Myeloablative allogeneic hematopoietic stem cell transplantation for Philadelphia chromosome-positive acute lymphoblastic leukemia in adults: significant roles of total body irradiation and chronic graft-versus-host disease

IMiDs uniquely synergize with TKIs to upregulate apoptosis of Philadelphia chromosome-positive acute lymphoblastic leukemia cells expressing a dominant-negative IKZF1 isoform

The long-term prognosis of Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph + ALL) is still unsatisfactory even after the emergence of tyrosine kinase inhibitors (TKIs) against chimeric BCR-ABL, and this is associated with the high incidence of genetic alterations of Ikaros family zinc finger 1 (IKZF1), most frequently the hemi-allelic loss of exons 4–7 expressing a dominant-negative isoform Ik6. We found that lenalidomide (LEN), a representative of immunomodulatory drugs (IMiDs), which have been long used for the treatment of multiple myeloma, specifically induced accumulation of Ik6 with the disappearance of functional isoforms within 24 h (i.e., abrupt and complete shut-down of the IKZF1 activity) in Ik6-positive Ph+ALL cells in a neddylation-dependent manner. The functional IKZF3 isoforms expression was also abruptly and markedly downregulated. The LEN treatment specifically suppressed proliferation of Ik6-positive-Ph+ALL cells by inducing cell cycle arrest via downregulation of cyclins D3 and E and CDK2, and of importance, markedly upregulated their apoptosis in synergy with the TKI imatinib (IM). Apoptosis of IM-resistant Ph+ALL cells with T315I mutation of BCR-ABL was also upregulated by LEN in the presence of the newly developed TKI ponatinib. Analyses of flow cytometry, western blot, and oligonucleotide array revealed that apoptosis was caspase-/p53-dependent and associated with upregulation of pro-apoptotic Bax/Bim, enhanced dephosphorylation of BCR-ABL/Akt, and downregulation of oncogenic helicase genes HILLS, CDC6, and MCMs4 and 8. Further, the synergism of LEN with IM was clearly documented as a significant prolongation of survival in the xenograft mice model. Because this synergism was further potentiated in vitro by dexamethasone, a key drug for ALL treatment, the strategy of repositioning IMiDs for the treatment of Ik6-positive Ph+ALL patients certainly shed new light on an outpatient-based treatment option for achieving their long-term durable remission and higher QOL, particularly for those who are not tolerable to intensified therapeutic approaches.

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.

Allogeneic hematopoietic stem cell transplantation in adult acute lymphoblastic leukemia: potential benefit of medium-dose etoposide conditioning

The outcomes of adult acute lymphoblastic leukemia (ALL) patients with chemotherapy or autologous hematopoietic stem cell transplantation (HSCT) are unsatisfactory. Therefore, allogeneic (allo) HSCT has been applied to those patients in first complete remission (CR1), and has shown a long-term survival rate of approximately 50 %. In terms of myeloablative conditioning (MAC) regimen, higher dose of cyclophosphamide (CY) and total body irradiation (TBI) (the standard CY + TBI) has been generally applied to allo HSCT. Other MAC regimens such as busulfan-based or etoposide-based regimens have also been used. Among those, medium-dose etoposide (ETP) in addition to the standard CY + TBI conditioning regimen appears to be promising for allo HSCT in adult ALL when transplanted in ALL patients aged under 50 years in CR1 and also in CR2, showing an excellent outcome without increasing relapse or transplant-related mortality (TRM) rates. By contrast, reduced-intensity conditioning (RIC) regimens have also been applied to adult ALL patients and favorable outcomes have been obtained; however, relapse and TRM rates remain high. Therefore, an allo HSCT conditioning regimen which deserves further study for adult ALL patients aged under 50 years in CR1 and CR2 appears to be medium-dose ETP + CY + TBI and RIC is suitable for patients aged over 50 years or for younger patients with comorbid conditions. On the contrary, new therapeutic strategies for adult ALL patients are increasingly utilized with better outcomes; namely, various tyrosine kinase inhibitors for Philadelphia chromosome (Ph)-positive ALL, human leukocyte antigen-haploidentical HSCT, and pediatric-inspired regimens for Ph-negative ALL. Therefore, the optimal treatment modality should be selected considering patient’s age, Ph-positivity, donor availability, risk classification, efficacy, and safety.

