Inclusion Criteria:

• - Voluntarily participate in the study and signed informed consent with good compliance; - Age: 18 or above (when signing the informed consent form); Eastern Cooperative Oncology Group (ECOG) performance status (PS) score of 0 to 2; Life expectancy ≥ 24 weeks; - Patients diagnosed with Primary myelofibrosis (PMF), post polycythemia vera myelofibrosis (post-PV-MF), or post essential thrombocythemia myelofibrosis (post-ET-MF); - Those with moderate or high risk myelofibrosis evaluated according to Dynamic International Prognostic Scoring System (DIPSS) prognostic grading criteria, or those with high risk myelofibrosis according to National Comprehensive Cancer Network (NCCN) guidelines prognostic grading criteria; - Patients with poor efficacy of JAK inhibitors (for monotherapy of TQB3909, phase Ib and phase II cohort 2); - Patients who had not received JAK inhibitor treatment (for phase II cohort 1) - Spleen enlargement; - Peripheral blood primary cells and bone marrow primary cells are ≤10%; - No growth factor, colony stimulating factor, thrombopoietin or platelet transfusion was received within 2 weeks before the examination, and the blood routine indexes met the requirements within 7 days before the first administration.

• - The Main organ function is normal; - Men and women of childbearing age should agree to use contraceptive measures during the study period and within 6 months after the end of the study.

Exclusion Criteria:

• - Patients who have previously received allogeneic stem cell transplantation, or received autologous stem cell transplantation within 3 months before the first administration, or recently planned stem cell transplantation; - Patients who have previously received BCL-2 inhibitor combined with JAK inhibitor therapy; - Patients who have previously undergone splenectomy, or received splenic radiotherapy within 6 months before the first administration; - Other malignancies within 3 years prior to first administration or currently present.

• - Patients with multiple factors affecting oral or absorption of drugs; - Major surgical treatment or significant traumatic injury within 4 weeks prior to first administration; - Presence of congenital bleeding disorder and congenital coagulopathy; - Patients who had arterial/venous thrombosis events within 6 months before the first administration.

• - Have a history of mental drug abuse, or have a mental disorder.

• - Active or uncontrolled severe infection; - Active hepatitis B virus (HBV) infection, or hepatitis C virus (HCV) infection , or active Corona Virus Disease 2019 (COVID-19) infection; - Patients with grade III or above congestive heart failure, unstable angina pectoris or myocardial infarction, or arrhythmia requiring treatment, or QT interval prolongation within 6 months before the first administration; - Unsatisfactory blood pressure control despite standard therapy; - Patients with renal failure requiring hemodialysis or peritoneal dialysis; - Patients newly diagnosed with pulmonary interstitial fibrosis or drug-related interstitial lung disease within 3 months before the first administration; - Patients with a history of immunodeficiency disease or organ transplantation; - Patients with epilepsy requiring treatment; - Patients with uncontrolled pleural effusion, pericardial effusion or ascites; - There is a history of attenuated live vaccine inoculation within 4 weeks before the first administration, or attenuated live vaccine inoculation was planned during the study period.

• - People with known hypersensitivity to the study drug and excipients; - Patients diagnosed as active autoimmune diseases within 2 years before the first administration; - Those who participated in and used other anti-tumor clinical trial drugs within 4 weeks before the first administration.

• - Any MF treatment drugs, any immunomodulators, or any immunosuppressants were used within 2 weeks prior to the first dose.

• - According to the judgment of the investigators, some situations seriously endanger the safety of the subjects or affect the subjects to complete the study.

Arms

Interventions