New Therapeutic Strategies for Adult Acute Myeloid Leukemia

Shikonin, a natural naphthoquinone phytochemical, exerts anti-leukemia effects in human CBF-AML cell lines and zebrafish xenograft models

Core binding factor acute myeloid leukemia (CBF-AML) stands out as the most common type of adult AML, characterized by specific chromosomal rearrangements involving CBF genes, particularly t(8;21). Shikonin (SHK), a naphthoquinone phytochemical widely employed as a food colorant and traditional Chinese herbal medicine, exhibits antioxidant, anti-inflammatory, and anti-cancer activities. In this study, we aim to investigate the antileukemic effects of SHK and its underlying mechanisms in human CBF-AML cells and zebrafish xenograft models. Our study revealed that SHK reduced the viability of CBF-AML cells. SHK induced cell cycle arrest, promoted cell apoptosis, and induced differentiation in Kasumi-1 cells. Additionally, SHK downregulated the gene expression of AML1-ETO and c-KIT in Kasumi-1 cells. In animal studies, SHK showed no toxic effects in zebrafish and markedly inhibited the growth of leukemia cells in zebrafish xenografts. Transcriptomic analysis showed that differentially expressed genes (DEGs) altered by SHK are linked to key biological processes like DNA repair, replication, cell cycle regulation, apoptosis, and division. Furthermore, KEGG pathways associated with cell growth, such as the cell cycle and p53 signaling pathway, were significantly enriched by DEGs. Analysis of AML-associated genes in response to SHK treatment using DisGeNET and the STRING database indicated that SHK downregulates the expression of cell division regulators regarding AML progression. Finally, we found that SHK combined with cytarabine synergistically reduced the viability of Kasumi-1 cells. In conclusion, our findings provide novel insights into the mechanisms of SHK in suppressing leukemia cell growth, suggesting its potential as a chemotherapeutic agent for human CBF-AML.

Recent advancements in biomarkers, therapeutics, and associated challenges in acute myeloid leukemia

Acute myeloid leukemia (AML) is a common type of leukemia that has a high mortality rate. The reasons for high mortality in patients with AML are therapeutic resistance, limited ability to predict duration of response, and likelihood of cancer relapse. Biomarkers, such as leukemic stem cell biomarkers, circulatory biomarkers, measurable residual disease biomarkers, and molecular biomarkers, are used for prognosis, diagnosis, and targeted killing to selectively eliminate AML cells. They also play an indispensable role in providing therapeutic resistance to patients with AML. Therefore, targeting these biomarkers will improve the outcome of AML patients. However, identifying biomarkers that can differentiate between treatment-responsive and non-responsive AML patients remains a challenge. This review discusses recent advancements in AML biomarkers, promising therapeutics, and associated challenges in the treatment of AML.

Reactive oxygen species and its role in pathogenesis and resistance to therapy in acute myeloid leukemia

Relapse following a short clinical response to therapy is the major challenge for the management of acute myeloid leukemia (AML) patients. Leukemic stem cells (LSC), as the source of relapse, have been investigated for their metabolic preferences and their alterations at the time of relapse. As LSC rely on oxidative phosphorylation (OXPHOS) for energy requirement, reactive oxygen species (ROS), as by-products of OXPHOS, have been investigated for their role in the effectiveness of the standard AML therapy. Increased levels of non-mitochondrial ROS, generated by nicotinamide adenine dinucleotide phosphate oxidase, in a subgroup of AML patients add to the complexity of studying ROS. Although there are various studies presenting the contribution of ROS to AML pathogenesis, resistance, and its inhibition or activation as a target, a model that can clearly explain its role in AML has not been conceptualized. This is due to the heterogeneity of AML, the dynamics of ROS production, which is influenced by factors such as the type of treatment, cell differentiation state, mitochondrial activity, and also the heterogeneous generation of non-mitochondrial ROS and limited available data on their interaction with the microenvironment. This review summarizes these challenges and the recent progress in this field.

