Anemia Associated With Reduced Ruxolitinib Dosing and Poor Survival in MF
Key Takeaways:
- Lower doses of ruxolitinib: Among patients with myelofibrosis (MF), those with anemia were more likely to receive suboptimal doses of ruxolitinib compared to those without anemia, a strategy associated with reduced clinical benefit.
- More dose reductions and shorter treatment durations: Along with less time between treatment initiation and dose reduction, patients with anemia had significantly shorter treatment durations compared to those without, 16.7 months and 24.8 months, respectively.
- Worse survival outcomes: Rates of overall survival (OS) were lower among patients with baseline anemia, new or worsening anemia, and those who received less than 20 mg daily of ruxolitinib.
Anemia is a prevalent comorbidity among patients with MF and is present at diagnosis for approximately 40% of patients. The presence of anemia is associated with worse survival outcomes, likely because affected patients receive lower doses of ruxolitinib, which may negatively impact the therapy’s effectiveness.
Building on the limited research on the effect of ruxolitinib dosing strategies and anemia on survival outcomes, researchers evaluated real-world treatment patterns and outcomes among patients with MF with and without anemia who were treated with ruxolitinib.
Study Methods and Outcomes
The study assessed data from the US Flatiron Health electronic health record–derived deidentified database and identified adults with MF who initiated ruxolitinib between April 2013 and March 2023.
Outcomes included ruxolitinib dosing patterns, OS, and times between treatment initiation and dose reduction or discontinuation.
Patient Characteristics
The study included 383 patients with MF, 175 (46%) with anemia and 208 (54%) without anemia at baseline.
Patients with baseline anemia had higher rates of comorbidities than those without, 95% and 66%, respectively. The most common comorbidities were cardiovascular disease and hypertension.
Dosing Patterns
Starting doses of ruxolitinib were lower among patients with baseline anemia. Patients with anemia were more likely to initiate treatment at 5 mg twice daily than patients without anemia, 31% and 15%, respectively. In addition, fewer patients in this cohort began treatment at the recommended 20 mg twice daily compared to those without anemia, 25% and 33%, respectively.
Between the cohorts, 134 patients with anemia and 163 patients without anemia received ruxolitinib for 3 months or longer. During this period, 25% of patients with anemia and 16% of those without received ruxolitinib doses less than 20 mg daily.
Patients with anemia were more likely to experience dose escalations, which may be due to lower initial doses. While rates of dose reductions were comparable between cohorts, more patients with anemia experienced both reductions and escalations compared to those without anemia, 10% and 2%, respectively. This suggests that patients with anemia were more likely to have dose reductions shortly after an escalation.
Among patients treated with ruxolitinib for at least 3 months, 109 with anemia and 141 without anemia received treatment for 6 months or longer. During this period, 20% of patients with anemia and 13% of those without received ruxolitinib doses less than 20 mg daily.
The cohorts had similar rates of dose escalation. In contrast, the cohort with anemia had significantly higher rates of dose reductions compared to the cohort without anemia, 50% and 35%, respectively. Again, patients with anemia were more likely than those without to experience both reductions and escalations, 19% and 8%, respectively.
Time to Dose Reduction and Treatment Discontinuation
Patients with anemia had significantly shorter times between treatment initiation and dose reduction than those without, 5.6 months and 12.8 months, respectively.
Patients with anemia had shorter treatment durations as well, with a median duration of 16.7 months compared to that of 24.8 months in patients without anemia.
Anemia Associated With Lower OS
Patients with anemia had a significantly shorter median OS compared to those without anemia, 37.4 months and 64.9 months, respectively.
Lower doses of ruxolitinib were associated with worse OS. Among those who received ruxolitinib for 3 months, those who received less than 20 mg daily had a significantly shorter median OS than those who received 20 mg or more daily, 40.1 months and 53.1 months, respectively.
A total of 132 patients experienced new or worsening anemia during the study. This subgroup was associated with significantly shorter OS compared to patients with no new or worsening anemia, regardless of presence at baseline.
Implications for Managed Care
According to the authors, “Taken together, these findings highlight the substantial burden of anemia in JAK inhibitor-naive patients with myelofibrosis and the challenges associated with ruxolitinib treatment in these patients.”
Patients with anemia were more likely to receive lower doses of ruxolitinib. Since lower doses are associated with worse OS, alternatives targeted toward this population may be needed, such as utilizing full doses of other Janus kinase (JAK) inhibitors.
Since new or worsening anemia was also associated with worse OS, treatment decisions focused on preventing disease progression may be beneficial.
Reference
Kuykendall AT, Palandri F, Fillbrunn M, et al. Ruxolitinib treatment for myelofibrosis with anemia: a retrospective assessment of real-world patient characteristics, treatment patterns, and survival. Leukemia Lymphoma. 2026;67(5):1088-1099. doi:10.1080/10428194.2026.2628361
