Analysis of Predictive Factors for Early Response to Ruxolitinib in 320 Patients with Myelofibrosis From the Polish Adult Leukemia Group (PALG) Registry

INTRODUCTION

Ruxolitinib is widely used in myelofibrosis (MF). However, some patients do not optimally respond and require more efficacious treatment. Our analysis aimed to establish predictors of ruxolitinib response.

PATIENTS AND METHODS

We designed a multicenter, retrospective analysis of the efficacy of ruxolitinib treatment in patients with MF in 15 Polish hematology centers. As responses to ruxolitinib occur within the first 6 months, we used this point to evaluate the efficacy of treatment. Symptoms response was defined as ≥50% reduction of the MF constitutional symptoms assessed by Myeloproliferative Neoplasm Symptom Assessment Form Total Symptom Score (MPN-SAF TSS). Spleen response was defined as ≥50% reduction of the difference between the spleen's baseline length and the upper limit norm measured by ultrasonography.

RESULTS

320 MF patients were enrolled. At 6 months of therapy, the spleen response was detected in 140 (50%) patients, and symptoms response in 241 patients (76%). Multivariable analysis identified leukocytosis <25 G/L (OR 2.06, 95%CI: 1.12-3.88, P = .0200), and reticulin fibrosis MF 1 (OR 2.22, 95%CI: 1.11-4.46, P = .0249) contributed to better spleen response. The time interval between MF diagnosis and ruxolitinib administration shorter than 3 months, and platelets ≥150 G/L (OR 1.69, 95% CI 1.01-2.83, P = .0466) influenced symptoms response.

CONCLUSION

Establishing predictive factors for ruxolitinib response is particularly important given the potential for new therapies in MF. In patients with a low likelihood of responding to ruxolitinib, using other JAK inhibitors or adding a drug with a different mechanism of action to ruxolitinib may be of clinical benefit.

Real-life ruxolitinib experience in intermediate-risk myelofibrosis

Background

In this retrospective cohort of patients with primary, post-polycythemia vera, or post-essential thrombocythemia myelofibrosis, 57 patients with MF who received ruxolitinib for MF-related symptoms or symptomatic splenomegaly were evaluated.

Methods

The median age of the patients in this cohort was approximately 58 years. Of these, there were 33 patients (57.9%) in INT-1, 23 patients (40.4%) in INT-2, and 1 patient (1.8%) at high risk. Overall, spleen size reduction of at least 35% (spleen response) was achieved in 56.6% and 63.3% of all cohort and INT-1 risk at any time, respectively.

Results

Symptom response and clinical improvement were observed in 21.7% and 60.7% of patients, respectively. Anemia and thrombocytopenia were prevalent, but manageable. About 73.7% of patients continued treatment during a median follow-up of 22 months. Two-year OS probability was approximately 84.5% (95% CI, 63.1‒94.0%) and 62.3% (95% CI, 37.5‒79.6%) for the intermediate-1 and -2 risk groups, respectively.

Conclusion

Real-life experience in a community-based hospital confirms the efficacy and safety profile of ruxolitinib in intermediate-risk myelofibrosis. Treatment discontinuation rates were lower than those in clinical trials.