SUMOylation inhibitor TAK-981 (subasumstat) synergizes with 5-azacytidine in preclinical models of acute myeloid leukemia

Acute myeloid leukemias (AML) are severe hematomalignancies with dismal prognosis. The post-translational modification SUMOylation plays key roles in leukemogenesis and AML response to therapies. Here, we show that TAK-981 (subasumstat), a first-in-class SUMOylation inhibitor, is endowed with potent anti-leukemic activity in various preclinical models of AML. TAK-981 targets AML cell lines and patient blast cells in vitro and in vivo in xenografted mice with minimal toxicity on normal hematopoietic cells. Moreover, it synergizes with 5-azacytidine (AZA), a DNA-hypomethylating agent now used in combination with the BCL-2 inhibitor venetoclax to treat AML patients unfit for standard chemotherapies. Interestingly, TAK-981+AZA combination shows higher anti-leukemic activity than AZA+venetoclax combination both in vitro and in vivo, at least in the models tested. Mechanistically, TAK-981 potentiates the transcriptional reprogramming induced by AZA, promoting apoptosis, alteration of the cell cycle and differentiation of the leukemic cells. In addition, TAK-981+AZA treatment induces many genes linked to inflammation and immune response pathways. In particular, this leads to the secretion of type-I interferon by AML cells. Finally, TAK-981+AZA induces the expression of natural killer-activating ligands (MICA/B) and adhesion proteins (ICAM-1) at the surface of AML cells. Consistently, TAK-981+AZA-treated AML cells activate natural killer cells and increase their cytotoxic activity. Targeting SUMOylation with TAK-981 may thus be a promising strategy to both sensitize AML cells to AZA and reduce their immune-escape capacities.

Discovery of benzimidazole-indazole derivatives as potent FLT3-tyrosine kinase domain mutant kinase inhibitors for acute myeloid leukemia

The FMS-like tyrosine kinase 3 (FLT3) gene encodes a class III receptor tyrosine kinase that is expressed in hematopoietic stem cells. The mutations of FLT3 gene found in 30% of acute myeloid leukemia (AML), leads to an abnormal constitutive activation of FLT3 kinase of the receptor and results in immature myeloblast cell proliferation. Although small molecule drugs targeting the FLT3 kinase have been approved, new FLT3 inhibitors are needed owing to the side effects and drug resistances arising from kinase domain mutations, such as D835Y and F691L. In this study, we have developed benzimidazole-indazole based novel inhibitors targeting mutant FLT3 kinases through the optimization of diverse chemical moieties substituted around the core skeleton. The most optimized compound 22f exhibited potent inhibitory activities against FLT3 and FLT3/D835Y, with IC50 values of 0.941 and 0.199 nM, respectively. Furthermore, 22f exhibited strong antiproliferative activity against an AML cell line, MV4-11 cells with a GI50 of 0.26 nM. More importantly, 22f showed single-digit nanomolar GI50 values in the mutant FLT kinase expressed Ba/F3 cell lines including FLT-D835Y (GI50 = 0.29 nM) and FLT3-F691L (GI50 = 2.87 nM). Molecular docking studies indicated that the compound exhibits a well-fitted binding mode as a type 1 inhibitor in the homology model of active conformation of FLT3 kinase.

MaLiAmPi enables generalizable and taxonomy-independent microbiome features from technically diverse 16S-based microbiome studies

For studies using microbiome data, the ability to robustly combine data from technically and biologically distinct microbiome studies is a crucial means of supporting more robust and clinically relevant inferences. Formidable technical challenges arise when attempting to combine data from technically diverse 16S rRNA gene variable region amplicon sequencing (16S) studies. Closed operational taxonomic units and taxonomy are criticized as being heavily dependent upon reference sets and with limited precision relative to the underlying biology. Phylogenetic placement has been demonstrated to be a promising taxonomy-free manner of harmonizing microbiome data, but it has lacked a validated count-based feature suitable for use in machine learning and association studies. Here we introduce a phylogenetic-placement-based, taxonomy-independent, compositional feature of microbiota: phylotypes. Phylotypes were predictive of clinical outcomes such as obesity or pre-term birth on technically diverse independent validation sets harmonized post hoc. Thus, phylotypes enable the rigorous cross-validation of 16S-based clinical prognostic models and associative microbiome studies.

