A new open-label, phase 2 clinical trial (NCT05980806) will investigate the use of selinexor (Xpovio®), a selective inhibitor of nuclear export, in patients with myelofibrosis (MF) and moderate thrombocytopenia.

During the study, participants will receive a weekly oral dose of either 40 mg or 60 mg of selinexor depending on which arm of the study they are included in. The primary outcome of the study will be to investigate the percentage of patients who achieve a spleen volume reduction of greater than or equal to 35% based on MRI or CT scans from baseline and week 24.

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The number of serious adverse events, treatment-related adverse events, and treatment-emergent adverse events (TEAEs) along with the severity of the TEAEs will also be recorded during the study.

A number of other secondary outcomes including the proportion of patients with a total symptom score reduction of 50% or more at week 24, proportion of patients with an anemia response at week 24, the overall survival at the end of the study, and the overall response rate.

The pharmacokinetics of selinexor will also be investigated through the area under the concentration-time curve, the maximum plasma concentration (Cmax), and the time to achieve Cmax. Other secondary outcomes include the duration of mRNA induction of the receptor occupancy or exportin1 (XPO1) protein and the proportion of patients who have at least a Grade 1 decrease in fibrosis of the bone marrow from baseline until the end of the study.

The study will look to enroll an estimated 118 adult patients with MF, post essential thrombocythemia MF, or post polycythemia vera MF starting in March 2024. Patients will also need to be naïve to treatment with janus kinase (JAK)-inhibitors and have a spleen volume of greater than or equal to 450 cm3.

Selinexor is currently US Food and Drug Administration-approved for the treatment of diffuse large B-cell lymphoma and multiple myeloma in combination with dexamethasone or dexamethasone with bortezomab. It selectively inhibits the XPO1 protein which normally carries cargos out of the cell nucleus. Once exposed to selinexor, the cargos accumulate in the cell nucleus and lead to cell cycle arrest and apoptosis.


A study of selinexor monotherapy in subjects With JAK inhibitor (JAKi)-naïve myelofibrosis and moderate thrombocytopenia. ClinicalTrials.gov. Updated August 8, 2023. Accessed August 18, 2023.

Mechanism of action. Xpoviopro.com. Accessed August 18, 2023.