Is there a standard of care for relapsed AML?

FLT3-PROTACs for combating AML resistance: Analytical overview on chimeric agents developed, challenges, and future perspectives

The urgent and unmet medical demand of acute myeloid leukemia (AML) patients has driven the drug discovery process for expansion of the landscape of AML treatment. Despite the several agents developed for treatment of AML, more than 60 % of treated patients undergo relapse again after re-emission, thus, no complete cure for this complex disease has been reached yet. Targeted oncoprotein degradation is a new paradigm that can be employed to solve drug resistance, disease relapse, and treatment failure in complex diseases as AML, the most lethal hematological malignancy. AML is an aggressive blood cancer form and the most common type of acute leukemia, with bad outcomes and a very poor 5-year survival rate. FLT3 mutations occur in about 30 % of AML cases and FLT3-ITD is associated with poor prognosis of this disease. Prevalent FLT3 mutations include internal tandem duplication and point mutations (e.g., D835) in the tyrosine kinase domain, which induce FLT3 kinase activation and result in survival and proliferation of AML cells again. Currently approved FLT3 inhibitors suffer from limited clinical efficacy due to FLT3 reactivation by mutations, therefore, alternative new treatments are highly needed. Proteolysis-targeting chimera (PROTAC) is a bi-functional molecule that consists of a ligand of the protein of interest, FLT3 inhibitor in our case, that is covalently linked to an E3 ubiquitin ligase ligand. Upon FLT3-specific PROTAC binding to FLT3, the PROTAC can recruit E3 for FLT3 ubiquitination, which is subsequently subjected to proteasome-mediated degradation. In this review we tried to address the question if PROTAC technology has succeeded in tackling the disease relapse and treatment failure of AML. Next, we explored the latest FLT3-targeting PROTACs developed in the past few years such as quizartinib-based PROTACs, dovitinib-based PROTACs, gilteritinib-based PROTACs, and others. Then, we followed with a deep analysis of their advantages regarding potency improvement and overcoming AML drug resistance. Finally, we discussed the challenges facing these chimeric molecules with proposed future solutions to circumvent them.

High expression of ARHGEF5 predicts unfavorable prognosis in acute myeloid leukemia

Acute myeloid leukemia (AML) is a highly heterogeneous hematological neoplasm, highlighting the need for new molecular markers to improve prognosis prediction and therapeutic strategies. While Rho guanine nucleotide exchange factor 5 (ARHGEF5) is known to be overexpressed in various cancers, its role in AML is not well understood. This study investigates the correlation between ARHGEF5 expression and AML using data from the Cancer Genome Atlas (TCGA). ARHGEF5 expression levels in AML patients and normal samples were compared using the Wilcoxon rank-sum test. The Kaplan-Meier method and Cox regression analysis (CRA) assessed the association between ARHGEF5 expression and patient survival. A prognostic nomogram was constructed using CRA, incorporating patient age and cytogenetic risk.Our findings indicate significant overexpression of ARHGEF5 in AML compared to normal samples. Elevated ARHGEF5 levels were associated with poor prognosis, particularly in patients ≤ 60 years, those with NPM1 mutations, FLT3 mutation-positive, and wild-type RAS (P < 0.05). CRA confirmed that high ARHGEF5 expression independently predicts poor prognosis. Additionally, 412 differentially expressed genes (DEGs) were identified between high and low ARHGEF5 expression groups, with 216 genes upregulated and 196 downregulated. Pathway enrichment analyses using GO and KEGG, along with protein-protein interaction network and single sample gene set enrichment analyses, revealed key pathways and immune cell associations linked to ARHGEF5. These findings suggest that ARHGEF5 overexpression could serve as a biomarker for unfavorable outcomes in AML, providing insights into the underlying mechanisms of AML onset and progression.

