The JAK2 inhibitor rovadicitinib proved more effective than hydroxyurea in patients with JAK inhibitor-naïve, intermediate-2 or high-risk myelofibrosis in a phase 2 trial presented at the ESMO Congress 2024.
These results “support the use of rovadicitinib as a new treatment option” for these patients, said study presenter Ling Pan, of West China Hospital, Sichuan University, in Chengdu, China.
The trial (NCT05020652) enrolled 105 patients with intermediate-2 or high-risk primary, post-polycythemia vera, or post-essential thrombocythemia myelofibrosis. All patients had received no prior JAK inhibitor treatment and had palpable splenomegaly.
Patients were randomly assigned 2:1 to receive rovadicitinib at 15 mg twice daily plus placebo (n=72) or hydroxyurea at 0.5 g twice daily plus placebo (n=35). Baseline characteristics were well balanced between the arms.
Treatment continued for 24 weeks, at which point patients who achieved a spleen volume reduction of 35% or greater (SVR35) maintained treatment as assigned. Those who had not achieved SVR35 by week 24 received open-label rovadicitinib at 15 mg twice daily until treatment termination criteria were met.
At week 24, the SVR35 rate was 58.33% in the rovadicitinib arm and 22.86% in the hydroxyurea arm (P =.0006). The best spleen response rate during the study period was 63.89% with rovadicitinib and 31.43% with hydroxyurea (P =.0017).
The proportion of patients who achieved a 50% or greater reduction in total symptom score at week 24 was 61.11% with rovadicitinib and 45.71% with hydroxyurea (P =.136). The best symptom response rate during the study period was 77.78% with rovadicitinib and 54.29% with hydroxyurea (P =.0136).
Eighteen patients who initially received hydroxyurea but switched to rovadicitinib after week 24 were included in the safety analysis, so 90 patients were evaluable in the rovadicitinib arm and 35 patients were evaluable in the hydroxyurea arm.
The rate of treatment-emergent adverse events (TEAEs) was 97.78% in the rovadicitinib arm and 100% in the hydroxyurea arm. The rate of grade 3 or higher TEAEs was 51.11% and 77.14%, respectively. The rate of serious TEAEs was 31.11% and 40.00%, respectively.
The most common grade 3 or higher hematologic TEAEs (in the rovadicitinib and hydroxyurea arms, respectively) were platelet count decrease (20.00% and 17.14%) and anemia (28.89% and 60.00%). The most common grade 3 or higher non-hematologic TEAE was hyperkalemia (6.67%) in the rovadicitinib arm and weight gain (2.86%) in the hydroxyurea arm.