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

Outcome of AML patients with IDH2 mutations in real world before the era of IDH2 inhibitors

Describing the prognosis of sub-groups of acute myeloid leukemia (AML) patients treated in real world with current therapies is becoming increasingly relevant to estimate the benefit that new targeted drugs will bring in the field. This is particularly the case when novel drugs are registered on the basis of non-randomized studies. IDH2 inhibitors have recently emerged as promising drugs in patients with IDH2^R140 or IDH2^R172 mutations. Enasidenib, a first-in-class IDH2 inhibitor, has been approved following promising results of a phase 1-2 clinical trial in relapsed or refractory AML patients with IDH2 mutations. In this study, we described the characteristics, treatments and outcome of 75 IDH2 mutated patients both at diagnosis and relapse or refractory disease. Among the 33 relapsed/refractory AML patients with either IDH2^R140 or IDH2^R172, 28 (84.8%) patients received salvage therapy and 14 achieved a complete response (50%). Median duration of response was 15.2 months. Median, 1-y, 3-y and 5-y OS were 15.1 months (IQR, 4.6-37.7), 53.1% (95% CI, 33.2-69.5), 29.2% (95% CI, 12.6-48.1) and 24.4% (95% CI, 9.3-43.1), respectively. In responding patients, median OS was 37.7 months and 1-y, 3-y and 5-y OS was 85.7%, 57.1% and 47.6%, respectively. In non-responding patients, median OS was 5.0 months (IQR, 4.5-8.6) and 1-y and 3-y OS was 17.9% and 0%, respectively. Thus, a substantial number of R/R AML patients with IDH2 mutations can be salvaged by current treatments and benefit from prolonged survival. It is expected that novel targeted agents such as enasidenib will further improve efficacy and safety in the next future.

Next Generation Sequencing in AML-On the Way to Becoming a New Standard for Treatment Initiation and/or Modulation?

Acute myeloid leukemia (AML) is a clonal disease caused by genetic abberations occurring predominantly in the elderly. Next generation sequencing (NGS) analysis has led to a deeper genetic understanding of the pathogenesis and the role of recently discovered genetic precursor lesions (clonal hematopoiesis of indeterminate/oncogenic potential (CHIP/CHOP)) in the evolution of AML. These advances are reflected by the inclusion of certain mutations in the updated World Health Organization (WHO) 2016 classification and current treatment guidelines by the European Leukemia Net (ELN) and National Comprehensive Cancer Network (NCCN) and results of mutational testing are already influencing the choice and timing of (targeted) treatment. Genetic profiling and stratification of patients into molecularly defined subgroups are expected to gain ever more weight in daily clinical practice. Our aim is to provide a concise summary of current evidence regarding the relevance of NGS for the diagnosis, risk stratification, treatment planning and response assessment in AML, including minimal residual disease (MRD) guided approaches. We also summarize recently approved drugs targeting genetically defined patient populations with risk adapted- and individualized treatment strategies.

An efficient sample size adaptation strategy with adjustment of randomization ratio

In clinical trials, sample size reestimation is a useful strategy for mitigating the risk of uncertainty in design assumptions and ensuring sufficient power for the final analysis. In particular, sample size reestimation based on unblinded interim effect size can often lead to sample size increase, and statistical adjustment is usually needed for the final analysis to ensure that type I error rate is appropriately controlled. In current literature, sample size reestimation and corresponding type I error control are discussed in the context of maintaining the original randomization ratio across treatment groups, which we refer to as "proportional increase." In practice, not all studies are designed based on an optimal randomization ratio due to practical reasons. In such cases, when sample size is to be increased, it is more efficient to allocate the additional subjects such that the randomization ratio is brought closer to an optimal ratio. In this research, we propose an adaptive randomization ratio change when sample size increase is warranted. We refer to this strategy as "nonproportional increase," as the number of subjects increased in each treatment group is no longer proportional to the original randomization ratio. The proposed method boosts power not only through the increase of the sample size, but also via efficient allocation of the additional subjects. The control of type I error rate is shown analytically. Simulations are performed to illustrate the theoretical results.

Developing an instrument to assess patient preferences for benefits and risks of treating acute myeloid leukemia to promote patient-focused drug development

Objective Acute myeloid leukemia (AML) is a progressive blood cancer with few effective treatment options. As part of a patient-focused drug development (PFDD) initiative led by the Leukemia and Lymphoma Society (LLS), this study sought to use a community-centered approach to develop and pilot an instrument to measure patient preferences for the benefits and risks of treating AML. Methods Instrument development was informed by a literature review, engagement with expert stakeholders (n = 12), engagement with community stakeholders, and pre-testing. A discrete-choice experiment (DCE), in which participants made choices between 16 pairs of hypothetical treatments, was developed with five attributes: event-free survival, complete remission, time in hospital, short-term side-effects, and long-term side-effects. A pilot test was conducted and analyzed using conditional logistic regression. Results are presented using relative attribute importance (RAI) scores. Results Patients with AML and caregivers were engaged in developing (n = 15), pre-testing (n = 13), and pilot testing (n = 26) the instrument. The pilot included patients with AML (n = 18) and caregivers of living or deceased patients with AML (n = 8). Participants had a mean age of 50 years (range =24-81), and were mostly college educated (n = 22), privately insured (n = 21), and employed (n = 13). Based on the DCE, complete remission was identified as the most important attribute (RAI =10), followed by event-free survival (3.7), time in hospital (2.8), long-term side-effects (2.3), and short-term side-effects (2.1). Conclusion The mixed-methods approach to PFDD was welcomed by all stakeholders and there was strong endorsement to implement this DCE as part of a national survey. Key points for decision makers The Leukemia and Lymphoma Society (LLS) initiated an independent effort to promote patient-focused drug development (PFDD). This study presents the development and piloting of a preference study as a first step in this initiative. Results of this pilot study were used to guide a PFDD meeting to discuss the lived experience of patients and caregivers affected by AML. Productive engagement by all patients, caregivers, and stakeholders throughout the process resulted in strong endorsement of the project's approach and recognition of the need to conduct a national study.