In silico predicted compound targeting the IQGAP1-GRD domain selectively inhibits growth of human acute myeloid leukemia

Acute myeloid leukemia (AML) is fatal in the majority of adults. Identification of new therapeutic targets and their pharmacologic modulators are needed to improve outcomes. Previous studies had shown that immunization of rabbits with normal peripheral WBCs that had been incubated with fluorodinitrobenzene elicited high titer antibodies that bound to a spectrum of human leukemias. We report that proteomic analyses of immunoaffinity-purified lysates of primary AML cells showed enrichment of scaffolding protein IQGAP1. Immunohistochemistry and gene-expression analyses confirmed IQGAP1 mRNA overexpression in various cytogenetic subtypes of primary human AML compared to normal hematopoietic cells. shRNA knockdown of IQGAP1 blocked proliferation and clonogenicity of human leukemia cell-lines. To develop small molecules targeting IQGAP1 we performed in-silico screening of 212,966 compounds, selected 4 hits targeting the IQGAP1-GRD domain, and conducted SAR of the 'fittest hit' to identify UR778Br, a prototypical agent targeting IQGAP1. UR778Br inhibited proliferation, induced apoptosis, resulted in G2/M arrest, and inhibited colony formation by leukemia cell-lines and primary-AML while sparing normal marrow cells. UR778Br exhibited favorable ADME/T profiles and drug-likeness to treat AML. In summary, AML shows response to IQGAP1 inhibition, and UR778Br, identified through in-silico studies, selectively targeted AML cells while sparing normal marrow.

Midostaurin plus daunorubicin or idarubicin for young and older adults with FLT3-mutated AML: a phase 3b trial

The pivotal RATIFY study demonstrated midostaurin (50 mg twice daily) with standard chemotherapy significantly reduced mortality in adult patients (<60 years) with newly diagnosed (ND) FLT3mut acute myeloid leukemia (AML). Considering that AML often present in older patients who show poor response to chemotherapy, this open-label, multicenter phase 3b trial was designed to further assess safety and efficacy of midostaurin plus chemotherapy in induction, consolidation, and maintenance monotherapy in young (≤60 years) and older (>60 years) patients with FLT3mut ND-AML. Compared with RATIFY, this study extended midostaurin treatment from 14 days to 21 days, substituted anthracyclines (idarubicin or daunorubicin), and introduced variation in standard combination chemotherapy dosing ("7+3" or "5+2" in more fragile patients). Total 301 patients (47.2% >60 years and 82.7% with FLT3-ITDmut) of median age 59 years entered induction phase. Overall, 295 patients (98.0%) had at least 1 adverse event (AE), including 254 patients (84.4%) with grade ≥3 AE. The grade ≥3 serious AEs occurred in 134 patients. No difference was seen in AE frequency between age groups, but grade ≥3AE frequency was higher in older patients. Overall, complete remission (CR) rate including incomplete hematologic recovery (CR + CRi) (80.7% [95% confidence interval, 75.74-84.98]) was comparable between age groups (≤60 years [83.5%]; >60 to ≤70 years [82.5%]; in patients >70 years [64.1%]) and the type of anthracycline used in induction. CR + CRi rate was lower in males (76.4%) than females (84.4%). Overall, the safety and efficacy of midostaurin remains consistent with previous findings, regardless of age, sex, or induction regimen. The trial is registered at www.clinicaltrials.gov as #NCT03379727.

Twist1 Promoter Methylation Regulates the Proliferation and Apoptosis of Acute Myeloid Leukemia Cells via PI3K/AKT Pathway

Twist-related protein 1 (Twist1) is a widely recognized oncogene in acute myeloid leukemia (AML), and its promoter methylation is related with the progression of solid tumors. However, the association between Twist1 promoter methylation and AML has not been well studied. Twist1 mRNA expression was detected using quantitative real-time polymerase chain reaction (qRT-PCR). The protein levels of Twist1 and phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) signal were measured via western blotting. Methylation-specific PCR was performed to detect the methylation status of Twist1 promoter. CCK-8 assay and flow cytometry were used to reveal cellular biological effects. Twist1 expression and promoter methylation level were significantly upregulated in AML tissues and cell lines and were further downregulated in demethylating agent 5'-azacitidine (5-Aza)-treated cells. Ectopic expression of Twist1 increased AML cell viability, while reducing apoptosis, and attenuated the effects of 5-Aza on the proliferation and apoptosis. We also found that the PI3K/AKT signaling pathway was positively regulated by Twist1. Our findings revealed that Twist1 accelerates the tumorigenesis of AML cells by promoting its promoter methylation via the activation of PI3K/AKT signaling pathway.

