Considerations to comprehensive care for the older individual with myelofibrosis.

Over the last decade, we have witnessed a massive increase in available clinical agents, both in the clinical trial setting and following commercial use approval, directed to reduced life expectancy as well as the considerable symptom, splenic and anaemia burden associated with myelofibrosis. Given the median age of onset of the disease, coupled with an ageing population globally, we will be caring for an increasingly aged myelofibrosis cohort in future years. We will need to adapt our approach, emphasizing the holistic management of the older individual with myelofibrosis accordingly. Out with the pharmacological management of the disease, consideration needs to be given to interventions based on concurrent illness, comprehensive geriatric assessments, frailty, polypharmacy and drug-drug interactions, nutritional issues, psychological concerns (depression, anxiety or distress), cognitive decline and social/economic aspects. Within this review, we summarise available data addressing these issues, outline knowledge gaps and suggest a summative and holistic approach to the older individual with myelofibrosis.

[Influencing factors of iron metabolism assessment in patients with myelodysplastic syndrome: A retrospective study].

Objective: To analyze the influencing factors of iron metabolism assessment in patients with myelodysplastic syndrome. Methods: MRI and/or DECT were used to detect liver and cardiac iron content in 181 patients with MDS, among whom, 41 received regular iron chelation therapy during two examinations. The adjusted ferritin (ASF) , erythropoietin (EPO) , cardiac function, liver transaminase, hepatitis antibody, and peripheral blood T cell polarization were detected and the results of myelofibrosis, splenomegaly, and cyclosporine were collected and comparative analyzed in patients. Results: We observed a positive correlation between liver iron concentration and ASF both in the MRI group and DECT groups (r=0.512 and 0.606, respectively, P<0.001) , only a weak correlation between the heart iron concentration and ASF in the MRI group (r=0.303, P<0.001) , and no significant correlation between cardiac iron concentration and ASF in the DECT group (r=0.231, P=0.053) . Moreover, transfusion dependence in liver and cardiac [MRI group was significantly associated with the concentration of iron in: LIC: (28.370±10.706) mg/g vs (7.593±3.508) mg/g, t=24.30, P<0.001; MIC: 1.81 vs 0.95, z=2.625, P<0.05; DECT group: liver VIC: (4.269±1.258) g/L vs (1.078±0.383) g/L, t=23.14, P<0.001: cardiac VIC: 1.69 vs 0.68, z=3.142, P<0.05]. The concentration of EPO in the severe iron overload group was significantly higher than that in the mild to moderate iron overload group and normal group (P<0.001) . Compared to the low-risk MDS group, the liver iron concentration in patients with MDS with cyclic sideroblasts (MDS-RS) was significantly elevated [DECT group: 3.80 (1.97, 5.51) g/L vs 1.66 (0.67, 2.94) g/L, P=0.004; MRI group: 13.7 (8.1,29.1) mg/g vs 11.6 (7.1,21.1) mg/g, P=0.032]. Factors including age, bone marrow fibrosis, splenomegaly, T cell polarization, use of cyclosporine A, liver aminotransferase, and hepatitis antibody positive had no obvious effect on iron metabolism. Conclusion: There was a positive correlation between liver iron concentration and ASF in patients with MDS, whereas there was no significant correlation between cardiac iron concentration and ASF. Iron metabolism was affected by transfusion dependence, EPO concentration, and RS.

