Non-Pharmacologic Management of Splenomegaly for Patients with Myelofibrosis: Is There Any Role for Splenectomy or Splenic Radiation in 2020?

The use of splenic embolization in immune thrombocytopenia: A systematic review and meta-analysis

The effectiveness of splenic embolization (SE) in treating refractory immune thrombocytopenia (ITP) remains uncertain. A systematic literature review was undertaken to assess the effectiveness and safety of SE in treating both paediatric and adult patients with ITP. We conducted an extensive search employing predefined criteria. We extracted platelet counts at baseline and at multiple intervals following SE, along with details of the proportion of embolized spleen parenchyma and the proportion of patients exhibiting complete or partial platelet count responses. We identified nine eligible reports for the analysis of effectiveness (228 patients) and 15 reports for the safety analysis (151 patients). Pooled estimates of complete response (platelet count >100 × 109/L) and overall response (platelet count >30 × 109/L) were 50.1% (95% CI: 38-62.3) and 74.4% (95% CI: 64.9-83.9) respectively. Most studies applied an embolization of at least 60% of the spleen parenchyma. Nearly all the patients suffered from mild adverse events (AEs), 1.3% suffered from serious AEs and one patient died (0.7%). In conclusion, SE resulted in an overall response rate in 74.4% of patients with ITP. However, this finding derives from uncontrolled studies of low to moderate quality.

New approaches to tackle cytopenic myelofibrosis

Myelofibrosis (MF) is a clonal hematopoietic stem cell neoplasm characterized by constitutional symptoms, splenomegaly, and risks of marrow failure or leukemic transformation and is universally driven by Jak/STAT pathway activation. Despite sharing this pathogenic feature, MF disease behavior can vary widely. MF can generally be categorized into 2 distinct subgroups based on clinical phenotype: proliferative MF and cytopenic (myelodepletive) MF. Compared to proliferative phenotypes, cytopenic MF is characterized by lower blood counts (specifically anemia and thrombocytopenia), more frequent additional somatic mutations outside the Jak/STAT pathway, and a worse prognosis. Cytopenic MF presents unique therapeutic challenges. The first approved Jak inhibitors, ruxolitinib and fedratinib, can both improve constitutional symptoms and splenomegaly but carry on-target risks of worsening anemia and thrombocytopenia, limiting their use in patients with cytopenic MF. Supportive care measures that aim to improve anemia or thrombocytopenia are often ineffective. Fortunately, new treatment strategies for cytopenic MF are on the horizon. Pacritinib, selective Jak2 inhibitor, was approved in 2022 to treat patients with symptomatic MF and a platelet count lower than 50 × 109/L. Several other Jak inhibitors are in development to extend therapeutic benefits to those with either anemia or thrombocytopenia. While many other novel non-Jak inhibitor therapies are in development for MF, most carry a risk of hematologic toxicities and often exclude patients with baseline thrombocytopenia. As a result, significant unmet needs remain for cytopenic MF. Here, we discuss clinical implications of the cytopenic MF phenotype and present existing and future strategies to tackle this challenging disease.

Pre-transplant Splenic Irradiation in Patients with Myeloproliferative Neoplasms

Purpose

Allogeneic hematopoietic cell transplantation (HCT) serves as the only curative treatment option for patients with myelofibrosis and other myeloproliferative neoplasms. Splenomegaly commonly manifests in patients with myeloproliferative neoplasms and can lead to delayed or poor engraftment, increased transfusion burden, and worse survival. Methods to decrease the effect of splenomegaly include splenectomy and splenic irradiation. We sought to report on clinical outcomes for patients treated with splenic irradiation as part of their transplant conditioning.

Methods and Materials

Patients with splenomegaly measuring greater than 22 cm were referred for splenic irradiation. They received radiation to the entire spleen to 10 Gy in 5 fractions using 3-dimensional conformal radiation with anteroposterior/posteroanterior or opposed tangent fields. Blood counts were monitored closely on treatment. Changes in splenic size were measured using first and last treatment image guided radiation therapy and pre- and posttransplant diagnostic imaging.

Results

Seventeen patients completed pretransplant splenic irradiation between 2012 and 2021. Median platelet, white blood cell, and hemoglobin levels decreased on treatment. One patient required platelet transfusion and 3 required packed red blood cell transfusions. Mean decrease in spleen size during radiation was -8.5% in the craniocaudal dimension. Prolonged decreases, measured 2 to 12 months after transplant, averaged 14.64%. All patients engrafted. Fourteen (82.4%) were alive at time of analysis with median follow-up of 4.2 years from hematopoietic cell transplantation.

Conclusions

Splenic irradiation offers a safe method of managing significant splenomegaly as part of transplant conditioning. Transplant outcomes in this series were excellent. Prospective data may be beneficial to determine the absolute benefit of this addition to pretransplant conditioning in this patient population.

Improving symptom burden and quality of life in patients with myelofibrosis: current strategies and future directions

INTRODUCTION

Myelofibrosis (MF) is a complex and aggressive hematologic malignancy resulting from JAK/STAT-driven myeloproliferation and abnormal fibrogenesis. The clinical manifestations are heterogeneous and negatively impact quality of life and survival. JAK inhibitors improve symptoms and splenomegaly to a variable degree in a proportion of patients, but the effects for many patients are insufficient or short-lived.

AREAS COVERED

This review examines the constellation of symptoms that befall patients with MF, describes methods to quantify and serially monitor these symptoms, and evaluates pharmacologic and non-pharmacologic interventions for disease-related symptoms. The review also includes a discussion of areas of unmet medical need, and proposes future methods for meeting this need.

EXPERT OPINION

The treatment landscape for MF is evolving rapidly. The most effective therapies or combinations of therapies will likely simultaneously impact both the malignant hematopoietic stem cell and mechanisms of aberrant fibrogenesis that drive this disease. The goals of treatment for patients with myelofibrosis should be to improve length and quality of life. Clinical trials must be designed with these goals in mind, with endpoints focused on overall survival and symptom reduction, as opposed to surrogate endpoints such as spleen volume reduction.