Ruxolitinib treatment reduces monocytic superoxide radical formation without affecting hydrogen peroxide formation or systemic oxidative nucleoside damage in myelofibrosis

Assessment of Total Antioxidant Capacity, 8-Hydroxy-2'-deoxy-guanosine, the Genetic Landscape, and Their Associations in BCR::ABL-1-Negative Chronic and Blast Phase Myeloproliferative Neoplasms

Myeloproliferative neoplasms (MPNs), namely, polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), are clonal stem cell disorders defined by an excessive production of functionally mature and terminally differentiated myeloid cells. MPNs can transform into secondary acute myeloid leukemia (sAML/blast phase MPN) and are linked to alterations in the redox balance, i.e., elevated concentrations of reactive oxygen species and markers of oxidative stress (OS), and changes in antioxidant systems. We evaluated OS in 117 chronic phase MPNs and 21 sAML cases versus controls by measuring total antioxidant capacity (TAC) and 8-hydroxy-2'-deoxy-guanosine (8-OHdG) concentrations. TAC was higher in MPNs than controls (p = 0.03), particularly in ET (p = 0.04) and PMF (p = 0.01). MPL W515L-positive MPNs had higher TAC than controls (p = 0.002) and triple-negative MPNs (p = 0.01). PMF patients who had treatment expressed lower TAC than therapy-free subjects (p = 0.03). 8-OHdG concentrations were similar between controls and MPNs, controls and sAML, and MPNs and sAML. We noted associations between TAC and MPNs (OR = 1.82; p = 0.05), i.e., ET (OR = 2.36; p = 0.03) and PMF (OR = 2.11; p = 0.03), but not sAML. 8-OHdG concentrations were not associated with MPNs (OR = 1.73; p = 0.62) or sAML (OR = 1.89; p = 0.49). In conclusion, we detected redox imbalances in MPNs based on disease subtype, driver mutations, and treatment history.

Mesenchymal stromal cells in tumor microenvironment remodeling of BCR-ABL negative myeloproliferative diseases

Chronic myeloproliferative neoplasms encompass the BCR-ABL1-negative neoplasms polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). These are characterized by calreticulin (CALR), myeloproliferative leukemia virus proto-oncogene (MPL) and the tyrosine kinase Janus kinase 2 (JAK2) mutations, eventually establishing a hyperinflammatory tumor microenvironment (TME). Several reports have come to describe how constitutive activation of JAK-STAT and NFκB signaling pathways lead to uncontrolled myeloproliferation and pro-inflammatory cytokines secretion. In such a highly oxidative TME, the balance between Hematopoietic Stem Cells (HSCs) and Mesenchymal Stromal Cells (MSCs) has a crucial role in MPN development. For this reason, we sought to review the current literature concerning the interplay between HSCs and MSCs. The latter have been reported to play an outstanding role in establishing of the typical bone marrow (BM) fibrotic TME as a consequence of the upregulation of different fibrosis-associated genes including PDGF- β upon their exposure to the hyperoxidative TME characterizing MPNs. Therefore, MSCs might turn to be valuable candidates for niche-targeted targeting the synthesis of cytokines and oxidative stress in association with drugs eradicating the hematopoietic clone.

Ruxolitinib Reduces Oxidative Stress in Patients With Primary Myelofibrosis: A Multicenter Study

Introduction

Primary myelofibrosis (PM) has a lower overall survival rate than other myeloproliferative neoplasms, and leukemic transformation is the most common cause of death. Increased oxidative stress has an important role in leukemic transformation in these patients. In this study, we aimed to find an answer to the question, "Could Ruxolitinib, which has been widely used in patients with myelofibrosis in recent years, have a role in reducing oxidative stress in these patients?".

Methods

A total of 106 patients with PM and 111 healthy volunteers were included in this study. We collected the serum samples of healthy volunteers and patients with myelofibrosis at the time of diagnosis and one month after the initiation of Ruxolitinib treatment. Ischemia modified albumin (IMA), native thiol, total thiol, and disulfide levels were studied. The disulfide/native thiol, disulfide/total thiol, and native thiol/total thiol ratios were calculated.

Results

IMA, native thiol, total thiol, disulfide levels, disulfide/native thiol, and disulfide/total thiol ratios at the time of diagnosis were significantly different in patients with myelofibrosis compared to the control group (p=0.001). Ruxolitinib significantly reduced oxidative stress when the measurements in the first month after Ruxolitinib were compared with those at the time of diagnosis (p=0.001). In patients with ASXL1 mutation, intermediate-2 risk, and high-risk according to the Dipps-plus score, the decrease in oxidative stress in the first month of treatment was more significant than at the time of diagnosis.