Influencing factors of iron metabolism assessment in patients with myelodysplastic syndrome: A retrospective study / 中华血液学杂志

Objective: To analyze the influencing factors of iron metabolism assessment in patients with myelodysplastic syndrome. Methods: MRI and/or DECT were used to detect liver and cardiac iron content in 181 patients with MDS, among whom, 41 received regular iron chelation therapy during two examinations. The adjusted ferritin (ASF) , erythropoietin (EPO) , cardiac function, liver transaminase, hepatitis antibody, and peripheral blood T cell polarization were detected and the results of myelofibrosis, splenomegaly, and cyclosporine were collected and comparative analyzed in patients. Results: We observed a positive correlation between liver iron concentration and ASF both in the MRI group and DECT groups (r=0.512 and 0.606, respectively, P<0.001) , only a weak correlation between the heart iron concentration and ASF in the MRI group (r=0.303, P<0.001) , and no significant correlation between cardiac iron concentration and ASF in the DECT group (r=0.231, P=0.053) . Moreover, transfusion dependence in liver and cardiac [MRI group was significantly associated with the concentration of iron in: LIC: (28.370±10.706) mg/g vs (7.593±3.508) mg/g, t=24.30, P<0.001; MIC: 1.81 vs 0.95, z=2.625, P<0.05; DECT group: liver VIC: (4.269±1.258) g/L vs (1.078±0.383) g/L, t=23.14, P<0.001: cardiac VIC: 1.69 vs 0.68, z=3.142, P<0.05]. The concentration of EPO in the severe iron overload group was significantly higher than that in the mild to moderate iron overload group and normal group (P<0.001) . Compared to the low-risk MDS group, the liver iron concentration in patients with MDS with cyclic sideroblasts (MDS-RS) was significantly elevated [DECT group: 3.80 (1.97, 5.51) g/L vs 1.66 (0.67, 2.94) g/L, P=0.004; MRI group: 13.7 (8.1,29.1) mg/g vs 11.6 (7.1,21.1) mg/g, P=0.032]. Factors including age, bone marrow fibrosis, splenomegaly, T cell polarization, use of cyclosporine A, liver aminotransferase, and hepatitis antibody positive had no obvious effect on iron metabolism. Conclusion: There was a positive correlation between liver iron concentration and ASF in patients with MDS, whereas there was no significant correlation between cardiac iron concentration and ASF. Iron metabolism was affected by transfusion dependence, EPO concentration, and RS.

Myelofibrosis Pattern in 68Ga-PSMA PET/CT of a Patient With Recurrence Prostate Cancer.

ABSTRACT: We present the case of a 64-year-old man with prostate adenocarcinoma, Gleason score 7, after radical prostatectomy and adjuvant radiotherapy in 2015. Because of high risk and perineural invasion, hormonotherapy was indicated. PSA levels began to rise, and at PSA level of 0.9 ng/mL, he was referred for 68Ga-PSMAPET/CT. It showed focal uptake in the right femur and diffuse tracer accumulation in bone marrow. The patient was previously diagnosed with macrocytic anemia. He underwent bone marrow biopsy. Based on clinical, laboratory, and histopathology results, myelodysplastic fibrosis was diagnosed. Diffuse uptake of 68Ga-PSMA was the sign of the bone marrow stimulation.

Portosystemic shunt is an effective treatment for complications of portal hypertension in hepatic myeloid metaplasia and improves nutritional status.

In patients affected by myelofibrosis with hepatic myeloid metaplasia (HMM), portal hypertension (PHT) complications may develop. In this case series, we analysed the efficacy and safety of transjugular portosystemic shunt (TIPS) in the treatment of PHT-related complications and its effects on the nutritional status. Six patients were evaluated and the average follow-up period after TIPS was 33 (IQR 5) months. None of the patients developed hepatic failure, nor any recurrence of variceal bleeding was recorded. No additional paracentesis or endoscopic prophylactic treatment for PHT-related complications were required. In all subjects, the average dose of diuretics was almost halved three months after TIPS. Three patients died during the follow-up, but none for liver-related causes. All patients showed an improvement in the global nutritional status. In conclusion, TIPS represent an effective and safe treatment option for patients affected by complications of PHT secondary to HMM and drives to an improvement of the nutritional status.

High-throughput drug screening identifies the ATR-CHK1 pathway as a therapeutic vulnerability of CALR mutated hematopoietic cells.

