Prevalence of pulmonary hypertension in myelofibrosis

Hematopoietic stem cells and extramedullary hematopoiesis in the lungs

Hematopoietic stem cells are key players in hematopoiesis as the body maintains a physiologic steady state, and the signaling pathways and control mechanisms of these dynamic cells are implicated in processes from inflammation to cancer. Although the bone marrow is commonly regarded as the site of hematopoiesis and hematopoietic stem cell residence, these cells also circulate in the blood and reside in extramedullary tissues, including the lungs. Flow cytometry is an invaluable tool in evaluating hematopoietic stem cells, revealing their phenotypes and relative abundances in both healthy and diseased states. This review outlines current protocols and cell markers used in flow cytometric analysis of hematopoietic stem and progenitor cell populations. Specific niches within the bone marrow are discussed, as are metabolic processes that contribute to stem cell self-renewal and differentiation, as well as the role of hematopoietic stem cells outside of the bone marrow at physiologic steady state. Finally, pulmonary extramedullary hematopoiesis and its associated disease states are outlined. Hematopoiesis in the lungs is a new and emerging concept, and discovering ways in which the study of lung-resident hematopoietic stem cells can be translated from murine models to patients will impact clinical treatment.

Clinical Phenotype and Outcomes of Pulmonary Hypertension Associated with Myeloproliferative Neoplasms: A Population-based Study

Rationale: Precapillary pulmonary hypertension (PH) is a rare and largely unrecognized complication of myeloproliferative neoplasms (MPNs), including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (MF). Objectives: To describe characteristics and outcomes of MPN-associated PH. Methods: We report clinical, functional, and hemodynamic characteristics, classification, and outcomes of patients with PV, ET, or primary MF in the French PH registry. Measurements and Main Results: Ninety patients with MPN (42 PV, 35 ET, 13 primary MF) presented with precapillary PH with severe hemodynamic impairment, with a median mean pulmonary arterial pressure and pulmonary vascular resistance of 42 mm Hg and 6.7 Wood units, respectively, and impaired clinical conditions, with 71% in New York Heart Association functional classes III/IV and having a median 6-minute-walk distance of 310 m. Half of the patients were diagnosed with chronic thromboembolic PH (CTEPH); the other half were considered to have group 5 PH. MF was preferentially associated with group 5 PH, whereas PV and ET were generally related to CTEPH. Proximal lesions were diagnosed in half of the patients with CTEPH. Thromboendarterectomy was performed in 18 selected patients with high risk of complications (5 early deaths). Overall survival at 1, 3, and 5 years was 67%, 50%, and 34% in group 5 PH and 81%, 66%, and 42% in CTEPH, respectively. Conclusions: PH is a life-threatening condition potentially occurring in MPN. There are multiple mechanisms, with equal diagnoses of CTEPH and group 5 PH. Physicians should be aware that PH strongly affects the burden of patients with MPN, especially in group 5 PH, with unknown pathophysiological mechanisms.

Ten years of treatment with ruxolitinib for myelofibrosis: a review of safety

Myelofibrosis (MF) is a chronic myeloproliferative neoplasm characterized by bone marrow fibrosis, anemia, extramedullary hematopoiesis, and splenomegaly. Patients with MF are at risk for reduced survival versus the general population and often experience burdensome signs and symptoms that reduce quality of life. The oral Janus kinase (JAK) 1/JAK2 inhibitor ruxolitinib was initially approved by the US Food and Drug Administration in 2011 for the treatment of patients with intermediate or high-risk MF, including primary MF, post-polycythemia vera MF, and post-essential thrombocythemia MF, based on efficacy and safety findings from the randomized, controlled, phase 3 COMFORT trials. Over a decade later, ruxolitinib continues to be the standard of care in higher-risk MF, and dose optimization and management remain crucial for safely maximizing clinical benefits of ruxolitinib. This review summarizes the safety profile of ruxolitinib in patients with MF in the COMFORT trials leading up to approval and in the subsequent JUMP, ROBUST, EXPAND, and REALISE trials; in pooled analyses; and in postmarketing analyses in the 10 years following approval. There is a focus on the occurrence of common hematologic and nonhematologic adverse events, with guidance provided on the management of patients with anemia or thrombocytopenia, including dosing strategies based on findings from the REALISE and EXPAND trials. Finally, to ensure a greater understanding of the safety profile of ruxolitinib, practical considerations are discussed.