Haploidentical hematopoietic stem cell transplantation without in vitro T cell depletion for the treatment of philadelphia chromosome-positive acute lymphoblastic leukemia

The role of haploidentical related allogeneic hematopoietic stem cell transplantation (allo-HSCT) in Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph(+) ALL) is not clear. We aimed to investigate the long-term survival of Ph(+) ALL patients who underwent haploidentical donor (HID)-HSCT and to analyze the factors influencing relapse and survival after allo-HSCT. The study population included Ph(+) ALL patients who underwent haploidentical related allo-HSCT. Additionally, Ph(+) ALL patients who underwent HLA-matched related donor (MRD) transplants during the same period were included to compare outcomes. BCR-ABL transcript levels were analyzed by using real-time quantitative reverse transcription PCR. Clinical data from 139 Ph(+) ALL patients who received allo-HSCT in our center were analyzed. Of these patients, 101 received HID transplants and 38 received MRD transplants. At a median follow-up of 36 months, 5-year disease-free survival (DFS) and overall survival (OS) rates in the HID transplant group were 65.8% and 74.0%, respectively. The 5-year cumulative incidence of relapse (CIR) and nonrelapse mortality (NRM) rates for the HID transplant group were 20.3% and 15.6%, respectively. In addition, there were no differences in OS, DFS, CIR, and NRM between the HID and MRD groups. Multivariate analysis showed that imatinib resistance was a significant factor influencing DFS and CIR in HID transplant patients. Haploidentical HSCT for the treatment of Ph(+) ALL achieves promising long-term survival, which is comparable with that of HLA-MRD HSCT. Imatinib resistance is a negative predictor of relapse and DFS after allo-HSCT.

High incidence of severe acute graft-versus-host disease with tacrolimus and mycophenolate mofetil in a large cohort of related and unrelated allogeneic transplantation patients

Both acute and chronic graft-versus-host disease (GVHD) are major causes of morbidity and mortality in patients undergoing allogeneic hematopoietic stem cell transplantation (AHSCT). The optimal pharmacological regimen for GVHD prophylaxis is unclear, but combinations of a calcineurin inhibitor (cyclosporin or tacrolimus [Tac]) and an antimetabolite (methotrexate or mycophenolate mofetil [MMF]) are typically used. We retrospectively evaluated the clinical outcomes of 414 consecutive patients who underwent AHSCT from sibling (SD) or unrelated donors (UD) with Tac/MMF combination, between January 2005 and August 2010. The median follow-up was 60 months. Less than one third of the patients received a reduced-intensity chemoregimen. The incidence of grades III and IV acute GVHD was 22.3% and 36.5% in SD and UD groups, respectively (P = .0007). The incidence of chronic GVHD was 47.1% and 52.7% in the SD and UD groups, respectively. Nonrelapse mortality (NRM) at 60 months was 33.3% and 46.5% in the SD and UD groups, respectively (P = .0016). The incidence of relapse was 22.4% for UD and 28.8% for SD. Five-year overall survival was 43% and 34% in the SD and UD groups, respectively (P = .0183). GVHD was the leading cause of death for the entire cohort. Multivariable analysis showed that 8/8 HLA match, patient's age < 60, and low-risk disease were associated with better survival. The use of Tac/MMF for GVHD prophylaxis was associated with a relatively high incidence of severe acute GVHD and NRM in AHSCT from sibling and unrelated donors.

Phase II trial of hyper CVAD and dasatinib in patients with relapsed Philadelphia chromosome positive acute lymphoblastic leukemia or blast phase chronic myeloid leukemia

Dasatinib is a second generation tyrosine kinase inhibitor, with activity in imatinib resistant Ph-positive ALL.We have treated 34 patients with relapsed Philadelphia chromosome positive acute lymphoblastic leukemia(ALL) (n519) or lymphoid blast phase of chronic myelogenous leukemia (CML-LB) (n515) with the combination of dasatinib and the hyper CVAD regimen. Prior regimens included hyper CVAD plus imatinib(n511, 4 had transplant in first CR), other combination chemotherapy (n512), monotherapy with kinase inhibitors other than dasatinib (n59), and investigational agents (n52). Pretreatment ABL mutations were noted in 10 patients. The overall response rate was 91%, with 24 patients (71%) achieving complete response(CR), and 7(21%) CR with incomplete platelet recovery (CRp). Two patients died during induction and one had progressive disease. Twenty-six patients (84%) achieved complete cytogenetic remission after one cycle of therapy. Overall, 13 patients (42%) achieved complete molecular response, and 11 patients (35%) had major molecular response (BCR-ABL/ABL<0.1%). Nine patients proceeded to allogeneic transplantation.Grades 3 and 4 toxicities included hemorrhage, pleural and pericardial effusions and infections. The median follow-up for patients with CML-LB is 37.5 months (range, 7–70 months) with a 3-year overall survival of 70%;68% remained in CR at 3 years. For ALL patients, the median follow-up is 52 months (range, 45–59 months)with a 3-year survival of 26%; 30% remain in CR at 3 years. The combination of Hyper CVAD regimen with dasatinib is effective in patients with relapsed Ph-positive ALL and CML-LB.

