New drug approvals in acute myeloid leukemia: what's the best end point?

Poor post-induction outcomes in patients with acute myeloid leukemia previously treated with hypomethylating agents

Patients with acute myeloid leukemia (AML) who have failed hypomethylating agents (HMA) have a poor prognosis. We examined whether high intensity induction chemotherapy could abrogate negative outcomes in 270 patients with AML or other high-grade myeloid neoplasms. Prior HMA therapy was significantly associated with a lower overall survival (OS) as compared to a reference group of patients with secondary disease without prior HMA therapy (median 7.2 vs 13.1 months). In patients with prior HMA therapy, high intensity induction was associated with a non-significant trend toward longer OS (median 8.2 vs 4.8 months) and decreased rates of treatment failure (39% vs 64%). These results redemonstrate poor outcomes in patients with prior HMA and suggest possible benefit of high intensity induction that should be evaluated in future studies.

Use of endpoints in phase III randomized controlled trials for acute myeloid leukemia over the last 15 years: a systematic review

We systematically evaluated the primary and secondary endpoints used in acute myeloid leukemia (AML) phase III randomized controlled trials (RCTs). We included 238 phase III AML RCTs in the past 15 years that reported 279 primary endpoints and 657 secondary endpoints. Overall survival (OS), progression-free survival (PFS), event-free survival (EFS), and complete remission (CR) were primary endpoints in 120 (43%), 34 (12%), 30 (11%), and 41 (15%) studies, respectively. OS (12.5%), PFS (13.2%), CR (14%), safety (11%), and EFS (9%) were commonly reported secondary endpoints. Among primary endpoints, a higher use of OS (OR 2.03, 95%CI 1.10-3.75, p = 0.023) and lower use of PFS (OR 0.25, 95%CI 0.12-0.52, p < 0.001) was observed from 2014 to 2021 compared to 2006-2013; CR was frequently used in relapsed/refractory compared to frontline RCTs (OR 2.20, 95%CI 1.11-4.38, p = 0.025); EFS was frequently used in frontline compared to relapsed/refractory AML RCTs (OR 10.11, 95%CI 1.34-76.34, p = 0.025). A higher trend in the use of clinically meaningful and objective endpoint of OS over the last 15 years.

Anticancer effects of disulfiram: a systematic review of in vitro, animal, and human studies

BACKGROUND AND OBJECTIVES

Cancer morbidity and mortality rates remain high, and thus, at present, considerable efforts are focused on finding drugs with higher sensitivity against tumor cells and fewer side effects. Disulfiram (DSF), as an anti-alcoholic drug, kills the cancer cells by inducing apoptosis. Several preclinical and clinical studies have examined the potential of repurposing DSF as an anticancer treatment. This systematic review aimed to assess evidence regarding the antineoplastic activity of DSF in in vitro and in vivo models, as well as in humans.

METHODS

Two authors independently conducted this systematic review of English and Chinese articles from the PubMed, Embase, and the Cochrane Library databases up to July 2019. Eligible in vitro studies needed to include assessments of the apoptosis rate by flow cytometry using annexin V/propidium iodide, and studies in animal models and clinical trials needed to examine tumor inhibition rates, and progression-free survival (PFS) and overall survival (OS), respectively. Data were analyzed using descriptive statistics.

RESULTS

Overall, 35 studies, i.e., 21 performed in vitro, 11 based on animal models, and three clinical trials, were finally included. In vitro and animal studies indicated that DSF was associated with enhanced apoptosis and tumor inhibition rates, separately. Human studies showed that DSF prolongs PFS and OS. The greatest anti-tumor activity was observed when DSF was used as combination therapy or as a nanoparticle-encapsulated molecule. There was no noticeable body weight loss after DSF treatment, which indicated that there was no major toxicity of DSF.

CONCLUSIONS

This systematic review provides evidence regarding the anti-tumor activity of DSF in vitro, in animals, and in humans and indicates the optimal forms of treatment to be evaluated in future research.

