Acute Myeloid Leukemia Stem Cells in Minimal/Measurable Residual Disease Detection

Translating molecular insights into clinical success: alkaloid-based therapies for leukemia

Alkaloids, a diverse class of naturally occurring compounds, have shown significant potential in the treatment of leukemia by targeting key molecular pathways and cellular mechanisms. This review discusses several potent alkaloids, such as homoharringtonine, chaetominine, matrine, and jerantinine B, which induce apoptosis, cell cycle arrest, and autophagy and inhibit signaling pathways including PI3K/Akt/mTOR, MAPK, and NF-κB. For instance, homoharringtonine induces apoptosis in acute myeloid leukemia (AML) cells via the SP1/TET1/5hmC/FLT3/MYC axis, while chaetominine enhances chemosensitivity by inhibiting the PI3K/Akt/Nrf2 pathway. In addition, targeting leukemia stem cells (LSCs) with alkaloids such as zalypsis offers promise due to its ability to induce apoptosis without significantly affecting normal hematopoietic stem cells. The modulation of the immune response, such as the inhibition of NF-κB activation by noscapine, further underscores the potential of alkaloids in overcoming treatment resistance. Various studies have demonstrated the efficacy of alkaloids across different leukemia types. For example, jerantinine B targets AML cells, while vincristine has shown success in lymphocytic leukemia. Clinical trials have also highlighted the benefits of alkaloids, including homoharringtonine, which achieved a 79.9% complete remission rate in AML patients. However, adverse effects such as neutropenia and hepatotoxicity necessitate careful management. Collectively, these findings emphasize the need for further research into alkaloid-based combination therapies to enhance efficacy and minimize toxicity, providing a promising avenue for innovative leukemia treatments.

The epigenetic role of EZH2 in acute myeloid leukemia

Acute myeloid leukemia (AML), a malignant disease of the bone marrow, is characterized by the clonal expansion of myeloid progenitor cells and a block in differentiation. The high heterogeneity of AML significantly impedes the development of effective treatment strategies. Enhancer of zeste homolog 2 (EZH2), the catalytic subunit of the polycomb repressive complex 2 (PRC2), regulates the expression of downstream target genes through the trimethylation of lysine 27 on histone 3 (H3K27me3). Increasing evidence suggests that the dysregulation of EZH2 expression in various cancers is closely associated with tumorigenesis. In the review, we examine the role of EZH2 in AML, highlighting its crucial involvement in regulating stemness, proliferation, differentiation, immune response, drug resistance and recurrence. Furthermore, we summarize the application of EZH2 inhibitors in AML treatment and discuss their potential in combination with other therapeutic modalities. Therefore, targeting EZH2 may represent a novel and promising strategy for the treatment of AML.

Potential Use of Exosomal Non-Coding MicroRNAs in Leukemia Therapy: A Systematic Review

Leukemia is a heterogeneous group of hematological malignancies. Despite the enormous progress that has been made in the field of hemato-oncology in recent years, there are still many problems related to, among others, disease recurrence and drug resistance, which is why the search for ideal biomarkers with high clinical utility continues. Research shows that exosomes play a critical role in the biology of leukemia and are associated with the drug resistance, metastasis, and immune status of leukemias. Exosomes with their cargo of non-coding RNAs act as a kind of intermediary in intercellular communication and, at the same time, have the ability to manipulate the cell microenvironment and influence the reaction, proliferative, angiogenic, and migratory properties of cells. Exosomal ncRNAs (in particular, circRNAs and microRNAs) appear to be promising cell-free biomarkers for diagnostic, prognostic, and treatment monitoring of leukemias. This review examines the expression of exosomal ncRNAs in leukemias and their potential regulatory role in leukemia therapy but also in conditions such as disease relapse, drug resistance, metastasis, and immune status. Given the key role of ncRNAs in regulating gene networks and intracellular pathways through their ability to interact with DNA, transcripts, and proteins and identifying their specific target genes, defining potential functions and therapeutic strategies will provide valuable information.

Mass cytometric single cell immune profiles of peripheral blood from acute myeloid leukemia patients in complete remission with measurable residual disease

Measurable residual disease (MRD) is detected in approximately a quarter of AML chemotherapy responders, serving as a predictor for relapse and shorter survival. Immunological control of residual disease is suggested to prevent relapse, but the mechanisms involved are not fully understood. We present a peripheral blood single cell immune profiling by mass cytometry using a 42-antibody panel with particular emphasis on markers of cellular immune response. Six healthy donors were compared with four AML patients with MRD (MRD+) in first complete remission (CR1MRD+). Three of four patients demonstrated a favorable genetic risk profile, while the fourth patient had an unfavorable risk profile (complex karyotype, TP53-mutation) and a high level of MRD. Unsupervised clustering using self-organizing maps and dimensional reduction analysis was performed for visualization and analysis of immune cell subsets. CD57+ natural killer (NK)-cell subsets were found to be less abundant in patients than in healthy donors. Both T and NK cells demonstrated elevated expression of activity and maturation markers (CD44, granzyme B, and phosho-STAT5 Y694) in patients. Although mass cytometry remains an expensive method with limited scalability, our data suggest the utility for employing a 42-plex profiling for cellular immune surveillance in whole blood, and possibly as a biomarker platform in future clinical trials. The findings encourage further investigations of single cell immune profiling in CR1MRD+ AML-patients.

Correction: Srinivasan Rajsri et al. Acute Myeloid Leukemia Stem Cells in Minimal/Measurable Residual Disease Detection. Cancers 2023, 15, 2866

In the original publication [...].

Therapeutic targeting of leukemia stem cells in acute myeloid leukemia

One of the distinguishing properties of hematopoietic stem cells is their ability to self-renew. Since self-renewal is important for the continuous replenishment of the hematopoietic stem cell pool, this property is often hijacked in blood cancers. Acute myeloid leukemia (AML) is believed to be arranged in a hierarchy, with self-renewing leukemia stem cells (LSCs) giving rise to the bulk tumor. Some of the earliest characterizations of LSCs were made in seminal studies that assessed the ability of prospectively isolated candidate AML stem cells to repopulate the entire heterogeneity of the tumor in mice. Further studies indicated that LSCs may be responsible for chemotherapy resistance and therefore act as a reservoir for secondary disease and leukemia relapse. In recent years, a number of studies have helped illuminate the complexity of clonality in bone marrow pathologies, including leukemias. Many features distinguishing LSCs from normal hematopoietic stem cells have been identified, and these studies have opened up diverse avenues for targeting LSCs, with an impact on the clinical management of AML patients. This review will discuss the role of self-renewal in AML and its implications, distinguishing characteristics between normal and leukemia stem cells, and opportunities for therapeutic targeting of AML LSCs.