Context: Philadelphia-negative myeloproliferative neoplasms (Ph- MPNs), including polycythemia vera (PV), essential thrombocythemia (ET), and myelofibrosis (MF), are clonal disorders of hematopoietic stem cells characterized by excessive proliferation of myeloid lineages and progressive bone marrow dysfunction. While the international literature offers robust data on these conditions, information specific to the Brazilian population remains scarce. Understanding the clinical and epidemiological features of patients in Brazil, in comparison to global data, is crucial to identifying potential regional differences and guiding therapeutic strategies.

Objective: To describe the clinical and epidemiological characteristics, clinical outcomes, and access to diagnosis and treatment among patients with Philadelphia-negative myeloproliferative neoplasms (Ph- MPNs) treated within the Brazilian public health system (SUS).

Methods: From August 2023 to July 2025, 253 patients from five public health institutions were registered in a REDCAP database. Information was retrospectively analyzed from physical and electronic medical records. The project was authorized by local research ethics committees, and all patients signed informed consent forms authorizing the use of their data.

Results: A total of 253 patients with Philadelphia-negative myeloproliferative neoplasms (Ph- MPNs) were included, from 15 Brazilian states, with most from Rio de Janeiro (66%). Diagnoses included essential thrombocythemia (ET, 34%), polycythemia vera (PV, 27.2%), pre-fibrotic myelofibrosis (pre-MF, 16.8%), and overt myelofibrosis (MF, 22%). There was a female predominance (56.5%), especially among ET cases (2:1 ratio). The mean age at diagnosis was 59.75 years, being lower in ET (57.0) and higher in PV (62.8). About 72% had comorbidities, mainly hypertension, diabetes, smoking, and coronary disease. The most frequent driver mutation was JAK2 V617F (67.8%), followed by CALR (21%) and MPL (2%). Venous thrombotic events occurred in 12.4% of patients, mostly in those with MF, with lower limb and portal vein thrombosis as the most common presentations; 87% of these cases had the JAK2 mutation. Arterial events occurred in 16%, mainly among PV patients, of whom 77% had JAK2 V617F. Hemorrhagic events were observed in 6.8%, mostly gastrointestinal and in MF cases. Fatigue was the most common symptom at diagnosis (38%), followed by weight loss (19%). The mean MPN-SAF TSS score was 23.84, highest in PV patients (27.36). Most MF patients had intermediate-2 or high-risk IPSS (67%), while 82% of PV and 39% of ET patients were classified as high-risk according to respective prognostic scores. Regarding treatment, 66% of patients received hydroxyurea as first-line therapy. Only 4 MF patients had access to JAK2 inhibitors as initial treatment. Among PV patients, 83% used antiplatelet agents, and 13% were hydroxyurea-intolerant or resistant. Conclusions: This study represents the real-world clinical and epidemiological characteristics of Brazilian patients with Ph- MPNs treated within the public healthcare system. Well-designed, population-based registries are a valuable source of high-quality data. Beyond providing epidemiological insights, they help identify real-world specificities, enabling more personalized research and targeted interventions—especially important in resource-limited settings such as Brazil. This represents the first large Brazilian registry focused on Ph- MPNs, which is still ongoing. With the expansion of this dataset, we expect to enhance not only our understanding of the diseases but also the standard of care delivered to our unique patient population.

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2025
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