Distinguishing AML from MDS: a fixed blast percentage may no longer be optimal

Patients with acute myeloid leukemia (AML) have conventionally received more intense therapy than patients with myelodysplastic syndrome (MDS). Although less intense therapies are being used more often in AML, the dichotomy between AML and MDS remains, with the presence of ≥20% myeloblasts in marrow or peripheral blood generally regarded as defining AML. Consequently, patients with 19% blasts are typically ineligible for AML studies, and patients with 21% blasts are ineligible for MDS studies. Here we cite biologic and clinical data to question this practice. Biologically, abnormalities in chromosome 3q26 and mutations in NPM1 and FLT3, regarded as AML associated, also occur in MDS. The genetic signatures of MDS, particularly cases with 10% to 19% blasts (MDS-EB2), resemble those of AML following a preceding MDS (secondary AML). Mutationally, secondary AML appears at least as similar to MDS-EB2 as to de novo AML. Patients presenting with de novo AML but with secondary-type AML mutations seem to have the same poor prognosis associated with clinically defined secondary AML. Seattle data indicate that after accounting for European LeukemiaNet 2017 risk, age, performance status, clinically secondary AML, and treatment including allogeneic transplantation, patients with World Health Organization-defined AML (n = 769) have similar rates of overall survival, event-free survival, and complete remission (CR)/CR with incomplete hematologic recovery as patients with MDS-EB2 (n = 202). We suggest defining patients with 10% to 30% blasts (AML/MDS) as eligible for both AML and MDS studies. This would permit empiric testing of the independent effect of blast percentage on outcome, allow patients access to more therapies, and potentially simplify the regulatory approval process.

Adjunctive Volasertib in Patients With Acute Myeloid Leukemia not Eligible for Standard Induction Therapy: A Randomized, Phase 3 Trial

In this phase 3 trial, older patients with acute myeloid leukemia ineligible for intensive chemotherapy were randomized 2:1 to receive the polo-like kinase inhibitor, volasertib (V; 350 mg intravenous on days 1 and 15 in 4-wk cycles), combined with low-dose cytarabine (LDAC; 20 mg subcutaneous, twice daily, days 1–10; n = 444), or LDAC plus placebo (P; n = 222). Primary endpoint was objective response rate (ORR); key secondary endpoint was overall survival (OS). Primary ORR analysis at recruitment completion included patients randomized ≥5 months beforehand; ORR was 25.2% for V+LDAC and 16.8% for P+LDAC (n = 371; odds ratio 1.66 [95% confidence interval (CI), 0.95–2.89]; P = 0.071). At final analysis (≥574 OS events), median OS was 5.6 months for V+LDAC and 6.5 months for P+LDAC (n = 666; hazard ratio 0.97 [95% CI, 0.8–1.2]; P = 0.757). The most common adverse events (AEs) were infections/infestations (grouped term; V+LDAC, 81.3%; P+LDAC, 63.5%) and febrile neutropenia (V+LDAC, 60.4%; P+LDAC, 29.3%). Fatal AEs occurred in 31.2% with V+LDAC versus 18.0% with P+LDAC, most commonly infections/infestations (V+LDAC, 17.1%; P+LDAC, 6.3%). Lack of OS benefit with V+LDAC versus P+LDAC may reflect increased early mortality with V+LDAC from myelosuppression and infections.

Role of Minimal Residual Disease Testing in Acute Myeloid Leukemia

Minimal or measurable residual disease (MRD) after therapy is the most important independent prognostic factor in acute myeloid leukemia. MRD measured by multiparametric flow cytometry and real-time quantitative polymerase chain reaction has been integrated into risk stratification and used to guide future treatment strategies. Recent technological advances have allowed the application of the novel molecular method, high-throughput sequencing, in MRD detection in clinical practice to improve sensitivity and specificity. Randomized studies are needed to address outstanding issues, including the optimal methods and timing of MRD testing and interlaboratory standardization to facilitate comparisons, to further improve MRD-directed interventions.