Functional Precision Medicine Provides Clinical Benefit in Advanced Aggressive Hematologic Cancers and Identifies Exceptional Responders

Personalized medicine aims to match the right drug with the right patient by using specific features of the individual patient's tumor. However, current strategies of personalized therapy matching provide treatment opportunities for less than 10% of patients with cancer. A promising method may be drug profiling of patient biopsy specimens with single-cell resolution to directly quantify drug effects. We prospectively tested an image-based single-cell functional precision medicine (scFPM) approach to guide treatments in 143 patients with advanced aggressive hematologic cancers. Fifty-six patients (39%) were treated according to scFPM results. At a median follow-up of 23.9 months, 30 patients (54%) demonstrated a clinical benefit of more than 1.3-fold enhanced progression-free survival compared with their previous therapy. Twelve patients (40% of responders) experienced exceptional responses lasting three times longer than expected for their respective disease. We conclude that therapy matching by scFPM is clinically feasible and effective in advanced aggressive hematologic cancers. SIGNIFICANCE: This is the first precision medicine trial using a functional assay to instruct n-of-one therapies in oncology. It illustrates that for patients lacking standard therapies, high-content assay-based scFPM can have a significant value in clinical therapy guidance based on functional dependencies of each patient's cancer.See related commentary by Letai, p. 290.This article is highlighted in the In This Issue feature, p. 275.

New prognostic factors and scoring system for patients with acute myeloid leukemia

Acute myeloid leukemia (AML) is a malignant disease originating from myeloid hematopoietic stem or progenitor cells. It is important to identify molecules associated with the prognosis of AML and conduct an individual risk assessment for different patients. In the present study, the RNA expression profile of 132 patients with AML and 337 healthy individuals were downloaded from the University of California Santa Cruz Xena and the Genotype-Tissue Expression project databases. Differentially expressed mRNA (DEmRNA) transcripts between normal blood and AML blood were identified. Among these, prognosis-associated signature mRNA molecules were screened using univariate Cox and least absolute shrinkage and selection operator regression. A total of four genes, namely, family with sequence similarity 124 member B (FAM124B), 4-hydroxyphenylpyruvate dioxygenase-like protein (HPDL), myeloperoxidase (MPO) and purinergic receptor P2Y1 (P2RY1), were identified using multivariate Cox regression analysis and were used to construct a prognostic scoring system. Moreover, the expression levels of HPDL and MPO were higher in the samples with high immunity scores and estimate scores (sum of stromal score and immune score), compared with those with low scores. Reverse transcription-quantitative PCR and western blot analysis were used to confirm the upregulation of the four candidate genes in AML cell lines as well as in clinical AML samples. In summary, the present study identified a novel mRNA-based prognostic risk scoring system for patients with AML. The four genes used in this scoring system may also play an important role in AML.

Hypomethylating Agents (HMAs) as Salvage Therapy in Relapsed or Refractory AML: An Italian Multicentric Retrospective Study

Data on the use of azacytidine and decitabine as salvage therapy for acute myeloid leukemia are limited. We retrospectively reviewed clinical records of 100 patients treated with hypomethylating agents (HMA) as salvage therapy in nine Italian institutions. A total of 24% of patients obtained a response to HMA (CR, PR, or CRi), while 26% showed a stable disease (SD); 50% of patients experienced progressive disease. Median OS was 6.5 months. OS in patients with de novo AML was 6.1 months, while OS in patients with secondary AML (sAML) was 12.3 months (p = 0.037). Median OS after HMA in patients with SD as best response to HMA was similar to median OS in patients with response to HMA (10.6 months vs. 13 months). On multivariate analysis, OS difference between patients who obtained a response versus patients who did not was significant (p = 0.0037). OS difference in sAML was significantly better than in de novo AML (p < 0.00001). HMA showed a remarkable efficacy in terms of response rate and OS in a subgroup of patients (sAMLs), historically characterized by a poor outcome. Therefore, 5Azacitidine and decitabine may represent a good clinical option in a selected patient population with relapsed or refractory AML, unsuitable for allo-HSCT.