Pinostrobin modulates FOXO3 expression, nuclear localization, and exerts antileukemic effects in AML cells and zebrafish xenografts

Acute myeloid leukemia (AML) is a disease characterized by abnormal cell proliferation in the bone marrow and is the most common quickly progressive leukemia in adults. Pinostrobin, a flavonoid phytochemical, has been reported to exhibit antioxidant, anti-inflammatory, and anticancer properties. In this study, we aimed to investigate the antileukemic effects of pinostrobin and its molecular mechanisms in human AML cells. Our study found that pinostrobin (0-80 μM) significantly reduced the viability of human AML cells, with the pronounced cytotoxic effects observed in MV4-11 > MOLM-13 > HL-60 > U-937 > THP-1 cells. Pinostrobin was found to suppress leukemia cell proliferation, modulate cell cycle progression, promote cell apoptosis, and induce monocytic differentiation in MV4-11 cells. In animal studies, pinostrobin significantly suppressed the growth of leukemia cells in a zebrafish xenograft model. Microarray-based transcriptome analysis showed that the differentially expressed genes (DEGs) in pinostrobin-treated cells were strongly associated with enriched Gene Ontology (GO) terms related to apoptotic process, cell death, cell differentiation, cell cycle progression, and cell division. Combining DisGeNET and STRING database analysis revealed that pinostrobin upregulates forkhead box 3 (FOXO3), a tumor suppressor in cancer development, and plays an essential role in controlling AML cell viability. Our study demonstrated that pinostrobin increases FOXO3 gene expression and promotes its nuclear translocation, leading to the inhibition of cell growth. Finally, the study found that pinostrobin, when combined with cytarabine, synergistically reduces the viability of AML cells. Our current findings shed light on pinostrobin's mechanisms in inhibiting leukemia cell growth, highlighting its potential as a chemotherapeutic agent or nutraceutical supplement for AML prevention or treatment.

A Review of FLT3 Kinase Inhibitors in AML

Acute myeloid leukemia (AML) is a highly aggressive illness distinguished by the accumulation of abnormal hematopoietic precursors in both the bone marrow and peripheral blood. The prevalence of FLT3 gene mutations is high and escalates the probability of relapse and mortality. The survival rates for AML patients, particularly those over 65, are low. FLT3 mutation screening at diagnosis is mandatory, and FLT3 inhibitors are crucial in treating AML patients with mutations. There are two categories of FLT3 mutations: FLT3-ITD located in the juxtamembrane domain and FLT3-TKD in the tyrosine kinase domain. FLT3-ITD is the most common type, affecting nearly a quarter of patients, whereas FLT3-TKD only affects 6-8% of patients. FLT3 inhibitors are now crucial in treating AML patients with FLT3 mutations. When dealing with FLT3-mutated AML, the recommended course of treatment typically involves chemotherapy and midostaurin, followed by allogeneic hematopoietic cell transplantation (HCT) to maximize the likelihood of success. Maintenance therapy can lower the risk of relapse, and gilteritinib is a better option than salvage chemotherapy for relapsed or refractory cases. Clinical trials for new or combined therapies are the most effective approach. This review discusses treatment options for patients with FLT3-mutated AML, including induction chemotherapy and options for relapsed or refractory disease. Additional treatment options may become available as more studies are conducted based on the patient's condition and susceptibility.

SUMO specific peptidase 1 decreases after induction treatment, and its reduction predicts lower disease risk, better treatment response, longer survival of acute myeloid leukemia

Small ubiquitin-related modifier-specific peptidase 1 (SENP1) takes part in the pathogenesis and progression of hematological malignancies, while its clinical role in acute myeloid leukemia (AML) is unclear. This study aimed to explore the potential of SENP1 to serve as a biomarker reflecting disease risk, treatment response, and survival of AML. A total of 110 AML patients, 30 disease controls (DCs), and 30 healthy controls (HCs) were included. SENP1 in bone marrow samples was detected by RT-qPCR. SENP1 was the top in AML patients (median (interquartile range (IQR)): 2.429 (1.854-3.772)), the second top in DCs (median (IQR): 1.587 (1.023-2.217)), and the lowest in HCs (median (IQR): 0.992 (0.806-1.702)) (p < 0.001). In AML patients, SENP1 was positively associated with white blood cells (rs = 0.210, p = 0.028) and bone marrow blasts (rs = 0.212, p = 0.026) but negatively linked to Inv(16) or t(16;16) presence (p = 0.040). Furthermore, SENP1 was decreased post-treatment vs. at baseline (before induction treatment) in total AML patients (p < 0.001), and in patients with CR (p < 0.001), but not in patients with non-CR (p = 0.055). Additionally, SENP1 at baseline slightly (p = 0.050) but SENP1 post-treatment dramatically (p < 0.001) decreased in patients with CR compared to those with non-CR. Notably, low SENP1 at baseline was related to prolonged EFS (p = 0.007) and OS (p = 0.039); meanwhile, declined SENP1 post-induction treatment showed a more predominant linkage with satisfied EFS (p < 0.001) and OS (p < 0.001). SENP1 is decreased after induction therapy, whose reduction is related to low disease risk, favorable treatment response, and prolonged survival of AML.