Clinical value of event-free survival in acute myeloid leukemia

The value of event-free survival (EFS) as an end point in acute myeloid leukemia (AML) trials has been questioned. We hypothesized that rather than a surrogate for overall survival (OS), improvement in EFS may decrease the use of health care. In this retrospective study, we identified 400 patients with AML who were treated on first-line therapy trials and had OS between 2 and 36 months. We captured health care use from diagnosis until death or until the patient was censored at stem cell transplantation (SCT). We used correlation and regression analysis to determine the relation between health care use and EFS. Among patients with newly diagnosed AML, 35% had adverse-risk AML, 48% received intensive chemotherapy, and 28% received hypomethylating agents. The median EFS censored at SCT was 9.7 months. Longer EFS led to a significant decline in health care use regardless of OS. This held true for all observations, including overall health care use (r = -0.45), sum of clinic visits, emergency room visits, hospitalizations, consultations (r = -0.44), sum of invasive procedures, laboratory and imaging studies (r = -0.51), and blood product transfusions (r = -0.19). These correlations were stronger for patients who achieved a complete remission and held true across age, treatment, and disease risk subgroups. In patients with newly diagnosed AML, improvement in EFS correlates with a decrease in all health care use irrespective of OS duration.

Statistical considerations in clinical trial design with event-free survival as the primary efficacy endpoint

In late-phase confirmatory clinical trials in the oncology field, time-to-event (TTE) endpoints are commonly used as primary endpoints for establishing the efficacy of investigational therapies. Among these TTE endpoints, overall survival (OS) is always considered as the gold standard. However, OS data can take years to mature, and its use for measurement of efficacy can be confounded by the use of post-treatment rescue therapies or supportive care. Therefore, to accelerate the development process and better characterize the treatment effect of new investigational therapies, other TTE endpoints such as progression-free survival and event-free survival (EFS) are applied as primary efficacy endpoints in some confirmatory trials, either as a surrogate for OS or as a direct measure of clinical benefits. For evaluating novel treatments for acute myeloid leukemia, EFS has been gradually recognized as a direct measure of clinical benefits. However, the application of an EFS endpoint is still controversial mainly due to the debate surrounding definition of treatment failure (TF) events. In this article, we investigate the EFS endpoint with the most conservative definition for the timing of TF, which is Day 1 since randomization. Specifically, the corresponding non-proportional hazard pattern of the EFS endpoint is investigated with both analytical and numerical approaches.

Clinical Trial Design and Drug Approval in Oncology: A Primer for the Advanced Practitioner in Oncology

Evidenced-based practice requires timely and accurate integration of scientific advances. This presents a challenge for the oncology clinician given the robust pace of scientific discovery and the increasing number of new drug approvals and expanded indications for previously approved drugs. All currently available antineoplastic therapies have been developed through the clinical trials process. Advanced practitioners (APs) in oncology are often involved in the conduct of clinical trials as primary investigators, sub-investigators, study coordinators, or in the delivery and monitoring of care to patients enrolled in these trials. A prerequisite to evidenced-based practice is understanding how clinical trials are conducted and how to critically analyze published results of studies leading to U.S. Food & Drug Administration approval. Any AP involved in the clinical management and supportive care of patients receiving antineoplastic therapies should be able to critically review published data to glean findings that warrant a change in practice. The goals of this manuscript are to summarize key elements of the clinical trial process for oncology drug development and approval in the United States and to provide a primer for the interpretation of clinical data.

Evaluation of event-free survival as a robust end point in untreated acute myeloid leukemia (Alliance A151614)

Event-free survival (EFS) is controversial as an end point for speeding approvals in newly diagnosed acute myeloid leukemia (AML). We aimed to examine the robustness of EFS, specifically timing of complete remission (CR) in defining induction failure and impact of hematopoietic cell transplantation (HCT). The study included 1884 untreated AML patients enrolled across 5 trials conducted through Alliance for Clinical Trials in Oncology using anthracycline and cytarabine induction chemotherapy. EFS was defined as time from randomization/registration to induction failure, relapse, or death. Three definitions of induction failure were evaluated: failure to achieve CR by 60 days after randomization/registration, failure to achieve CR by the end of all protocol-defined induction courses, and failure to achieve CR by the end of all protocol-defined treatment. We considered either censoring or no censoring at time of non-protocol-mandated HCT. Although relapse and death are firm end points, the determination of induction failure was not consistent across studies. There was minimal impact of censoring at HCT on EFS estimates; however, median EFS estimates differed considerably based on the timing of CR in defining induction failure, with the magnitude of difference being large enough in most cases to lead to incorrect conclusions about efficacy in a single-arm trial, if the trial definition was not consistent with the definition used for the historical control. Timing of CR should be carefully examined in the historical control data used to guide the design of single-arm trials using EFS as the primary end point. Trials were registered at www.clinicaltrials.gov as #NCT00085124, #NCT00416598, # NCT00651261, #NCT01238211, and #NCT01253070.

