Pacritinib (Vonjo), a JAK1-sparing inhibitor of JAK2/IRAK1/ACV1, elicited improvements in hemoglobin levels and platelet counts in patients with myelofibrosis and anemia who were treated in real-world clinical settings, according to data presented at the
Among the 148 patients with myelofibrosis and anemia who had data for at least 90 days post-index, 44% met the criteria for hemoglobin response, with 75% achieving a response within 90 days. Additionally, at index, 84% of patients who achieved a hemoglobin response by day 90 had moderate or severe anemia. Of the patients who achieved a hemoglobin response by day 90 (n = 49), the median time from myelofibrosis diagnosis to index was 11.4 months (IQR, 0.9-33.6), and the median time to hemoglobin response from index was 33 days. Notably, 44.9% of patients were treated with second-line pacritinib, and the median duration of treatment with pacritinib was 5.2 months (IQR, 3.3-9.8) in those who had at least 9 months of follow-up.
“These real-world findings align with the guideline recommendations for the use of pacritinib in patients with [myelofibrosis] and anemia,” lead study author Raajit K. Rampal, MD, PhD, director of the Center for Hematologic Malignancies and the Myeloproliferative Neoplasms Program at Memorial Sloan Kettering Cancer Center, and colleagues wrote in a poster presentation.
What Was the Background and Methodology of This Real-World Study?
In the phase 3 PERSIST-2 trial (NCT02055781), pacritinib demonstrated a reduction in anemia-related transfusion requirements in patients with myelofibrosis who were not transfusion independent.2 In the study, 49% of patients (n = 20/41) who achieved at least a 50% reduction in transfusion over any 12-week period were treated with pacritinib compared with 9% (n = 4/43) in those treated with best available therapy, which comprised erythroid support therapies (P < .0001).
Data from the real-world study were collected using the Integra-PrecisionQ database, which included electronic health and practice management data. Of note, 80% of data were obtained from community oncology practices.1 The database was used to determine patients with myelofibrosis who had initiated treatment with pacritinib (index) between June 1, 2022, and June 30, 2024, in real-world settings.
Furthermore, patients were included if they had at least 90 days of follow-up from index and had complete laboratory data, provided that those data were established from the index date to the end of data availability, end of study, or death, whichever came first. Treatment patterns, such as the line of therapy with any myelofibrosis-directed treatment, were evaluated overall and by baseline hemoglobin levels; these included severe anemia (hemoglobin at <8 g/dL), moderate anemia (8-10 g/dL), and mild/no anemia (>10 g/dL).
Treatment-related outcomes evaluated also included hemoglobin response, platelet count, and hemoglobin levels through the end of the study. The objective of the study was to assess hemoglobin response in patients with myelofibrosis, which included patients with anemia who received pacritinib in the real-world setting.
What Are the Baseline Patient Characteristics?
Among the patients included in the real-world study (n = 49), the median age was 76 years (IQR, 67.0-82.0), and the majority of patients were male (55.1%) and White (59.1%). The median platelet count at index was 72.0 x 109/L (IQR, 32.0-159.0), and the median hemoglobin levels at index were 7.5 g/dL (IQR, 6.9-8.5). Anemia at index was severe in 61.2% of patients, moderate in 22.4%, and mild/no anemia in 16.3%. The median follow-up from index was a median of 10.0 months (IQR, 5.0-15.0).
What Were Hemoglobin and Platelet Responses Like With Pacritinib?
From index through day 90, hemoglobin levels increased with a 17% median change and remained stable through day 180. In the overall population, the median hemoglobin levels were 7.5 g/dL (IQR, 6.9-8.5) at index, 8.8 g/dL (IQR, 7.6-10.4) at day 90, and 8.8 g/dL (IQR, 7.4-10.3).
Regarding platelet responses with pacritinib, overall platelet counts remained stable through day 180. Of note, improvements in platelet count at day 90 were reported in patients with moderate and mild/no anemia, and remained stable in patients with severe anemia up to day 180. In the overall population, the median platelet count was 72.0 x 109/L (IQR, 32.0-159.0) at index, 82.0 x 109/L (IQR, 27.5-218.0) at day 90, and 64.5 x 109/L (IQR, 33.8-139.5) at day 180.
References
- Rampal RK, Marrone M, Morere L, et al. Hematologic response in patients with myelofibrosis treated with pacritinib in real-world clinical settings. Clin Lymphoma Myeloma Leuk. 2025; 25 (suppl 1): S686. doi:10.1016/S2152-2650(25)02157-3
- Oh ST, Mesa RA, Harrison CN, et al. Pacritinib is a potent ACVR1 inhibitor with significant anemia benefit in patients with myelofibrosis. Blood Adv. 2023;7(19):5835-5842. doi:10.1182/bloodadvances.2023010151