Mutations of calreticulin (CALR) are the second most prevalent driver mutations in essential thrombocythemia and primary myelofibrosis. To identify potential targeted therapies for CALR mutated myeloproliferative neoplasms, we searched for small molecules that selectively inhibit the growth of CALR mutated cells using high-throughput drug screening. We investigated 89 172 compounds using isogenic cell lines carrying CALR mutations and identified synthetic lethality with compounds targeting the ATR-CHK1 pathway. The selective inhibitory effect of these compounds was validated in a co-culture assay of CALR mutated and wild-type cells. Of the tested compounds, CHK1 inhibitors potently depleted CALR mutated cells, allowing wild-type cell dominance in the co-culture over time. Neither CALR deficient cells nor JAK2V617F mutated cells showed hypersensitivity to ATR-CHK1 inhibition, thus suggesting specificity for the oncogenic activation by the mutant CALR. CHK1 inhibitors induced replication stress in CALR mutated cells revealed by elevated pan-nuclear staining for γH2AX and hyperphosphorylation of RPA2. This was accompanied by S-phase cell cycle arrest due to incomplete DNA replication. Transcriptomic and phosphoproteomic analyses revealed a replication stress signature caused by oncogenic CALR, suggesting an intrinsic vulnerability to CHK1 perturbation. This study reveals the ATR-CHK1 pathway as a potential therapeutic target in CALR mutated hematopoietic cells.

Quality of Life in Myeloproliferative Neoplasms: Symptoms and Management Implications.

Myeloproliferative neoplasms include essential thrombocythemia, polycythemia vera, and myelofibrosis. They are characterized by abnormal myeloid proliferation. Patients suffer from debilitating constitutional symptoms and splenomegaly. There have been advances in understanding the impact on quality of life in myeloproliferative neoplasms. Owing to the chronicity of these diseases, symptoms are considered in response criteria for clinical trials. This review wills cover how quality of life is measured in patients with myeloproliferative neoplasm. We review the impact of treatment options, including JAK inhibitors, allogeneic stem cell transplantation, and medications in development. We discuss nonpharmacologic methods of improving symptoms and quality of life.

Transcriptome profiling reveals target in primary myelofibrosis together with structural biology study on novel natural inhibitors regarding JAK2.

This study aimed to identify effective targets for carcinogenesis of primary myelofibrosis (PMF), as well as to screen ideal lead compounds with potential inhibition effect on Janus kinase 2 to contribute to the medication design and development. Gene expression profiles of GSE26049, GSE53482, GSE61629 were obtained from the Gene Expression Omnibus database. The differentially expressed genes were identified, and functional enrichment analyses such as Gene Ontology, protein-protein interaction network etc., were performed step by step. Subsequently, highly-precise computational techniques were conducted to identify potential inhibitors of JAK2. A series of structural biology methods including virtual screening, ADMET (absorption, distribution, metabolism, excretion, and toxicity) prediction, molecule docking, molecular dynamics simulation etc., were implemented to discover novel natural compounds. Results elucidated that PMF patients had abnormal LCN2, JAK2, MMP8, CAMP, DEFA4, LTF, MPO, HBD, STAT4, EBF1 mRNA expression compared to normal patients. Functional enrichment analysis revealed that these genes were mainly enriched in erythrocyte differentiation, neutrophil degranulation and killing cells of other organisms. Two novel natural compounds, ZINC000013513540 and ZINC000004099068 were found binding to JAK2 with favorable interaction energy together with high binding affinity. They were predicted with non-Ames mutagenicity, low-rodent carcinogenicity, less developmental toxicity potential as well as non-toxicity with liver. Molecular dynamics simulation demonstrated that these two complexes: ZINC000013513540-JAK2 and ZINC000004099068-JAK2 could exist stably under natural circumstances. In conclusion, this study revealed hub genes in the carcinogenesis of PMF. ZINC000013513540 and ZINC000004099068 were promising drugs in dealing with PMF. This study may also accelerate exploration of new drugs.

Successful Treatment of Invasive Fungal Infection Due to Highly Resistant Aspergillus calidoustus in an Allogeneic Hematopoietic Cell Transplant Recipient.

