Management of Myelofibrosis: from Diagnosis to New Target Therapies

Myelofibrosis and allogeneic transplantation: critical points and challenges

New available drugs allow better control of systemic symptoms associated with myelofibrosis (MF) and splenomegaly but they do not modify the natural history of progressive and poor prognosis disease. Thus, hematopoietic stem cell transplantation (HSCT) is still considered the only available curative treatment for patients with MF. Despite the increasing number of procedures worldwide in recent years, HSCT for MF patients remains challenging. An increasingly complex network of the patient, disease, and transplant-related factors should be considered to understand the need for and the benefits of the procedure. Unfortunately, prospective trials are often lacking in this setting, making an evidence-based decision process particularly arduous. In the present review, we will analyze the main controversial points of allogeneic transplantation in MF, that is, the development of more sophisticated models for the identification of eligible patients; the need for tools offering a more precise definition of expected outcomes combining comorbidity assessment and factors related to the procedure; the decision-making process about the best transplantation time; the evaluation of the most appropriate platform for curative treatment; the impact of splenomegaly; and splenectomy on outcomes.

Therapeutic Results and Survival of Patients with Myelofibrosis Treated with Ruxolitinib-A Real-Life Longitudinal Study

The aim of this study was to analyze the therapeutic results and survival of patients with myelofibrosis treated with ruxolitinib in comparison with a group on standard therapy. It is a cross-sectional, retrospective, non-interventional, real-life study that was performed between January 2000 and February 2023. Patients treated between 2000 and 2016, before the introduction of ruxolitinib, constituted the control group (n = 45), while those treated after May 2016, after ruxolitinib inclusion, constituted the active group (n = 66). Demographic characteristics, clinical indicators, the severity of the disease, and survival were explored using Kaplan-Meier survival analyses. Spearman's correlation, linear regression, and other statistical analyses were performed. According to the Kaplan-Meier analysis, there was a 75.33% reduction in the fatality risk in the sample. On a general-population level, the fatality risk in the group treated with ruxolitinib varied between 7.9% and 77.18% compared to that of the risk in the control group. There was a decrease in blood parameters (leukocytes, hemoglobin, and platelets) and spleen size. During the first six months, the spleen size of the patients on ruxolitinib decreased by 6%, and during the second six months, it decreased by another 9%. This study shows that patients in a real-life clinical setting treated with ruxolitinib exhibited improved clinical signs of the disease, had a lower symptom severity, and survived longer than patients on standard therapy before ruxolitinib's entrance into the national market. The improvements correlate with those reported in randomized clinical trials.

Immune Dysregulation and Infectious Complications in MPN Patients Treated With JAK Inhibitors

BCR-ABL1-negative myeloproliferative neoplasms are burdened by a reduced life expectancy mostly due to an increased risk of thrombo-hemorrhagic events, fibrotic progression/leukemic evolution, and infectious complications. In these clonal myeloid malignancies, JAK2V617F is the main driver mutation, leading to an aberrant activation of the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway. Therefore, its inhibition represents an attractive therapeutic strategy for these disorders. Several JAK inhibitors have entered clinical trials, including ruxolitinib, the first JAK1/2 inhibitor to become commercially available for the treatment of myelofibrosis and polycythemia vera. Due to interference with the JAK-STAT pathway, JAK inhibitors affect several components of the innate and adaptive immune systems such as dendritic cells, natural killer cells, T helper cells, and regulatory T cells. Therefore, even though the clinical use of these drugs in MPN patients has led to a dramatic improvement of symptoms control, organ involvement, and quality of life, JAK inhibitors–related loss of function in JAK-STAT signaling pathway can be a cause of different adverse events, including those related to a condition of immune suppression or deficiency. This review article will provide a comprehensive overview of the current knowledge on JAK inhibitors’ effects on immune cells as well as their clinical consequences, particularly with regards to infectious complications.

