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ZGJAK002 trial: Efficacy and safety of jaktinib in patients with MF

Mar 18, 2024
Learning objective: After reading this article, learners will be able to cite a new clinical development in myelofibrosis.

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Jaktinib, a Janus kinase, and activin A receptor type I inhibitor, is a deuterated form of momelotinib and has shown promising results for treating patients with myelofibrosis (MF), specifically in spleen volume reduction and symptom relief.

Here, we summarize a long-term follow-up of the ZGJAK002 trial (NCT03886415) published by Zhang et al.1 in American Journal of Hematology assessing the safety and efficacy of jaktinib in Chinese patients with intermediate to high-risk MF.

Study design1

  • Phase II, open-label dose comparison trial 30.7 months after trial initiation
  • Patients (N = 118) were assigned 100 mg jaktinib twice daily (BID, n = 66) or 200 mg jaktinib once daily (QD, n = 52)
  • The primary endpoint was the proportion of patients with 35% decrease in spleen volume (SVR35) at Week 24.
  • Secondary endpoints included total symptom score improvement by 50% (TSS50), improvement in anemia, and safety profile.

Key findings1

  • More patients achieved SVR35 with 100 mg BID vs 200 mg QD (Figure 1)
    • The proportion of patients achieving spleen volume reductions increased over time, indicating durable responses
  • TSS50 improvements and hemoglobin levels were sustained in both groups from Week 48 to Week 120 in long-term follow-up results (Table 1).
  • No further safety signals were identified in either cohort, common Grade 3 adverse events outlined in Table 1.

Table 1. Key long-term efficacy and safety data for jaktinib 100 mg BID and 200 mg QD regimens*


100 mg BID (n=66)

200 mg QD (n=52)

TSS50 (%)

              Week 48



              Week 120



Mean hemoglobin change (g/L)

              Week 48



              Week 120



Grade 3 AEs (%)







              Infectious pneumonia



AE, adverse event; BID, twice daily; TSS50; total symptom score improvement by 50%; QD, once daily.
*Adapted from Zhang, et al.1

  • Median overall survival was not met by either cohort, with 36-month survival rates of 78.0% vs 73.6%, respectively
    • Deaths were reported in 18.2% and 25%, respectively

Figure 1. SVR35 in patients with intermediate to high-risk MF treated with 100 mg BID or 200 mg QD jaktinib* 

BID, twice daily; MF, myelofibrosis; QD, once daily; SVR35, spleen volume reduction 35%.
*Adapted from Zhang, et al.1

Key learnings

  • Both 100 mg BID and 200 mg QD regimens of jaktinib demonstrated a sustained improvement in SVR35, anemia, and TSS50. However, a higher proportion of patients achieved SVR35 with 100 mg BID.
  • Along with sustained elevation of hemoglobin levels and consistent safety profile, this long-term data supports further evaluation of 100 mg BID over 200 mg QD in patients with intermediate to high-risk MF who require a rapid spleen response.

  1. Zhang Y, Zhou H, Jiang Z, et al. 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. Am J Hematol. Online ahead of print. DOI:10.1002/ajh.27245


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