A Novel MCL1 Inhibitor Combined with Venetoclax Rescues Venetoclax-Resistant Acute Myelogenous Leukemia

Suppression of apoptosis by expression of antiapoptotic BCL2 family members is a hallmark of acute myeloblastic leukemia (AML). Induced myeloid leukemia cell differentiation protein (MCL1), an antiapoptotic BCL2 family member, is commonly upregulated in AML cells and is often a primary mode of resistance to treatment with the BCL2 inhibitor venetoclax. Here, we describe VU661013, a novel, potent, selective MCL1 inhibitor that destabilizes BIM/MCL1 association, leads to apoptosis in AML, and is active in venetoclax-resistant cells and patient-derived xenografts. In addition, VU661013 was safely combined with venetoclax for synergy in murine models of AML. Importantly, BH3 profiling of patient samples and drug-sensitivity testing ex vivo accurately predicted cellular responses to selective inhibitors of MCL1 or BCL2 and showed benefit of the combination. Taken together, these data suggest a strategy of rationally using BCL2 and MCL1 inhibitors in sequence or in combination in AML clinical trials. SIGNIFICANCE: Targeting antiapoptotic proteins in AML is a key therapeutic strategy, and MCL1 is a critical antiapoptotic oncoprotein. Armed with novel MCL1 inhibitors and the potent BCL2 inhibitor venetoclax, it may be possible to selectively induce apoptosis by combining or thoughtfully sequencing these inhibitors based on a rational evaluation of AML.See related commentary by Leber et al., p. 1511.This article is highlighted in the In This Issue feature, p. 1494.

Improved Survival by Adding Lomustine to Conventional Chemotherapy for Elderly Patients With AML Without Unfavorable Cytogenetics: Results of the LAM-SA 2007 FILO Trial

Purpose

Acute myeloid leukemia (AML) in elderly patients has a poor prognosis. In an attempt to improve outcome for these patients, the prospective open-label phase III LAM-SA 2007 (Adding Lomustine to Chemotherapy in Older Patients With Acute Myelogenous Leukemia (AML), and Allogeneic Transplantation for Patients From 60 to 65 Years Old) trial randomly assigned patients to a standard induction regimen with lomustine added or to a consolidation regimen with cytarabine and idarubicin.

Patients and Methods

Adults age 60 years or older with previously untreated AML who were fit to receive intensive chemotherapy and who were without unfavorable cytogenetics received standard chemotherapy with lomustine (idarubicin, cytarabine, and lomustine [ICL]) or without (idarubicin and cytarabine [IC]). The primary objective of the study was overall survival (OS); secondary objectives were response rate, cumulative incidence of relapse (CIR), event-free survival (EFS), and safety.

Results

From February 2008 to December 2011, 459 patients were enrolled. Comparing patients in the IC and ICL arms, complete response or complete response with incomplete recovery was achieved in 74.9% versus 84.7% ( P = .01). The proportional hazards assumption was rejected for OS ( P = .02), which led us to consider two separate time intervals: during and after induction. There was no significant difference between the two arms during induction, although induction deaths were 3.7% versus 7.7%, respectively ( P = .11). However, significantly better results were observed after induction with an improved 2-year OS of 56% in the ICL arm versus 48% in the IC arm ( P = .02). At 2 years, EFS was improved at 41% in the ICL arm versus 26% in the IC arm ( P = .01). The CIR at 2 years was 41.2% in the ICL arm versus 60.9% in the IC arm ( P = .003). Grade 3 and 4 toxicities, mostly hematologic, were significantly higher in the ICL arm ( P = .04), and fewer patients required a second treatment after ICL.

Conclusion

Adding lomustine to standard chemotherapy significantly improved the outcome of elderly patients with AML.

Synergistic suppression effect on tumor growth of acute myeloid leukemia by combining cytarabine with an engineered oncolytic vaccinia virus

BACKGROUND

In consideration of the drug resistance and side effects associated with cytarabine, one of the most effective drugs for the treatment of acute myeloid leukemia (AML), there is a need for safer and effective strategies.

METHODS

In the present investigation, we fabricated a new oncolytic vaccinia virus (oVV-ING4), which expresses the inhibitor of growth family member 4 (ING4) and explored its antitumor activity individually and in combination with cytarabine in AML cells.

RESULTS

The experiments confirmed that oVV can efficiently and specifically infect leukemia cells, and augment the ING4 gene expression. Flow cytometry and western blot demonstrated that oVV-ING4 enhances apoptosis and G2/M phase arrest in AML cells, and causes remarkable cancer cell death. In addition, the synergistic efficiency of oVV-ING4 and cytarabine was investigated in vitro and in vivo; the combination significantly inhibited the survival of leukemia cells in vitro and xenografted KG-1 AML tumor growth in vivo.

CONCLUSION

In brief, oVV-ING4 can increase the sensitivity of leukemia cells to cytarabine and induce cell apoptosis in vitro and in vivo. Thus, oVV-ING4 may be a promising therapeutic candidate for leukemia and in combination with cytarabine represents a potential antitumor therapy.

Management of primary refractory acute myeloid leukemia in the era of targeted therapies

Primary refractory acute myeloid leukemia (AML), or primary induction failure, represents a continued challenge in clinical management. This review presents an overview of primary refractory disease and a discussion of risk factors for induction failure, including current evidence regarding the impact of karyotype and molecular mutation status on responsiveness to chemotherapy. We review the evidence for various treatment options for refractory AML including salvage chemotherapy regimens, allogeneic hematopoietic stem cell transplantation, targeted agents, and non-intensive therapies such as hypomethylating agents. A therapeutic approach to this patient population is presented, and several new and emerging therapies are reviewed.

Efficacy of common salvage chemotherapy regimens in patients with refractory or relapsed acute myeloid leukemia: A retrospective cohort study

To assess treatment response and overall survival (OS) in refractory or relapsed acute myeloid leukemia (R/R AML) patients treated by different common salvage chemotherapy regimens.Medical records data from 142 R/R AML patients were reviewed in this retrospective study. Patients were treated with regimens based on the following drugs: cytarabine, granulocyte colony-stimulating factor (G-CSF), and fludarabine (FLAG) (n = 46); cytarabine and G-CSF in addition to aclarubicin or daunorubicin (CAG/DAG) (n = 30); cytarabine, G-CSF, and cladribine (CLAG) (n = 27); cytarabine, etoposide, and mitoxantrone (MEA) (n = 17); cytarabine plus idarubicin, daunorubicin, or mitoxantrone (IA/DA/MA) (n = 12); and homoharringtonine, cytarabine, and aclarubicin or daunorubicin (HAA/HAD) (n = 10).A total of 43 (35.2%) patients achieved complete remission (CR), 60 (49.2%) patients achieved overall remission rate (ORR), and 18 (14.8%) patients received allogeneic hematopoietic stem cell transplantation (allo-HSCT) after CR. Median OS was 8.0 (95% CI 6.6-9.4) months with a 1-year OS rate of (29.9 ± 3.9)% and 3-year OS rate of (11.1 ± 3.6)%. No difference of CR (P = .621), ORR (P = .385), and allo-HSCT (P = .537) achievement was observed among different chemotherapy regimens. Interestingly, we observed that the CLAG-based regimen did not affect CR (P = .165), while it achieved a numerically higher ORR (P = .093) and was an independent factor for prolonged OS (P = .016). No other regimens were determined to be correlated with CR, ORR, or OS.FLAG-, CAG/DAG-, CLAG-, MEA-, IA/DA/MA- and HAA/HAD-based regimens were found to achieve similar CR rates, while the CLAG-based regimen achieved numerically higher ORR rates and significant favorable OS. Therefore, CLAG-based regimens should be a prioritized treatment option for R/R AML patients.