A 2:1 randomized, open-label, phase II study of selinexor vs. physician's choice in older patients with relapsed or refractory acute myeloid leukemia

Selinexor, a selective inhibitor of nuclear export, has demonstrated promising activity in patients with acute myeloid leukemia (AML). This randomized, phase II study evaluated selinexor 60 mg twice weekly (n = 118) vs. physician's choice (PC) treatment (n = 57) in patients aged ≥60 years with relapsed/refractory (R/R) AML. The primary outcome was overall survival (OS). Median OS did not differ significantly for selinexor vs. PC (3.2 vs. 5.6 months; HR = 1.18 [95% CI: 0.79-1.75]; p = 0.422). Complete remission (CR) plus CR with incomplete hematologic recovery trending in favor of selinexor occurred in a minority of patients. Selinexor treated patients had an increased incidence of adverse events. The most common grade ≥3 adverse events were thrombocytopenia, febrile neutropenia, anemia, hyponatremia. Despite well-balanced baseline characteristics, there were numerically higher rates of TP53 mutations, prior myelodysplastic syndrome, and lower absolute neutrophil counts in the selinexor group; warranting further investigation of selinexor in more carefully stratified R/R AML patients.Registered trial: NCT02088541.

Immunotherapy in AML: a brief review on emerging strategies

Acute myeloid leukemia (AML), the most common form of leukemia amongst adults, is one of the most important hematological malignancies. Epidemiological data show both high incidence rates and low survival rates, especially in secondary cases among adults. Although classic and novel chemotherapeutic approaches have extensively improved disease prognosis and survival, the need for more personalized and target-specific methods with less side effects have been inevitable. Therefore, immunotherapeutic methods are of importance. In the following review, primarily a brief understanding of the molecular basis of the disease has been represented. Second, prior to the introduction of immunotherapeutic approaches, the entangled relationship of AML and patient's immune system has been discussed. At last, mechanistic and clinical evidence of each of the immunotherapy approaches have been covered.

Predictive impact of residual disease detected using multiparametric flow cytometry on risk stratification of paediatric acute myeloid leukaemia with normal karyotype

INTRODUCTION

Residual disease (RD) detected using multiparametric flow cytometry (MFC) is an independent predictive variable of relapse in acute myeloid leukaemia (AML). However, RD thresholds and optimal assessment time points remain to be validated.

MATERIAL AND METHODS

We investigated the significance of RD after induction therapy in paediatric AML with normal karyotype between June 2008 and June 2018. Bone marrow samples from 73 patients were collected at the end of the first (BMA-1) and second (BMA-2) induction courses to monitor RD using MFC.

RESULTS

Presence of RD after BMA-1 and/or BMA-2 correlated with poor relapse-free (RFS) and overall survival at 0.1% RD cutoff level. Receiver operating characteristic curve showed that RD cutoff levels of 1.3% and 0.5% after BMA-1 and BMA-2, respectively, predicted events with the highest sensitivity and specificity. In multivariable analysis, RD after BMA-2 was the strongest independent risk predictor for poor RFS (hazard ratio 2.934; 95% confidence interval: 1.106-7.782; P = .031).

CONCLUSIONS

Our study therefore suggests that an RD level ≥0.5% after BMA-2 has a significant predictive impact on the prognosis of AML patients having normal karyotype and thus guide the stratification of treatment strategies.

Taming Cell-to-Cell Heterogeneity in Acute Myeloid Leukaemia With Machine Learning

Acute Myeloid Leukaemia (AML) is a phenotypically and genetically heterogenous blood cancer characterised by very poor prognosis, with disease relapse being the primary cause of treatment failure. AML heterogeneity arise from different genetic and non-genetic sources, including its proposed hierarchical structure, with leukemic stem cells (LSCs) and progenitors giving origin to a variety of more mature leukemic subsets. Recent advances in single-cell molecular and phenotypic profiling have highlighted the intra and inter-patient heterogeneous nature of AML, which has so far limited the success of cell-based immunotherapy approaches against single targets. Machine Learning (ML) can be uniquely used to find non-trivial patterns from high-dimensional datasets and identify rare sub-populations. Here we review some recent ML tools that applied to single-cell data could help disentangle cell heterogeneity in AML by identifying distinct core molecular signatures of leukemic cell subsets. We discuss the advantages and limitations of unsupervised and supervised ML approaches to cluster and classify cell populations in AML, for the identification of biomarkers and the design of personalised therapies.