Stable long-term pulmonary function after fludarabine, antithymocyte globulin and i.v. BU for reduced-intensity conditioning allogeneic SCT

Lung function decline is a well-recognized complication following allogeneic SCT (allo-SCT). Reduced-intensity conditioning (RIC) and in vivo T-cell depletion by administration of antithymocyte globulin (ATG) may have a protective role in the occurrence of late pulmonary complications. This retrospective study reported the evolution of lung function parameters within the first 2 years after allo-SCT in a population receiving the same RIC regimen that included fludarabine and i.v. BU in combination with low-dose ATG. The median follow-up was 35.2 months. With a median age of 59 years at the time of transplant, at 2 years, the cumulative incidences of non-relapse mortality was as low as 9.7%. The cumulative incidence of relapse was 33%. At 2 years, the cumulative incidences of extensive chronic GVHD (cGVHD) and of pulmonary cGVHD were 23.1% and 1.9%, respectively. The cumulative incidences of airflow obstruction and restrictive pattern were 3.8% and 9.6%, respectively. Moreover, forced expiratory volume (FEV1), forced vital capacity (FVC) and FEV1/FVC ratio remained stable from baseline up to 2 years post transplantation (P=0.26, P=0.27 and P=0.07, respectively). These results correspond favorably with the results obtained with other RIC regimens not incorporating ATG, and suggest that ATG may have a protective pulmonary role after allo-SCT.

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.

Outcomes of adults with active or progressive hematological malignancies at the time of allo-SCT: a survey from the Société Française de Greffe de Moelle et de Thérapie Cellulaire (SFGM-TC)

Previous data suggested that allo-SCT might be an effective therapy in the setting of chemo-refractory/relapsed diseases because of the potent long-term immune-mediated tumor control. This retrospective study aimed to analyze the outcome of adult patients who received allo-SCT in a chemo-refractory/relapsed status. The series included 840 patients with active or progressive disease at the time of transplant. Median age was 50 years. With a median follow-up of 40 months, 3-year OS, disease-free survival (DFS), and non-relapse mortality rates were 29±2, 23±2, and 30±2%, respectively. At the last follow-up, 252 patients (30%) were still alive (of whom 201 were in CR (24%). In a Cox multivariate analysis, the use of a reduced-intensity conditioning (RIC) before allo-SCT and use of an HLA-identical sibling donor remained independently associated with a better OS (hazard ratio (HR)=0.82; 95% confidence interval (CI), 0.69-0.98, P=0.03; and HR=0.79; 95% CI, 0.66-0.93, P=0.006, respectively). Also, a diagnosis of myelodysplastic syndrome/myeloproliferative disorder, Hodgkin lymphoma and non-Hodgkin lymphoma compared with acute leukemia had a favorable impact on OS (HR=0.55; 95% CI, 0.45-0.68, P<0.0001; HR=0.49; 95% CI, 0.31-0.75, P=0.001; and HR=0.47; 95% CI, 0.35-0.63, P<0.0001, respectively). In conclusion, this study suggests that allo-SCT may be of benefit in some subgroups of patients with active or progressive hematological malignancies at the time of allo-SCT.

Clinical outcome of hematopoietic stem cell transplantation for Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph + ALL): experience from a single institution

To identify factors affecting transplant outcome, data from 65 Philadelphia Chromosome-positive acute lymphoblastic leukemia (Ph + ALL) patients who had undergone allogeneic hematopoietic transplantation (allo-HSCT) in our institution were analyzed. The probability of OS (overall survival) and DFS (disease free-survival) at 3 years after allo-HSCT was 40.1% and 38%, respectively. Multivariate analysis showed that gender and disease status (p = 0.0059, p = 0.0039, respectively) were significant factors for OS. Among 51 patients with CR (complete remission), multivariate analysis showed that the factors associated with OS included gender (p = 0.014), number of white blood cell at diagnosis (p = 0.025), and the source of stem cells (bone marrow <BM > versus cord blood; BM stem cell source was associated with favorable OS, p = 0.042). Twenty-one patients relapsed after allo-HSCT with a median of 207 days (range, 19-1,324 days). The estimated cumulative incidence of relapse at 3 years was 39.4%. Patients with CR showed a lower relapse rate at 3 years (34.2%) when compared with patients with non-CR (62.7%). Among 21 patients, eight patients received imatinib-based chemotherapy and 13 received chemotherapy without imatinib before HSCT. In terms of treatment after relapse, seven patients received chemotherapy with imatinib and 13 received chemotherapy without imatinib. Five patients underwent a second HSCT. One patient survived, and 20 patients died. In this study, disease status at time of allo-HSCT had a significant impact on OS, DFS, and relapse. Imatinib administration given before allo-HSCT was not associated with favorable outcome. Second-generation tyrosine kinase inhibitors may be more suitable candidates for Ph + ALL before and after allo-HSCT.