Results of second salvage therapy in 673 adults with acute myelogenous leukemia treated at a single institution since 2000

BACKGROUND

The prognosis is poor for patients who have relapsed-refractory acute myelogenous leukemia (AML). Most published reports analyzed results from therapies in first-salvage AML or in studies that were conducted before 2000. Several novel agents and strategies are being tested for potential approval as treatment for patients with relapsed-refractory AML in second salvage. Therefore, it is important to establish the historic results of anti-AML therapies in this setting in the modern era. The objective of the current study was to analyze the results from second salvage therapies in patients with AML since 2000 with regard to response and survival.

METHODS

In total, 673 patients who received second salvage therapies for AML since 2000 were analyzed. Their median age was 60 years (range, 18-89 years). Salvage therapy consisted of cytarabine-based regimens in 267 patients, noncytarabine combinations in 37, hypomethylating agent-based regimens in 136, and phase 1 and 2 single agents in 233.

RESULTS

Eighty-six of the 673 patients (13%) achieved a complete response (CR) or a CR with low platelet count (CRp). The median duration of CR-CRp was 7.2 months. The median survival was 4.4 months (95% confidence interval, 4.0-4.8 months), and the 1-year survival rate was 16% (95% confidence interval, 14%-19%). Multivariate analysis identified the following as independent adverse factors for achievement of CR-CRp: platelets < 50 × 10⁹ /L (P < .001), complex karyotype with ≥3 chromosomal abnormalities (P = .02), regimens that did not include cytarabine or hypomethylating agents (P = .014), and no prior CR lasting ≥12 months with frontline or salvage 1 therapies (P < .001). The independent adverse factors associated with worse survival were age ≥60 years (P = .01), platelets < 50 × 10⁹ /L (P = .02), peripheral blasts ≥ 20% (P = .03), albumin ≤ 3 g/dL (P = .04), and complex karyotype (P = .003). The authors also applied and validated, in the current population, the 2 multivariate-derived prognostic models for CR and survival developed in their previous study of 594 patients who received treatment for second salvage AML from the previous 2 decades.

CONCLUSIONS

This large-scale analysis establishes the modern historic results of second salvage therapy in AML and validates the prognostic models associated with outcome. These data could be used to analyze the differential benefits of current or future investigational strategies under evaluation in this setting and for the purpose of potential approval of new agents in the United States and the world. Cancer 2018;124:2534-40. © 2018 American Cancer Society.

Novel Therapies for Acute Myeloid Leukemia: Are We Finally Breaking the Deadlock?

Acute myeloid leukemia (AML) is one of the best studied malignancies, and significant progress has been made in understanding the clinical implications of its disease biology. Unfortunately, drug development has not kept pace, as the '7+3' induction regimen remains the standard of care for patients fit for intensive therapy 40 years after its first use. Temporal improvements in overall survival were mostly confined to younger patients and driven by improvements in supportive care and use of hematopoietic stem cell transplantation. Multiple forms of novel therapy are currently in clinical trials and are attempting to bring bench discoveries to the bedside to benefit patients. These novel therapies include improved chemotherapeutic agents, targeted molecular inhibitors, cell cycle regulators, pro-apoptotic agents, epigenetic modifiers, and metabolic therapies. Immunotherapies in the form of vaccines; naked, conjugated and bispecific monoclonal antibodies; cell-based therapy; and immune checkpoint inhibitors are also being evaluated in an effort to replicate the success seen in other malignancies. Herein, we review the scientific basis of these novel therapeutic approaches, summarize the currently available evidence, and look into the future of AML therapy by highlighting key clinical studies and the challenges the field continues to face.

Advances in the drug therapies of acute myeloid leukemia (except acute wpromyelocytic leukemia)

Acute myeloid leukemia (AML) is a heterogeneous hematologic malignancy, characterized by the clonal expansion of myeloid blasts in the peripheral blood, bone marrow, and/or other tissues. The new drugs used for treating AML are facing a big challenge, and the candidates include cytotoxic drugs, targeted small-molecule inhibitors, and monoclonal antibodies. In recent years, active research has focused on several new agents for including them in the large antileukemic drug family. This review aims to introduce some of these new drugs and highlights new advances made in the old drugs, mainly in the last 5 years.

Enhancement of radiosensitivity by the novel anticancer quinolone derivative vosaroxin in preclinical glioblastoma models

Purpose

Glioblastoma multiforme (GBM) is the most aggressive brain tumor. The activity of vosaroxin, a first-in-class anticancer quinolone derivative that intercalates DNA and inhibits topoisomerase II, was investigated in GBM preclinical models as a single agent and combined with radiotherapy (RT).

Results

Vosaroxin showed antitumor activity in clonogenic survival assays, with IC₅₀ of 10−100 nM, and demonstrated radiosensitization. Combined treatments exhibited significantly higher γH2Ax levels compared with controls. In xenograft models, vosaroxin reduced tumor growth and showed enhanced activity with RT; vosaroxin/RT combined was more effective than temozolomide/RT. Vosaroxin/RT triggered rapid and massive cell death with characteristics of necrosis. A minor proportion of treated cells underwent caspase-dependent apoptosis, in agreement with in vitro results. Vosaroxin/RT inhibited RT-induced autophagy, increasing necrosis. This was associated with increased recruitment of granulocytes, monocytes, and undifferentiated bone marrow–derived lymphoid cells. Pharmacokinetic analyses revealed adequate blood-brain penetration of vosaroxin. Vosaroxin/RT increased disease-free survival (DFS) and overall survival (OS) significantly compared with RT, vosaroxin alone, temozolomide, and temozolomide/RT in the U251-luciferase orthotopic model.

Materials and Methods

Cellular, molecular, and antiproliferative effects of vosaroxin alone or combined with RT were evaluated in 13 GBM cell lines. Tumor growth delay was determined in U87MG, U251, and T98G xenograft mouse models. (DFS) and (OS) were assessed in orthotopic intrabrain models using luciferase-transfected U251 cells by bioluminescence and magnetic resonance imaging.

Conclusions

Vosaroxin demonstrated significant activity in vitro and in vivo in GBM models, and showed additive/synergistic activity when combined with RT in O6-methylguanine methyltransferase-negative and -positive cell lines.