Analyses of Genes Critical to Tumor Survival Reveal Potential 'Supertargets': Focus on Transcription

The identification of mechanisms that underlie the biology of individual tumors is aimed at the development of personalized treatment strategies. Herein, we performed a comprehensive search of genes (termed Supertargets) vital for tumors of particular tissue origin. In so doing, we used the DepMap database portal that encompasses a broad panel of cell lines with individual genes knocked out by CRISPR/Cas9 technology. For each of the 27 tumor types, we revealed the top five genes whose deletion was lethal in the particular case, indicating both known and unknown Supertargets. Most importantly, the majority of Supertargets (41%) were represented by DNA-binding transcription factors. RNAseq data analysis demonstrated that a subset of Supertargets was deregulated in clinical tumor samples but not in the respective non-malignant tissues. These results point to transcriptional mechanisms as key regulators of cell survival in specific tumors. Targeted inactivation of these factors emerges as a straightforward approach to optimize therapeutic regimens.

Targeting the p53 signaling pathway in cancers: Molecular mechanisms and clinical studies

Tumor suppressor p53 can transcriptionally activate downstream genes in response to stress, and then regulate the cell cycle, DNA repair, metabolism, angiogenesis, apoptosis, and other biological responses. p53 has seven functional domains and 12 splice isoforms, and different domains and subtypes play different roles. The activation and inactivation of p53 are finely regulated and are associated with phosphorylation/acetylation modification and ubiquitination modification, respectively. Abnormal activation of p53 is closely related to the occurrence and development of cancer. While targeted therapy of the p53 signaling pathway is still in its early stages and only a few drugs or treatments have entered clinical trials, the development of new drugs and ongoing clinical trials are expected to lead to the widespread use of p53 signaling-targeted therapy in cancer treatment in the future. TRIAP1 is a novel p53 downstream inhibitor of apoptosis. TRIAP1 is the homolog of yeast mitochondrial intermembrane protein MDM35, which can play a tumor-promoting role by blocking the mitochondria-dependent apoptosis pathway. This work provides a systematic overview of recent basic research and clinical progress in the p53 signaling pathway and proposes that TRIAP1 is an important therapeutic target downstream of p53 signaling.

CYAD-01, an autologous NKG2D-based CAR T-cell therapy, in relapsed or refractory acute myeloid leukaemia and myelodysplastic syndromes or multiple myeloma (THINK): haematological cohorts of the dose escalation segment of a phase 1 trial

BACKGROUND

CYAD-01 is an autologous chimeric antigen receptor (CAR) T-cell product based on the natural killer (NK) group 2D (NKG2D) receptor, which binds eight ligands that are overexpressed in a wide range of haematological malignancies but are largely absent on non-neoplastic cells. Initial clinical evaluation of a single infusion of CYAD-01 at a low dose in patients with relapsed or refractory acute myeloid leukaemia, myelodysplastic syndromes, and multiple myeloma supported the feasibility of the approach and prompted further evaluation of CYAD-01. The aim of the present study was to determine the safety and recommended phase 2 dosing of CYAD-01 administered without preconditioning or bridging chemotherapy.

