Is there a role for postremission therapy in older adults with acute myelogenous leukemia (AML)?

MRP4/ABCC4 expression is regulated by histamine in acute myeloid leukemia cells, determining cAMP efflux

Intracellular cAMP (i-cAMP) levels play an important role in acute myeloid leukemia (AML) cell proliferation and differentiation. Its levels are the result of cAMP production, degradation, and exclusion. We have previously described histamine H₂ receptors and MRP4/ABCC4 as two potential targets for AML therapy. Acting through histamine H₂ receptors, histamine increases cAMP production/synthesis, while MRP4/ABCC4 is responsible for the exclusion of this cyclic nucleotide. In this study, we show that histamine treatment induces MRP4/ABCC4 expression, augmenting cAMP efflux, and that histamine, in combination with MRP inhibitors, is able to reduce AML cell proliferation. Histamine, through histamine H₂ receptor, increases i-cAMP levels and induces MRP4 transcript and protein levels in U937, KG1a, and HL-60 cells. Moreover, histamine induces MRP4 promoter activity in HEK293T cells transfected with histamine H₂ receptor (HEK293T-H₂ R). Our results support that the cAMP/Epac-PKA pathway, and not MEK/ERK nor PI3K/AKT signaling cascades, is involved in histamine-mediated upregulation of MRP4 levels. Finally, the addition of histamine potentiates the inhibition of U937, KG1a, and HL-60 cell proliferation induced by MRP4 inhibitors. Our data highlight that the use of a poly-pharmacological approach aimed at different molecular targets would be beneficial in AML treatment.

Selecting initial treatment of acute myeloid leukaemia in older adults

More than half of the patients with acute myeloid leukaemia (AML) are older than 60years. The treatment outcomes in this group remain poor with a median overall survival of <1year. Selecting initial treatment for these patients involves an assessment of 'fitness' for induction chemotherapy. This is done based on patient and disease-related characteristics which help to estimate treatment-related mortality and chance of complete remission with induction chemotherapy. If the risk of treatment-related mortality is high and/or the likelihood of a patient achieving a complete remission is low, lower-intensity treatment (low-dose cytarabine, decitabine and azacitidine) should be discussed. As outcomes in both groups of patients remain poor, enrolment into clinical trials of novel agents with varying mechanisms of action should be considered for all older adults with AML. Novel agents in Phase III development include CPX-351, guadecitabine (SGI-110), quizartinib, crenolanib, sapacitabine, vosaroxin and volasertib.

Conventional chemotherapy or hypomethylating agents for older patients with acute myeloid leukaemia?

Acute myeloid leukaemia (AML) is the second more frequent hematologic malignancy in developed countries and primarily affects older adults with a median age at diagnosis of 69 years. Given the progressive ageing of the general population, the incidence of the disease in elderly people is expected to further increase in the years to come. Along with cytogenetics at diagnosis, age represents the most relevant prognostic factor in AML, in that the outcome steadily declines with increasing age. Reasons for poor prognosis include more frequent unfavourable karyotype and other adverse biologic characteristics, such as high rates of expression of genes drug resistance related and high prevalence of secondary AML. Noticeably, as compared with young adults, poorer results in elderly patients have been reported within any cytogenetic and molecular prognostic subgroup, because of frequent comorbid diseases, which render many patients ineligible to intensive chemotherapy. Therefore, predictive models have been developed with the aim of achieving best therapeutic results avoiding unnecessary toxicity. Following conventional induction therapy, older AML patients have complete remission rates in the range of 45-65%, and fewer than 10% of them survive for a minimum of 5 years. On the other hand, hypomethylating agents, such as azacytidine and decitabine offer the possibility of long-term disease control without necessarily achieving complete remission and can represent a reasonable alternative to intensive chemotherapy. Either intensive chemotherapy or hypomethylating agents have lights and shadows, and the therapeutic selection is often influenced by physician's and patient's attitude rather than definite criteria. Research is progress in order to assess predictive biologic factors, which would help clinicians in the selection of patients who can take actual benefit from different therapeutic options.

Acute myeloid leukemia with translocation (8;21) or inversion (16) in elderly patients treated with conventional chemotherapy: a collaborative study of the French CBF-AML intergroup

PURPOSE

Acute myeloid leukemia (AML) with translocation (t) (8;21) or inversion (inv) (16) is associated with a favorable prognosis when treated with intensive chemotherapy. In elderly patients, these AML types are rare, and intensive treatments are much less tolerated. We conducted a retrospective study to evaluate the characteristics and outcome of AML with t(8;21) or inv(16) in the elderly.

PATIENTS AND METHODS

Patients with t(8;21) or inv(16) AML who were age 60 years or older and who received at least one course of induction chemotherapy were included. Postremission therapy consisted of low-dose maintenance chemotherapy (n = 72) or intensive consolidation (n = 56).

RESULTS

A total of 147 patients were analyzed. The median age was 67 years. Sixty patients had t(8;21), and 87 patients had inv(16). A total of 129 patients achieved complete response (CR) after one or two induction courses (ie, 88% CR rate), and 15 patients (10%) died early (ie, during the 8 weeks after induction). During a median follow-up of 48 months, the 5-year probabilities of overall survival (OS) and leukemia-free survival (LFS) were 31% and 27%, respectively. Multivariate analysis showed a negative impact of high WBC, impaired performance status, and deletion (9q) on OS and LFS. Administration of intensive consolidation was associated with better LFS only in patients with t(8;21). In addition, the need for critical care during induction independently predicted lower LFS.