Invasive aspergillosis (IA) is the most common invasive fungal infection following a hematopoietic cell transplant, with emerging cryptic species exhibiting resistance to commonly used antifungals such as azoles. These species have been increasingly found after the introduction of anti-mold prophylaxis. We report a case of a 56-year-old female with primary myelofibrosis whose allogeneic hematopoietic cell transplant was complicated by disseminated fungal infection (skin, lung) due to Aspergillus calidoustus, a cryptic specie. Treatment of Aspergillus species remains challenging as these cryptic species are usually resistant to azoles including voriconazole which is the first line of treatment of IA. Infection was successfully treated with surgical excision and combination antifungal therapy based on in vitro susceptibility and synergy testing. Therapy included isavuconazole, a drug that has been shown to be non-inferior to voriconazole in the treatment of invasive mold infections.

Vitamin B6 deficiency is prevalent in primary and secondary myelofibrosis patients.

Vitamin B6 (VB6) deficiency contributes to oncogenesis and tumor progression in certain cancers, and is prevalent in cancer patients in general. VB6 is also an essential element of heme synthesis, and deficiency can lead to anemia. Primary myelofibrosis (PMF) and secondary myelofibrosis (sMF) are myeloproliferative neoplasms often presenting with anemia along with other cytopenias. We performed a prospective study to determine whether PMF and sMF patients suffer from VB6 deficiency, and whether VB6-deficient patients show improvement of anemias with VB6 supplementation. Twelve PMF patients and 11 sMF patients were analyzed. A total of 16 of 23 patients (69.6%) were found to have VB6 deficiency, but VB6 supplementation with pyridoxal phosphate hydrate did not elevate hemoglobin levels in deficient patients. None of the patients presented with vitamin B12, iron, or copper deficiencies. Four patients showed serum folate levels below the lower limit of normal and eight patients showed serum zinc levels below the lower limit of normal; however, these deficiencies were marginal and unlikely to contribute to anemia. Compared to VB6-sufficient patients, VB6-deficient patients showed significantly lower serum folate levels and higher serum copper levels. Studies elucidating the relationship of VB6 deficiency and etiology of PMF/sMF are warranted.

Pacritinib to treat myelofibrosis patients with thrombocytopenia.

INTRODUCTION: Treatment with ruxolitinib, a selective JAK1/2 inhibitor, has significantly improved the lives of patients with myelofibrosis. Unfortunately, this treatment is frequently limited by cytopenias, precluding a high-risk group characterized by baseline thrombocytopenia. Additionally, there are no approved treatments for patients who have progressed while receiving ruxolitinib. Pacritinib is a novel JAK2/FLT3 inhibitor associated with less treatment-related myelosuppression that has the potential to fill these unmet treatment needs. Areas covered: This review will describe the preclinical rationale for JAK2/FLT3 inhibition, review the pharmacology of pacritinib, and detail available clinical data for pacritinib treatment of myelofibrosis. The circumstances surrounding the full clinical hold temporarily placed on pacritinib will also be explored. Expert commentary: Pacritinib has demonstrated promising results in patients with myelofibrosis and thrombocytopenia. Improvements in splenomegaly and symptom burden were observed with the 200 mg twice-daily dose in PERSIST-2, including those with platelet counts <50,000 mm. Safety concerns pertaining to cardiovascular events and bleeding that arose in an early analysis of PERSIST-2 were likely related to the advanced disease state enrolled rather than clear attribution to pacritinib. The results of an ongoing dose-finding, phase II study are eagerly awaited in order to move this promising myelofibrosis therapy forward.

Iron toxicity - Its effect on the bone marrow.

