Post-remission treatment for adult patients with acute lymphoblastic leukemia in first remission: is there a role for autologous stem cell transplantation?

Allogeneic stem cell transplantation (alloSCT) or autologous SCT (autoSCT) and intensive consolidation/intensification courses plus maintenance chemotherapy for 1 to 2 years are currently the major options for post-remission treatment of adult patients with acute lymphoblastic leukemia (ALL) in first remission. Comparison of their value with respect to relapse prevention, disease-free survival, and overall survival has been impossible until recently when the results of several randomized trials became available. Herein, we try to dissect data from these randomized trials to evaluate the role of autoSCT in patients with ALL in complete remission. Five prospectively randomized trials were found in which patients with a family donor were eligible for an alloSCT and the remaining patients were randomized between autoSCT and continuation chemotherapy. In addition, in two prospectively randomized trials all patients with a donor were eligible for an alloSCT and the remaining patients were eligible for autoSCT. Using intention to treat, in the majority of ALL studies alloSCT is superior to autoSCT or intensive continuation chemotherapy. It still has to be determined which subgroups of ALL benefit most of allogeneic transplantation, since in some trials the advantage of allogeneic transplantation was confined to the standard-risk ALL patients and in other trials to the high-risk patients. With respect to the role of autoSCT compared to continuation chemotherapy, both treatment modalities show equal, although for high-risk ALL inferior, overall survival chances. In one large trial the disease-free survival in the autoSCT arm was inferior to that in the chemotherapy arm. This finding may eventually have an impact on the overall survival rate. Currently, the main benefit of autoSCT may be its short duration compared with the continuation chemotherapy regimen.     

Measurable residual disease in acute lymphoblastic leukemia: How low is low enough?

Quantification of measurable residual disease (MRD) in acute lymphoblastic leukemia (ALL) is a well-established clinical tool used to risk stratify patients during the course of chemotherapy, immunotherapy, and/or transplant therapy. As technologies evolve, the sensitivity for quantifying exceptionally low disease burden using either next generation sequencing (NGS) or next generation flow cytometry (NGF) has improved. It is now possible to detect MRD and quantify it precisely in patients who would previously have been deemed MRD negative by older, lower sensitivity methods. Persistence or recurrence of ALL disease burden above 10^?4 (0.01%) is accepted as the minimum threshold for making clinical decisions, but with NGS and NGF, clinicians now confront decision-making with disease burdens sometimes quantified to as low as 10^?6 (0.0001%, or one leukemia cell in a million leukocytes). Emerging data suggest these higher sensitivity methods are superior for identifying patients at lowest risk for relapse, but it remains controversial whether to institute therapies such as blinatumomab or chimeric antigen receptor (CAR)-T cells or move patients to allogeneic hematopoietic cell transplant (alloHCT) when they have quantifiable disease burden less than 10^?4. With additional evidence to facilitate integration of highly sensitive MRD quantification into clinical care and to contextualize MRD within the genotype of individual patients, it will likely be increasingly possible to identify patients able to avoid alloHCT and potentially even de-escalate therapy.     

Acute lymphoblastic leukemia in older adults: curtain call for conventional chemotherapy?

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Could intensified treatment in childhood acute lymphoblastic leukemia improve outcome independently of risk factors?

PURPOSE: Many risk-directed therapeutic protocols have been proposed in acute lymphoblastic leukemia (ALL). However, the relapse rates remain high. The effectiveness of each protocol depends on how quickly the clearance of blast cells is achieved. In an attempt to improve survival, by minimizing treatment toxicity and relapse rate, different therapeutic protocols were used every 3 yr in our Unit. PATIENTS AND METHODS: During 1991-2000, 132 children with ALL were diagnosed in our Unit. Modified and intensified NY II and BFM protocols, in three consecutive periods [(Hematology/Oncology Pediatric Department of the University of Athens) HOPDA-91, HOPDA-94, HOPDA-97] were used. RESULTS: At a median follow-up time of 96 months, the 8-year overall survival (OS) was 88% +/- 3%, whereas the event-free survival (EFS) was 85% +/- 3%. There was a significant increase of the 5-year EFS of the high-risk (HR) group through time (65% in HOPDA-91 vs. 80% in HOPDA-97), whereas EFS of the low risk (LR) group in HOPDA-97 was 96%. Five cases relapsed (3.8%), four of which underwent successful bone marrow transplantation. Fifteen children died (13 diagnosed by 1996, two in the last 4 yr). CONCLUSION: Modification of the protocols significantly improved survival in both HR and LR groups. The intensified regimen in the LR group did not increase the adverse toxic events, but on the contrary was extremely effective.     

