Pacritinib and Momelotinib Display Positive Real-World Impact on Anemia and Transfusion Needs in Myelofibrosis

Jeremy DiGennaro, MD

Although long-term follow-up was limited, treatment with the JAK2 inhibitors pacritinib (Vonjo) and/or momelotinib (Ojjaara) led to favorable effects on anemia and transfusion requirements among patients with myelofibrosis, according to findings from a real-world study presented in a poster during the 2024 ASH Annual Meeting.¹

Patients who received momelotinib (n = 32) had a median hemoglobin count of 8.7 g/dL (range, 6.5-1.2) at the start of therapy which increased to 9.0 g/dL after 3 months of treatment (P = .021). The median platelet count at the start of therapy was 141 x 10⁹/L (range 15 x 10⁹-504 x 10⁹) and increased to 116 x 10⁹/L after 3 months (P = .317). Patients required a mean of 1.9 red blood cell (RBC) units/month at the start of therapy and 0.47 units/month after 3 months of treatment (P = .015).

Patients treated with pacritinib (n = 27) had a median hemoglobin count of 8.5 g/dL (range, 6.9-12.9) at the start of treatment and a median count of 9.1 g/dL following 3 months of therapy (P = .402). The median platelet count at the start of therapy was 65 x 10⁹/L(range, 18 x 10⁹-441 x 10⁹) compared with 31 x 10⁹/L after 3 months of treatment (P = .303). Patients required a mean of 2.4 RBC units/month at the start of therapy vs 0.75 RBC units/month after 3 months of therapy (P = .099).

“The goal of this project was to [examine] the patients who have been treated so far at Moffitt Cancer Center with either pacritinib and/or momelotinib to gain a better understanding of the hematologic responses of these therapies, the duration of treatment, and other real-world data regarding these agents after they got their approvals,” Jeremy DiGennaro, MD, said during the presentation. “Patients receiving momelotinib and pacritinib are typically older with extended disease duration, multiple prior lines of therapy, high-risk mutations, and cytopenia. Pacritinib-treated patients have more prominent baseline thrombocytopenia. [However], there were favorable impacts on anemia and transfusion requirements [with both agents], although we still do need more long-term follow-up.”

DiGennaro is an internal medicine resident physician at the University of South Florida Morsani College of Medicine in Tampa.

In February 2022, the FDA granted accelerated approval to pacritinibfor the treatment of adult patients with intermediate or high-risk primary or secondary myelofibrosis with a platelet count below 50,000/µL.² Momelotinib was approved by the FDA in September 2023 for the treatment of adult patients with intermediate or high-risk myelofibrosis, including primary myelofibrosis or secondary myelofibrosis, and anemia.³

To conduct their real-world study, investigators analyzed data from the first 50 patients treated at Moffitt Cancer Center with pacritinib or momelotinib.¹ Study authors collected treatment history, demographic, hematologic, and genetic data. Hematologic values and transfusion requirements were assessed every 3 months. The objective of the study was to gain a better understanding of the hematologic responses, duration of therapy, and other real-world data with pacritinib or momelotinib following their FDA approvals.

The median age in the momelotinib group was 75.5 years, the median disease duration was 6.5 years, and the median number of prior lines of therapy was 2. Most patients (75%) had splenomegaly at the start of therapy and 47% had high-risk mutations. The median duration of treatment was 8.2 months and 22% of patients had RBC transfusion dependence at the start of therapy. Seven patients discontinued therapy due to non-hematologic/gastrointestinal (GI) toxicity and 3 discontinued treatment due to thrombocytopenia.

In the pacritinib group, the median age was 77 years, the median disease duration was 3.7 years, and the median number of prior lines of therapy was 2.5. Most patients had high-risk mutations (52%) and splenomegaly at the start of therapy (78%). Thirty percent of patients were RBC transfusion dependent at the start of therapy and the median duration of treatment was 3.3 months. Seven patients discontinued treatment due to GI toxicity and another 6 did so due to death.

Additional data from the real-world study demonstrated that the 6-month overall survival (OS) rates among patients who received momelotinib and pacritinib were 96% and 73%, respectively. The 9-month OS rates were 96% and 64%, respectively (P = .037).

Patients who were transitioning off ruxolitinib (Jakafi) in the momelotinib arm experienced a median change in hemoglobin of 1.42 g/dL at 3 months compared with 0.42 g/dL among patients who did not receive ruxolitinib within 2 months of receiving momelotinib (P = .177). In the pacritinib group, patients who were transitioning off ruxolitinib experienced a median change in hemoglobin of 0.3 g/dL at 3 months compared with –0.4 g/dL among those who did not receive recent ruxolitinib treatment (P = .095).

The median change in platelet count was 33 x 10⁹/L among patients who were transitioning off ruxolitinib in the momelotinib group compared with 10 x 10⁹/L among patients who did not recently receive ruxolitinib (P = .223). In the pacritinib group, the median change in platelet count was –40 x 10⁹/L among patients transitioning off ruxolitinib compared with 5 x 10⁹/L among those who did not receive recent treatment with ruxolitinib (P = .188).

“Future considerations for this [research] are to create a multicenter project with longer follow-up,” DiGennaro said in conclusion.

References

1. DiGennaro JV, Concepcion G, Al Ali NH, et al. Post-approval utilization of pacritinib and momelotinib in patients with myelofibrosis and analysis of early treatment outcomes. Blood. 2024;144(suppl 1):4561. doi:10.1182/blood-2024-202579
2. FDA approves drug for adults with rare form of bone marrow disorder. FDA. Updated March 1, 2022. Accessed December 9, 2024. https://www.fda.gov/drugs/news-events-human-drugs/fda-approves-drug-adults-rare-form-bone-marrow-disorder
3. Ojjaara (momelotinib) approved in the US as the first and only treatment indicated for myelofibrosis patients with anaemia. News release. GlaxoSmithKline. September 15, 2023. Accessed December 9, 2024. https://www.gsk.com/en-gb/media/press-releases/ojjaara-momelotinib-approved-in-the-us-as-the-first-and-only-treatment-indicated-for-myelofibrosis-patients-with-anaemia