Excess iron can be extremely toxic for the body and may cause organ damage in the absence of iron chelation therapy. Preclinical studies on the role of free iron on bone marrow function have shown that iron toxicity leads to the accumulation of reactive oxygen species, affects the expression of genes coding for proteins that regulate hematopoiesis, and disrupts hematopoiesis. These effects could be partially attenuated by iron-chelation treatment with deferasirox, suggesting iron toxicity may have a negative impact on the hematopoietic microenvironment. Iron toxicity is of concern in transfusion-dependent patients. Importantly, iron chelation with deferasirox can cause the loss of transfusion dependency and may induce hematological responses, although the mechanisms through which deferasirox exerts this action are currently unknown. This review will focus on the possible mechanisms of toxicity of free iron at the bone marrow level and in the bone marrow microenvironment.

The Development and Use of Janus Kinase 2 Inhibitors for the Treatment of Myeloproliferative Neoplasms.

Following the discovery of the JAK2V617F mutation, Janus kinase (JAK) 2 inhibitors were developed as rationally designed therapy in myeloproliferative neoplasms (MPNs). Although JAK2 inhibitors have clinical efficacy in MPN, they are not clonally selective for the JAK2V617F-mutant cells. Because activated JAK-signal transducer and activator of transcription (STAT) signaling is a common feature of MPN, JAK2 inhibitors are efficacious regardless of the specific MPN phenotypic driver mutation. The Food and Drug Administration approved the JAK1/JAK2 inhibitor, ruxolitinib, for the treatment of myelofibrosis and polycythemia vera. Additional JAK2 inhibitors are currently in advanced phased clinical trials.

Cutaneous phaeohyphomycosis in a hematopoietic stem cell transplant patient caused by Alternaria rosae: First case report.

Alternaria species have been reported as a rare cause of fungal infection in organ and stem cell transplant recipients, but to date, no reports have been published of infection in humans caused by Alternaria rosae. Here, we report cutaneous A. rosae infection in a 66-year-old farmer with a history of primary myelofibrosis who had undergone allogeneic unrelated donor hematopoietic stem cell transplantation. Forty-nine days post transplant, he presented with a nodule on the thumb with no findings suggestive of disseminated infection. Pathology, culture, and molecular speciation showed the nodule was caused by cutaneous A. rosae. He had been on voriconazole as antifungal prophylaxis, but was found to have a subtherapeutic voriconazole level. He was switched to posaconazole based on published in vitro data showing its superior efficacy in Alternaria treatment. Susceptibility testing showed that the A. rosae isolate was indeed susceptible to posaconazole. His cutaneous lesion remained stable, but he died from respiratory failure secondary to lobar pneumonia. At lung autopsy, A. rosae was not identified in the lungs. We believe this to be the first published report, to our knowledge, of A. rosae infection in humans.

New strategies in myelofibrosis: the evolving paradigm of disease pathogenesis, prognostication and treatment.

Myelofibrosis (MF) is the most severe among the classical Philadelphia-negative myeloproliferative neoplasms that also include essential thrombocytemia and polycythemia vera. Myelofibrosis is characterized by numerous genetic lesions, often variously associated with each other, and by an aggressive clinical phenotype leading to severely reduced survival. Also, the inflammatory microenvironment plays a key role in disease initiation and progression. Because of the complexity of its pathogenesis and the variability of clinical features, MF is a disease that requires a personalized approach and remains orphan of curative treatments besides allogeneic transplantation. JAK2 inhibitors have marked a remarkable progress, because they alleviate systemic symptoms and reduce splenomegaly but have a limited effect on survival, on mutation load, and on marrow fibrosis. Here, we review the main contributing factors to MF pathogenesis and prognosis, focusing on how these factors relate to therapeutic choices. We discuss results from ongoing studies of JAK2 inhibitors and report on new therapeutic strategies that proved effective in early preclinical and clinical trials, including combination treatments, antifibrotic agents, and telomerase inhibitors.