CONCLUSION

Because of a high CR rate, induction chemotherapy should be considered systematically for elderly patients who have AML with t(8;21) or inv(16). The high risk of relapse suggests that alternative strategies of postremission therapy are warranted.

Feasibility of autologous peripheral blood stem cell transplantation in elderly patients with acute myeloid leukemia

Most studies showing that autologous stem cell transplantation (ASCT) is feasible in older patients with acute myeloid leukemia (AML) referred to highly selected patients considered as eligible after complete remission (CR) achievement and bone marrow or peripheral blood stem cell (PBSC) collection. This study evaluated the feasibility of ASCT from 155 consecutive AML patients aged over 60 years (median age 72 years, range 61 - 94) programmed to receive ASCT by using PBSCs after CR achievement. Overall, 90 out of 155 patients (58%) were judged as eligible for aggressive chemotherapy and 45 (50%) achieved CR. Among these, 36 (80%) received consolidation and 32 (89% of consolidated) were monitored for PBSC mobilization. A successful collection was registered in 25/32 patients (78% of monitored). Finally, 20 patients received ASCT. Reasons for not autografting five mobilizing patients included relapse pre-ASCT, toxicity, and refusal. Median survival was 4 months for the whole patient population and 19 months for patients actually autografted. Overall, 20 out of 90 patients accrued into intensive chemotherapy (22%) and 20 out of the entire patient population (13%) underwent ASCT. It is concluded that APBSCT can result in an improvement of therapeutic results in AML of the elderly, but it is feasible in a minority of selected patients.

Autologous stem cell transplantation for elderly patients with acute myeloid leukaemia conditioned with continuous infusion idarubicin and busulphan

Different studies have suggested the potential utility of autologous stem cell transplantation (ASCT) in acute myeloid leukaemia (AML) of the elderly with encouraging results in selected patients. However, while the introduction of peripheral blood stem cells (PBSC) has consistently reduced morbidity and mortality of the procedure, relapse still represents the major cause of ASCT failure. One possibility to ameliorate therapeutic results could rely on the adoption of conditioning regimens specifically designed for AML. We report therapeutic results from a series of 40 AML patients older than 60 years (median age 67 years) autografted in first complete remission (CR), after conditioning with continuous infusion (c.i.) high dose idarubicin and busulphan. Fourty patients (median age: 67 years) received 2 days c.i. idarubicin at 20 mg/m(2)/day, followed by 3 days oral or intravenous busulphan (4 mg/kg/day) as conditioning. No case of transplant-related mortality occurred. Cardiac toxicity was absent, while 31 patients (77%) had grade 3-4 mucositis. After a median follow-up of 25 months, median disease free and overall survival (OS) for the whole patient population were 13 and 22 months, respectively. Three patients died while in CR from causes unrelated to AML. Better results were achieved in patients with intermediate karyotype as opposed to those with adverse cytogenetics. Our data confirm the feasibility of a conditioning regimen based on high-dose idarubicin plus busulphan in older selected AML patients and suggest clinical improvement in patients with normal cytogenetics.

Consolidation therapy: what should be the standard of care?

Adults 18-60 years old with acute myelogenous leukemia (AML) should undergo some form of postremission therapy, however, how much and what kinds of postremission chemotherapy remain unclear. In contrast, for older patients more than one cycle of chemotherapy postremission does not appear justified except perhaps in those rare patients with favorable cytogenetics who are young enough to tolerate standard therapy and in whom there is still an option for cure. Routine postremission therapy is not justifiable for those with unfavorable cytogenetics. However, the median age of AML patients approaches 70 years; this is a group of patients who often reach minimal disease, but with a median disease-free survival of only 4 to 5 months, regardless of their cytogenetics, and are therefore an ideal patient group for clinical studies. Older patients have limited tolerance for intensive regimens, although relatively nontoxic agents exist that can be explored. The issue of maintenance remains open.

Current therapeutic strategies for acute myeloid leukaemia

Improvements in survival in adult acute myeloid leukaemia (AML) have yet to be gleaned from either refinements in the understanding of the pathophysiology of the disease or from the expanding pool of targeted therapies. Outcomes have remained particularly dismal in older patients. Ongoing and planned trials will assess the effects of drugs targeting biological pathways whose clinical importance may vary as a function of the unique genotype and phenotype of each case of AML. The success of these ventures will ultimately require well-designed clinical trials in subsets of patients with risk being dependent not only on age and cytogenetics, but on additional, increasingly quantifiable biological variables. Inhibitors of fms-like tyrosine kinase-3, farnesyl transferase, apoptotic and angiogenic pathways are being studied alone and in combination with chemotherapy. Biological therapies, including monoclonal antibodies, peptide vaccines and interleukin-2, are undergoing evaluation. The role of autologous as well as allogeneic myeloablative and reduced-intensity transplantation continues to be defined. Several potentially useful new cytotoxic agents are being introduced. Critically important to advancing the field in light of such an increasing number of choices is a reassessment of traditional phase II trial designs so that more efficient evaluation of new therapies may take place, even as well-designed phase III trials continue to be performed.