Innovative strategies to improve hematopoietic stem cell transplant outcomes in myelofibrosis

Myelofibrosis (MF) is a clonal myeloproliferative neoplasm characterized by inflammation, marrow fibrosis, and an inherent risk of blastic transformation. Hematopoietic allogeneic stem cell transplant is the only potentially curative therapy for this disease, however, survival gains observed for other transplant indications over the past two decades have not been realized for MF. The role of transplantation may also evolve with the use of novel targeted agents. The chronic inflammatory state associated with MF necessitates pretransplantation assessment of end-organ function. Applying the transplant methodology employed for other myeloid disorders to patients with MF fails to acknowledge differences in the underlying disease pathophysiology. Limited understanding of the causes of poor transplant outcomes in this cohort has prevented refinement of transplant eligibility criteria in MF. There is increasing evidence of heterogeneity in molecular disease grade, beyond the clinical manifestations which have traditionally guided transplant timing. Exploring the physiological consequences of disease chronicity unique to MF, acknowledging the heterogeneity in disease grade, and using advanced prognostic models, molecular diagnostics and other organ function diagnostic tools, we present an innovative review of strategies with the potential to improve transplant outcomes in this disease. Larger, prospective studies which consider the impact of molecular-based disease grade are needed for MF transplantation.

Case of Pulmonary Extramedullary Hematopoiesis Responding to Ruxolitinib

We report a case of 43-year-old woman diagnosed with essential thrombocythemia in 1992. She was diagnosed with secondary myelofibrosis in 2011. Later, she suffered mild dyspnea, which gradually worsened. She was admitted to our hospital to evaluate the cause in 2014. Chest computed tomography showed ground-glass opacity (GGO) in the lungs. A lung biopsy revealed various hematopoietic cells, including abnormal megakaryocytes, infiltrating the alveolar septum, suggesting pulmonary extramedullary hematopoiesis. She was successfully treated by ruxolitinib and her disease is well controlled for more than 7 years. To keep this phenomenon in mind when see the patients with dyspnea is important.

Evaluation of hemodynamic parameters among patients with myeloproliferative neoplasms and suspected pulmonary hypertension

Myeloproliferative neoplasms (MPNs) are associated with pulmonary hypertension (PH). We studied MPN patients who underwent right-heart-catheterization (RHC) to identify hemodynamic differences between MPN-subtypes. Per RHC, hemodynamics were classified as pre, post or combined pre and post-capillary PH. One-way analysis-of-variance (ANOVA) was used to compare hemodynamic differences among MPN-subtypes. Correlation of RVSP between trans-thoracic echocardiography (TTE) and RHC was evaluated. We included 68 patients. Median age was 63. Fifty-nine percent were male and 87% Caucasian. Polycythemia vera and essential thrombocythemia were the most common subtypes. On TTE, 91.5% had PH. On RHC, only 29% met criteria for pre-capillary PH. No MPN-subtype was more likely than others to have pre-capillary PH. Bland-Altman analysis showed significant intra-person variability between TTE and RHC-derived right ventricular systolic pressures. Post-capillary involvement is more common than precapillary PH in MPN. Type of PH does not appear to differ by MPN-subtype.