METHODS

The multicentre THINK study was an open-label, dose-escalation, phase 1 study for patients with relapsed or refractory acute myeloid leukaemia, myelodysplastic syndromes, or multiple myeloma, after at least one previous line of therapy. Patients were recruited from five hospitals in the USA and Belgium. The dose-escalation segment evaluated three dose levels: 3 × 10⁸ (dose level one), 1 × 10⁹ (dose level two), and 3 × 10⁹ (dose level three) cells per infusion with a 3 + 3 Fibonacci study design using a schedule of three infusions at 2-week intervals followed by potential consolidation treatment consisting of three additional infusions. The occurrence of dose-limiting toxicities post-CYAD-01 infusion was assessed as the primary endpoint in the total treated patient population. The trial was registered with ClinicalTrials.gov, NCT03018405, and EudraCT, 2016-003312-12, and has been completed.

FINDINGS

Between Feb 6, 2017, and Oct 9, 2018, 25 patients were registered in the haematological dose-escalation segment. Seven patients had manufacturing failure for insufficient yield and two had screening failure. 16 patients were treated with CYAD-01 (three with multiple myeloma and three with acute myeloid leukaemia at dose level one; three with acute myeloid leukaemia at dose level two; and six with acute myeloid leukaemia and one with myelodysplastic syndromes at dose level three). Median follow-up was 118 days (IQR 46-180). Seven patients (44%) had grade 3 or 4 treatment-related adverse events. In total, five patients (31%) had grade 3 or 4 cytokine release syndrome across all dose levels. One dose-limiting toxicity of cytokine release syndrome was reported at dose level three. No treatment-related deaths occurred, and the maximum tolerated dose was not reached. Three (25%) of 12 evaluable patients with relapsed or refractory acute myeloid leukaemia or myelodysplastic syndromes had an objective response. Among responders, two patients with acute myeloid leukaemia proceeded to allogeneic haematopoietic stem-cell transplantation (HSCT) after CYAD-01 treatment, with durable ongoing remissions (5 and 61 months).

INTERPRETATION

Treatment with a multiple CYAD-01 infusion schedule without preconditioning is well tolerated and shows anti-leukaemic activity, although without durability outside of patients bridged to allogeneic HSCT. These phase 1 data support the proof-of-concept of targeting NKG2D ligands by CAR T-cell therapy. Further clinical studies with NKG2D-based CAR T-cells are warranted, potentially via combinatorial antigen targeted approaches, to improve anti-tumour activity.

FUNDING

Celyad Oncology.

A potential area of use for immune checkpoint inhibitors: Targeting bone marrow microenvironment in acute myeloid leukemia

Acute myeloid leukemia (AML) arises from the cells of myeloid lineage and is the most frequent leukemia type in adulthood accounting for about 80% of all cases. The most common treatment strategy for the treatment of AML includes chemotherapy, in rare cases radiotherapy and stem cell and bone marrow transplantation are considered. Immune checkpoint proteins involve in the negative regulation of immune cells, leading to an escape from immune surveillance, in turn, causing failure of tumor cell elimination. Immune checkpoint inhibitors (ICIs) target the negative regulation of the immune cells and support the immune system in terms of anti-tumor immunity. Bone marrow microenvironment (BMM) bears various blood cell lineages and the interactions between these lineages and the noncellular components of BMM are considered important for AML development and progression. Administration of ICIs for the AML treatment may be a promising option by regulating BMM. In this review, we summarize the current treatment options in AML treatment and discuss the possible application of ICIs in AML treatment from the perspective of the regulation of BMM.

Naturally selected CD7 CAR-T therapy without genetic editing demonstrates significant antitumour efficacy against relapsed and refractory acute myeloid leukaemia (R/R-AML)

Background

The survival rate for patients with relapsed and refractory acute myeloid leukaemia (R/R-AML) remains poor, and treatment is challenging. Chimeric antigen receptor T cells (CAR-T cells) have been widely used for haematologic malignancies. Current CAR-T therapies for acute myeloid leukaemia mostly target myeloid-lineage antigens, such as CD123 and CD33, which may be associated with potential haematopoietic toxicity. As a lineage-specific receptor, CD7 is expressed in acute myeloid leukaemia cells and T cells but is not expressed in myeloid cells. Therefore, the use of CD7 CAR-T cells for R/R-AML needs to be further explored.

Methods

In this report, immunohistochemistry and flow cytometry were used to analyse CD7 expression in clinical samples from R/R-AML patients and healthy donors (HDs). We designed naturally selected CD7 CAR-T cells to analyse various functions and in vitro antileukaemic efficacy based on flow cytometry, and xenograft models were used to validate in vivo tumour dynamics.

