Evaluation of gecacitinib vs hydroxyurea in patients with intermediate-2 or high-risk myelofibrosis: final analysis results from a randomized phase 3 study

To compare the efficacy and safety of gecacitinib (also known as jaktinib) with hydroxyurea (HU) in treating myelofibrosis (MF) patients. In this multicenter, randomized phase 3 trial (ZGJAK016), intermediate- or high-risk primarily JAK inhibitor naïve MF patients were assigned in a 2:1 ratio to receive either gecacitinib (100 mg twice a day, BID) or HU (500 mg BID). The primary endpoint was the proportion of patients with ≥35% reduction in spleen volume (SVR35) from baseline at week 24. Secondary endpoints included the best spleen response rate, the proportion of patients with a ≥50% reduction in total symptom score (TSS50), anemia improvement, and safety profile. At 24 weeks, the SVR35 was reached by 64.8% of patients on gecacitinib (46/71), compared to 26.5% on HU (9/34), P = 0.0002. The best spleen response rates were also superior for gecacitinib at 81.7%, vs 32.4% for HU, P < 0.0001. The TSS50 rates were 62.0% for gecacitinib- and 50% for HU-treated patients. Among non-transfusion-dependent patients with baseline hemoglobin (HGB) ≤ 100 g/L, 31.0% (13/42) in the gecacitinib group showed a ≥20 g/L increase in HGB, compared to 15.0% (3/20) in HU group. The common grade ≥ 3 treatment-emergent adverse events (TEAEs), including anemia (26.8% vs 44.1%), thrombocytopenia (15.5% vs 32.4%), leukopenia (2.8% vs 20.6%), and neutropenia (1.4% vs 20.6%), were less frequent with gecacitinib than HU. Treatment discontinuation due to TEAEs was lower in gecacitinib (7.0%) compared to HU (11.8%). Gecacitinib demonstrates superior efficacy and a more favorable safety profile compared to HU, making it a promising treatment option for managing MF, particularly in patients with anemia (This trial was registered with ClinicalTrials.gov, (NCT04617028)).