Prevalence and risk factors for Pulmonary Hypertension associated with chronic Myeloproliferative Neoplasms

OBJECTIVES

Pulmonary hypertension (PH) is commonly reported in Philadelphia-chromosome negative myeloproliferative neoplasms (MPNs) including polycythemia vera (PV), essential thrombocythemia (ET), and myelofibrosis (MF). PH may be diagnosed directly by right heart catheterization (RHC) or estimated by transthoracic echocardiography (TTE). Survival is shortened by PH but despite the potential significance of PH to management and prognosis of MPN, estimates of its prevalence in MPNs vary and risk factors for the condition are poorly established. We performed a systematic review and meta-analysis of available studies to fill this void.

METHODS

We searched EMBASE, MEDLINE, and Clinicaltrials.gov for the terms "pulmonary hypertension," "myeloproliferative disorders," "polycythemia vera," "essential thrombocythemia," and "myelofibrosis." We restricted analysis to the 1999-2019 window to improve uniformity of MPN diagnostic criteria. We retrieved 221 records and, after abstract and full-text screening, identified 17 papers meeting criteria for inclusion in our meta-analysis. A modified Newcastle-Ottawa scale was used to assess quality.

RESULTS

Results for 935 patients were available, 309 of these having PH (33%). Using logistic mixed-effect regression, we found that diagnosis mode (RHC vs TTE) and MPN duration influenced PH prevalence. Studies employing predominantly TTE yielded prevalence estimates ~5-fold higher than those using RHC (35% vs 7.2%). We identified MF and duration of MPN as significant risk factors for development of PH.

CONCLUSIONS

Prevalence of PH in MPNs is poorly understood with estimates ranging from 3.8% to 58%. Patients with MF and longer duration of disease seem at particularly high risk and should be carefully monitored for PH.

Transforming growth factor β-mediated micromechanics modulates disease progression in primary myelofibrosis

Primary myelofibrosis (PMF) is a Ph‐negative myeloproliferative neoplasm (MPN), characterized by advanced bone marrow fibrosis and extramedullary haematopoiesis. The bone marrow fibrosis results from excessive proliferation of fibroblasts that are influenced by several cytokines in the microenvironment, of which transforming growth factor‐β (TGF‐β) is the most important. Micromechanics related to the niche has not yet been elucidated. In this study, we hypothesized that mechanical stress modulates TGF‐β signalling leading to further activation and subsequent proliferation and invasion of bone marrow fibroblasts, thus showing the important role of micromechanics in the development and progression of PMF, both in the bone marrow and in extramedullary sites. Using three PMF‐derived fibroblast cell lines and transforming growth factor‐β receptor (TGFBR) 1 and 2 knock‐down PMF‐derived fibroblasts, we showed that mechanical stress does stimulate the collagen synthesis by the fibroblasts in patients with myelofibrosis, through the TGFBR1, which however seems to be activated through alternative pathways, other than TGFBR2.

Prevalence and risk factors of high echocardiographic probability of pulmonary hypertension in myeloproliferative neoplasms patients

Pulmonary hypertension (PH) is emerging as a complication of myeloproliferative neoplasms (MPNs). This was a prospective study conducted at Chiang Mai University Hospital. The primary objective was to determine the prevalence of high echocardiographic probability of PH in MPNs patients. The secondary objectives were to determine risk factors of PH and the correlation between risk factors and peak tricuspid regurgitation velocity (TRV_max). All MPNs patients aged over 18 years, including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), were enrolled. All eligible patients underwent echocardiography for evaluation of the probability of PH in line with the 2015 European Society of Cardiology (ESC) and the European Respiratory Society (ERS) Guidelines. Sixty-six patients with a median age of 59 years were enrolled. There were 35 PV, 25 ET, and 6 PMF patients included. The prevalence of high echocardiographic probability of PH was 4.55% (2 ET and 1 PMF). Risk factors associated with high echocardiographic probability of PHT were not analyzed. There were three risk factors associated with increased TRV_max, specifically lower hemoglobin, older age, and the presence of JAK2V617F mutation. The prevalence of high echocardiographic probability of PH in MPNs patients was 4.55%.