When Less Is More: Reevaluating the Role of Intensive Chemotherapy for Older Adults With Acute Myeloid Leukemia in the Modern Era

Impact of type of induction therapy on outcomes in older adults with AML after allogeneic stem cell transplantation

Although venetoclax-based lower-intensity regimens have greatly improved outcomes for older adults with acute myeloid leukemia (AML) who are unfit for intensive chemotherapy, the optimal induction for older patients with newly diagnosed AML who are suitable candidates for hematopoietic stem cell transplant (HSCT) is controversial. We retrospectively analyzed the post HSCT outcomes of 127 patients ≥60 years of age who received induction therapy at our institution with intensive chemotherapy (IC; n = 44), lower-intensity therapy (LIT) without venetoclax (n = 29), or LIT with venetoclax (n = 54) and who underwent allogeneic HSCT in the first remission. The 2-year relapse-free survival (RFS) was 60% with LIT with venetoclax vs 54% with IC, and 41% with LIT without venetoclax; the 2-year overall survival (OS) was 72% LIT with venetoclax vs 58% with IC, and 41% with LIT without venetoclax. The benefit of LIT with venetoclax induction was greatest in patients with adverse-risk AML (2-year OS: 74%, 46%, and 29%, respectively). Induction with LIT, with or without venetoclax, was associated with the lowest rate of nonrelapse mortality (NRM) (2-year NRM: 17% vs 27% with IC; P = .04). Using multivariate analysis, the type of induction therapy did not significantly affect any of the post HSCT outcomes evaluated; hematopoietic cell transplantation-specific comorbidity index was the only factor that independently predicted RFS and OS. LIT plus venetoclax followed by HSCT is a feasible treatment strategy in older, fit, HSCT-eligible patients with newly diagnosed AML and may be particularly beneficial for those with adverse-risk disease.

Hypomethylating agents for the treatment of myelodysplastic syndromes and acute myeloid leukemia: Past discoveries and future directions

Azacitidine and decitabine are hypomethylating agents that have dose-dependent epigenetic and cytotoxic effects and are widely used in the treatment of myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). In this review, we discuss the path to regulatory approval of azacitidine and decitabine, highlighting the substantial efforts that have been made to optimize the dosing schedule and administration of these drugs, including the development of new, oral formulations of both agents. We also review novel combination strategies that are being investigated in ongoing clinical trials for patients with MDS and AML, as well as efforts to expand the current indications of these agents.

Drug Resistance Mechanisms of Acute Myeloid Leukemia Stem Cells

Acute myeloid leukemia (AML) is a polyclonal and heterogeneous hematological malignancy. Relapse and refractory after induction chemotherapy are still challenges for curing AML. Leukemia stem cells (LSCs), accepted to originate from hematopoietic stem/precursor cells, are the main root of leukemogenesis and drug resistance. LSCs are dynamic derivations and possess various elusive resistance mechanisms. In this review, we summarized different primary resistance and remolding mechanisms of LSCs after chemotherapy, as well as the indispensable role of the bone marrow microenvironment on LSCs resistance. Through a detailed and comprehensive review of the spectacle of LSCs resistance, it can provide better strategies for future researches on eradicating LSCs and clinical treatment of AML.

Choosing between intensive and less intensive front-line treatment approaches for older patients with newly diagnosed acute myeloid leukaemia

The outcomes of older patients with acute myeloid leukaemia are inferior to their younger counterparts, because, in part, of a more aggressive disease biology and poorer tolerance of cytotoxic chemotherapy. Although intensive chemotherapy was historically considered the only effective treatment for these patients, many older patients are not suitable for intensive chemotherapy owing to comorbidities or general frailty. Determination of patient fitness for intensive chemotherapy is imperfect, and even older patients who appear to be suitable (also known as fit) for intensive chemotherapy can have high rates of morbidity and early and late mortality with this approach. Fortunately, the outcomes of older or unfit patients with acute myeloid leukaemia have substantially improved with the use of a hypomethylating agent plus venetoclax in the front-line setting. Although the formal approval of this combination is limited to patients aged 75 years or older, or those with a clinically significant comorbidity, the high response rates and survival improvement in these patients have led many practitioners to consider this low-intensity regimen in older patients without significant comorbidities and even in younger patients with high-risk disease features for whom the expected outcomes with intensive chemotherapy are poor. Modifications to the hypomethylating agent plus venetoclax backbone might further improve the outlook for these patients, particularly in some acute myeloid leukaemia subsets with a targetable mutation. In this Viewpoint, we review the retrospective and prospective data supporting both intensive chemotherapy and low-intensity venetoclax-based approaches in older patients with acute myeloid leukaemia. We also discuss our own approach to the management of older or unfit patients with acute myeloid leukaemia, including how cytomolecular features have a role in establishing the optimal front-line therapy.

Impact of frontline treatment approach on outcomes in patients with secondary AML with prior hypomethylating agent exposure

BACKGROUND

Treated secondary acute myeloid leukemia (ts-AML)-i.e., AML arising from a previously treated antecedent hematologic disorder-is associated with very poor outcomes. The optimal frontline treatment regimen for these patients is uncertain.

METHODS

We retrospectively analyzed 562 patients who developed AML from preceding myelodysplastic syndrome or chronic myelomonocytic leukemia for which they had received a hypomethylating agent (HMA). Patients with ts-AML were stratified by frontline AML treatment with intensive chemotherapy (IC, n = 271), low-intensity therapy (LIT) without venetoclax (n = 237), or HMA plus venetoclax (n = 54).

RESULTS

Compared with IC or LIT without venetoclax, HMA plus venetoclax resulted in higher CR/CRi rates (39% and 25%, respectively; P = 0.02) and superior OS (1-year OS 34% and 17%, respectively; P = 0.05). The benefit of HMA plus venetoclax was restricted to patients with non-adverse risk karyotype, where HMA plus venetoclax resulted in a median OS of 13.7 months and 1-year OS rate of 54%; in contrast, for patients with adverse risk karyotype, OS was similarly dismal regardless of treatment approach (median OS 3-5 months). A propensity score analysis accounting for relevant clinical variables confirmed the significant OS benefit of HMA plus venetoclax, as compared with other frontline treatment approaches. In a landmark analysis, patients with ts-AML who underwent subsequent hematopoietic stem cell transplantation (HSCT) had superior 3-year OS compared to non-transplanted patients (33% vs. 8%, respectively; P = 0.003).

CONCLUSIONS

The outcomes of ts-AML are poor but may be improved with use of an HMA plus venetoclax-based regimen, followed by HSCT, particularly in those with a non-adverse risk karyotype.