Reinduction chemotherapy regimen involved decitabine and cladribine improves the prognosis of patients with relapsed or refractory acute myeloid leukemia: A preliminary study

Relapsed/refractory acute myeloid leukemia (R/R-AML) is characterized by a high incidence, short survival and poor prognosis. Presently, no unified effective reinduction chemotherapy regimen has been developed. Therefore, the use of reinduction chemotherapy regimens before allogeneic hematopoietic stem cell transplantation (allo-HSCT) is controversial. Our study aims to analyze the prognostic factors of R/R-AML and to evaluate the efficacy of the regimen involved decitabine, cladribine, idarubicin or homoharringtonine, and cytarabine (DCIA/DCHA). Clinical and survival data of 112 R/R-AML patients were obtained. Among the 102 R/R-AML patients that were treated with conventional regimens, we found that poor prognosis was related to a greater proportion of bone marrow blasts (>70%) and not achieving complete remission (non-CR) after the first reinduction chemotherapy. Hematopoietic stem cell transplantation (of which 89.47% was allo-HSCT) following CR after the first reinduction chemotherapy often improves the prognosis. Of the 10 R/R-AML patients that were treated with the DCIA/DCHA regimen, nine patients achieved CR or complete response with incomplete hematopoietic recovery (CRi) after one course of chemotherapy. The median overall survival of the 10 patients was 10.14 (1.23-29.13) months. In conclusion, non-CR was associated with poor prognosis in R/R-AML. Therefore, intensive reinduction chemotherapy should be selected to achieve CR. This creates conditions for allo-HSCT and improves prognosis of R/R-AML patients. The DCIA/DCHA regimen showed good efficacy and tolerable adverse reactions in R/R-AML treatment. This combination may be used as a bridging regimen for allo-HSCT in R/R-AML.

High Expression of CLEC11A Predicts Favorable Prognosis in Acute Myeloid Leukemia

Background

Acute myeloid leukemia (AML) is a heterogeneous disease of the hematopoietic system, for which identification of novel molecular markers is potentially important for clinical prognosis and is an urgent need for treatment optimization.

Methods

We selected C-type lectin domain family 11, member A (CLEC11A) for study via several public databases, comparing expression among a variety of tumors and normal samples as well as different organs and tissues. To investigated the relationship between CLEC11A expression and clinical characteristics, we derived an AML cohort from The Cancer Genome Atlas (TCGA); we also investigated the Bloodspot and HemaExplorer databases. The Kaplan-Meier method and log-rank test were used to evaluate the associations between CLEC11A mRNA expression, as well as DNA methylation, and overall survival (OS), event-free survival (EFS), and relapse-free survival (RFS). DNA methylation levels of CLEC11A from our own 28 de novo AML patients were assessed and related to chemotherapeutic outcomes. Bioinformatics analysis of CLEC11A was carried out using public databases.

Results

Multiple public databases revealed that CLEC11A expression was higher in leukemia. The TCGA data revealed that high CLEC11A expression was linked with favorable prognosis (OS p-value = 2e-04; EFS p-value = 6e-04), which was validated in GSE6891 (OS p-value = 0; EFS p-value = 0; RFS p-value = 2e-03). Methylation of CLEC11A was negatively associated with CLEC11A expression, and high CLEC11A methylation level group was linked to poorer prognosis (OS p-value = 1e-02; EFS p-value = 2e-02). Meanwhile, CLEC11A hypermethylation was associated with poor induction remission rate and dismal survival. Bioinformatic analysis also showed that CLEC11A was an up-regulated gene in leukemogenesis.

Conclusion

CLEC11A may be used as a prognostic biomarker, and could do benefit for AML patients by providing precise treatment indications, and its unique gene pattern should aid in further understanding the heterogeneous AML mechanisms.

