An observational study in Myeloproliferative Neoplasms/Myelofibrosis, sponsored by Affiliated Hospital of Nantong University. Not yet recruiting at 1 site in China. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-09.
Sponsored by Affiliated Hospital of Nantong University · Observational
This is a multicenter, prospective, real-world observational study designed to evaluate the efficacy and safety of jaktinib in patients with myelofibrosis (MF) who have failed ruxolitinib treatment (including refractory, relapsed, or intolerant cases). The primary outcome measure is the proportion of patients achieving anemia response at week 24. Secondary outcome measures include MF-related symptom response rate (≥50% reduction in total symptom score, TSS50) at week 24, spleen volume reduction ≥35% (SVR35) at week 24, progression-free survival (PFS), leukemia-free survival (LFS), overall survival (OS), and safety/tolerability. This study will provide real-world evidence to support the use of jaktinib as a valuable treatment option for MF patients with ruxolitinib failure, a population with limited therapeutic alternatives.
Myelofibrosis (MF) is a BCR::ABL1-negative myeloproliferative neoplasm (MPN) characterized by progressive splenomegaly, debilitating systemic symptoms, abnormal blood cell counts, and a risk of leukemic transformation. Patients often suffer from progressive anemia, thrombocytopenia, and systemic symptoms including fatigue, dyspnea, night sweats, weight loss, fever, and bone pain. Notably, the incidence of anemia at diagnosis in Chinese patients with primary MF (PMF) is 67%, significantly higher than that observed in Western counterparts (35%), underscoring a critical unmet need for therapies that address anemia in this population.
Mutations in JAK2, CALR, or MPL genes, found in approximately 90% of patients, lead to hyperactivation of the JAK-STAT pathway, which is pivotal in the pathogenesis of MF. JAK inhibitors have become a cornerstone of MF treatment. Ruxolitinib, a selective JAK1/JAK2 inhibitor, was the first approved JAK inhibitor and has demonstrated efficacy in reducing spleen size and improving symptoms. However, its long-term use is limited by several factors. In the Chinese population, the SVR35 rate at week 24 is only 27% (A2202 study), which is lower than the rates reported in Asian (31.7%) and Western populations (41.9% in COMFORT-I). Furthermore, treatment-related anemia and thrombocytopenia frequently necessitate dose reductions or discontinuation, with over 60% of patients requiring dose modification due to adverse events. Ultimately, a substantial proportion of patients discontinue ruxolitinib because of loss of response, lack of efficacy, or intolerance. After ruxolitinib discontinuation, the median survival is only 13 months, with worse outcomes in patients who also have anemia and thrombocytopenia. In China, treatment options for patients with ruxolitinib failure remain limited. Therefore, there is an urgent unmet clinical need for effective and well-tolerated therapies for MF patients who have failed ruxolitinib.
Jaktinib (also known as gecacitinib) is a novel inhibitor targeting both JAK and ACVR1. By inhibiting JAK1, JAK2, JAK3, and TYK2, it blocks the JAK-STAT signaling pathway, thereby alleviating inflammation and splenomegaly. Through a mechanism shared with momelotinib, jaktinib inhibits ACVR1 activity, which downregulates hepcidin expression, improves iron metabolism imbalance, and increases hemoglobin levels, thereby reducing the occurrence of anemia and transfusion dependency in patients with MF. This dual mechanism makes jaktinib particularly well-suited for MF patients who have developed anemia during or after ruxolitinib therapy.
Multiple clinical trials of jaktinib in MF have been conducted in China. The phase II study ZGJAK002 (NCT03886415) enrolled 118 patients with intermediate- or high-risk MF and demonstrated a SVR35 rate of 44.5% at week 24 (54.8% in the 100 mg twice-daily group vs. 31.3% in the 200 mg once-daily group, p = 0.0199), with TSS50 response rates of 69.6% and 57.5%, respectively, and low incidences of grade ≥3 drug-related anemia (24.0%) and thrombocytopenia (12.5%). The phase II study ZGJAK006 (NCT04217993) specifically evaluated jaktinib in patients with MF who were intolerant to ruxolitinib, demonstrating a SVR35 rate of 43.2% (95% CI 29.7%-57.8%) at week 24 with tolerable hematological toxicity. The phase II study ZGJAK017 (NCT04851535) further evaluated jaktinib in patients with MF who were resistant to ruxolitinib, and the phase III study ZGJAK016 (NCT04617028) compared jaktinib with hydroxyurea in JAK inhibitor-naïve MF patients. The 2026 Guidelines of the Chinese Society of Clinical Oncology (CSCO) have recommended jaktinib as a Category I core agent for patients with intermediate- or high-risk MF, as well as low-risk MF with symptomatic disease.
