolimus, and methylprednisolone were used for prophylaxis of graft-versus-host disease. Engraftment of neutrophils was observed on day 12, and complete donor chimerism was obtained by day 24. The posttransplantation course was uneventful. Although the patient had a relapse 10 months later, this case demonstrated that transplantation from a haploidentical donor is clearly a feasible alternative for patients who desperately need rescue transplantation.