Myelofibrosis: an update on current pharmacotherapy and future directions

JAK2 inhibitors for the treatment of Philadelphia-negative myeloproliferative neoplasms: current status and future directions

The overactivation of Janus kinases 2 (JAK2) by gain-of-function mutations in the JAK2, Myeloproliferative leukemia virus oncogene, or Calreticulin genes are the most important factor in the development of Philadelphia-negative myeloproliferative neoplasms (MPNs). The discovery of the JAK2V617F mutation is a significant breakthrough in understanding the pathogenesis of MPNs, and inhibition of JAK2 abnormal activation has become one of the most effective strategies against MPNs. Currently, three JAK2 inhibitors for treating MPNs have been approved, and several are being evaluated in clinical trials. However, persistent challenges in terms of drug resistance and off-target effects remain unresolved. In this review, we introduce and classify the available JAK2 inhibitors in terms of their mechanisms and clinical considerations. Additionally, through an analysis of target points, binding modes, and structure-activity inhibitor relationships, we propose strategies such as combination therapy and allosteric inhibitors to overcome specific challenges. This review offers valuable insights into current trends and future directions for optimal management of MPNs using JAK2 inhibitors.

Biosimilar erythropoiesis-stimulating agents are an effective and safe option for the management of myelofibrosis-related anemia

OBJECTIVES

Erythropoiesis-stimulating agents (ESA) have an established role in treating anemia in hematological malignancies. However, their role, particularly biosimilar ESA (B-ESA), in myelofibrosis (MF) is not well established.

METHODS

This study retrospectively collected data on 96 MF patients treated with B-ESA (alpha/zeta) for the management of anemia to assess safety, efficacy (anemia response [AR]), and survival.

RESULTS

Seventy-seven patients (80%) obtained AR. The median time to AR was 2.5 months. In multivariate analysis, significant predictive factors of AR were transfusion independency (p = .006) and ferritin levels <200 ng/ml (p = .009) at baseline. After a median follow-up of 43.8 months from diagnosis, 38 patients (39%) died, 11 (28.9%) from leukemic evolution. Only two patients (2.5%) stopped B-ESA for toxicity. The 24-month survival was significantly affected by response to B-ESA (70.8% in AR vs. 55.3% in non-responder patients, p = .016). In multivariate analysis, age ≤ 70 years (p = .029) and Hb > 8.5 g/dl (p = .047) at baseline were significantly associated with improved survival, with a trend for longer survival in AR patients (p = .06).

CONCLUSIONS

B-ESA seems to be an effective and well-tolerated option for anemia treatment in the MF setting. This strategy deserves further clinical investigation.

Using in silico modelling and FRET-based assays in the discovery of novel FDA-approved drugs as inhibitors of MERS-CoV helicase

A Förster resonance energy transfer (FRET)-based assay was used to screen the FDA-approved compound library against the MERS-CoV helicase, an essential enzyme for virus replication within the host cell. Five compounds inhibited the helicase activity with submicromolar potencies (IC₅₀, 0.73-1.65 µM) and ten compounds inhibited the enzyme with micromolar potencies (IC₅₀, 19.6-502 µM). The molecular operating environment (MOE) was used to dock the identified inhibitors on the MERS-CoV helicase nucleotide binding. Strong inhibitors docked well in the nucleotide-binding site and established interactions with some of the essential residues. There was a reasonable correlation between the observed IC₅₀ values and the MOE docking scores of the strong inhibitors (r ² = 0.74), indicating the ability of the in silico docking model to predict the binding of strong inhibitors. In silico docking could be a useful complementary tool used with the FRET-based assay to predict new MERS-CoV helicase inhibitors. The identified inhibitors could potentially be used in the clinical development of new antiviral treatment for MERS-CoV and other coronavirus related diseases, including coronavirus disease 2019 (COVID-19).