Validation of the Functional Assessment of Cancer Therapy-Leukemia instrument in patients with acute myeloid leukemia who are not candidates for intensive therapy

BACKGROUND

The objective of this study was to validate the Functional Assessment of Cancer Therapy-Leukemia (FACT-Leu) in patients with acute myeloid leukemia (AML) who are not candidates for intensive therapy.

METHODS

A sample of 317 patients with AML who were not eligible for intensive chemotherapy completed the FACT-Leu and EuroQol 5-Dimension (EQ-5D) measures (Utility Index and Visual Analogue Scale) every 28 days until the end of treatment. Internal consistency reliability was estimated with Cronbach's α. Concurrent validity was examined with correlations between FACT-Leu and EQ-5D scales, and known-groups validity was examined by determining whether FACT-Leu scales distinguished between Eastern Cooperative Oncology Group (ECOG) performance status ratings (PSRs) and between maximum adverse event toxicities at the baseline. This study examined responsiveness to change by anchoring change in the FACT-Leu scales to a 0.10 change in the EQ-5D Health Utility Index.

RESULTS

Cronbach's α usually exceeded the threshold for good (≥0.80) or excellent reliability (≥0.90). Correlations between FACT-Leu and EQ-5D scales were moderate (r > 0.50) or high (r > 0.70). FACT-Leu scales distinguished between ECOG PSR groups with large effect sizes for an ECOG PSR of 0 versus an ECOG PSR of 2 (0.50 ≤ d < 0.80). In addition, Functional Assessment of Cancer Therapy-General, Additional Concerns, FACT-Leu Total, and Trial Outcomes Index scales distinguished between patients with grade 3 or lower maximum adverse event toxicities and those with maximum adverse event toxicities higher than grade 3, but effect sizes were small (d < 0.50). Finally, FACT-Leu scale coefficients for a 0.10 change in the 5-level version of the EQ-5D HUI ranged between -0.01 and 4.30.

CONCLUSIONS

The FACT-Leu is a suitable outcome measure for AML clinical trials among patients not eligible for intensive therapy, and it may have value for clinical monitoring.

Age at Diagnosis and Patient Preferences for Treatment Outcomes in AML: A Discrete Choice Experiment to Explore Meaningful Benefits

BACKGROUND

The recent expansion of treatment options in acute myeloid leukemia (AML) has necessitated a greater understanding of patient preferences for treatment benefits, about which little is known.

METHODS

We sought to quantify and assess heterogeneity of the preferences of AML patients for treatment outcomes. An AML-specific discrete choice experiment (DCE) was developed involving multiple stakeholders. Attributes included in the DCE were event-free survival (EFS), complete remission (CR), time in the hospital, short-term side effects, and long-term side effects. Continuously coded conditional, stratified, and latent-class logistic regressions were used to model preferences of 294 patients with AML.

RESULTS

Most patients were white (89.4%) and in remission (95.0%). A 10% improvement in the chance of CR was the most meaningful offered benefit (P < 0.001). Patients were willing to trade up to 22 months of EFS or endure 8.7 months in the hospital or a two-step increase in long-term side effects to gain a 10% increase in chance of CR. Patients diagnosed at 60 years or older (21.6%) more strongly preferred to avoid short-term side effects (P = 0.03). Latent class analysis showed significant differences of preferences across gender and insurance status.

CONCLUSIONS

In this national sample of mostly AML survivors, patients preferred treatments that maximized chance at remission; however, significant preference heterogeneity for outcomes was identified. Age and gender may affect patients' preferences.

IMPACT

Survivor preferences for outcomes can inform patient-focused drug development and shared decision-making. Further studies are necessary to investigate the use of DCEs to guide treatment for individual patients.

Recent drug approvals for newly diagnosed acute myeloid leukemia: gifts or a Trojan horse?

