Long-term follow-up of the imatinib GRAAPH-2003 study in newly diagnosed patients with de novo Philadelphia chromosome-positive acute lymphoblastic leukemia: a GRAALL study

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.

Ph+ ALL patients in first complete remission have similar survival after reduced intensity and myeloablative allogeneic transplantation: impact of tyrosine kinase inhibitor and minimal residual disease

The efficacy of reduced intensity conditioning (RIC) allogeneic hematopoietic cell transplantation (HCT) for Philadelphia chromosome positive (Ph+) acute lymphoblastic leukemia (ALL) is uncertain. We analyzed 197 adults with Ph+ ALL in first complete remission; 67 patients receiving RIC were matched with 130 receiving myeloablative conditioning (MAC) for age, donor type and HCT year. Over 75% received pre-HCT tyrosine kinase inhibitors (TKIs), mostly imatinib; 39% (RIC) and 49% (MAC) were minimal residual disease (MRD)(neg) pre-HCT. At a median 4.5 years follow-up, 1-year transplant-related mortality (TRM) was lower in RIC (13%) than MAC (36%; P=0.001) while the 3-year relapse rate was 49% in RIC and 28% in MAC (P=0.058). Overall survival (OS) was similar (RIC 39% (95% confidence interval (CI) 27-52) vs 35% (95% CI 27-44); P=0.62). Patients MRD(pos) pre-HCT had higher risk of relapse with RIC vs MAC (hazard ratio (HR) 1.97; P=0.026). However, patients receiving pre-HCT TKI in combination with MRD negativity pre-RIC HCT had superior OS (55%) compared with a similar MRD population after MAC (33%; P=0.0042). In multivariate analysis, RIC lowered TRM (HR 0.6; P=0.057), but absence of pre-HCT TKI (HR 1.88; P=0.018), RIC (HR 1.891; P=0.054) and pre-HCT MRD(pos) (HR 1.6; P=0.070) increased relapse risk. RIC is a valid alternative strategy for Ph+ ALL patients ineligible for MAC and MRD(neg) status is preferred pre-HCT.

Emerging drugs for acute lymphocytic leukemia

INTRODUCTION

Acute lymphoblastic leukemia (ALL) is typically treated with complex multi-agent chemotherapy regimens over a prolonged time period. Long-term outcomes depend on the age of the patient and the biological characteristics of the leukemic cells. While pediatric patients achieve cure more often than adults, therapy can continue to be improved for all patients with this disease.

AREAS COVERED

The current management strategy for ALL is reviewed. Recently, targeted therapies have been shown to improve survival in subsets of patients, most notably in those with Philadelphia chromosome-positive ALL or with leukemic cells that express the surface antigen CD20. Several innovative compounds are under investigation, and the most promising ones to date will be discussed.

EXPERT OPINION

The incorporation of monoclonal antibody therapy represents a targeted and powerful approach to the management of ALL. Bispecific T-cell engaging agents, such as blinatumomab, are able to facilitate immune-mediated killing of leukemia cells. Immunoconjugates (i.e., monoclonal antibodies linked to various cytotoxins) allow small doses of very potent chemotherapy to be delivered directly to a leukemia cell with hope of sparing normal tissue. As the genetic and molecular characterization of ALL is more completely understood, patients will receive treatment plans that are more individualized than previously possible.

Acute lymphoblastic leukemia in adults: encouraging developments on the way to higher cure rates

Conventional cytotoxic chemotherapy for adult acute lymphoblastic leukemia (ALL) is not adequate to cure most patients of the disease. Complete remission is achieved in the majority of patients, but responses are often not durable. Allogeneic stem cell transplant is used for patients with high risk features, including those who are positive for minimal residual disease after induction and consolidation therapy. Nevertheless, transplant is a toxic intervention, and does not guarantee long-term disease-free survival. Monoclonal antibodies target surface antigens present on leukemic blasts, with the aim of minimizing off-target toxicity. Rituximab, an antibody directed against CD20, prolongs the survival of younger adults with ALL when added to chemotherapy in the frontline setting. Novel agents, such as the cytotoxin-antibody conjugate inotuzumab, and the bispecific T-cell engaging compound blinatumomab, have exhibited marked antileukemic activity in the relapsed setting. As these agents continue in clinical development, it will be important to eventually incorporate them in the frontline treatment approach. We review current strategies for treating adult ALL, with a focus on novel and targeted therapies that are under development.

Improving results of autologous stem cell transplantation for Philadelphia-positive acute lymphoblastic leukaemia in the era of tyrosine kinase inhibitors: a report from the Acute Leukaemia Working Party of the European Group for Blood and Marrow Transplantation

BACKGROUND

Outcome of Philadelphia-positive acute lymphoblastic leukaemia (Ph+ ALL) improved significantly with the introduction of tyrosine kinase inhibitors (TKIs). Autologous stem cell transplantation (ASCT) has never been considered a standard of care in this setting. The aim of our study was to analyse if results of ASCT improved in the era of TKIs.

PATIENTS AND METHODS

One-hundred and seventy-seven adults with Ph+ ALL treated with ASCT in first complete remission were analysed for the impact of year of transplantation on outcome. Additional analysis was performed including 32 patients for whom detailed data on the use of TKIs and the status of minimal residual disease were collected.

RESULTS

The probability of the overall survival (OS) at 3 years increased from 16% for transplants performed between 1996 and 2001 to 48% between 2002 and 2006 and 57% between 2007 and 2010 (P<.0001). Leukaemia-free survival (LFS) was 11%, 39% and 52%, respectively (P<.0001). Relapse incidence decreased from 70% to 45% and 45% (P=.01), respectively, while non-relapse mortality was 19%, 15% and 3% (P=.08). In a multivariate analysis, year of ASCT was the only independent factor influencing the risk of treatment failure (hazard ratio (HR)=0.37; P<.001). In a subgroup of 22 patients actually treated with TKIs and being in complete molecular remission at the time of ASCT, the LFS rate at 3 years was 65%.

CONCLUSIONS

Results of ASCT for Ph+ ALL improved significantly over time. Prospective, innovative studies are needed to verify the role of ASCT in this patient setting.

Role of tyrosine kinase inhibitors in the management of Philadelphia chromosome-positive acute lymphoblastic leukemia

The Philadelphia chromosome is the most common cytogenetic abnormality found in adult patients diagnosed with acute lymphoblastic leukemia. The result of this abnormality is the BCR-ABL protein, a constitutively active kinase involved in cell signaling and survival. When managed with multiagent chemotherapy regimens alone, patients have traditionally had an inferior outcome in terms of remission duration and overall survival when compared with patients who are Philadelphia chromosome-negative. Small-molecule tyrosine kinase inhibitors, such as imatinib and dasatinib, directly inhibit the BCR-ABL kinase, offering a targeted approach as a therapeutic option. As a result of several clinical trials with adequate follow-up, imatinib combined with chemotherapy represents the current standard of care for patients with newly diagnosed disease. Allogeneic stem cell transplantation has previously been the only modality to offer the potential for a cure, and it still should be considered for all patients deemed able to tolerate such an intervention. Second-generation tyrosine kinase inhibitors, such as dasatinib, may further improve the outcome in these patients. The role of molecular monitoring and the use of tyrosine kinase inhibitors after stem cell transplantation are areas of active investigation, and the results of ongoing trials will help to clarify the optimal management of these patients.