Minimal residual disease before and after transplantation for childhood acute lymphoblastic leukaemia: is there any room for intervention?

Eighty‐two children and adolescents who underwent allogeneic transplantation for acute lymphoblastic leukaemia in remission (period 2001–2011, median follow‐up 4·9 years) had been assessed for minimal residual disease (MRD) by real‐time quantitative polymerase chain reaction before and at 1, 3, 6, 9 and 12 months after transplantation. Five‐year event‐free survival (EFS) and cumulative incidence of relapse were 77·7% [standard error (SE) 5·7] and 11·4% (SE 4·4), respectively, for patients with pre‐transplant MRD <1 × 10^?4 (68%), versus 30·8% (SE 9·1; P < 0·001) and 61·5% (SE 9·5; P < 0·001), respectively, for those with MRD ≥1 × 10^?4 (32%). Pre‐transplant MRD ≥1 × 10^?4 was associated with a 9·2‐fold risk of relapse [95% confidence interval (CI) 3·54–23·88; P < 0·001] compared with patients with MRD <1 × 10^?4. Patients who received additional chemotherapy pre‐transplant to reduce MRD had a fivefold reduction of risk of failure (hazard ratio 0·19, CI 0·05–0·70, P = 0·01). Patients who experienced MRD positivity post‐transplant did not necessarily relapse (5‐year EFS 40·3%, SE 9·3), but had a 2·5‐fold risk of failure (CI 1·05–5·75; P = 0·04) if any MRD was detected in the first 100 d, which increased to 7·8‐fold (CI 2·2–27·78; P = 0·002) if detected after 6 months. Anticipated immunosuppression‐tapering according to MRD may have improved outcome, nevertheless all patients with post‐transplant MRD ≥1 × 10^?3 ultimately relapsed, regardless of immunosuppression discontinuation or donor‐lymphocyte‐infusion. In conclusion, MRD before transplantation had the strongest impact on relapse and MRD positivity after transplantation, mostly if detected early and at low levels, did not necessarily imply relapse. Additional intensified chemotherapy and modulation of immunosuppression may reduce relapse risk and improve ultimate outcome.     

Low expression of costimulatory molecules and mRNA for cytokines are important mechanisms of immunosuppression in acute lymphoblastic leukemia in children?

Mechanisms leading blasts of acute lymphoblastic leukemia to escape from immune surveillance are still unknown. Only few reports showed that ALL cells are inefficient antigen presenting cells. The aim of the study was to assess expression of critical costimulatory/adhesion molecules and mRNA for main pro- and anti-inflammatory cytokines in ALL cells. Children with B-cell precursor ALL (n=20) were prospectively enrolled into the study. Expression of costimulatory/adhesion molecules (CD1a, CD11c, CD40, CD54, CD80, CD83, CD86, CD123, HLA class I and II) was assessed by flow cytometry and mRNA for cytokines (IFN-gamma, IL-10, IL-4, TGF-beta) - with real-time PCR. Results: 1) high expression was observed for HLA I and II class, moderate for CD40, CD83, CD86 and low or no expression for CD80, CD54, CD1a, CD11c and CD123; 2) we found expression of mRNA for IFN-gamma, IL-10, IL-4 and TGF-beta in blasts cells (but not in all specimens). We noted relatively lower expression of all assessed cytokines comparing to T-cells obtained from healthy donors but interestingly expression for IL-10 was higher in normal B-cells than in blast cells, and IFN-gamma and IL-4 were not found in normal B-cells. In summary we suggest that ALL-blasts present low expression of costimulatory/adhesion molecules and mRNA for cytokines and this probably contribute to the absence of host T- cells stimulation to immune response.     

Allogeneic transplantation for patients with Philadelphia chromosome positive acute lymphoblastic leukemia: Is it imperative in the tyrosine kinase inhibitor era?

