Pacritinib Shows Promising Real-World Benefits for Myelofibrosis With Anemia

Anemia remains a major challenge for patients with myelofibrosis (MF), significantly impacting both quality of life and clinical outcomes. The need for transfusions is particularly burdensome, making the search for therapies that can improve hemoglobin levels without worsening cytopenias an ongoing priority. A new real-world evidence evaluating pacritinib (PAC) suggests that the therapy may offer meaningful benefits in this setting, particularly for patients with baseline anemia.

Pacritinib, a JAK2/IRAK1/ACVR1 inhibitor that spares JAK1, has a distinct pharmacologic profile compared with other JAK inhibitors and can be administered at full dose even in cytopenic patients. In the PERSIST-2 clinical trial, PAC demonstrated a reduction in transfusion requirements for patients who were not transfusion-independent. The new analysis provides a real-world perspective, assessing hemoglobin (Hb) responses and platelet trends among patients treated with PAC in community oncology practices between June 2022 and June 2024.

The study used de-identified electronic health record data from patients with MF who initiated PAC and had at least 90 days of follow-up. Hemoglobin response was defined as an increase of at least 1.5 g/dL from baseline. Investigators categorized patients based on their baseline anemia severity—severe (Hb < 8.0 g/dL), moderate (8–10 g/dL), or mild/no anemia (>10 g/dL)—and summarized results using medians and interquartile ranges (IQR).

Among 148 PAC-treated patients with evaluable laboratory data, 65 (44%) achieved a hemoglobin response within a median of 40 days (IQR: 27-84) from treatment initiation. Nearly one-third (33%) of all patients achieved this improvement within the first 90 days, with a median time to response of 33 days (IQR: 22-44). Of those who responded by day 90, 61% had severe anemia at baseline, highlighting PAC’s potential efficacy even in patients with substantial hematologic compromise.

Hemoglobin levels remained stable through 180 days among responders across all baseline anemia categories, suggesting durable benefit. Platelet counts also demonstrated positive trends, particularly among patients with moderate or mild anemia at baseline. In these groups, platelet levels improved by day 90 and remained stable at day 180. Patients with severe anemia experienced stable platelet counts throughout the observation period, indicating that PAC did not exacerbate thrombocytopenia in this vulnerable subset.

Due to limited sample sizes, platelet assessments beyond 90 days in patients with mild or no anemia were not possible. Nevertheless, the consistency of hemoglobin and platelet trends across categories strengthens confidence in PAC’s hematologic tolerability.

For oncologists and pathway decision-makers, these results underscore PAC’s potential role in managing patients with MF with baseline cytopenias who are often ineligible for or intolerant of other JAK inhibitors. As the therapeutic landscape evolves, real-world data such as these provide critical context to inform treatment sequencing and optimize patient outcomes.

Reference

Rampal R, Eiffert S, Marrone M, et al. Hematologic response in patients with myelofibrosis treated with pacritinib in real-word clinical settings. J Clin Oncol. 2025;43:e23274-e23274(2025). doi:10.1200/JCO.2025.43.16_suppl.e23274