β-catenin and PPAR-γ levels in bone marrow of myeloproliferative neoplasm: an immunohistochemical and ultrastructural study

In accordance with increased proliferation in myeloproliferative neoplasm (MPN), the goal is to evaluate the immunoexpression of: β-catenin, PPAR-γ and Ki67 protein, to compare them with bone marrow ultrastructural characteristics in patients with MPN. Immunoexpression and electron microscopy of bone marrow was analyzed in 30 Ph-negative MPN patients, including per 10 patients with polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). The quantity of β-catenin immunoreactive cells was significantly higher in PV then in ET (p < 0.01) or PMF group of patients (p < 0.01) and also in ET versus PMF group of patients (p < 0.01). Erythroid lineage showed absent β-catenin staining without immunoreactivity in nucleus. In contrast, immunoreactivity for PPAR-γ was localized mostly in megakaryocytes and the highest number of PPAR-γ immunopositive cells was detected in PMF group of patients. In addition, the proliferative Ki67 index was significantly increased in the PMF and PV patients compared to patients with ET. Also, the megakaryocytes showed abnormal maturation in PMF group of patients as determined by ultrastructural analysis. These results indicated that PV dominantly expressed β-catenin and proliferation marker Ki67 in bone marrow, while PMF is linked preferentially to PPAR-γ immunopositive megakaryocytes characterized by abnormal maturation.

Intravascular large B-cell lymphoma associated with myelofibrosis: A case report

Myelofibrosis (MF) is often accompanied by chronic myeloid leukemia, hairy cell leukemia, or certain primary myeloproliferative neoplasms, but is rarely associated with lymphoid neoplasms. We herein describe a case of intravascular large B-cell lymphoma (IVLBCL) with MF. IVLBCL is a rare, aggressive type of extranodal B-cell lymphoma, defined by proliferation of lymphomatous cells within small-to medium-sized vessels. A 60-year-old woman was admitted to the hospital with anemia, thrombocytopenia and fever. Bone marrow biopsy findings included trilineage hematopoiesis, increased numbers of immature cells, markedly abnormal and enlarged megakaryocytes, and diffuse fibrosis in multiple focal areas throughout the entire bone marrow space. When the patient was first hospitalized, hepatosplenomegaly was not present. Although initially considered during differential diagnosis, an aggressive lymphoma could not be diagnosed prior to colonoscopy, which was conducted 4 weeks after admission. A biopsy of the terminal ileum revealed IVLBCL with cells with atypical nuclei. Immunophenotyping of the atypical large cells yielded a positive result for CD79a and negative results for terminal deoxynucleotidyl transferase, myeloperoxidase, CD3, CD10, CD20, B-cell lymphoma (Bcl)-2, Bcl-6 and cytomegalovirus. The patient was diagnosed with IVLBCL complicated by MF. This case may serve as a reminder that IVLBCL may be the cause of secondary MF.

The Dihydroxy Metabolite of the Teratogen Thalidomide Causes Oxidative DNA Damage

Thalidomide [α-(N-phthalimido)glutarimide] (1) is a sedative and antiemetic drug originally introduced into the clinic in the 1950s for the treatment of morning sickness. Although marketed as entirely safe, more than 10 000 babies were born with severe birth defects. Thalidomide was banned and subsequently approved for the treatment of multiple myeloma and complications associated with leprosy. Although known for more than 5 decades, the mechanism of teratogenicity remains to be conclusively understood. Various theories have been proposed in the literature including DNA damage and ROS and inhibition of angiogenesis and cereblon. All of the theories have their merits and limitations. Although the recently proposed cereblon theory has gained wide acceptance, it fails to explain the metabolism and low-dose requirement reported by a number of groups. Recently, we have provided convincing structural evidence in support of the presence of arene oxide and the quinone-reactive intermediates. However, the ability of these reactive intermediates to impart toxicity/teratogenicity needs investigation. Herein we report that the oxidative metabolite of thalidomide, dihydroxythalidomide, is responsible for generating ROS and causing DNA damage. We show, using cell lines, the formation of comet (DNA damage) and ROS. Using DNA-cleavage assays, we also show that catalase, radical scavengers, and desferal are capable of inhibiting DNA damage. A mechanism of teratogenicity is proposed that not only explains the DNA-damaging property but also the metabolism, low concentration, and species-specificity requirements of thalidomide.