Since 2017 the US Food and Drug Administration (FDA) has approved glasdegib, venetoclax, ivosidenib, midostaurin, CPX- 351, and gemtuzumab ozogamicin (GO) to treat persons with newly diagnosed acute myeloid leukemia. The European Medicines Agency (EMA) has done likewise for midostaurin, CPX-351, and GO. While increasing options for persons, particularly older ones, for whom current therapy is unsatisfactory, or simply not given, these approvals raise several concerns. Although the venetoclax and glasdegib approvals were for persons considered "unfit" for intensive induction, the criteria for fitness were not well defined (age ≥75 per se being insufficient) and are frequently subjective, making it likely that many subjects in the venetoclax and glasdegib registration trials were fit for intensive induction; for example, none had performance status 3-4. Fitness must be assessed together with the potential efficacy of a proposed therapy. We note the modest complete remission rates and durations in the venetoclax + hypomethylating agent trial. Although these formed the basis for FDA approval, it is unclear that better results might not have obtained with more intense induction, as several studies, with considerably longer-follow up, have suggested. Hence, we question the venetoclax (and glasdegib) approvals absent randomized comparisons with intense induction. Given the uncertain relation in older individuals between survival and complete remission (CR), much less responses less than CR, we are skeptical of the sole use of these responses in the ivosidenib and venetoclax approvals; we also question the use of survival, without event-free survival, in the glasdegib approval. Noting the midostaurin and CPX-351 approvals included populations not participating in the registration studies we suggest means to address this issue as well as those involving fitness, randomization, and endpoints.

Single-agent and combination biologics in acute myeloid leukemia

Acute myeloid leukemia (AML) is a heterogeneous malignancy characterized by recurrent genetic, epigenetic, and metabolic abnormalities. As a result of our increasing knowledge of the underlying biology of AML leading to rational drug development, several new targeted agents have been recently added to our therapeutic arsenal. The BCL2 inhibitor venetoclax in combination with low-dose cytarabine (LDAC) or hypomethylating agents (HMAs) is safe and effective in older patients with newly diagnosed AML ineligible for intensive chemotherapy. Glasdegib, a hedgehog pathway inhibitor, may be used in combination with LDAC for the same indication and improves survival compared with LDAC alone. In newly diagnosed, fit, older patients with therapy-related AML or AML with myelodysplasia-related changes, the liposome-encapsulated combination of daunorubicin and cytarabine (CPX-351) has shown superiority over the 7 + 3 regimen. The presence of an IDH1 or IDH2 mutation can be effectively targeted by ivosidenib or enasidenib, respectively. Gemtuzumab ozogamicin improves event-free survival in CD33+ patients with favorable or intermediate-risk cytogenetics. With new targeted agents available, comprehensive genomic characterization of AML at diagnosis and relapse is increasingly necessary to select optimal treatment. Herein, we review the new single-agent and combination biologics (omitting FLT3 inhibitors, which are discussed separately) and provide recommendations on how to best use and manage patients on these regimens in clinical practice.

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.

Acute myeloid leukemia: 2019 update on risk-stratification and management

Outcome in patients with acute myeloid leukemia (AML) ranges from death within a few days of beginning treatment (treatment related mortality, TRM) to likely cure. The major reason patients are not cured is resistance to treatment, often manifested as relapse from remission, rather than, even in older patients, TRM, whose incidence is decreasing. Knowledge of the pre-treatment mutation status of various genes has improved our ability to assign initial treatment and, of particular importance, knowledge of whether patients ostensibly in remission have measurable residual disease should influence subsequent management. Several new drugs have been approved by the FDA and we discuss their role in treatment.