A phase I-II study of plerixafor in combination with fludarabine, idarubicin, cytarabine, and G-CSF (PLERIFLAG regimen) for the treatment of patients with the first early-relapsed or refractory acute myeloid leukemia

Clinical outcomes of patients with acute myeloid leukemia (AML) showing the first primary refractory or early-relapsed disease remain very poor. The Programa Español de Tratamientos en Hematología (PETHEMA) group designed a phase I-II trial using FLAG-Ida (fludarabine, idarubicin, cytarabine, and G-CSF) plus high-dose intravenous plerixafor, a molecule inducing mobilization of blasts through the SDF-1α-CXCR4 axis blockade and potentially leading to chemosensitization of the leukemic cells. We aimed to establish a recommended phase 2 dose (RP2D) of plerixafor plus FLAG-Ida, as well as the efficacy and safety of this combination for early-relapsed (first complete remission (CR/CRi) < 12 months) or primary refractory AML. Between 2012 and 2015, 57 patients were enrolled, and 41 received the RP2D (median age 52 years [range, 18-64]). Among these patients, 20 (49%) achieved CR/CRi, and 3 (7%) died during induction. CR/CRi rate was 50% (13/26) among primary refractory and 47% (7/15) among early relapse. Overall, 25 patients (61%) were allografted. Median overall and disease-free survivals were 9.9 and 13 months, respectively. In summary, the combination of plerixafor plus FLAG-Ida resulted in a relatively high CR/CRi rate in adult patients with primary refractory or early relapsed AML, with an acceptable toxicity profile and induction mortality rate, bridging the majority of patients to allogeneic stem cell transplantation. ClinicalTrials.gov Identifier: NCT01435343.

A phase I study of lenalidomide plus chemotherapy with mitoxantrone, etoposide, and cytarabine for the reinduction of patients with acute myeloid leukemia

Patients with relapsed AML have a poor prognosis and limited responses to standard chemotherapy. Lenalidomide is an immunomodulatory drug that may modulate anti-tumor immunity. We performed a study to evaluate the safety and tolerability of lenalidomide with mitoxantrone, etoposide and cytarabine (MEC) in relapsed/refractory AML. Adult patients with relapsed/refractory AML were eligible for this phase I dose-escalation study. We enrolled 35 patients using a "3 + 3" design, with a 10 patient expansion cohort at the maximum tolerated dose (MTD). Lenalidomide was initially given days 1-14 and MEC days 4-8; due to delayed count recovery, the protocol was amended to administer lenalidomide days 1-10. The dose of lenalidomide was then escalated starting at 5 mg/d (5-10-25-50). The primary objective was tolerability and MTD determination, with secondary outcomes including overall survival (OS). The MTD of lenalidomide combined with MEC was 50 mg/d days 1-10. Among the 35 enrolled patients, 12 achieved complete remission (CR) (34%, 90%CI 21-50%); 30-day mortality was 6% and 60-day mortality 13%. The median OS for all patients was 11.5 months. Among 17 patients treated at the MTD, 7 attained CR (41%); the median OS was not reached while 12-month OS was 61%. Following therapy with MEC and lenalidomide, patient CD4+ and CD8+ T-cells demonstrated increased inflammatory responses to autologous tumor lysate. The combination of MEC and lenalidomide is tolerable with an RP2D of lenalidomide 50 mg/d days 1-10, yielding encouraging response rates. Further studies are planned to explore the potential immunomodulatory effect of lenalidomide and MEC.

Treatment of relapsed/refractory acute myeloid leukaemia in adults

The prognosis of relapsed acute myeloid leukaemia (AML) is poor and treatment is challenging. While the most potent treatment modality for patients who achieve a complete remission after relapse is still allogeneic haematopoietic cell transplantation (allo-HCT), both transplant-related mortality and relapse rates are high and many patients are not candidates for this approach. After a few decades of relative stasis in this field, a large number of novel approaches have become available to tackle this highly fatal disease. This is mostly due to our improved understanding of disease pathogenesis (including targetable mutations) and the anti-leukaemia potential of the immune system. Several small-molecule inhibitors and immunotherapeutic options are being explored in clinical trials and many more are in pre-clinical phase. Future studies will focus on novel and mechanistically driven combinations, sequential treatments, and low-toxicity maintenance strategies. While cure of relapsed/refractory AML without allo-HCT is currently unlikely, treatments are becoming less toxic and remissions are lasting longer.

Precision therapy for acute myeloid leukemia

Acute myeloid leukemia (AML) is a molecularly and clinically heterogeneous disease. Despite advances in understanding the pathogenesis of AML, the standard therapy remained nearly unchanged over the past three decades. With the poor survival for older patients and high relapse rate, multiple studies are ongoing to address this important issue. Novel therapies for AML, including the refinements of conventional cytotoxic chemotherapies and genetic and epigenetic targeted drugs, as well as immunotherapies, have been developed in recent years. Here, we present a mechanism-based review of some promising new drugs with clinical efficacy, focus on targeted drugs that are most potential to pave the road to success, and put forward the major challenges in promoting the precision therapy for AML.

What are the most promising new agents in acute myeloid leukemia?

PURPOSE OF REVIEW

Although the treatment paradigm for acute myeloid leukemia (AML) had been largely unchanged for many years, in-depth molecular characterization has revolutionized our understanding of mutations that drive the disease, subsequently serving to guide current clinical investigation. Furthermore, recent advances in the field have highlighted the importance of optimizing known efficacious agents by improving drug delivery or bypassing resistance mechanisms. The current status of novel agents which are shaping the clinical management of AML patients are summarized in this review.

RECENT FINDINGS

Practice changing findings over the past year include improved overall survival (OS) in a molecularly defined AML subgroup as well as in elderly patients with secondary AML (sAML). Specifically, synergistic combination of daunorubicin and cytarabine (i.e., CPX-351) was found to improve OS in sAML patients. Furthermore, although multiple mutation specific inhibitors have been developed, optimal combination with additional agents appears critical, as monotherapies have not resulted in durable remissions or improved outcomes. Improved OS via the addition of midostaurin to intensive chemotherapy in FLT3 mutant AML supports this concept.

SUMMARY

For the first time in AML, personalized therapy has become possible through improved understanding of the molecular architecture and survival pathways of an individual's disease. The landscape of AML treatment is encouraging, with multiple novel agents likely to gain approval over the next 5 years.

