Efficacy, safety, and survival findings after long-term follow-up of ZGJAK002: A phase 2 study comparing jaktinib at 100 mg twice daily (BID) and 200 mg once daily (QD) in patients with myelofibrosis

Jaktinib, a novel JAK and ACVR1 inhibitor, has exhibited promising results in treating patients with myelofibrosis (MF). ZGJAK002 is a Phase 2 trial aimed to assess the efficacy and safety of jaktinib 100 mg BID (N = 66) and 200 mg QD (N = 52) in JAK inhibitor-naive patients with intermediate- or high-risk MF. We herein present the long-term data with a median follow-up of 30.7 months. At data cutoff, 30.3% of patients in 100 mg BID and 28.8% in 200 mg QD were still continuing their treatment. The 100 mg BID group displayed a numerically higher best spleen response compared with the 200 mg QD group (69.7% vs. 46.2%), with 50.4% from the BID and 51.2% from the QD group maintaining spleen responses over 120 weeks. The 36-month survival rates were 78.2% in BID and 73.6% in QD group. The tolerability of jaktinib remained well, and common grade ≥3 adverse drug reactions included anemia (15.2% vs. 21.2%), thrombocytopenia (15.2% vs. 11.5%), and infectious pneumonia (10.6% vs. 1.9%) in BID and QD groups, respectively. By comparing the two groups, the incidence of adverse events (AEs) were similar, except for drug-related serious AEs (24.2% vs. 9.6%) and AEs leading to treatment discontinuation (15.2% vs. 7.7%), which were higher in BID group. The percentages of AEs resulting in death were comparable, with 6.1% in BID and 5.8% in QD group. These analyses further support the long-term durable efficacy and acceptable safety of jaktinib at 100 mg BID and 200 mg QD doses for treating MF.