Lysine-Specific Demethylase 1 (LSD1/KDM1A) Inhibition as a Target for Disease Modification in Myelofibrosis

Molecular Genetic Profile of Myelofibrosis: Implications in the Diagnosis, Prognosis, and Treatment Advancements

Myelofibrosis (MF) is an essential element of primary myelofibrosis, whereas secondary MF may develop in the advanced stages of other myeloid neoplasms, especially polycythemia vera and essential thrombocythemia. Over the last two decades, advances in molecular diagnostic techniques, particularly the integration of next-generation sequencing in clinical laboratories, have revolutionized the diagnosis, classification, and clinical decision making of myelofibrosis. Driver mutations involving JAK2, CALR, and MPL induce hyperactivity in the JAK-STAT signaling pathway, which plays a central role in cell survival and proliferation. Approximately 80% of myelofibrosis cases harbor additional mutations, frequently in the genes responsible for epigenetic regulation and RNA splicing. Detecting these mutations is crucial for diagnosing myeloproliferative neoplasms (MPNs), especially in cases where no mutations are present in the three driver genes (triple-negative MPNs). While fibrosis in the bone marrow results from the disturbance of inflammatory cytokines, it is fundamentally associated with mutation-driven hematopoiesis. The mutation profile and order of acquiring diverse mutations influence the MPN phenotype. Mutation profiling reveals clonal diversity in MF, offering insights into the clonal evolution of neoplastic progression. Prognostic prediction plays a pivotal role in guiding the treatment of myelofibrosis. Mutation profiles and cytogenetic abnormalities have been integrated into advanced prognostic scoring systems and personalized risk stratification for MF. Presently, JAK inhibitors are part of the standard of care for MF, with newer generations developed for enhanced efficacy and reduced adverse effects. However, only a minority of patients have achieved a significant molecular-level response. Clinical trials exploring innovative approaches, such as combining hypomethylation agents that target epigenetic regulators, drugs proven effective in myelodysplastic syndrome, or immune and inflammatory modulators with JAK inhibitors, have demonstrated promising results. These combinations may be more effective in patients with high-risk mutations and complex mutation profiles. Expanding mutation profiling studies with more sensitive and specific molecular methods, as well as sequencing a broader spectrum of genes in clinical patients, may reveal molecular mechanisms in cases currently lacking detectable driver mutations, provide a better understanding of the association between genetic alterations and clinical phenotypes, and offer valuable information to advance personalized treatment protocols to improve long-term survival and eradicate mutant clones with the hope of curing MF.

Inflammation and bone marrow fibrosis: novel immunotherapeutic targets

PURPOSE OF REVIEW

Myelofibrosis (MF) is primarily driven by constitutive activation of the Janus kinase/signal transducer of activators of transcription (JAK/STAT) pathway. While JAK inhibitors have shown to alleviate disease symptoms, their disease-modifying effects in MF are limited. The only curative treatment remains allogeneic stem cell transplantation, which can be applied to a minority of patients. As a result, there is a need to explore novel targets in MF to facilitate appropriate drug development and therapeutic pathways.

RECENT FINDINGS

Recent research has focused on identifying novel signals that contribute to the abnormal cross-talk between hematopoietic and stromal cells, which promotes MF and disease progression. Inflammation and immune dysregulation have emerged as key drivers of both the initiation and progression of MF. A growing number of actionable targets has been identified, including cytokines, transcription factors, signalling networks and cell surface-associated molecules. These targets exhibit dysfunctions in malignant and nonmalignant hematopoietic cells, but also in nonhematopoietic cells of the bone marrow. The study of these inflammation-related molecules, in preclinical models and MF patient's samples, is providing novel therapeutic targets.

SUMMARY

The identification of immunotherapeutic targets is expanding the therapeutic landscape of MF. This review provides a summary of the most recent advancements in the study of immunotherapeutic targets in MF.