Eficacia y seguridad del uso de ruxolitinib en pacientes con mielofibrosis primaria con respuesta inadecuada a terapia estándar inicial / Efficacy and safety of the use of ruxolitinib in patients with primary myelofibrosis with inadequate response to initial standard therapy

INTRODUCCIÓN: Antecedentes: El presente dictamen expone la evaluación de tecnología de la eficacia y seguridad ruxolitinib en pacientes con mielofibrosis primaria con respuesta inadecuada a terapia estándar inicial. Aspectos Generales: A mielofibrosis es un trastorno de la médula ósea que se caracteriza por una producción excesiva de reticulina y fibras de colágeno. La mielofibrosis puede originarse de diversas condiciones hematológicas, como, por ejemplo, una neoplasia mieloproliferativa previa, leucemia mieloide crónica, policitemia vera, o trombocitemia esencial. También puede originarse de condiciones no-hematológicas, como cáncer metastásico, tuberculosis, infecciones micóticas, VIH, trastornos metabólicos, adiación, toxinas, etc. Tecnologia Sanitaria de Interés: Ruxolitinib (Jakavi, Novartis) es un inhibidor selectivo de las quinasas asociadas a Janus (JAK) JAK1 y JAK2, previniendo la activación de la vía de señalización JAK-STAT. JAK1 juega un rol importante en la señalización de varias citosinas pro-inflamatorias, y JAK2 es usado principalmente por receptores de factores de crecimiento hematopoyético. Sus principales efectos celulares y sistémicos son la inhibición de la proliferación, inducción de apoptosis, y reducción de los niveles plasmáticos de citosinas. METODOLOGIA: Estrategia de Búsqueda: Se realizó una búsqueda de literatura publicada sobre Ruxolitinib en el tratamiento de ielofibrosis en las bases de datos: Medline y Tripdatabase. Adicionalmente, se ealizaron búsquedas en los portales web de entidades que realizan revisiones sistemáticas, evaluaciones de tecnologías sanitarias y guías de práctica clínica: The Cochrane Library, National Institute for Health and Care Excellence (NICE) del Reino Unido, European Society For Medical Oncology (ESMO), National Guideline of Clearinghouse (NGC), y National Comprehensive Cancer Network (NCCN) de los Estados Unidos, y The Scottish Intercollegiate Guidelines Network (SIGN) de Escocia. RESULTADOS: La presente evaluación de tecnología tuvo como objetivo obtener evidencia respecto a la eficacia de ruxolitinib en pacientes con mielofibrosis primaria con síntomas constitucionales asociados a la enfermedad, para el incremento en calidad de vida, disminución de síntomas constitucionales, y disminución de esplenomegalia. Nuestra búsqueda encontró evidencia de una guía de práctica clínica, una revisión sistemática Cochrane, una evaluación de tecnología y dos ensayos clínicos. Tanto la actualización de la guía del BCSH, la revisión sistemática Cochrane, y la evaluación de tecnología de NICE, se basan en los dos únicos ensayos clínicos de ruxolitinib en pacientes con mielofibrosis: COMFORT-I y COMFORT-II. Ambos estudios fueron auspiciados por la compañía farmacéutica elaboradora del ruxolitinib, lo que obliga a interpretar con cautela los resultados de dichos estudios por el alto riesgo de sesgo de la industria, especialmente si los efectos son imprecisos, modestos e inconsistentes como ha sido el caso de ambos estudios, como se detalla subsiguientemente. Hasta la actualidad, la evidencia disponible sobre ruxolitinib en mielofibrosis proviene de dos ensayos clínicos de fase III que muestra resultados con alto riesgo de sesgo y por lo tanto con algo grado de incertidumbre respecto al potencial beneficio frente a placebo que ofrecería este medicamento en lo referente a la calidad de vida, sobrevida global, síntomas constitucionales y tamaño del bazo. Además, cuando se le compara con otras terapias (agentes antineoplásicos, glucocorticoides, preparaciones anti-anemia, agentes inmunomoduladores, análogos de purina, análogos de pirimidina, análogos de mostaza de nitrógeno, antigonadotropinas, interferones), ruxolitinib no muestra diferencias estadísticamente robustas en parámetros clínicamente relevantes desde la perspectiva del paciente. Además, este medicamento se asocia a mayor riesgo de anemia, trombocitopenia y neutropenia respecto al placebo, aunque no frente a otras terapias (no se reportó neutropenia frente a mejor terapia disponible). CONCLUSIONES: La evidencia identificada en guías de práctica clínica, evaluaciones de tecnologías y revisiones sistemáticas se basa en sólo dos ensayos controlados aleatorizados, COMFORT 1 Y COMFORT II. Respecto a la calidad de vida, ambos estudios utilizaron el EORTC QLQ-C30 para evaluar este desenlace. No se reportó análisis estadístico de esta escala en COMFORT-I. Para el caso del COMFORT-11, la revisión Cochrane encontró que hubo un pequeño beneficio de ruxolitinib sobre mejor terapia disponible con una muy débil asociación estadística que hace difícil su interpretación en el contexto de un alto riesgo de sesgo por la gran proporción de pérdidas en el seguimiento, y el hecho que fue un estudio de etiqueta abierta. Similares limitaciones se tienen respecto a los síntomas constitucionales. La evidencia disponible sobre ruxolitinib en mielofibrosis es de baja calidad y por lo tanto con algo grado de incertidumbre respecto al potencial beneficio frente a placebo que ofrecería este medicamento en lo referente a la calidad de vida, sobrevida global, síntomas constitucionales y tamaño del bazo. Además, cuando se le compara con otras terapias (agentes antineoplásicos, glucocorticoides, preparaciones anti-anemia, agentes inmunomoduladores, análogos de purina, análogos de pirimidina, análogos de mostaza de nitrógeno, antigonadotropinas, interferones), ruxolitinib no muestra diferencias estadísticamente robustas en parámetros clínicamente relevantes desde la perspectiva del paciente. El Instituto de Evaluación en Tecnologías en Salud e Investigación-IETSI, no aprueba el uso de ruxolitinib en pacientes con mielofibrosis primaria con respuesta inadecuada a terapia estándar inicial.

