Case-Based Review

Acute Myeloid Leukemia

2018 July/August;13(4):37-46

References

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31. Gardin C, Chevret S, Pautas C, et al. Superior long-term outcome with idarubicin compared with high-dose daunorubicin in patients with acute myeloid leukemia age 50 years and older. J Clin Oncol 2013;31:321–7.

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35. Burnett AK, Russell NH, Hills RK, et al. A randomized comparison of daunorubicin 90 mg/m² vs 60 mg/m² in AML induction: results from the UK NCRI AML17 trial in 1206 patients. Blood 2015;125:3878–85.

36. Devillier R, Bertoli S, Prebet T, et al. Comparison of 60 or 90 mg/m(2) of daunorubicin in induction therapy for acute myeloid leukemia with intermediate or unfavorable cytogenetics. Am J Hematol 2015;90:E29–30.

37. Pautas C, Merabet F, Thomas X, et al. Randomized study of intensified anthracycline doses for induction and recombinant interleukin-2 for maintenance in patients with acute myeloid leukemia age 50 to 70 years: results of the ALFA-9801 study. J Clin Oncol 2010;28:808–14.

38. Lowenberg B. Sense and nonsense of high-dose cytarabine for acute myeloid leukemia. Blood 2013;121:26–8.

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40. Stone RM, Mandrekar SJ, Sanford BL, et al. Midostaurin plus chemotherapy for acute myeloid leukemia with a FLT3 mutation. N Engl J Med 2017;377:454–64.

41. Jen EY, Ko CW, Lee JE, et al. FDA approval: Gemtuzumab ozogamicin for the treatment of adults with newly-diagnosed CD33-positive acute myeloid leukemia. Clin Cancer Res 2018; doi: 10.1158/1078-0432. CCR-17-3179.

42. Sievers EL, Larson RA, Stadtmauer EA, et al. Efficacy and safety of gemtuzumab ozogamicin in patients with CD33-positive acute myeloid leukemia in first relapse. J Clin Oncol 2001;19:3244–54.

43. Petersdorf SH, Kopecky KJ, Slovak M, et al. A phase 3 study of gemtuzumab ozogamicin during induction and postconsolidation therapy in younger patients with acute myeloid leukemia. Blood 2013;121:4854–60.

44. Burnett AK, Russell NH, Hills RK, et al. Addition of gemtuzumab ozogamicin to induction chemotherapy improves survival in older patients with acute myeloid leukemia. J Clin Oncol 2012;30:3924–31.

45. Castaigne S, Pautas C, Terre C, et al. Effect of gemtuzumab ozogamicin on survival of adult patients with de-novo acute myeloid leukaemia (ALFA-0701): a randomised, open-label, phase 3 study. Lancet 2012;379:1508–16.

46. Kantarjian HM, Thomas XG, Dmoszynska A, et al. Multicenter, randomized, open-label, phase III trial of decitabine versus patient choice, with physician advice, of either supportive care or low-dose cytarabine for the treatment of older patients with newly diagnosed acute myeloid leukemia. J Clin Oncol 2012;30:2670–7.

47. Dombret H, Seymour JF, Butrym A, et al. International phase 3 study of azacitidine vs conventional care regimens in older patients with newly diagnosed AML with >30% blasts. Blood 2015;126:291–9.

48. Welch JS, Petti AA, Miller CA, et al. TP53 and decitabine in acute myeloid leukemia and myelodysplastic syndromes. N Engl J Med 2016;375:2023–36.

49. Amadori S, Suciu S, Selleslag D, et al. Gemtuzumab ozogamicin versus best supportive care in older patients with newly diagnosed acute myeloid leukemia unsuitable for intensive chemotherapy: results of the randomized phase III EORTC-GIMEMA AML-19 trial. J Clin Oncol 2016;34:972–9.

50. Miyawaki S, Ohtake S, Fujisawa S, et al. A randomized comparison of 4 courses of standard-dose multiagent chemotherapy versus 3 courses of high-dose cytarabine alone in postremission therapy for acute myeloid leukemia in adults: the JALSG AML201 Study. Blood 2011;117:2366–72.