Why isn't there a one-size-fits-all approach for relapsed/refractory acute myeloid leukemia? Insights into different variables for decision-making

Relapsed refractory acute myeloid leukemia (R/R AML) has a poor prognosis. While the heterogeneity and diversity of R/R AML pose hurdles towards defining a standard of care, there have been various advances over the years. These, however, have added to the complexity of decision-making for R/R AML. This review has summarized evidence that will provide insights into factors that influence treatment choices in R/R AML and determine whether ongoing clinical trials can aid in identifying a standard approach for different sub-groups of patients.

Is outcome of older people with acute myeloid leukemia improving with new therapeutic approaches and stem cell transplantation?

Introduction: The clinical outcome of older patients with acute myeloid leukemia (AML) is still poor, especially for those who are unfit to treatments aimed at altering the natural course of the disease. Hypomethylating agents (HMA) offer an important therapeutic opportunity to a consistent number of patients, but long-term results are largely unsatisfactory.Area covered: Recently, a number of new agents have been registered for AML, some of which selectively available for older patient population, with promising results in terms of response rate and survival. Furthermore, the upper age limit for allogeneic stem cell transplantation is constantly increasing, so that this procedure is offered and actually given to an increasing number of older patients with AML. A literature review was conducted of the PubMed database for articles published in English as well as for abstracts from most important and recent hematology meetings on AML in older patients.Expert opinion: Appropriate selection among different options on the basis of clinical fitness and molecular findings at diagnosis as well as at relapse would result in improvement of therapeutic results, sparing unnecessary toxicity and optimizing health systems resources.

Impact of genotype in relapsed and refractory acute myeloid leukaemia patients treated with clofarabine and cytarabine: a retrospective study

The treatment of relapsed/refractory (R/R) acute myeloid leukaemia (AML) remains a challenge. Among salvage chemotherapy regimens, the clofarabine and cytarabine (CLARA) combination has been widely evaluated and has a favourable safety/efficacy balance. Predictive factors of efficacy in patients with R/R AML are unclear, particularly the impact of AML-related gene mutations. We report our single-centre experience on 34 R/R AML patients treated with CLARA, with a focus on the genetic characterization of our cohort. CLARA yielded a 47% response rate among this poor-prognosis AML population, while two patients (5·8%) died due to treatment-related toxicity. The two-year progression-free survival and overall survival rates were 29·4% and 35·3%, respectively. Nine patients (26%) had long-term response with a median follow-up of 39·5 months among the responders, of whom six underwent haematopoietic stem cell transplantation. Adverse karyotype did not correlate with response or survival, and secondary AML were more frequent among responders to CLARA, suggesting that this combination may successfully salvage R/R AML patients regardless of adverse prognostic markers. We also observed that a low mutational burden and absence of splice mutations correlated with prolonged survival after CLARA, suggesting that extensive genotyping may have prognostic implications in R/R AML.

Current Therapeutic Results and Treatment Options for Older Patients with Relapsed Acute Myeloid Leukemia

Considerable progress has been made in the treatment of acute myeloid leukemia (AML). However, current therapeutic results are still unsatisfactory in untreated high-risk patients and poorer in those with primary refractory or relapsed disease. In older patients, reluctance by clinicians to treat unfit patients, higher AML cell resistance related to more frequent adverse karyotype and/or precedent myelodysplastic syndrome, and preferential involvement of chemorefractory early hemopoietic precursors in the pathogenesis of the disease further account for poor prognosis, with median survival lower than six months. A general agreement exists concerning the administration of aggressive salvage therapy in young adults followed by allogeneic stem cell transplantation; on the contrary, different therapeutic approaches varying in intensity, from conventional salvage chemotherapy based on intermediate⁻high-dose cytarabine to best supportive care, are currently considered in the relapsed, older AML patient population. Either patients' characteristics or physicians' attitudes count toward the process of clinical decision making. In addition, several new drugs with clinical activity described as "promising" in uncontrolled single-arm studies failed to improve long-term outcomes when tested in larger randomized clinical trials. Recently, new agents have been approved and are expected to consistently improve the clinical outcome for selected genomic subgroups, and research is in progress in other molecular settings. While relapsed AML remains a tremendous challenge to both patients and clinicians, knowledge of the molecular pathogenesis of the disease is fast in progress, potentially leading to personalized therapy in most patients.