The management and treatment of acute leukemias in the elderly population

INTRODUCTION

Treatment of elderly patients with acute leukemia is challenging. Older age is associated with increased risk of treatment-related toxicity. Currently, no consensus exists regarding optimal therapy in this patient population. Areas covered: The following review is a comprehensive summary of various therapeutic options reported over the past few years in elderly patients with acute leukemia. Expert commentary: While evidences can guide identification of frail older patients, sensitive assessment strategies are required to identify fit and vulnerable patients regardless of chronologic age. Individualized treatments may take into account not only an increase in survival, but also the maintenance or improvement in terms of quality of life, the management of symptoms, and a maximization of time outside of hospital care. In this setting, comprehensive geriatric assessments have been shown to improve routine assessment. Molecular abnormalities provide the genomic footprint for the development of targeted therapies. The addition of new monoclonal antibodies to conventional treatments also demonstrated promising primary results. Ongoing clinical trials testing the activity of these new agents may reshape treatment strategies in the elderly patient population.

Acute Myeloid Leukemia: How Do We Measure Success?

The development and approval of novel, effective therapies for acute myeloid leukemia (AML) has lagged behind other malignancies. Judging success of therapy with meaningful endpoints is critical to development of new treatments. Overall survival (OS) has typically been the parameter necessary for regulatory approval of experimental therapy in AML. Herein, we discuss different strategies to define outcomes for patients with AML and their relative challenges.

A Comparison of Clofarabine-based (GCLAC) and Cladribine-based (CLAG) Salvage Chemotherapy for Relapsed/Refractory AML

BACKGROUND

Salvage regimens for patients with relapsed/refractory acute myeloid leukemia (rrAML) lack comparative data for superiority. Thus, we conducted a retrospective analysis of clofarabine-based (GCLAC; granulocyte colony-stimulating factor [filgrastim], clofarabine, high-dose cytarabine) versus cladribine-based (CLAG; cladribine, cytarabine, granulocyte colony-stimulating factor [filgrastim]) regimens in rrAML.

PATIENTS AND METHODS

We identified 41 consecutive patients with rrAML who had received either GCLAC or CLAG from 2011 to 2014. The primary outcome measure was the complete remission (CR) rate defined according to the International Working Group criteria. The secondary outcomes included the proportion of patients who underwent allogenic stem cell transplantation and the rate of relapse-free survival and overall survival.

RESULTS

We found no significant differences in the baseline characteristics of the patients treated with GCLAC (n = 22) or CLAG (n = 19). The outcomes with these 2 regimens were not significantly different. Patients treated with GCLAC had a CR/CR with incomplete blood count recovery rate of 64% compared with 47% for the patients treated with CLAG (P = .36). Of the GCLAC patients, 45% underwent allogeneic stem cell transplantation compared with 26% of the CLAG patients (P = .32). The median relapse-free survival after GCLAC and CLAG was 1.59 years and 1.03 years, respectively (P = .75). The median overall survival after GCLAG and CLAG was 1.03 years and 0.70 years, respectively (P = .08). The drug costs were significantly different for GCLAC versus CLAG. Using an average wholesale price, the cost per patient per cycle was $60,821.60 for GCLAC and $4910.60 for CLAG.

CONCLUSION

A single-institutional retrospective analysis found no significant differences in the outcomes between GCLAC and CLAG for rrAML patients, although formal comparisons should be performed in a randomized clinical trial. The cost of GCLAC was greater than that of CLAG, which should be considered when evaluating the choice for the salvage chemotherapy options.

Midostaurin for the treatment of acute myeloid leukemia

Midostaurin is a multikinase tyrosine kinase inhibitor acting against targets known to be expressed in hematologic malignancies, especially acute myeloid leukemia. Midostaurin combined with chemotherapy followed by single-agent maintenance therapy elicited statistically significant and clinically meaningful improvement in overall survival versus placebo in patients with newly diagnosed FLT3-mutant acute myeloid leukemia. Although gastrointestinal events were more common with midostaurin, overall the drug was relatively well tolerated. Of note, midostaurin is metabolized by cytochrome P450–3A4 (CYP3A4); therefore, concomitant strong CYP3A4 inhibitors should be used with caution. Preliminary safety results from an ongoing trial evaluating midostaurin as a single agent in the post-transplant setting are encouraging. In addition, studies have evaluated its safety and efficacy in advanced systemic mastocytosis.

Treatment of Elderly Patients With Acute Myeloid Leukemia

OPINION STATEMENT

There is no standard of care for older patients with acute myeloid leukemia (AML) unfit for intensive chemotherapy. AML in older patients remains an area of significant unmet need necessitating novel therapeutic strategies. In older patients with normal cytogenetics, molecular variables can be helpful in refining risk. This molecular revolution has promoted a shift in the treatment paradigm of AML. Open new questions concern the necessity of an individualized therapy that may take into account not only an increase in survival but also the maintenance or improvement in terms of quality of life, the management of symptoms, and a maximization of time outside of hospital care. Molecular abnormalities provide the genomic footprint for the development of targeted therapies. Clinical trials testing the activity of these new agents are ongoing and may reshape treatment strategies for these patients. One promising strategy is to combine low-intensity treatments with novel agents.

Treatment of Relapsed/Refractory Acute Myeloid Leukemia

OPINION STATEMENT

Approximately 40-45% of younger and 10-20% of older adults with acute myeloid leukemia (AML) will be cured with current standard chemotherapy. The outlook is particularly gloomy for patients with relapsed and/or refractory disease (cure rates no higher than 10%). Allogeneic hematopoietic stem cell transplantation (HSCT), the only realistic hope of cure for these patients, is an option for only a minority. In recent years, much has been learned about the genomic and epigenomic landscapes of AML, and the clonal architecture of both de novo and secondary AML has begun to be unraveled. These advances have paved the way for rational drug development as new "drugable" targets have emerged. Although no new drug has been approved for AML in over four decades, with the exception of gemtuzumab ozogamycin, which was subsequently withdrawn, there is progress on the horizon with the possible regulatory approval soon of agents such as CPX-351 and midostaurin, the Food and Drug Administration "breakthrough" designation granted to venetoclax, and promising agents such as the IDH inhibitors AG-221 and AG-120, the smoothened inhibitor glasdegib and the histone deacetylase inhibitor pracinostat. In our practice, we treat most patients with relapsed/refractory AML on clinical trials, taking into consideration their prior treatment history and response to the same. We utilize targeted sequencing of genes frequently mutated in AML to identify "actionable" mutations, e.g., in FLT3 or IDH1/2, and incorporate small-molecule inhibitors of these oncogenic kinases into our therapeutic regimens whenever possible. In the absence of actionable mutations, we rationally combine conventional agents with other novel therapies such as monoclonal antibodies and other targeted drugs. For fit patients up to the age of 65, we often use high-dose cytarabine-containing backbone regimens. For older or unfit patients, we prefer hypomethylating agent-based therapy. Finally, all patients with relapsed/refractory AML are evaluated for allogeneic HSCT.