51. Schuurhuis GJ, Heuser M, Freeman S, et al. Minimal/measurable residual disease in AML: a consensus document from the European LeukemiaNet MRD Working Party. Blood 2018;131:1275–91.

52. Koreth J, Schlenk R, Kopecky KJ, et al. Allogeneic stem cell transplantation for acute myeloid leukemia in first complete remission: systematic review and meta-analysis of prospective clinical trials. JAMA 2009;301:2349–61.

53. Schlenk RF, Dohner K, Krauter J, et al. Mutations and treatment outcome in cytogenetically normal acute myeloid leukemia. N Engl J Med 2008;358:1909–18.

54. Pasquini MC, Logan B, Wu J, et al. Results of a phase III randomized, multi-center study of allogeneic stem cell transplantation after high versus reduced intensity conditioning in patients with myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML): Blood and Marrow Transplant Clinical Trials Network (BMT CTN) 0901. Blood 2015;126:LBA–8.

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56. Burnett AK, Goldstone A, Hills RK, et al. Curability of patients with acute myeloid leukemia who did not undergo transplantation in first remission. J Clin Oncol 2013;31:1293–301.

57. Ravandi F, Ritchie EK, Sayar H, et al. Vosaroxin plus cytarabine versus placebo plus cytarabine in patients with first relapsed or refractory acute myeloid leukaemia (VALOR): a randomised, controlled, double-blind, multinational, phase 3 study. Lancet Oncol 2015;16:1025–36.

58. Taksin AL, Legrand O, Raffoux E, et al. High efficacy and safety profile of fractionated doses of Mylotarg as induction therapy in patients with relapsed acute myeloblastic leukemia: a prospective study of the alfa group. Leukemia 2007;21:66–71.

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60. Fathi AT, DiNardo CD, Kline I, et al. Differentiation syndrome associated with enasidenib, a selective inhibitor of mutant isocitrate dehydrogenase 2: analysis of a phase 1/2 study. JAMA Oncol 2018;doi: 10.1001/jamaoncol.2017.4695.

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64. Marcucci G, Geyer S, Zhao W, et al. Adding KIT inhibitor dasatinib (DAS) to chemotherapy overcomes the negative impact of KIT mutation/over-expression in core binding factor (CBF) acute myeloid leukemia (AML): results from CALGB 10801 (Alliance) [abstract]. Blood 2014;124:8.

Induction Therapy

In patients who can tolerate intensive therapies, the role of anthracycline- and cytarabine-based treatment is well established. However, the choice of specific anthracycline is not well established. One study concluded that idarubicin and mitoxantrone led to better outcomes as compared to daunorubicin, while another showed no difference between these agents.^29,30 A pooled study of AML trials conducted in patients aged 50 years and older showed that while idarubicin led to a higher complete remission rate (69% versus 61%), the overall survival (OS) did not differ significantly.³¹ As for dosing, daunorubicin given at 45 mg/m² daily for 3 days has been shown to have lower complete remission rates and higher relapse rates than a dose of 90 mg/m² daily for 3 days in younger patients.^32–34 However, it is not clear whether the 90 mg/m² dose is superior to the frequently used dose of 60 mg/m².³⁵ A French study has shown comparable rates of complete remission, relapse, and OS between the 60 mg/m² and 90 mg/m² doses in patients with intermediate or unfavorable cytogenetics.³⁶

If idarubicin is used, a dose of 12 mg/m² for 3 days is considered the standard. In patients aged 50 to 70 years, there were no statistically significant differences in rates of relapse or OS between daunorubicin 80 mg/m² for 3 days versus idarubicin 12 mg/m² for 3 days versus idarubicin 12 mg/m² for 4 days.³⁷As for cytarabine, the bulk of the evidence indicates that a dose of 1000 mg/m² or higher should not be used.³⁸ As such, the typical induction chemotherapy regimen of choice is 3 days of anthracycline (daunorubicin or idarubicin) and 7 days of cytarabine (100–200 mg/m² continuous infusion), also known as the 7+3 regimen, which was first pioneered in the 1970s. In a recent phase 3 trial, 309 patients aged 60 to 75 years with high-risk AML (AML with myelodysplasia-related changes or t-AML) were randomly assigned to either the 7+3 regimen or CPX-351 (ie, nano-liposomal encapsulation of cytarabine and daunorubicin in a 5:1 molar ratio).³⁹A higher composite complete response rate (47.7% versus 33.3%; P = 0.016) and improved survival (9.56 months versus 5.95 months; hazard ratio [HR] 0.69, P = 0.005) were seen with CPX-351, leading to its approval by the FDA in patients with high-risk AML.