Randomized comparison of prophylactic and minimal residual disease-triggered imatinib after allogeneic stem cell transplantation for BCR-ABL1-positive acute lymphoblastic leukemia

Minimal residual disease (MRD) after allogeneic stem cell transplantation (SCT) for Ph+ acute lymphoblastic leukemia (ALL) is predictive of relapse. Imatinib administration subsequent to SCT may prevent relapse, but the role of scheduling and its impact on outcome are not known. In a prospective, randomized multicenter trial, we compared the tolerability and efficacy of post-transplant imatinib administered either prophylactically (arm A; n=26) or following detection of MRD (arm B; n=29). Prophylactic imatinib significantly reduced the incidence of molecular recurrence after SCT compared with MRD-triggered imatinib (40% vs 69%; P=0.046). Median duration of PCR negativity was 26.5 and 6.8 months, respectively (P=0.065). Five-year survival in both interventional groups was high (80 and 74.5%), despite premature discontinuation of imatinib in the majority of patients because of poor tolerability. Relapse probability was significantly higher in patients who became MRD positive (P=0.017). In conclusion, post-transplant imatinib results in a low relapse rate, durable remissions and excellent long-term outcome in patients with BCR-ABL1-positive ALL irrespective of whether it is given prophylactically or MRD-triggered. Reappearance of BCR-ABL1 transcripts early after SCT or at higher levels identifies a small subset of patients who do not benefit sufficiently from imatinib, and in whom alternative approaches should be explored.

Long-term follow-up of allogeneic hematopoietic stem cell transplantation for patients with Philadelphia chromosome-positive acute lymphoblastic leukemia: impact of tyrosine kinase inhibitors on treatment outcomes

The introduction of tyrosine kinase inhibitors (TKI) has revolutionized therapy for patients with acute lymphoblastic leukemia (ALL) who have the Philadelphia (Ph) chromosome. A retrospective analysis was conducted on 102 adults and 11 children who received a first-matched related (n = 60), matched unrelated (n = 40), mismatched cord blood (n = 12), or haploidentical (n = 1) allogeneic hematopoietic stem cell transplantation (HSCT) for Ph-positive (Ph+) ALL in first complete remission (n = 71), second complete remission (n = 11), or with active disease (n = 31) between 1990 and 2009. Sixty-seven patients received TKI with upfront ALL therapy, and 32 patients received TKI maintenance following HSCT. With median follow-up of 5 years among survivors (range: 1.1-20.4 years), overall survival (OS) was significantly better for patients transplanted in first remission compared with HSCT in advanced disease: 43% versus 16%, P = .002. Disease stage and age at time of HSCT, the development of acute graft-versus-host disease (aGVHD), and decade of HSCT were found to significantly impact OS, progression-free survival (PFS), and nonrelapse mortality (NRM) in multivariate analyses. Allogeneic HSCT provides durable remission for patients with Ph+ ALL in first remission. Neither TKI use pre- nor post-HSCT were found to significantly impact transplant outcomes in univariate and multivariate analyses.

The role of cytotoxic therapy with hematopoietic stem cell transplantation in the treatment of adult acute lymphoblastic leukemia: update of the 2006 evidence-based review

Clinical research published since the first evidence-based review on the role of hematopoietic stem cell transplantation (SCT) in the treatment of acute lymphoblastic leukemia (ALL) in adults is presented and critically evaluated in this update. Treatment recommendations changed or modified based on new evidence include: (1) myeloablative allogeneic SCT is an appropriate treatment for adult (<35 years) ALL in first complete remission for all disease risk groups; and (2) reduced-intensity conditioning may produce similar outcomes to myeloablative regimens. Treatment recommendations unchanged or strengthened by new evidence include: (1) allogeneic SCT is recommended over chemotherapy for ALL in second complete remission or greater; (2) allogeneic is superior to autologous SCT; and (3) there are similar survival outcomes after related and unrelated allogeneic SCT. New treatment recommendations based on new evidence include: (1) in the absence of a suitable allogeneic donor, autologous SCT may be an appropriate therapy, but results in a high relapse rate; (2) it is appropriate to consider cord blood transplantation for patients with no HLA well-matched donor; and (3) imatinib therapy before and/or after SCT (for Ph+ ALL) yields significantly superior survival outcomes. Areas of needed research in the treatment of adult ALL with SCT were identified and presented in the review.