Pharmacobiological Approach for the Clinical Development of Ruxolitinib in Myeloproliferative Neoplasms

Ruxolitinib, a JAK1 and JAK2 inhibitor drug, has recently been approved for the treatment of patients with high- or intermediate-risk myelofibrosis with symptomatic splenomegaly. Ruxolitinib is the first clinically useful targeted therapy in Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs). The aim of this paper is to indicate pharmacobiological aspects of ruxolitinib within the potential context of MPNs. Pharmacobiological assessments, in addition to knowledge of the risk profile for ruxolitinib in MPNs, are required. We propose hypotheses based on our experience in a splenectomized MPN patient with hyperproliferative bone marrow and moderate fibrosis receiving ruxolitinib. We believe that a true clinical development approach for this drug should include pharmacobiological assessments for ruxolitinib in addition to the disease risk profile of MPNs.

Bone marrow fibrosis in primary myelofibrosis: pathogenic mechanisms and the role of TGF-β

Primary myelofibrosis (PMF) is a Philadelphia chromosome negative myeloproliferative neoplasm (MPN) with adverse prognosis and is associated with bone marrow fibrosis and extramedullary hematopoiesis. Even though the discovery of the Janus kinase 2 (JAK2), thrombopoietin receptor (MPL) and calreticulin (CALR) mutations have brought new insights into the complex pathogenesis of MPNs, the etiology of fibrosis is not well understood. Furthermore, since JAK2 inhibitors do not lead to reversal of fibrosis further understanding of the biology of fibrotic process is needed for future therapeutic discovery. Transforming growth factor beta (TGF-β) is implicated as an important cytokine in pathogenesis of bone marrow fibrosis. Various mouse models have been developed and have established the role of TGF-β in the pathogenesis of fibrosis. Understanding the molecular alterations that lead to TGF-β mediated effects on bone marrow microenvironment can uncover newer therapeutic targets against myelofibrosis. Inhibition of the TGF-β pathway in conjunction with other therapies might prove useful in the reversal of bone marrow fibrosis in PMF.

The use of erythropoiesis-stimulating agents with ruxolitinib in patients with myelofibrosis in COMFORT-II: an open-label, phase 3 study assessing efficacy and safety of ruxolitinib versus best available therapy in the treatment of myelofibrosis

Background

Anemia is considered a negative prognostic risk factor for survival in patients with myelofibrosis. Most patients with myelofibrosis are anemic, and 35–54 % present with anemia at diagnosis. Ruxolitinib, a potent inhibitor of Janus kinase (JAK) 1 and JAK2, was associated with an overall survival benefit and improvements in splenomegaly and patient-reported outcomes in patients with myelofibrosis in the two phase 3 COMFORT studies. Consistent with the ruxolitinib mechanism of action, anemia was a frequently reported adverse event. In clinical practice, anemia is sometimes managed with erythropoiesis-stimulating agents (ESAs). This post hoc analysis evaluated the safety and efficacy of concomitant ruxolitinib and ESA administration in patients enrolled in COMFORT-II, an open-label, phase 3 study comparing the efficacy and safety of ruxolitinib with best available therapy for treatment of myelofibrosis. Patients were randomized (2:1) to receive ruxolitinib 15 or 20 mg twice daily or best available therapy. Spleen volume was assessed by magnetic resonance imaging or computed tomography scan.

Results

Thirteen of 146 ruxolitinib-treated patients had concomitant ESA administration (+ESA). The median exposure to ruxolitinib was 114 weeks in the +ESA group and 111 weeks in the overall ruxolitinib arm; the median ruxolitinib dose intensity was 33 mg/day for each group. Six weeks before the first ESA administration, 10 of the 13 patients had grade 3/4 hemoglobin abnormalities. These had improved to grade 2 in 7 of the 13 patients by 6 weeks after the first ESA administration. The rate of packed red blood cell transfusions per month within 12 weeks before and after first ESA administration remained the same in 1 patient, decreased in 2 patients, and increased in 3 patients; 7 patients remained transfusion independent. Reductions in splenomegaly were observed in 69 % of evaluable patients (9/13) following first ESA administration.

