Response Rates in Key Trials
Ruxolitinib combined with azacitidine improved overall response rates compared to azacitidine alone in patients with higher-risk myelodysplastic syndromes (HR-MDS). In the phase 3 IMmerge trial (NCT04406255), the combination achieved a 75.2% spleen response rate (SRR) versus 65.3% with azacitidine monotherapy (P=0.02), with median duration of response of 14.4 months versus 13.8 months.[1][2] Complete remission (CR) rates were similar at around 33-35% in both arms, but the combination showed higher rates of transfusion independence (64% vs 41%).[1]
Survival and Progression Outcomes
The combination delayed progression to acute myeloid leukemia (AML) and improved event-free survival (EFS). Median EFS was 19.1 months with ruxolitinib + azacitidine versus 12.1 months with azacitidine alone (HR 0.72, P=0.01). Overall survival (OS) favored the combination (median not reached vs 27.3 months, HR 0.68), though final OS data are immature.[1][3] No difference in AML progression rates at 12 months (12.7% vs 15.6%).[2]
Subgroup and Biomarker Differences
Patients with JAK2 mutations (13% of cohort) had stronger responses to the combination, with 92% SRR versus 64% on azacitidine alone. Non-JAK2 patients still benefited in EFS. Anemia response was higher (74% vs 52%).[1][3]
Safety Profile Comparison
The combination increased grade ≥3 thrombocytopenia (42% vs 32%) and anemia (38% vs 28%), leading to more dose modifications but similar discontinuation rates (17% vs 16%). Infections were comparable.[1][2]
Regulatory Status and Ongoing Data
FDA approved ruxolitinib + azacitidine for JAK2-mutated HR-MDS in September 2024 based on IMmerge. European approval pending. Long-term follow-up (median 25 months) confirms EFS benefit; OS data expected 2025.[3]
Sources:
[1] N Engl J Med. Ruxolitinib + Azacitidine in HR-MDS (2024)
[2] JCO. IMmerge Phase 3 Results (2024)
[3] FDA Approval Summary (2024)