Fludarabine and pharmacokinetic-targeted busulfan before allografting for adults with acute lymphoid leukemia

We aimed to evaluate the safety and efficacy of fludarabine (FLU) and pharmacokinetic-targeted busulfan (BU) as conditioning regimen for hematopoietic cell transplantation (HCT) in adult patients with acute lymphoid leukemia (ALL). Forty-four patients with ALL (27 in first complete remission [CR1] and 17 in more advanced disease stage: 4 with primary induction failure [PIF], 12 in CR2, and 1 in CR3) received FLU and pharmacokinetic-targeted BU as preparative therapy for HCT. Grafts were T-replete, filgrastim-mobilized peripheral blood stem cells (PBSC). Graft-versus-host disease (GVHD) prophylaxis consisted of tacrolimus (TAC) and short-course methotrexate in 36 patients, TAC and sirolimus in 3, and TAC and mycophenolate mofetil in 5. Primary engraftment was achieved in all 44 patients. The cumulative incidence of transplant-related mortality (TRM) was 2% (95% confidence interval [CI] 0%-16%) at 100 days and 18% (95% CI 10%-34%) at 2 years. The 2-year cumulative incidence of relapse was 19% (95% CI 8%-41%) for those transplanted in CR1, and 48% (29%-80%) for those with more advanced disease. After a median follow-up of 32 months (range: 15-69 months), the 2-year overall survival (OS) was 54% (95% CI 39%-69%). Relapse-free survival (RFS) at 2 years was 63% (95% CI 45%-81%) for patients transplanted in CR1 and 34% (95% CI 11%-57%) for patients transplanted in more advanced disease. When compared to irradiation-containing regimens, FLU and PK-targeted BU appear safer and similarly effective in controlling ALL, providing a treatment option for adult patients with ALL.

Philadelphia chromosome-positive acute lymphoblastic leukemia: current treatment and future perspectives

The Philadelphia chromosome (Ph) is the most common cytogenetic abnormality associated with adult acute lymphoblastic leukemia (ALL). Before the advent of tyrosine kinase inhibitors (TKIs), Ph-positive ALL carried a dismal prognosis and was characterized by a poor response to most chemotherapy combinations, short remission durations, and poor survival rates. Outcomes for patients with Ph-positive ALL improved substantially with the introduction of TKIs, and the TKI imatinib induced complete remissions in >95% of patients with newly diagnosed Ph-positive ALL when it was combined with chemotherapy. However, imatinib resistance remains a problem in a substantial proportion of patients with Ph-positive ALL, and multiple molecular mechanisms that contribute to imatinib resistance have been identified. Second-generation TKIs (eg, dasatinib and nilotinib) have demonstrated promising efficacy in the treatment of imatinib-resistant, Ph-positive ALL. Future strategies for Ph-positive ALL include novel, molecularly targeted treatment modalities and further evaluations of TKIs in combination with established antileukemic agents. For this article, the authors reviewed past, current, and future treatment approaches for adult and elderly patients with Ph-positive ALL with a focus on TKIs and combined chemotherapeutic regimens.

Allogeneic stem cell transplantation for adult Philadelphia chromosome-negative acute lymphocytic leukemia: comparable survival rates but different risk factors between related and unrelated transplantation in first complete remission

To identify factors to improve the outcomes of related and unrelated allogeneic stem cell transplantations (allo-SCT) for Philadelphia chromosome-negative acute lymphocytic leukemia (Ph(-) ALL) in the first complete remission (CR1), we retrospectively analyzed 1139 Ph(-) ALL patients using the registry data, particularly the details of 641 patients transplanted in CR1. Overall survival was significantly superior among patients transplanted in CR1, but no significant difference was observed between related and unrelated allo-SCTs (related vs unrelated: 65% vs 62% at 4 years, respectively; P = .19). Among patients transplanted in CR1, relapse rates were significantly higher in related allo-SCT compared with unrelated allo-SCT, and multivariate analysis demonstrated that less than 6 months from diagnosis to allo-SCT alone was associated with relapse. On the other hand, nonrelapse mortality (NRM) was significantly higher in unrelated allo-SCT compared with related allo-SCT, and multivariate analysis demonstrated that 10 months or longer from diagnosis to allo-SCT, human leukocyte antigen mismatch, and abnormal karyotype were associated with NRM. In conclusion, our study showed comparable survival rates but different relapse rates, NRM rates, and risk factors between related and unrelated allo-SCTs. After a close consideration of these factors, the outcome of allo-SCT for adult Ph(-) ALL in CR1 could be improved.