Therapies for acute myeloid leukemia: vosaroxin

Vosaroxin, a quinolone-derivative chemotherapeutic agent, was considered a promising drug for the treatment of acute myeloid leukemia (AML). Early-stage clinical trials with this agent led to a large randomized double-blind placebo-controlled study of vosaroxin in combination with intermediate-dose cytarabine for the treatment of relapsed or refractory AML. The study demonstrated better complete remission rates with vosaroxin, but there was no statistically significant overall survival benefit in the whole cohort. A subset analysis censoring patients who had undergone allogeneic stem cell transplantation, however, revealed a modest but statistically significant improvement in overall survival particularly among older patients. This article reviews the data available on vosaroxin including clinical trials in AML and offers an analysis of findings of these studies as well as the current status of vosaroxin.

Vosaroxin in combination with decitabine in newly diagnosed older patients with acute myeloid leukemia or high-risk myelodysplastic syndrome

Vosaroxin is an anti-cancer quinolone-derived DNA topoisomerase II inhibitor. We investigated vosaroxin with decitabine in patients ≥60 years of age with newly diagnosed acute myeloid leukemia (n=58) or myelodysplastic syndrome (≥10% blasts) (n=7) in a phase II non-randomized trial. The initial 22 patients received vosaroxin 90 mg/m² on days 1 and 4 with decitabine 20 mg/m² on days 1–5 every 4–6 weeks for up to seven cycles. Due to a high incidence of mucositis the subsequent 43 patients were given vosaroxin 70 mg/m² on days 1 and 4. These 65 patients, with a median age of 69 years (range, 60–78), some of whom with secondary leukemia (22%), adverse karyotype (35%), or TP53 mutation (20%), are evaluable. The overall response rate was 74% including complete remission in 31 (48%), complete remission with incomplete platelet recovery in 11 (17%), and complete remission with incomplete count recovery in six (9%). The median number of cycles to response was one (range, 1–4). Grade 3/4 mucositis was noted in 17% of all patients. The 70 mg/m² induction dose of vosaroxin was associated with similar rates of overall response (74% versus 73%) and complete remission (51% versus 41%, P=0.44), reduced incidence of mucositis (30% versus 59%, P=0.02), reduced 8-week mortality (9% versus 23%; P=0.14), and improved median overall survival (14.6 months versus 5.5 months, P=0.007). Minimal residual disease-negative status by multiparametric flow-cytometry at response (± 3 months) was achieved in 21 of 39 (54%) evaluable responders and was associated with better median overall survival (34.0 months versus 8.3 months, P=0.023). In conclusion, the combination of vosaroxin with decitabine is effective and well tolerated at a dose of 70 mg/m² and warrants randomized prospective evaluation. ClinicalTrials.gov: NCT01893320

A phase I/II randomized trial of clofarabine or fludarabine added to idarubicin and cytarabine for adults with relapsed or refractory acute myeloid leukemia

The purine nucleoside analogues clofarabine and fludarabine are active in acute myeloid leukemia (AML). We conducted a phase I/II randomized study of idarubicin and cytarabine with either clofarabine (CIA) or fludarabine (FIA) for relapsed or refractory AML. Clofarabine 15 mg/m² was identified as the recommended phase II dose. Eighty-one patients were assigned using adaptive randomization to CIA (n = 48) or FIA (n = 33). The complete response (CR)/CR without platelet recovery rate did not differ between CIA and FIA (38% versus 30%, respectively; p = .50). In both arms, more than half of patients who had received only one prior line of therapy achieved remission. The median event-free survival for CIA and FIA was 2.0 and 1.9 months (p = .48), and the median overall survival was 6.3 and 4.7 months, respectively (p = .28). No significant differences in adverse events or early mortality rates were observed. Overall, CIA and FIA resulted in similar response rates and survival in patients with relapsed/refractory AML.

Molecular and Pharmacologic Properties of the Anticancer Quinolone Derivative Vosaroxin: A New Therapeutic Agent for Acute Myeloid Leukemia

Vosaroxin is a first-in-class anticancer quinolone derivative that targets topoisomerase II and induces site-selective double-strand breaks in DNA, leading to tumor cell apoptosis. Vosaroxin has chemical and pharmacologic characteristics distinct from other topoisomerase II inhibitors due to its quinolone scaffold. The efficacy and safety of vosaroxin in combination with cytarabine were evaluated in patients with relapsed/refractory acute myeloid leukemia (AML) in a phase III, randomized, multicenter, double-blind, placebo-controlled study (VALOR). In this study, the addition of vosaroxin produced a 1.4-month improvement in median overall survival (OS; 7.5 months with vosaroxin/cytarabine vs. 6.1 months with placebo/cytarabine; hazard ratio [HR] 0.87, 95 % confidence interval [CI] 0.73−1.02; unstratified log-rank p\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$=$$\end{document}= 0.061; stratified log-rank p\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$=$$\end{document}=0.024), with the greatest OS benefit observed in patients ≥60 years of age (7.1 vs. 5.0 months; HR 0.75, 95 % CI 0.62−0.92; p\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$=$$\end{document}=0.003) and patients with early relapse (6.7 vs. 5.2 months; HR 0.77, 95 % CI 0.59−1.00; p\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$=$$\end{document}= 0.039), two AML patient groups that typically have poor prognosis. Here we review the chemical and pharmacologic properties of vosaroxin, how these properties are distinct from those of currently available topoisomerase II inhibitors, how they may contribute to the efficacy and safety profile observed in the VALOR trial, and the status of clinical development of vosaroxin for treatment of AML.

Therapy of older persons with acute myeloid leukaemia

Most persons age≥60 y with acute myeloid leukaemia (AML) die from their disease. When interpreting clinical trials data from these persons one must be aware of substantial selection biases. Randomized trials of post-remission treatments can be performed upfront or after achieving defined landmarks. Both strategies have important limitations. Selection of the appropriate treatment is critical. Age, performance score, co-morbidities and frailty provide useful data to treatment selection. If an intensive remission induction therapy is appropriate, therapy with cytarabine and an anthracycline is the most common regimen. Non-intensive therapies consist of the hypo-methylating drugs azacitidine and decitabine, low-dose cytarabine and supportive care. Feasibility of doing an allotransplant in older persons with AML is increasing. However, only very few qualify. Results of cytogenetic testing are risk factor in young and old persons with AML. Adverse abnormalities are more frequent in older persons. Although data about the frequency of mutations in older persons with AML is increasing their prognostic impact is less clear than in younger subjects. Neither differences in the distribution of cytogenetic risk, mutations, nor differences in clinical risk factors between younger and older persons with AML completely explain the age-dependent outcome. Many drugs are in clinical development in older persons with AML. Their potential role in the treatment of older persons with AML remains to be defined.