Interpretation of clinical endpoints in trials of acute myeloid leukemia

Treatment regimens for acute myeloid leukemia (AML) have remained largely unchanged until recently. Molecular advances have opened the door to targeted therapies, many of which are in late-phase clinical trials. As new therapeutic opportunities arise, it is appropriate to review key aspects of clinical trial design, statistical interpretation of outcomes, and methods of data reporting. Complete remission and overall survival (OS) are common primary endpoints in early-phase AML clinical trials. OS and event-free survival are frequent primary endpoints in phase 3 trials. Clinical trials are designed to address the primary endpoint using prespecified α and power levels. Interpretation of additional endpoints (eg, secondary endpoints and subgroup analyses) must be viewed in light of a trial's statistical design. Furthermore, variations in reporting of endpoints must be considered in order to understand trial outcomes. Time-to-event endpoints are typically reported using Kaplan-Meier curves, which are visually informative. Statistical data derived from these curves can be complex, and a variety of factors may impact interpretation. The purpose of this review is to discuss the nuances of common AML trial endpoints and their data presentation to better inform evaluation and understanding of clinical trial data.

Evaluating the Impact of the Addition of Cladribine to Standard Acute Myeloid Leukemia Induction Therapy

BACKGROUND

Treatment for acute myeloid leukemia (AML) has remained relatively unchanged over the past few decades. Although recent drug approvals have provided an increase in the number of treatment options in AML, further optimization of standard induction therapy is still necessary. The most commonly utilized induction options have been well studied, but there is a paucity of literature comparing the combination of idarubicin with cytarabine and cladribine.

OBJECTIVE

To assess the clinical effectiveness of the addition of cladribine to idarubicin and cytarabine (7+3 IA) induction therapy in the treatment of AML.

METHODS

This retrospective, propensity score-matched cohort study evaluated 37 patients with previously untreated AML who received either 7+3 IA or idarubicin, cytarabine, and cladribine (7+3+5 IAC) as induction therapy. The primary end point of this study was complete response (CR), with secondary end points including hospital length of stay (LOS), and adverse event rates.

RESULTS

After propensity score matching, odds of reaching CR in the 7+3+5 IAC cohort were increased by 33% (95% CI = 1.09-1.55; P < 0.01) compared with the 7+3 IA cohort. Patients who received cladribine were also found to have a reduction in hospital LOS by 3.5 days (95% CI = 0.07-6.85; P = 0.045) without an increase in adverse event rates.

CONCLUSION

The addition of cladribine to the 7+3 IA regimen may improve clinical outcomes when used as initial induction therapy, without increasing the incidence of adverse event rates.

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.

Response Rates as Predictors of Overall Survival: A Meta-Analysis of Acute Myeloid Leukemia Trials

Background: Response rates such as overall response rate (ORR), complete response (CR) and complete response with incomplete blood recovery (CRi) can be evaluated in a much shorter period of time than overall survival (OS), potentially accelerating decision making during drug development. The objective of this work was to evaluate the relationship between ORR, CR, CRi or better (CRi+CR) rates and median OS to determine whether response rates could be used as predictors of median OS in acute myeloid leukemia (AML).

Methods: A review of published literature was conducted to identify relevant AML clinical trials. Weighted linear regression was performed with various linearizing transformations of response rates and median OS. Covariates of interest were evaluated using a forward inclusion, backward elimination covariate model building procedure at α=0.01 and α=0.005, respectively.

Results: Twenty trials involving 26 cohorts were included in the meta-analysis. Azactidine treatment was a significant predictor with longer OS compared to decitabine or low dose cytarabine for a given response rate (P < 0.005). Linear regression analysis indicated that the correlation of both CRi or better rates and CR rates with median OS was higher than that of ORR with median OS. The final model showed a strong correlation between CRi or better rates and median OS (R²=0.66).

Conclusion: Significant correlation between CRi or better rates and median OS in AML highlights the potential for CRi or better rate, in addition to CR rate, to serve as surrogate markers for median OS.