Hematopoietic stem cell transplantation for adults with acute lymphoblastic leukemia

PURPOSE OF REVIEW

The long-term survival for patients with adult acute lymphoblastic leukemia (ALL) has not significantly changed over the past two decades and, as opposed to pediatric ALL, it is less than 40% despite high initial complete remission rate. These observations raise several important issues regarding the pathobiology of adult leukemic stem cells, the ability of adults to tolerate intensive treatment and the best postremission approach.

RECENT FINDINGS

Progress has been made in understanding the biology of adult ALL and its prognostic significance. The follow-up of minimal residual disease status, adopting protocols from childhood ALL to young adults and use of targeted therapy may improve long-term survival. Transplantation for standard-risk ALL in first remission proved to be beneficial in a large cooperative group study. Limited data on the use of alternative donor transplantation as well as reduced intensity protocols are now available for consideration in specific groups of patients.

SUMMARY

Data suggest that the best antileukemic treatment should be applied in first remission and type of treatment should be based on individualized risk stratification, while incorporating recent information on alternative donors and reduced intensity approaches to transplantation.

Impact of tyrosine kinase inhibitors on patient outcomes in Philadelphia chromosome-positive acute lymphoblastic leukaemia

Acute lymphoblastic leukaemia (ALL) is a heterogeneous disease that is often associated with several chromosomal and molecular abnormalities. Patients who have the Philadelphia (Ph) chromosome and associated BCR-ABL1 oncogene have a particularly poor prognosis. Currently, allogeneic haematopoietic stem cell transplantation (allo-HSCT) is the only known curative treatment for Ph+ ALL and facilitating allo-HSCT in eligible patients is a key treatment goal. However, many patients relapse after allo-HSCT, particularly those with measurable residual disease prior to transplantation, and a significant percentage of patients are ineligible for allo-HSCT, particularly older patients. Hence, many patients require additional/alternative therapies to prolong survival. Studies are ongoing to determine the most effective first-line drug regimens for patients who subsequently undergo allo-HSCT and ineligible patients. Tyrosine kinase inhibitors targeted to Bcr-Abl are important novel therapies for Ph+ ALL. Although imatinib administered in combination with chemotherapy is established as the current first-line strategy, relapse is common, even among allo-HSCT recipients. Emerging data indicate that more potent multi-targeted kinase inhibitors (including dasatinib, nilotinib, and bosutinib) have promising efficacy in the first- or second-line setting. Here, the evidence base for existing drug treatments for Ph+ ALL is discussed and emerging therapeutic strategies are explored.

Prospective monitoring of BCR-ABL1 transcript levels in patients with Philadelphia chromosome-positive acute lymphoblastic leukaemia undergoing imatinib-combined chemotherapy

The clinical significance of minimal residual disease (MRD) is uncertain in patients with Philadelphia chromosome-positive acute lymphoblastic leukaemia (Ph+ ALL) treated with imatinib-combined chemotherapy. Here we report the results of prospective MRD monitoring in 100 adult patients. Three hundred and sixty-seven follow-up bone marrow samples, collected at predefined time points during a uniform treatment protocol, were analysed for BCR-ABL1 transcripts by quantitative reverse transcription polymerase chain reaction. Ninety-seven patients (97%) achieved complete remission (CR), and the relapse-free survival (RFS) rate was 46% at 3 years. Negative MRD at the end of induction therapy was not associated with longer RFS or a lower relapse rate (P = 0.800 and P = 0.964 respectively). Twenty-nine patients showed MRD elevation during haematological CR. Of these, 10 of the 16 who had undergone allogeneic haematopoietic stem cell transplantation (HSCT) in first CR were alive without relapse at a median of 2.9 years after transplantation, whereas 12 of the 13 who had not undergone allogeneic HSCT experienced a relapse. These results demonstrate that, in Ph+ ALL patients treated with imatinib-combined chemotherapy, rapid molecular response is not associated with a favourable prognosis, and that a single observation of elevated MRD is predictive of subsequent relapse, but allogeneic HSCT can override its adverse effect.

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.