Mitoxantrone, etoposide and cytarabine following epigenetic priming with decitabine in adults with relapsed/refractory acute myeloid leukemia or other high-grade myeloid neoplasms: a phase 1/2 study

DNA methyltransferase inhibitors sensitize leukemia cells to chemotherapeutics. We therefore conducted a phase 1/2 study of mitoxantrone, etoposide, and cytarabine following “priming” with 5-10 days of decitabine (dec/MEC) in 52 adults (median age 55 [range: 19-72] years) with relapsed/refractory acute myeloid leukemia (AML) or other high-grade myeloid neoplasms. During dose escalation in cohorts of 6-12 patients, all dose levels were well-tolerated. As response rates appeared similar with 7 and 10-days of decitabine, a 7-day course was defined as the recommended phase 2 dose (RP2D). Among 46 patients treated at/above the RP2D, 10 (22%) achieved a complete remission (CR), 8 without measurable residual disease; five additional patients achieved CR with incomplete platelet recovery, for an overall response rate of 33%. Seven patients (15%) died within 28 days of treatment initiation. Infection/neutropenic fever, nausea, and mucositis were the most common adverse events. While the CR rate compared favorably to a matched historic control population (observed/expected CR ratio=1.77), CR rate and survival were similar to two contemporary salvage regimens used at our institution (G-CLAC and G-CLAM). Thus, while meeting the pre-specified efficacy goal, we found no evidence that dec/MEC is substantially better than other cytarabine-based regimens currently used for relapsed/refractory AML.

The preclinical discovery of vosaroxin for the treatment of acute myeloid leukemia

INTRODUCTION

Acute myeloid leukemia (AML) represents a disease with a very poor outcome and remains an area of significant unmet need necessitating novel therapeutic strategies. Among novel therapeutic agents, vosaroxin is a first-in-class anticancer quinolone derivative that targets topoisomerase II and induces site-selective double-strand breaks in DNA, leading to tumor cell apoptosis. Areas covered: Herein, the authors provide a comprehensive review of the preclinical development of vosaroxin. This includes coverage of vosaroxin's mechanism of action in addition to its pharmacology and of the main studies reported over the past few years with vosaroxin when used to treat adult AML. Expert opinion: Given that vosaroxin is associated with fewer potential side effects, it may be of benefit to elderly patients with relapsed/refractory AML and to those with additional comorbidities who have previously received an anthracycline and cytarabine combination. Furthermore, vosaroxin also was seen to be active in multidrug-resistant preclinical models. However, further studies have to be performed to better evaluate its place in the armamentarium against AML.

Long-Term Follow-Up and Impact of Comorbidity before Allogeneic Hematopoietic Stem Cell Transplantation in Patients with Relapsed or Refractory Acute Myeloid Leukemia-Lessons Learned from the Prospective BRIDGE Trial

In patients with relapsed or refractory (r/r) acute myeloid leukemia (AML), allogeneic hematopoietic stem cell transplantation (HSCT) is considered to be the only treatment providing long-term disease control. The BRIDGE trial studied the safety and efficacy of a clofarabine-based salvage therapy before HSCT in patients with r/r AML. Here, we report the long-term follow-up of this phase II multicenter trial and exploratory analyses on the impact of comorbidity on outcome. Eighty-four patients with a median age of 61 years (range, 40 to 75) were enrolled. Patients were scheduled for at least 1 cycle of salvage therapy with CLARA (clofarabine 30 mg/m²; cytarabine 1 g/m², days 1 to 5). Chemo-responsive patients with a donor received HSCT after first CLARA. The conditioning regimen consisted of clofarabine 30 mg/m², day -6 to -3, and melphalan 140 mg/m² day -2. The Eastern Cooperative Oncology Group (ECOG) score, the hematopoietic cell transplantation-specific comorbidity index (HCT-CI), and the Cumulative Illness Rating Scale were obtained at study enrollment as well as before HSCT. Sixty-seven percent of the patients received HSCT within the trial. After a median follow up of 40 months, the estimated 3-year overall survival (OS) for all enrolled patients and those with HSCT within the trial was 40% and 55%, respectively. Relapse-free survival for patients who underwent transplantation with a complete remission afterwards (n = 50) was 48%, calculated from the day of transplantation. In multivariate analysis, both the HCT-CI and ECOG score had a statistically significant impact on OS with a hazard ratio of 1.22 (P = .025)and 1.72 (P = .001), respectively. Using a clofarabine-based salvage therapy combined with early allogeneic HSCT, we were able to achieve good long-term results for patients with r/r AML. In this cohort, both the HCT-CI and the ECOG scores gave prognostic information on OS, showing the feasibility and clinical relevance of comorbidity evaluation at the time of diagnosis of r/r AML patients.

Vosaroxin in relapsed/refractory acute myeloid leukemia: efficacy and safety in the context of the current treatment landscape

Treatment for acute myeloid leukemia (AML) generally consists of a combination of cytarabine and an anthracycline. Although induction therapy leads to complete remission (CR) for most patients, refractoriness to chemotherapy or relapse after initial response is associated with poor outcomes. The 1-year survival rates after first relapse have been reported at 29%, declining to 11% at 5 years. Prognosis is particularly poor among older patients whose higher prevalence of unfavorable cytogenetics and high frequency of comorbidities diminish their ability to tolerate intensive chemotherapy. There is no standard of care for relapsed/refractory (R/R) AML, and no new therapies have shown consistently superior outcomes in this setting in over two decades. Vosaroxin is an anticancer quinolone derivative (AQD) that was evaluated in combination with cytarabine for the treatment of R/R AML in the randomized, double-blind, placebo-controlled, phase III VALOR study (n = 711). Compared with placebo/cytarabine, the vosaroxin/cytarabine regimen demonstrated favorable CR rates and survival in patients ⩾60 years of age, with toxicities similar to other AML regimens. Here we review outcomes of recent studies of commonly used chemotherapy regimens for the treatment of R/R AML and evaluate the results of the VALOR trial in the context of the current treatment landscape.