Conclusions

Concomitant use of an ESA with ruxolitinib was well tolerated and did not affect the efficacy of ruxolitinib. Further investigations evaluating the effects of ESAs to alleviate anemia in ruxolitinib-treated patients are warranted (ClinicalTrials.gov identifier, NCT00934544; July 6, 2009).

Promising new therapies in advanced pancreatic adenocarcinomas

Pancreatic ductal adenocarcinoma is a lethal disease due to late diagnosis, early metastasis and the lack of effective therapies. In patients with metastatic disease, 1-year survival ranges from 17 to 23% and 5-year survival is less than 5%. This necessitates an urgent need for developing more effective therapies. Targeting the neoplastic cells has been largely ineffective due to the dense stroma, which is a physical barrier for effective drug delivery and also a source for different factors that promote tumor progression and immunosuppression. In this review, we focus on understanding the complex biology of this tumor as it relates to the evaluation of previously failed molecularly targeted trials and review potential new therapies that are emerging in the treatment of metastatic pancreatic ductal adenocarcinoma.

Ruxolitinib for the treatment of primary myelofibrosis

PURPOSE

The pharmacology, pharmacokinetics, pharmacogenomics, clinical efficacy, and safety profile of ruxolitinib for the treatment of primary myelofibrosis are reviewed.

SUMMARY

Ruxolitinib, an oral tyrosine kinase inhibitor that targets the Janus-associated kinases (JAKs) 1 and 2, has been recently approved for the treatment of patients with intermediate- or high-risk myelofibrosis. Unlike previous treatment options for patients with myelofibrosis, ruxolitinib offers a targeted therapy option for these patients who often suffer with severe and debilitating symptoms associated with the disease process. After oral administration, ruxolitinib is rapidly absorbed and can be given without regard to meals. Ruxolitinib is primarily metabolized by the cytochrome P-450 (CYP) 3A4 isoenzyme system; therefore, if concomitant use with a strong CYP3A4 inhibitor is unavoidable, an initial dosage reduction is warranted. Two Phase III randomized trials comparing ruxolitinib to either placebo or best available therapy found a rapid and sustained response in the reduction of spleen size and improvements in constitutional symptoms and quality of life, with one study demonstrating an improvement in overall survival. The most commonly reported serious adverse effects of ruxolitinib are anemia and thrombocytopenia. Ruxolitinib is administered as an oral tablet given twice daily, with the initial starting dosage based on the baseline platelet count. Dosage reductions are based on the development of thrombocytopenia.

CONCLUSION

By directly targeting both JAK1 and JAK2 through small-molecule inhibition, ruxolitinib elicits a reduction in splenomegaly and disease-related symptoms in patients with intermediate- or high-risk myelofibrosis while maintaining an acceptable toxicity profile and a low treatment-discontinuation rate.

Targeting EGFR signalling in chronic lung disease: therapeutic challenges and opportunities

Chronic respiratory diseases, including pulmonary fibrosis, chronic obstructive pulmonary disease (COPD) and lung cancer, are the second leading cause of death among Europeans. Despite this, there have been only a few therapeutic advances in these conditions over the past 20 years. In this review we provide evidence that targeting the epidermal growth factor receptor (EGFR) signalling pathway may represent a novel therapeutic panacea for treating chronic lung disease. Using evidence from human patient samples, transgenic animal models, and cell and molecular biology studies we highlight the roles of this signalling pathway in lung development, homeostasis, repair, and disease ontogeny. We identify mechanisms underlying lung EGFR pathway regulation and suggest how targeting these mechanisms using new and existing therapies has the potential to improve future lung cancer, COPD and pulmonary fibrosis patient outcomes.