Recent advances in therapies for primary myelofibrosis

Primary myelofibrosis (PMF), polycythemia vera (PV) and essential thrombocythemia (ET) form the classical BCR-ABL1-negative myeloproliferative neoplasms (MPNs) that are driven by a constitutive activation of JAK2 signaling. PMF as well as secondary MF (post-ET and post-PV MF) are the most aggressive MPNs. Presently, there is no curative treatment, except allogenic hematopoietic stem cell transplantation. JAK inhibitors, essentially ruxolitinib, are the therapy of reference for intermediate and high-risk MF. However, presently the current JAK inhibitors behave mainly as anti-inflammatory drugs, improving general symptoms and spleen size without major impact on disease progression. A better understanding of the genetics of MF, the biology of its leukemic stem cells (LSCs), the mechanisms of fibrosis and of cytopenia and the role of inflammatory cytokines has led to new approaches with the development of numerous therapeutic agents that target epigenetic regulation, telomerase, apoptosis, cell cycle, cytokines and signaling. Furthermore, the use of a new less toxic form of interferon-α has been revived, as it is presently one of the only molecules that targets the mutated clone. These new approaches have different aims: (a) to provide alternative therapy to JAK inhibition; (b) to correct cytopenia; and (c) to inhibit fibrosis development. However, the main important goal is to find new disease modifier treatments, which will profoundly modify the progression of the disease without major toxicity. Presently the most promising approaches consist of the inhibition of telomerase and the combination of JAK2 inhibitors (ruxolitinib) with either a BCL2/BCL-xL or BET inhibitor. Yet, the most straightforward future approaches can be considered to be the development of and/or selective inhibition of JAK2V617F and the targeting MPL and calreticulin mutants by immunotherapy. It can be expected that the therapy of MF will be significantly improved in the coming years.

Histone demethylases in the regulation of immunity and inflammation

Pathogens or danger signals trigger the immune response. Moderate immune response activation removes pathogens and avoids excessive inflammation and tissue damage. Histone demethylases (KDMs) regulate gene expression and play essential roles in numerous physiological processes by removing methyl groups from lysine residues on target proteins. Abnormal expression of KDMs is closely associated with the pathogenesis of various inflammatory diseases such as liver fibrosis, lung injury, and autoimmune diseases. Despite becoming exciting targets for diagnosing and treating these diseases, the role of these enzymes in the regulation of immune and inflammatory response is still unclear. Here, we review the underlying mechanisms through which KDMs regulate immune-related pathways and inflammatory responses. In addition, we also discuss the future applications of KDMs inhibitors in immune and inflammatory diseases.

Chemical Inhibitors Targeting the Histone Lysine Demethylase Families with Potential for Drug Discovery

The dynamic regulation of histone methylation and demethylation plays an important role in the regulation of gene expression. Aberrant expression of histone lysine demethylases has been implicated in various diseases including intractable cancers, and thus lysine demethylases serve as promising therapeutic targets. Recent studies in epigenomics and chemical biology have led to the development of a series of small-molecule demethylase inhibitors that are potent, specific, and have in vivo efficacy. In this review, we highlight emerging small-molecule inhibitors targeting the histone lysine demethylases and their progress toward drug discovery.

Ruta angustifolia Pers. (Narrow-Leaved Fringed Rue): Pharmacological Properties and Phytochemical Profile

The genus Ruta in the family Rutaceae includes about 40 species, such as the well-known plants R. graveolens L. (common rue) or R. chalepensis L. (fringed rue), but also much lesser-known species such as R. angustifolia Pers. (narrow-leaved fringed rue). This rue specie, originating from the Mediterranean region, is well-distributed in Southeast Asia, notably in the Indo-Chinese peninsula and other territories. In some countries, such as Malaysia, the plant is used to treat liver diseases and cancer. Extracts of R. angustifolia display antifungal, antiviral and antiparasitic effects. Diverse bioactive natural products have been isolated from the aerial parts of the plant, notably quinoline alkaloids and furocoumarins, which present noticeable anti-inflammatory, antioxidant and/or antiproliferative properties. The present review discusses the main pharmacological properties of the plant and its phytoconstituents, with a focus on the anticancer activities evidenced with diverse alkaloids and terpenoids isolated from the aerial parts of the plant. Quinoline alkaloids such as graveoline, kokusaginine, and arborinine have been characterized and their mode of action defined. Arborinine stands as a remarkable inhibitor of histone demethylase LSD1, endowed with promising anticancer activities. Other anticancer compounds, such as the furocoumarins chalepin and rutamarin, have revealed antitumor effects. Their mechanism of action is discussed together with that of other bioactive natural products, including angustifolin and moskachans. Altogether, R. angustifolia Pers. presents a rich phytochemical profile, fully consistent with the traditional use of the plant to treat cancer. This rue species, somewhat neglected, warrant further investigations as a medicinal plant and a source of inspiration for drug discovery and design.

Correction: Gill, H. Lysine-Specific Demethylase 1 (LSD1/KDM1A) Inhibition as a Target for Disease Modification in Myelofibrosis. Cells 2022, 11, 2107

The authors would like to make the following corrections to the published paper [...].