Bone marrow fibrosis is a central pathological feature and World Health Organization major diagnostic criterion of myelofibrosis. Although bone marrow fibrosis is seen in a variety of malignant and non-malignant disease states, the deposition of reticulin and collagen fibrosis in the bone marrow of patients with myelofibrosis is believed to be mediated by the myelofibrosis hematopoietic stem/progenitor cell, contributing to an impaired microenvironment favoring malignant over normal hematopoiesis. Increased expression of inflammatory cytokines, lysyl oxidase, transforming growth factor-β, impaired megakaryocyte function, and aberrant JAK-STAT signaling have all been implicated in the pathogenesis of bone marrow fibrosis. A number of studies indicate that bone marrow fibrosis is an adverse prognostic variable in myeloproliferative neoplasms. However, modern myelofibrosis prognostication systems utilized in risk-adapted treatment approaches do not include bone marrow fibrosis as a prognostic variable. The specific effect on bone marrow fibrosis of JAK2 inhibition, and other rationally based therapies currently being evaluated in myelofibrosis, has yet to be fully elucidated. Hematopoietic stem cell transplantation remains the only curative therapeutic approach that reliably results in resolution of bone marrow fibrosis in patients with myelofibrosis. Here we review the pathogenesis, biological consequences, and prognostic impact of bone marrow fibrosis. We discuss the rationale of various anti-fibrogenic treatment strategies targeting the clonal hematopoietic stem/progenitor cell, aberrant signaling pathways, fibrogenic cytokines, and the tumor microenvironment.

Tremblay and colleagues asked whether patients receiving either routine anticoagulation or antiplatelet therapy for existing conditions prior to becoming ill with COVID-19 have different outcomes from patients receiving neither therapy. After matching for existing comorbidities, this retrospective observational study finds no evidence for an effect of prediagnosis anticoagulation on mortality.

Guidelines currently favor vitamin K antagonists or low-molecular-weight heparins for treatment of noncirrhotic portal vein thrombosis (ncPVT). Use of direct oral anticoagulants (DOACs) in PVT has been met with concern because of the lack of data. We conducted a retrospective study to investigate the efficacy and safety of DOACs for the treatment of ncPVT, and to compare them with standard therapies: 330 patients with ncPVT, followed-up for a mean 41.6 months, received warfarin (n = 108), enoxaparin (n = 70), rivaroxaban (n = 65), apixaban (n = 20), dabigatran (n = 8), fondaparinux (n = 2), or no anticoagulation (n = 57). The primary outcome was complete radiographic resolution (CRR) of PVT. Secondary outcomes included recanalization of occlusive PVT, cavernous transformation of the PV, development of chronic portal hypertensive symptoms (cPHS), and major bleeding. DOACs were associated with the highest CRR rates (dabigatran, 6/8 [75%]; apixaban, 13/20 [65%]; rivaroxaban, 42/65 [65%]). Enoxaparin was associated with a CRR rate similar to that of the DOACs (40/70 = 57%). Warfarin was associated with worse outcomes in this regard (CRR rate, 31% [33/108]; hazard ratio [HR] DOACs:warfarin, 2.91; 95% confidence interval [CI], 1.87-4.52; P < .0001). DOACs were associated with recanalization rates similar to enoxaparin and greater than warfarin (HR DOACs:warfarin, 3.45; 95% CI, 1.93-6.18; P < .0001). DOACs were associated with lower rates of cPHS, although this did not attain significance (DOACs, 8/93 [9%]; enoxaparin, 13/70 [19%]; warfarin, 31/108 [29%]). DOACs were associated with less major bleeding relative to warfarin (HR DOACs:warfarin, 0.20; 95% CI, 0.05-0.86; P = .0307). Patients harboring JAK2V617F, those with no evident predisposing factor for PVT, and those with occlusive thrombus demonstrated worse outcomes. DOACs appear effective and safe for the treatment of ncPVT.

There are unresolved questions regarding the association between persistent leukocytosis and risk of thrombosis and disease evolution in polycythemia vera (PV), as much of the published literature on the topic does not appropriately use repeated-measures data or time-dependent modeling to answer these questions. To address this knowledge gap, we analyzed a retrospective database of 520 PV patients seen at 10 academic institutions across the United States. Taking hematologic laboratory data at ∼3-month intervals (or as available) for all patients for duration of follow-up, we used group-based trajectory modeling to identify latent clusters of patients who follow distinct trajectories with regard to their leukocyte, hematocrit, and platelet counts over time. We then tested the association between trajectory membership and hazard of 2 major outcomes: thrombosis and disease evolution to myelofibrosis, myelodysplastic syndrome, or acute myeloid leukemia. Controlling for relevant covariates, we found that persistently elevated leukocyte trajectories were not associated with the hazard of a thrombotic event (P = .4163), but were significantly associated with increased hazard of disease evolution in an ascending stepwise manner (overall P = .0002). In addition, we found that neither hematocrit nor platelet count was significantly associated with the hazard of thrombosis or disease evolution.

Severe cases of coronavirus disease 2019 (COVID‐19) are usually accompanied by an exuberant immune response comparable to cytokine release syndrome (CRS), with markedly elevated serum levels of proinflammatory cytokines which are thought to be a major drivers of morbidity and mortality for these patients (Huang, et al 2020). Several drugs with anti‐inflammatory properties (tocilizumab, siltuximab, sarilumab, anakinra, among others) have been suggested as adjuncts to supportive care in the management of COVID‐19, and several clinical trials are underway (NCT04315298, NCT04317092, NCT04306705).