Given this robust clinical evidence, the present multicenter, prospective, real-world observational study aims to evaluate the effectiveness and safety of jaktinib in patients with MF who have failed ruxolitinib treatment (including refractory, relapsed, or intolerant cases) under routine clinical practice. As a non-interventional study, it will not influence treatment decisions but will systematically capture longitudinal data to reflect actual clinical outcomes. The primary endpoint is the proportion of patients achieving anemia response at week 24, defined as an increase in hemoglobin level or a reduction in transfusion requirement according to predefined criteria (IWG-MRT criteria). Secondary endpoints include MF-related symptom response rate (≥50% reduction in MPN-SAF TSS, TSS50) at week 24, the proportion of patients achieving ≥35% spleen volume reduction (SVR35) at week 24, progression-free survival (PFS), leukemia-free survival (LFS), overall survival (OS), and safety/tolerability assessed by adverse events, serious adverse events, laboratory abnormalities, and treatment discontinuation rates.
This study will generate essential real-world evidence on jaktinib in MF patients with ruxolitinib failure, providing clinicians with data to optimize treatment strategies and improve outcomes in this challenging patient population.
625 studies on the registry are indexed under Primary Myelofibrosis; 124 are open to participants now.
This study's planned enrollment of 80 is below the median of 125 across 73 observational studies indexed under Primary Myelofibrosis.
Browse Primary Myelofibrosis studies →Affiliated Hospital of Nantong University is the lead sponsor of 97 studies on the registry; 57 are open to participants now.
Compared within Primary Myelofibrosis, this study's primary condition as ClinicalTrials.gg classifies it; the registry's first condition term is Myeloproliferative Disorders. The counts are of registry records indexed under each term, refreshed daily. How we classify →
Myelofibrosis patients receiving jaktinib treatment
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Patients must belong to one of the following three cohorts:
MF is defined as a condition where, after being treated with ruxolitinib for ≥3 months, the spleen volume was reduced by \<10% as assessed by the magnetic resonance imaging (MRI)/computed tomography (CT), or \< 30% in spleen size by palpation compared with the baseline mea- surement.
Relapsed MF is defined as a situation where after receiving ruxolitinib treatment for ≥3 months, there is a spleen regrowth (SVR \<10% by MRI/CT, or \<30% in spleen size by palpation from the base- line measurement), following an initial spleen response.
Ruxolitinib intolerant is defined as patients who have received or are receiving ruxolitinib treatment for no less than 28 days and have at least one of the following conditions during its treatment: RBC transfusions still required or increased in frequency; grade 3 or higher anemia, thrombocytopenia, and hematoma and/or hemorrhage occurred.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
A line of therapy is one course of treatment, which may combine several drugs. First-line is the first course given; second-line follows when that stops working or is not tolerated.
“Two prior lines” means two courses that count separately under the study’s rules — not simply two drugs. Ask the study team if you are unsure how yours are counted.
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.
A score of how well the liver works in people with liver disease such as cirrhosis: class A is mild, B moderate and C severe.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Relapsed and refractory
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Line of therapy
A line of therapy is one course of treatment, which may combine several drugs. First-line is the first course given; second-line follows when that stops working or is not tolerated.
“Two prior lines” means two courses that count separately under the study’s rules — not simply two drugs. Ask the study team if you are unsure how yours are counted.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECOG performance status
A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.
Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Allogeneic and autologous transplant
Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Child-Pugh class
A score of how well the liver works in people with liver disease such as cirrhosis: class A is mild, B moderate and C severe.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Jaktinib oral 50-100 mg twice daily
anemia response
Proportion of participants achieving anemia response at week 24
Time frame: 24 weeks
TSS50
Proportion of participants with a total symptom score reduction of ≥50% (TSS50) at 24 weeks
Time frame: 24 weeks
SVR35
Proportion of participants with a spleen volume reduction of ≥35% (SVR35) from baseline at week 24
Time frame: 24 weeks
Progression-free survival (PFS)
The time from the first dose to any of the following events: spleen volume increased by ≥25% from the lowest value recorded; death of any cause.
Time frame: 24 months
Leukemia-free survival (LFS)
The time from the first dose to any of the following events: bone marrow smear showed blast cells ≥20%; peripheral blood smear blast cells ≥20% and the absolute blast count ≥1×10E9/L lasts for at least 2 weeks; death of any cause.
Time frame: 24 months
Overall survival (OS)
OS was defined as the time from the first dose to death.
Time frame: 24 weeks
Safety and tolerability
The safety and tolerability were evalu- ated from the first dose of jaktinib to 28 days after the last dose. Adverse events (AEs) were graded according to the Common Toxicity Criteria for Adverse Events (CTCAE) version 5.0.
Time frame: 24 months
Plan to share: No
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From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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Affiliated Hospital of Nantong University