Before the advent of tyrosine kinase inhibitors (TKIs), Philadelphia chromosome positive acute lymphoblastic leukemia (Ph+ ALL) was associated with dismal survival without allogeneic hematopoietic stem cell transplantation (allo-HSCT). Recent evidence has demonstrated that the combination of TKI and chemotherapy can result in a high rate of complete remission, thereby enabling more patients to proceed to allo-HSCT. However, with more studies reporting non-inferior outcomes with TKI and chemotherapy combination without allo-HSCT, the need for allo-HSCT in Ph+ ALL has become less certain. This review summarizes evidence that will address the relevance of allo-HSCT in Ph+ ALL.     

What is the potential for thrombopoietic agents in acute leukemia?

In the 16 years since thrombopoietin was identified and cloned, much has been learned about its biochemistry, how it is regulated, and its involvement in a wide range of functions in a variety of cell lineages. The first generation of recombinant human thrombopoietins, rHuTPO and pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF), were shown to increase platelet counts in patients with immune thrombocytopenia, in platelet apheresis donors, and in patients receiving nonmyeloablative chemotherapy. Their effects in patients with acute myeloid leukemia (AML) showed no benefit at a wide range of doses and schedules. The two second-generation TPO mimetics approved by the US Food and Drug Administration (FDA) for the treatment of ITP, romiplostim and eltrombopag, are now being studied in a number of thrombocytopenic disorders including those due to chemotherapy and hepatitis C. Since romiplostim is comparable to the first-generation recombinant thrombopoietins, it may not be beneficial in AML treatment; however, given its novel mechanism of action, eltrombopag may be a TPO potentiator and if given at the proper time during chemotherapy, may enable AML patients to recover platelet counts sooner.     

Is there still a role for low-dose cytosine arabinoside in de novo acute myeloid leukemia in the elderly?

Summary Seventy-seven elderly patients (median age 72, range 59–85) with de novo AML were treated with lowdose Ara C (10 mg/m²/12 h over 21 days, for one or two courses). Thirteen (17%) achieved complete remission (CR), 16 (21%) partial remission (PR); 28 (35%) had resistant leukemia, and 20 (26%) early death or death during hypoplasia. Most (86%) of the patients had severe pancytopenia and 58% were hospitalized. Overall median survival was 3 months. Median duration of CR was 9 months. Five CR were longer than 1 year, and two were longer than 4 years. All but one PR were 9 months, and 12/16 were 4 months. Karnofsky index and karyotype (the latter performed for 52 patients) were the only significant prognostic factors of response to treatment (including CR + PR) and survival: poor response rate (8%) and survival (median 0.7 months) were found in patients with Karnofsky index < 60, compared with 44% and 4 months, respectively, in patients with Karnofsky index 60; likewise, patients with rearrangements of chromosome 5 and/or 7 or complex rearrangements had a response rate of 13% and median survival of 1.5 months, compared with 68% and 8 months, respectively, in patients with normal karyotype or single abnormalities (not involving chromosomes 5, 7, or 8). Patients with isolated trisomy 8 had a response rate of 37% but short median survival (2.5 months). Significantly longer survival was seen in responders. Our findings suggest that, overall, low-dose Ara C yields limited results in AML in the elderly. However, it could remain a useful option in elderly patients with AML who are not candidates for intensive chemotherapy (even with the support of growth factors), provided their general condition is not too altered and they do not have an unfavorable karyotype (i.e., rearrangements of chromosomes 5 or 7 or complex abnormalities).     

Regulatory T cells in acute myelogenous leukemia: is it time for immunomodulation?

The microenviroment of acute myelogenous leukemia (AML) is suppressive for immune effector cells. Regulatory T cells (Tregs) have been recognized as a contributor factor and may be recruited and exploited by leukemic cells to evade immunesurveillance. Studies have shown that the frequencies of marrow and blood Tregs are greater in patients with AML than in control patients. Although increased Tregs have been associated with a decreased risk of GVHD after allogeneic HCT and hence may impede the graft-versus-tumor effect, recent findings indicate that that this may not be the case. Because there is a need to improve outcomes of standard treatment (chemotherapy with or without allogeneic HCT) in AML, targeting Tregs present an outstanding opportunity in AML because discoveries may apply throughout its treatment. Here, we review data on the roles of Tregs in mediating immune system-AML interactions. We focused on in vitro, animal, and observational human studies of Tregs in AML biology, development, prognosis, and therapy in different settings (eg, vaccination and HCT). Manipulation of Tregs or other types of immunomodulation may become a part of AML treatment in the future.