The 7+3 regimen has served as a backbone onto which other drugs have been added in clinical trials—the majority without any clinical benefits—for patients who can tolerate intensive therapy. In this context, the role of 2 therapies recently approved by the FDA must be discussed. In the RATIFY trial, 717 patients aged 18 to 59 years with AML and a FLT3 mutation were randomly assigned to receive standard chemotherapy (induction and consolidation therapy) plus either midostaurin or placebo; those who were in remission after consolidation therapy received either midostaurin or placebo in the maintenance phase.⁴⁰The primary endpoint was met as midostaurin improved OS (HR 0.78, P = 0.009). The benefit of midostaurin was consistent across all FLT3 subtypes and mutant allele burdens, regardless of whether patients proceeded to allogeneic stem cell transplant (allo-SCT). Based on the results of RATIFY, midostaurin was approved by the FDA for treatment of AML patients who are positive for the FLT3 mutation. Whether more potent and selective FLT3 inhibitors like gilteritinib, quizartinib, or crenolanib improve the outcomes is currently under investigation in various clinical trials.²⁰

The development of gemtuzumab ozogamicin (GO) has been more complicated. GO, an antibody-drug conjugate comprised of a CD33-directed humanized monoclonal antibody linked covalently to the cytotoxic agent calicheamicin, binds CD33 present on the surface of myeloid leukemic blasts and immature normal cells of myelomonocytic lineage.⁴¹ The drug first received an accelerated approval in 2000 as monotherapy (2 doses of 9 mg/m² 14 days apart) for the treatment of patients 60 years of age and older with CD33-positive AML in first relapse based on the results of 3 open-label multicenter trials.^41,42However, a confirmatory S0106 trial in which GO 6 mg/m² was added on day 4 in newly diagnosed AML patients was terminated early when an interim analysis showed an increased rate of death in induction (6% versus 1%) and lack of improvement in complete response, disease-free survival, or OS with the addition of GO.⁴³ This study led to the withdrawal of GO from the US market in 2010. However, 2 randomized trials that studied GO using a different dose and schedule suggested that the addition of GO to intensive chemotherapy improved survival outcomes in patients with favorable and intermediate-risk cytogenetics.^44,45 The results of the multicenter, open-label phase 3 ALFA-0701 trial, which randomly assigned 271 patients aged 50 to 70 years with newly diagnosed AML to daunorubicin and cytarabine alone or in combination with GO (3 mg/m² on days 1, 4, and 7 during induction and day 1 of 2 consolidation courses), showed a statistically significant improvement in event-free survival (17.3 months versus 9.5 months; HR 0.56 [95% confidence interval 0.42 to 0.76]).⁴⁵ Again, the survival benefits were more pronounced in patients with favorable or intermediate-risk cytogenetics than in those with unfavorable cytogenetics. The results of this trial led to the re-approval of GO in newly diagnosed AML patients.  

For patients who cannot tolerate intensive therapies, the 2 main therapeutic options are low-dose cytarabine (LDAC) and the hypomethylating agents (HMA) azacitidine and decitabine. A phase 3 trial of decitabine versus mostly LDAC (or best supportive care, BSC) demonstrated favorable survival with decitabine (7.7 months versus 5.0 months).⁴⁶ In the AZA-AML-001 trial, azacitidine improved median survival (10.4 months versus 6.5 months) in comparison to the control arm (LDAC, 7+3, BSC).⁴⁷ Emerging data has also suggested that HMAs may be particularly active in patients with unfavorable-risk AML, a group for which LDAC has been shown to be especially useless.⁴⁸As such, HMA therapies are generally preferred over LDAC in practice. Finally, it is pertinent to note that GO can also be used as monotherapy based on the results of the open-label phase 3 AML-19 study in which GO demonstrated a survival advantage over BSC (4.9 months versus 3.6 months, P = 0.005).⁴⁹