New Markers of Disease Progression in Myelofibrosis

Primary myelofibrosis (PMF) is a myeloproliferative neoplasm due to the clonal proliferation of a hematopoietic stem cell. The vast majority of patients harbor a somatic gain of function mutation either of JAK2 or MPL or CALR genes in their hematopoietic cells, resulting in the activation of the JAK/STAT pathway. Patients display variable clinical and laboratoristic features, including anemia, thrombocytopenia, splenomegaly, thrombotic complications, systemic symptoms, and curtailed survival due to infections, thrombo-hemorrhagic events, or progression to leukemic transformation. New drugs have been developed in the last decade for the treatment of PMF-associated symptoms; however, the only curative option is currently represented by allogeneic hematopoietic cell transplantation, which can only be offered to a small percentage of patients. Disease prognosis is based at diagnosis on the classical International Prognostic Scoring System (IPSS) and Dynamic-IPSS (during disease course), which comprehend clinical parameters; recently, new prognostic scoring systems, including genetic and molecular parameters, have been proposed as meaningful tools for a better patient stratification. Moreover, new biological markers predicting clinical evolution and patient survival have been associated with the disease. This review summarizes basic concepts of PMF pathogenesis, clinics, and therapy, focusing on classical prognostic scoring systems and new biological markers of the disease.

Long-term safety and efficacy of givinostat in polycythemia vera: 4-year mean follow up of three phase 1/2 studies and a compassionate use program

Polycythemia vera (PV) is a BCR-ABL1-negative myeloproliferative neoplasm (MPN) characterized by excessive proliferation of erythroid, myeloid, and megakaryocytic components in the bone marrow, mainly due to a Janus kinase 2 gene mutation (JAK2^V617F). Givinostat, a histone-deacetylase inhibitor that selectively targets JAK2^V617F cell growth, has demonstrated good efficacy and safety in three phase 1/2 studies in patients with PV. This manuscript focuses on the 4-year mean (2.8 year median) follow-up of an open-label, long-term study that enrolled 51 patients with PV (out of a total of 54 with MPN) who received clinical benefit from givinostat in these previous studies or on compassionate use, and who continued to receive givinostat at the last effective and tolerated dose. The primary objectives are to determine givinostat's long-term safety and tolerability, and efficacy evaluated by the investigators according to internationally recognized response criteria. During follow-up, only 10% of PV patients reported Grade 3 treatment-related adverse events (AEs), while none had Grade 4 or 5 treatment-related AEs. The overall response rate for the duration of follow-up was always greater than 80% in patients with PV. In conclusion, givinostat demonstrated a good safety and efficacy profile in patients with PV, data supporting long-term use in this population.

JAK-Inhibitoren für die Behandlung hämatoonkologischer Erkrankungen

Die konstitutive Aktivierung des JAK-STAT-Signalwegs ist charakteristisch für die Pathogenese der myeloproliferativen Neoplasien, speziell der primären Myelofibrose, der Polycythaemia vera und der essentiellen Thrombozythämie. Die Einführung von oral verfügbaren JAK-Inhibitoren in die Klinik brachte einen entscheidenden Fortschritt für die pharmakologische Behandlung der Myelofibrose und der Polycythaemia vera, wenngleich damit noch keine Heilung verbunden ist. Im Vordergrund steht die Verbesserung der Lebensqualität der meist älteren Patienten durch Kontrolle krankheitsbedingter konstitutioneller Symptome, Reduktion einer bestehenden Splenomegalie und Vermeidung insbesondere von thromboembolischen Folgekomplikationen. Darüber hinaus kann die Therapie von Myelofibrose-Patienten mit JAK-Inhibitoren jedoch auch deren Krankheitsverlauf verlangsamen und ihr Gesamtüberleben verlängern. Der bislang einzige in Europa zugelassene JAK-Inhibitor Ruxolitinib hemmt die Isoformen JAK1 und JAK2 und besitzt sowohl antiinflammatorisches als auch antiproliferatives Potenzial. Damit zeigt dieser Inhibitor überdies eine gute Wirkung in der Therapie der Graft-versus-Host-Erkrankung nach allogener hämatopoetischer Stammzelltransplantation. Mit Fedratinib, Pacritinib und Momelatinib befinden sich derzeit 3 weitere vielversprechende JAK-Inhibitoren mit etwas unterschiedlichen Wirkprofilen in der klinischen Phase III-Testung. Diese zeigen auch bei Patienten mit unwirksamer oder unverträglicher Vorbehandlung mit Ruxolitinib Wirksamkeit, sodass eine kontinuierliche Weiterentwicklung der entsprechenden Therapiestrategien abzusehen ist.