Preclinical rationale for TGF-ß inhibition as a therapeutic target for the treatment of myelofibrosis.

To assess the role of abnormal transforming growth factor-beta (TGF-ß) signaling in the pathogenesis of primary myelofibrosis (PMF), the effects of the TGF-ß receptor-1 kinase inhibitor SB431542 on ex vivo expansion of hematopoietic cells in cultures from patients with JAK2V617+-polycythemia vera (PV) or PMF (JAK2V617F+, CALRpQ365f+, or unknown) and from normal sources (adult blood, AB, or cord blood, CB) were compared. In cultures of normal sources, SB431542 significantly increased by 2.5-fold the number of progenitor cells generated by days 1-2 (CD34+) and 6 (colony-forming cells) (CB) and that of precursor cells, mostly immature erythroblasts, by days 14-17 (AB and CB). In cultures of JAK2V617F+-PV, SB431542 increased by twofold the numbers of progenitor cells by day 10 and had no effect on that of precursors cells by days 12-17 (∼fourfold increase in all cases). In contrast, SB431542 had no effect on the number of either progenitor or precursor cells in cultures of JAK2V617F+ and CALR pQ365fs+ PMF. These ontogenetic- and disease-specific effects were associated with variegation in the ability of SB431542 to induce CD34+ cells from AB (increased), CB (decreased), or PV and PMF (unaffected) into cycle and erythroblasts in proliferation (increased for AB and PV and unaffected for CB and PMF). Differences in expansion of erythroblasts from AB, CB, and PV were associated with differences in activation of TGF-ß signaling (SHCY317, SMAD2S245/250/255, and SMAD1S/S/SMAD5S/S/SMAD8S/S) detectable in these cells by phosphoproteomic profiling. In conclusion, treatment with TGF-ß receptor-1 kinase inhibitors may reactivate normal hematopoiesis in PMF patients, providing a proliferative advantage over the unresponsive malignant clone.