Conclusion

Ruxolitinib may be an effective treatment for reducing oxidative stress in patients with PM. The reduction in oxidative stress parameters with treatment in patients with ASXL1 mutation, intermediate-2, and high-risk patients was observed to be higher.

Synergic Crosstalk between Inflammation, Oxidative Stress, and Genomic Alterations in BCR-ABL-Negative Myeloproliferative Neoplasm

Philadelphia-negative chronic myeloproliferative neoplasms (MPNs) have recently been revealed to be related to chronic inflammation, oxidative stress, and the accumulation of reactive oxygen species. It has been proposed that MPNs represent a human inflammation model for tumor advancement, in which long-lasting inflammation serves as the driving element from early tumor stage (over polycythemia vera) to the later myelofibrotic cancer stage. It has been theorized that the starting event for acquired stem cell alteration may occur after a chronic inflammation stimulus with consequent myelopoietic drive, producing a genetic stem cell insult. When this occurs, the clone itself constantly produces inflammatory components in the bone marrow; these elements further cause clonal expansion. In BCR-ABL1-negative MPNs, the driver mutations include JAK 2, MPL, and CALR. Transcriptomic studies of hematopoietic stem cells from subjects with driver mutations have demonstrated the upregulation of inflammation-related genes capable of provoking the development of an inflammatory state. The possibility of acting on the inflammatory state as a therapeutic approach in MPNs appears promising, in which an intervention operating on the pathways that control the synthesis of cytokines and oxidative stress could be effective in reducing the possibility of leukemic progression and onset of complications.

Exploring redox vulnerabilities in JAK2V617F-positive cellular models

Background

In Philadelphia chromosome-negative myeloproliferative neoplasm (MPN) models, reactive oxygen species (ROS) are elevated and have been implicated in genomic instability, JAK2/STAT signaling amplification, and disease progression. Although the potential effects of ROS on the MPN phenotype, the effects of ruxolitinib treatment on ROS regulation have been poorly explored. Herein, we have reported the impact of ruxolitinib on redox signaling transcriptional network, and the effects of diphenyleneiodonium (DPI), a pan NOX inhibitor, in JAK2^V617F-driven cellular models.

Method

Redox signaling-related genes were investigated in SET2 cells upon ruxolitinib treatment by RNA-seq (GEO accession GSE69827). SET2 and HEL cells, which represent JAK2^V617F-positive MPN cellular models with distinct sensitivity to apoptosis induced by ruxolitinib, were used. Cell viability was evaluated by MTT, apoptosis by annexin V/PI and flow cytometry, and cell signaling by quantitative PCR and Western blot.

Main results

Ruxolitinib impacted on a network composed of redox signaling-related genes, and DUOX1 and DUOX2 were identified as potential modulators of ruxolitinib response. In SET2 and HEL cells, DPI reduced cell viability and, at low doses, it significantly potentiated ruxolitinib-induced apoptosis. In the molecular scenario, DPI inhibited STAT3, STAT5 and S6 ribosomal protein phosphorylation and induced PARP1 cleavage in JAK2^V617F-positive cells. DPI combined with ruxolitinib increased PARP1 cleavage in SET2 cells and potentiated ruxolitinib-reduced STAT3, STAT5 and S6 ribosomal protein in HEL cells.

Conclusion

Our study reveals a potential adaptation mechanism for resistance against ruxolitinib by transcriptionally reprogramming redox signaling in JAK2^V617F cells and exposes redox vulnerabilities with therapeutic value in MPN cellular models.

A journey through infectious risk associated with ruxolitinib

Ruxolitinib has proved to be effective for the treatment of patients with myelofibrosis (either primary or secondary) and polycythaemia vera, and its approval led to a significant change in the current treatment algorithm. Despite its efficacy and beyond its well described haematological toxicity, a peculiar immunosuppressive effect emerged as our clinical experience grew, both within and outside of a clinical trial setting. Definite and negative interactions with multiple pathways of the immune system of patients have been reported so far, involving both adaptive and innate immune responses. These pathophysiological mechanisms may contribute to the increased risk of reactivation of silent infections (e.g., tuberculosis, hepatitis B virus and varicella zoster virus) that have been associated with the drug. Even though such infectious events may be fatal or may lead to significant impairment of organ function, compromising the eligibility of patients for an allotransplant procedure, there are no dedicated guidelines that may help us in assessing and managing the risk of developing serious infections. On this basis, our aim for the present work was to review the current knowledge on the pathophysiological mechanisms through which ruxolitinib may exert its immunosuppressive effect, and to illustrate our personal approach to the management of three peculiar clinical scenarios, for which a risk-based algorithm is suggested.