Early thrombotic events and preemptive systemic anticoagulation following splenectomy for myelofibrosis

Primary myelofibrosis: 2021 update on diagnosis, risk-stratification and management

DISEASE OVERVIEW

Primary myelofibrosis (PMF) is a myeloproliferative neoplasm (MPN) characterized by stem cell-derived clonal myeloproliferation that is often but not always accompanied by JAK2, CALR, or MPL mutations. Additional disease features include bone marrow reticulin/collagen fibrosis, aberrant inflammatory cytokine expression, anemia, hepatosplenomegaly, extramedullary hematopoiesis (EMH), constitutional symptoms, cachexia, leukemic progression, and shortened survival.

DIAGNOSIS

Bone marrow morphology is the primary basis for diagnosis. Presence of JAK2, CALR, or MPL mutation, expected in around 90% of the patients, is supportive but not essential for diagnosis; these mutations are also prevalent in the closely related MPNs, namely polycythemia vera (PV) and essential thrombocythemia (ET). The 2016 World Health Organization classification system distinguishes "prefibrotic" from "overtly fibrotic" PMF; the former might mimic ET in its presentation. Furthermore, approximately 15% of patients with ET or PV might progress into a PMF-like phenotype (post-ET/PV MF) during their clinical course.

ADVERSE MUTATIONS

SRSF2, ASXL1, and U2AF1-Q157 mutations predict inferior survival in PMF, independent of each other and other risk factors. RAS/CBL mutations predicted resistance to ruxolitinib therapy.

ADVERSE KARYOTYPE

Very high risk abnormalities include -7, inv (3), i(17q), +21, +19, 12p-, and 11q-.

RISK STRATIFICATION

Two new prognostic systems for PMF have recently been introduced: GIPSS (genetically-inspired prognostic scoring system) and MIPSS70+ version 2.0 (MIPSSv2; mutation- and karyotype-enhanced international prognostic scoring system). GIPSS is based exclusively on mutations and karyotype. MIPSSv2 includes, in addition, clinical risk factors. GIPSS features four and MIPSSv2 five risk categories.

RISK-ADAPTED THERAPY

Observation alone is advised for MIPSSv2 "low" and "very low" risk disease (estimated 10-year survival 56%-92%); allogeneic hematopoietic stem cell transplant (AHSCT) is the preferred treatment for "very high" and "high" risk disease (estimated 10-year survival 0%-13%); treatment-requiring patients with intermediate-risk disease (estimated 10-year survival 30%) are best served by participating in clinical trials. In non-transplant candidates, conventional treatment for anemia includes androgens, prednisone, thalidomide, and danazol; for symptomatic splenomegaly, hydroxyurea and ruxolitinib; and for constitutional symptoms, ruxolitinib. Fedratinib, another JAK2 inhibitor, has now been FDA-approved for use in ruxolitinib failures. Splenectomy is considered for drug-refractory splenomegaly and involved field radiotherapy for non-hepatosplenic EMH and extremity bone pain.

NEW DIRECTIONS

A number of new agents, alone or in combination with ruxolitinib, are currently under investigation for MF treatment (ClinicalTrials.gov); preliminary results from some of these clinical trials were presented at the 2020 ASH annual meeting and highlighted in the current document.

Splenectomy in Myelofibrosis: Indications, Efficacy, and Complications

Splenomegaly, which may range from a few centimeters below the left costal border to massive dimensions, is one of the most characteristic features in patients with advanced myelofibrosis (MF). Splenectomy may offer an effective therapeutic option for treating massive splenomegaly in patients with MF, and especially in cases of disease refractory to conventional drugs, but it is associated with a number of complications as well as substantial morbidity and mortality. Whether splenectomy should be performed before allogeneic hematopoietic stem-cell transplantation is also controversial, and there is a lack of prospective randomized clinical trials that assess the role of splenectomy before hematopoietic stem-cell transplantation in patients with MF. Although splenectomy is not routinely performed before transplantation, it may be appropriate in patients with massive splenomegaly and related symptoms, so long as the higher risk of graft failure in such cases is taken into account. This review aims to describe the efficacy, indications, and complications of splenectomy in patients with MF; and to evaluate the long-term impact of splenectomy on patient survival and risk of disease transformation.

Primary myelofibrosis: 2019 update on diagnosis, risk-stratification and management

DISEASE OVERVIEW

Primary myelofibrosis (PMF) is a myeloproliferative neoplasm (MPN) characterized by stem cell-derived clonal myeloproliferation that is often but not always accompanied by JAK2, CALR, or MPL mutations; additional disease features include bone marrow stromal reaction including reticulin fibrosis, abnormal cytokine expression, anemia, hepatosplenomegaly, extramedullary hematopoiesis (EMH), constitutional symptoms, cachexia, leukemic progression, and shortened survival.

DIAGNOSIS

Diagnosis of PMF is based on bone marrow morphology. Presence of JAK2, CALR, or MPL mutation, expected in ∼ 90% of the patients, is supportive but not essential for diagnosis. The revised 2016 World Health Organization (WHO) classification system distinguishes "prefibrotic" from "overtly fibrotic" PMF; the former might mimic ET in its presentation and it is prognostically relevant to distinguish the two.

RISK STRATIFICATION

Two new prognostic systems for PMF have recently been introduced: GIPSS (genetically inspired prognostic scoring system) and MIPSS70+ version 2.0 (mutation- and karyotype-enhanced international prognostic scoring system). GIPSS is based exclusively on mutations and karyotype. MIPSS70+ version 2.0 utilizes both genetic and clinical risk factors. GIPSS features four and MIPSS70+ version 2.0 five risk categories. MIPSS70+ version 2.0 requires an online score calculator (http://www.mipss70score.it) while GIPPS offers a lower complexity prognostic tool.

RISK-ADAPTED THERAPY

Observation alone is advised for MIPSS70+ version 2.0 "low" and "very low" risk disease (estimated 10-year survival 56%-92%); allogeneic stem cell transplant is the preferred treatment of choice for "very high" and "high" risk disease (estimated 10-year survival 0-13%); treatment-requiring patients with intermediate-risk disease (estimated 10-year survival 30%) are best served by participating in clinical trials. All other treatment approaches, including the use of JAK2 inhibitors, are mostly palliative and should not be used in the absence of clear treatment indications. Conventional treatment for anemia includes androgens, prednisone, thalidomide and danazol, for symptomatic splenomegaly hydroxyurea and ruxolitinib and for constitutional symptoms ruxolitinib. Splenectomy is considered for drug-refractory splenomegaly and involved field radiotherapy for nonhepatosplenic EMH and extremity bone pain.