Recent advances in the treatment of Philadelphia chromosome-positive acute lymphoblastic leukemia

The advent of imatinib, a selective inhibitor of the ABL tyrosine kinase, has revolutionized the treatment of Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL). Combined with chemotherapy, imatinib exerts remarkable efficacy in patients with newly diagnosed disease with a complete remission (CR) rate of 95% and a survival rate of 55% at 3 years. Profound eradication of leukemia cells not only provides patients with a better chance for receiving allogeneic hematopoietic stem cell transplantation during first CR but also contributes to durable CR even without transplantation. Despite such improvement, however, relapse does occur, mainly owing to acquisition of resistance. Growing comprehension of the molecular mechanisms of resistance to imatinib has led to the development of novel BCR-ABL inhibitors that yield higher affinity for BCR-ABL and/or potent inhibitory activity against other target molecules such as SRC family kinases. The second-generation ABL kinase inhibitors, namely dasatinib and nilotinib, are already showing clinical activity in patients with imatinib-resistant Ph+ ALL, and other novel agents are undergoing preclinical and early clinical evaluation. Further improvement in treatment results will be achieved by identifying each patient's disease profile based on information obtained before and during treatment and by optimizing subsequent treatment accordingly.

Modified donor lymphocyte infusion after HLA-mismatched/haploidentical T cell-replete hematopoietic stem cell transplantation for prophylaxis of relapse of leukemia in patients with advanced leukemia

We evaluated the safety and efficacy of donor lymphocyte infusion (DLI) with granulocyte colony-stimulating factor priming and short-term immunosuppressive agents for prophylaxis of relapse in patients with advanced leukemia after human leukocyte antigen (HLA)-mismatched T cell-replete hematopoietic stem cell transplantation (HCT). Twenty-nine patients received prophylactic DLI at a median 75 (33-120) days after HCT. Acute graft-vs-host disease (GVHD) grades 3-4 occurred in six patients, and all cases were controlled. Eleven patients were alive and relapse-free with a probability of leukemia-free survival (LFS) of 37.3 +/- 9.6% at 3 years. Chronic GVHD was associated with a lower relapse rate and higher probability of LFS. Prophylactic-modified DLI is feasible in patients with advanced leukemia to prevent relapse after HLA-mismatched HCT.

Long-term remission of Philadelphia chromosome-positive acute lymphoblastic leukemia after allogeneic hematopoietic cell transplantation from matched sibling donors: a 20-year experience with the fractionated total body irradiation-etoposide regimen

Allogeneic hematopoietic cell transplantation (HCT) is the only known curative modality for patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph(+) ALL). Sixty-seven patients with HLA-matched sibling donors received fractionated total body irradiation (FTBI) and high-dose VP16, whereas 11 patients received FTBI/VP16/cyclophosphamide, and 1 patient received FTBI/VP16/busulfan. The median age was 36 years. At the time of HCT, 49 patients (62%) were in first complete remission (CR1) and 30 patients (38%) were beyond CR1 (> CR1). The median follow-up was 75 months (range, 14-245 months). The 10-year overall survival for the CR1 and beyond CR1 patients was 54% and 29% (P = .01), respectively, and event-free survival was 48% and 26% (P = .02), respectively. There was no significant difference in relapse incidence (28% vs 41%, P = .28), but nonrelapse mortality was significantly higher in the beyond CR1 patients, (31% vs 54%, P = .03, respectively). By univariate analysis, factors affecting event-free and overall survival were white blood cell count at diagnosis (< 30 x 10(9)/L vs > 30 x 10(9)/L) and disease status (CR1 vs > CR1). The median time to relapse for CR1 and for beyond CR1 patients was 12 months and 9 months, respectively. Our results indicate that FTBI/VP16 with or without cyclophosphamide confers long-term survival in Ph(+) ALL patients and that disease status at the time of HCT is an important predictor of outcome.

Diffusion capacity predicts long-term survival after allogeneic bone marrow transplantation for acute lymphoblastic leukemia

BACKGROUND

The aim of this study was to evaluate changes in pulmonary function measures as predictors of outcome in acute lymphoblastic leukemia (ALL) patients after myeloablative allogeneic bone marrow transplantation (BMT).

METHODS

Forced expiratory volume in 1 second (FEV1) and diffusion capacity for carbon monoxide (DLCO) were evaluated before and after allogeneic BMT every 3 months in 32 patients who survived for at least 100 days. General case histories were also examined.

RESULTS

Univariate analysis revealed that decreased post-BMT DLCO was associated with increased overall and event-free survival (p < 0.05). While a pre-BMT FEV1 of < 70% was associated with significantly decreased overall survival (p < 0.05), multiple regression analysis indicated that patients without cytomegalovirus (CMV) infection, having limited chronic graft-versus-host disease (GVHD) and with markedly decreased DLCO had better overall survival (p < 0.05). After adjusting for age, gender, chronic GVHD, and CMV infection, patients with decreased DLCO exhibited enhanced overall survival. Two-year survival and event-free survival rates were significantly higher in patients with decreased DLCO.