Measurable residual disease testing in acute myeloid leukaemia

There is considerable interest in developing techniques to detect and/or quantify remaining leukaemia cells termed measurable or, less precisely, minimal residual disease (MRD) in persons with acute myeloid leukaemia (AML) in complete remission defined by cytomorphological criteria. An important reason for AML MRD-testing is the possibility of estimating the likelihood (and timing) of leukaemia relapse. A perfect MRD-test would precisely quantify leukaemia cells biologically able and likely to cause leukaemia relapse within a defined interval. AML is genetically diverse and there is currently no uniform approach to detecting such cells. Several technologies focused on immune phenotype or cytogenetic and/or molecular abnormalities have been developed, each with advantages and disadvantages. Many studies report a positive MRD-test at diverse time points during AML therapy identifies persons with a higher risk of leukaemia relapse compared with those with a negative MRD-test even after adjusting for other prognostic and predictive variables. No MRD-test in AML has perfect sensitivity and specificity for relapse prediction at the cohort- or subject levels and there are substantial rates of false-positive and -negative tests. Despite these limitations, correlations between MRD-test results and relapse risk have generated interest in MRD-test result-directed therapy interventions. However, convincing proof that a specific intervention will reduce relapse risk in persons with a positive MRD-test is lacking and needs testing in randomized trials. Routine clinical use of MRD-testing requires further refinements and standardization/harmonization of assay platforms and results reporting. Such data are needed to determine whether results of MRD-testing can be used as a surrogate end point in AML therapy trials. This could make drug-testing more efficient and accelerate regulatory approvals. Although MRD-testing in AML has advanced substantially, much remains to be done.

Leukemic stem cells: identification and clinical application

Leukemic stem cells (LSCs) in acute myeloid leukemia (AML) represent a low-frequency subpopulation of leukemia cells that possess stem cell properties distinct from the bulk leukemia cells, including self-renewal capacity and drug resistance. Due to these properties, LSCs are supposed to facilitate the development of relapse. The existence of LSCs is demonstrated by the ability to engraft and initiate human AML in immune-compromised mouse models. Although several lines of evidence suggest the complex heterogeneity of phenotypes displayed by LSC, many studies consider the CD34+/CD38- compartment as the most relevant. To increase the understanding of the true LSC, techniques such as multicolor flow cytometry, side-population assay and ALDH assay are utilized in many laboratories and could aid in this. A better understanding of different LSC phenotypes is necessary to enhance risk group classification, guide clinical decision-making and to identify new therapeutic targets. These efforts to eliminate LSC should ultimately improve the dismal AML outcome by preventing relapse development.

Diagnosis and management of AML in adults: 2017 ELN recommendations from an international expert panel

The first edition of the European LeukemiaNet (ELN) recommendations for diagnosis and management of acute myeloid leukemia (AML) in adults, published in 2010, has found broad acceptance by physicians and investigators caring for patients with AML. Recent advances, for example, in the discovery of the genomic landscape of the disease, in the development of assays for genetic testing and for detecting minimal residual disease (MRD), as well as in the development of novel antileukemic agents, prompted an international panel to provide updated evidence- and expert opinion-based recommendations. The recommendations include a revised version of the ELN genetic categories, a proposal for a response category based on MRD status, and criteria for progressive disease.

Acute myeloid leukemia: 2016 Update on risk-stratification and management

Evidence suggest that even patients aged 70 or above benefit from specific AML therapy. The fundamental decision in AML then becomes whether to recommend standard or investigational treatment. This decision must rest on the likely outcome of standard treatment. Hence we review factors that predict treatment related mortality and resistance to therapy, the latter the principal cause of failure even in patients aged 70 or above. We emphasize the limitations of prediction of resistance based only on pre- treatment factors and stress the need to incorporate post-treatment factors, for example indicators of minimal residual disease. We review various newer therapeutic options and considerations that underlie the decision to recommend allogeneic hematopoietic cell transplant. Am. J. Hematol. 91:825-846, 2016. © 2016 Wiley Periodicals, Inc.

Precision medicine in acute myeloid leukemia: Hope, hype or both?

Precision medicine is interchangeably used with personalized medicine, genomic medicine and individualized medicine. Collectively, these terms refer to at least 5 distinct concepts in the context of AML. 1st, using molecular or omics data (e.g. genomics, epigenomics, transcriptomics, proteomics) to delineate or define subtypes of AML. 2nd, using these data to select the best therapy for someone with an AML subtype, such as a person with a FLT3-mutation. 3rd, using these data to monitor therapy-response such as measurable residual disease [MRD]-testing. 4th, using results of MRD-testing to select from amongst therapy-options such as additional chemotherapy or a haematopoietic cell transplant. And 5th, using these data to identify persons with hereditary forms of AML with potential therapy and surveillance implications. Here, we review these 5 conceptions and delineate where precision medicine is likely to afford greatest hope and where instead our rhetoric may constitute hype.