Emerging therapies for acute myeloid leukemia

Acute myeloid leukemia (AML) is characterized by clinical and biological heterogeneity. Despite the advances in our understanding of its pathobiology, the chemotherapy-directed management has remained largely unchanged in the past 40 years. However, various novel agents have demonstrated clinical activity, either as single agents (e.g., isocitrate dehydrogenase (IDH) inhibitors, vadastuximab) or in combination with standard induction/consolidation at diagnosis and with salvage regimens at relapse. The classes of agents described in this review include novel cytotoxic chemotherapies (CPX-351 and vosaroxin), epigenetic modifiers (guadecitabine, IDH inhibitors, histone deacetylase (HDAC) inhibitors, bromodomain and extraterminal (BET) inhibitors), FMS-like tyrosine kinase receptor 3 (FLT3) inhibitors, and antibody-drug conjugates (vadastuximab), as well as cell cycle inhibitors (volasertib), B-cell lymphoma 2 (BCL-2) inhibitors, and aminopeptidase inhibitors. These agents are actively undergoing clinical investigation alone or in combination with available chemotherapy.

A phase 1 clinical trial of single-agent selinexor in acute myeloid leukemia

Selinexor is a novel, first-in-class, selective inhibitor of nuclear export compound, which blocks exportin 1 (XPO1) function, leads to nuclear accumulation of tumor suppressor proteins, and induces cancer cell death. A phase 1 dose-escalation study was initiated to examine the safety and efficacy of selinexor in patients with advanced hematological malignancies. Ninety-five patients with relapsed or refractory acute myeloid leukemia (AML) were enrolled between January 2013 and June 2014 to receive 4, 8, or 10 doses of selinexor in a 21- or 28-day cycle. The most frequently reported adverse events (AEs) in patients with AML were grade 1 or 2 constitutional and gastrointestinal toxicities, which were generally manageable with supportive care. The only nonhematological grade 3/4 AE, occurring in >5% of the patient population, was fatigue (14%). There were no reported dose-limiting toxicities or evidence of cumulative toxicity. The recommended phase 2 dose was established at 60 mg (∼35 mg/m²) given twice weekly in a 4-week cycle based on the totality of safety and efficacy data. Overall, 14% of the 81 evaluable patients achieved an objective response (OR) and 31% percent showed ≥50% decrease in bone marrow blasts from baseline. Patients achieving an OR had a significant improvement in median progression-free survival (PFS) (5.1 vs 1.3 months; P = .008; hazard ratio [HR], 3.1) and overall survival (9.7 vs 2.7 months; P = .01; HR, 3.1) compared with nonresponders. These findings suggest that selinexor is safe as a monotherapy in patients with relapsed or refractory AML and have informed subsequent phase 2 clinical development. This trial was registered at www.clinicaltrials.gov as #NCT01607892.

Natural Compounds as Anticancer Agents Targeting DNA Topoisomerases

DNA topoisomerases are important cellular enzymes found in almost all types of living cells (eukaryotic and prokaryotic). These enzymes are essential for various DNA metabolic processes e.g. replication, transcription, recombination, chromosomal decatenation etc. These enzymes are important molecular drug targets and inhibitors of these enzymes are widely used as effective anticancer and antibacterial drugs. However, topoisomerase inhibitors have some therapeutic limitations and they exert serious side effects during cancer chemotherapy. Thus, development of novel anticancer topoisomerase inhibitors is necessary for improving cancer chemotherapy. Nature serves as a repertoire of structurally and chemically diverse molecules and in the recent years many DNA topoisomerase inhibitors have been identified from natural sources. The present review discusses anticancer properties and therapeutic importance of eighteen recently identified natural topoisomerase inhibitors (from the year 2009 to 2015). Structural characteristics of these novel inhibitors provide backbones for designing and developing new anticancer drugs.

Metabolism and disposition of the anticancer quinolone derivative vosaroxin, a novel inhibitor of topoisomerase II

Background Vosaroxin is a first-in-class anticancer quinolone derivative that is being investigated for patients with relapsed or refractory acute myeloid leukemia (AML). The primary objective of this study was to quantitatively determine the pharmacokinetics of vosaroxin and its metabolites in patients with advanced solid tumors. Methods This mass balance study investigated the pharmacokinetics (distribution, metabolism, and excretion) of vosaroxin in cancer patients after a single dose of 60 mg/m^{2 14}C-vosaroxin, administered as short intravenous injection. Blood, urine and feces were collected over 168 h after injection or until recovered radioactivity over 24 h was less than 1% of the administered dose (whichever was earlier). Total radioactivity (TRA), vosaroxin and metabolites were studied in all matrices. Results Unchanged vosaroxin was the major species identified in plasma, urine, and feces. N-desmethylvosaroxin was the only circulating metabolite detected in plasma, accounting for <3% of the administered dose. However, in plasma, the combined vosaroxin + N-desmethylvosaroxin AUC_0-∞ was 21% lower than the TRA AUC_0-∞ , suggesting the possible formation of protein bound metabolites after 48 h when the concentration-time profiles diverged. The mean recovery of TRA in excreta was 81.3% of the total administered dose; 53.1% was excreted through feces and 28.2% through urine. Conclusions Unchanged vosaroxin was the major compound found in the excreta, although 10 minor metabolites were detected. The biotransformation reactions were demethylation, hydrogenation, decarboxylation and phase II conjugation including glucuronidation.

Impact of salvage regimens on response and overall survival in acute myeloid leukemia with induction failure

We evaluated the impact of salvage regimens and allogeneic hematopoietic cell transplantation (allo-HCT) in acute myeloid leukemia (AML) with induction failure. Between 1993 and 2009, 3324 patients with newly diagnosed AML were enrolled in 5 prospective treatment trials of the German-Austrian AML Study Group. After first induction therapy with idarubicin, cytarabine and etoposide (ICE), 845 patients had refractory disease. In addition, 180 patients, although responding to first induction, relapsed after second induction therapy. Of the 1025 patients with induction failure, 875 (median age 55 years) received intensive salvage therapy: 7+3-based (n=59), high-dose cytarabine combined with mitoxantrone (HAM; n=150), with all-trans retinoic acid (A; A-HAM) (n=247), with gemtuzumab ozogamicin and A (GO; GO-A-HAM) (n=140), other intensive regimens (n=165), experimental treatment (n=27) and direct allo-HCT (n=87). In patients receiving intensive salvage chemotherapy (n=761), response (complete remission/complete remission with incomplete hematological recovery (CR/CRi)) was associated with GO-A-HAM treatment (odds ratio (OR), 1.93; P=0.002), high-risk cytogenetics (OR, 0.62; P=0.006) and age (OR for a 10-year difference, 0.75; P<0.0001). Better survival probabilities were seen in an extended Cox regression model with time-dependent covariables in patients responding to salvage therapy (P<0.0001) and having the possibility to perform an allo-HCT (P<0.0001). FLT3 internal tandem duplication, mutated IDH1 and adverse cytogenetics were unfavorable factors for survival.