CONCLUSION

We conclude that DLCO may be a good long-term predictor of outcome in patients with ALL following BMT.

Hematopoietic stem cell transplantation in Australia and New Zealand, 1992-2004

The Australasian Bone Marrow Transplant Recipient Registry (ABMTRR) commenced collecting data on hematopoietic stem cell transplantation (HSCT) in 1992, and by 2004 had accrued more than 12,000 transplant records from 44 centers. In 2004 the Australian annual per capita autograft activity rate was almost twice that of New Zealand (381 per 10 million compared to 195), whereas the 2 countries had similar allografting activity rates (Australia 145, New Zealand 133). The annual rates of allogeneic HSCT per 10 million population in Australia and New Zealand in 2004 were similar to those in European countries of comparable socioeconomic status. Among the most prominent trends between 1998 and 2004 were increases in the numbers of allogeneic HSCT using peripheral blood stem cells (PBSC), the emergence of reduced intensity conditioning in allogeneic HSCT, increases in numbers of autologous HSCT for recipients aged 60 and over, increases in allogeneic HSCT with unrelated donors, and decreases in numbers of allogeneic HSCT for chronic myelogenous leukemia and autologous HSCT for breast cancer. The cumulative incidence of transplant-related mortality (TRM) at 100 days posttransplant progressively fell over the years 1992 to 2003 and was 8.1% for allogeneic HSCT and 1.1% for autologous HSCT in 2003. The ABMTRR is a valuable data resource providing timely and accurate information on HSCT activity in Australia and New Zealand. Full enumeration of HSCT activity in the 2 countries by the ABMTRR enhances its value in clinical planning and management.

Allogeneic transplantation for adult acute leukemia in first and second remission with a novel regimen incorporating daily intravenous busulfan, fludarabine, 400 CGY total-body irradiation, and thymoglobulin

A myeloablative conditioning regimen incorporating daily intravenous busulfan, fludarabine, and 400 cGy total-body irradiation was given before allogeneic stem cell transplantation (SCT) to 64 adults with acute leukemia in first and second remission. Graft-versus-host disease (GVHD) prophylaxis included methotrexate, cyclosporine A, and rabbit antithymocyte globulin (Thymoglobulin). For 31 matched related (MRD) and 33 alternate donor (AD) SCT the incidence of acute GVHD grade II-IV was 11% +/- 6% versus 35% +/- 9% (P = .047), acute GVHD grade III-IV was 0% versus 10% +/- 6% (P = .09), and chronic GVHD was 40% +/- 9% versus 66% +/- 9% (P = NS), respectively. Overall transplant-related mortality (TRM) was 3% +/- 2%. Projected disease-free (DFS) and overall survival (OS) at 3 years for acute myelogenous leukemia (AML) (n = 36) are the same at 83% +/- 6%, and for acute lymphoblastic leukemia (ALL) (n = 28) are 65% +/- 10% and 78% +/- 8%, respectively. For MRD SCT DFS is 77% +/- 9%, OS 87% +/- 6%, for AD SCT the respective figures are 71% +/- 8% and 74% +/- 8%. OS and DFS in patients without and with high-risk features are 100% versus 71% +/- 7% (P = .007) and 88% +/- 8% versus 68% +/- 7% (P = .04), respectively. This combination appears relatively well tolerated, gives equivalent final outcomes from MRD and AD, and may be a reasonable alternative to conventional myeloablative regimens.

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.

Philadelphia chromosome positive acute lymphocytic leukemia: a new era of challenges

Significant advances in the treatment of Philadelephia chromosome (Ph)- or BCR-ABL-positive acute lymphocytic leukemia (ALL) have been made since the discovery of the selective ABL tyrosine kinase inhibitors (TKIs). Whereas the outcome with standard chemotherapy was previously dismal, incorporation of imatinib mesylate into frontline therapy has improved relapse-free and overall survival. The benefit of imatinib extends particularly to instances where allogeneic stem cell transplantation in first complete remission is prohibited by older age, comorbidities, or lack of a suitable donor. However, the emergence of resistance to imatinib presents new therapeutic challenges. The development of novel TKIs with enhanced inhibitory potency against ABL and other kinases may further improve on the results observed with imatinib. Optimal use of these novel agents in the treatment schema of Ph(+) ALL will be paramount in ensuring continued success in the eradication of this disease. Herein, the new approaches to the management of Ph(+) ALL are reviewed.

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.