Results

We calculated the percentage of cells with CD7 expression in R/R-AML patients with minimal residual disease (MRD) (5/16, 31.25%) from our institution and assessed CD7 expression in myeloid and lymphoid lineage cells of R/R-AML patients, concluding that CD7 is expressed in T cells but not in myeloid cells. Subsequently, we designed and constructed naturally selected CD7 CAR-T cells (CD7 CAR). We did not perform CD7 antigen knockdown on CD7 CAR-T cells because CD7 molecule expression is naturally eliminated at Day 12 post transduction. We then evaluated the ability to target and kill CD7+ acute myeloid leukaemia cells in vitro and in vivo. Naturally selected CD7 CAR-T cells efficiently killed CD7+ acute myeloid leukaemia cells and CD7+ primary blasts of R/R-AML patients in vitro and significantly inhibited leukaemia cell growth in a xenograft mouse model.

Conclusion

Naturally selected CD7 CAR-T cells represent an effective treatment strategy for relapsed and refractory acute myeloid leukaemia patients in preclinical studies.

Oral Antineoplastics in Acute Myeloid Leukemia: A Comprehensive Review

AML is a biologically and clinically heterogeneous disease that is associated with poor overall long-term survival. The expanding knowledge of genomic landscape in AML as well as advancements in molecular and chemical biology over the pathway in AML. After 40 years of stagnancy, the recent approval of numerous novel oral anti-leukemic agents for the treatment of AML has changed both the armamentarium of medications and treatment paradigms. These agents have unique clinical considerations in terms of administration, adverse effects, and monitoring parameters which may differ from clinician's historical expectations. Understanding the data, indication and clinical considerations for such novel oral anti-leukemic agents is paramount for clinicians caring patients with AML.

Ovarian cancer subtypes based on the regulatory genes of RNA modifications: Novel prediction model of prognosis

BACKGROUND

Ovarian cancer (OC) is a female reproductive system tumor. RNA modifications play key roles in gene expression regulation. The growing evidence demonstrates that RNA methylation is critical for various biological functions, and that its dysregulation is related to the progression of cancer in human.

METHOD

OC samples were classified into different subtypes (Clusters 1 and 2) based on various RNA-modification regulatory genes (RRGs) in the process of RNA modifications (m1A, m6A, m6Am, m5C, m7G, ac4C, m3C, and Ψ) by nonnegative matrix factorization method (NMF). Based on differently expressed RRGs (DERRGs) between clusters, a pathologically specific RNA-modification regulatory gene signature was constructed with Lasso regression. Kaplan-Meier analysis and receiver operating characteristic (ROC) curves were used to evaluate the prognostic ability of the identified model. The correlations of clinicopathological features, immune subtypes, immune scores, immune cells, and tumor mutation burden (TMB) were also estimated between different NMF clusters and riskscore groups.

RESULTS

In this study, 59 RRGs in the process of RNA modifications (m1A, m6A, m6Am, m5C, m7G, ac4C, m3C, and Ψ) were obtained from TCGA database. These RRGs were interactional, and sample clusters based on these regulators were significantly correlated with survival rate, clinical characteristics (involving survival status and pathologic stage), drug sensibility, and immune microenvironment. Furthermore, Lasso regression based on these 21 DERRGs between clusters 1 and 2 constructed a four-DERRG signature (ALYREF, ZC3H13, WTAP, and METTL1). Based on this signature, 307 OC patients were classified into high- and low-risk groups based on median value of riskscores from lasso regression. This identified signature was significantly associated with overall survival, radiation therapy, age, clinical stage, cancer status, and immune cells (involving CD4+ memory resting T cells, plasma cells, and Macrophages M1) of ovarian cancer patients. Further, GSEA revealed that multiple biological behaviors were significantly enriched in different groups.

CONCLUSIONS

OC patients were classified into two subtypes per these RRGs. This study identified four-DERRG signature (ALYREF, ZC3H13, WTAP, and METTL1) in OC, which was an independent prognostic model for patient stratification, prognostic evaluation, and prediction of response to immunotherapy in ovarian cancer by classifying OC patients into high- and low-risk groups.