Sobi Receives US FDA Fast Track Designation for pacritinib in VEXAS Syndrome

WALTHAM, Mass., Sept. 09, 2026 (GLOBE NEWSWIRE) -- Sobi North America, the North American affiliate of Swedish Orphan Biovitrum AB (Sobi^®), today announced that the US Food and Drug Administration (FDA) has granted Fast Track designation to pacritinib for the treatment of VEXAS syndrome. Pacritinib is a dual IRAK1/JAK2 inhibitor currently in Phase ll development for VEXAS syndrome.

Fast Track designation is designed to facilitate the development and expedite the review of medicines to treat serious conditions that may fill an unmet medical need.

“Achieving FDA’s Fast Track designation for pacritinib is an important milestone and recognizes its potential as an investigational treatment for people living with VEXAS syndrome” said Lydia Abad-Franch, MD, Head of R&D and Medical Affairs, and Chief Medical Officer at Sobi. “There is a critical need for new treatment options for people living with this debilitating condition, who often face serious complications and limited therapeutic choices. With this designation, we look forward to working even more closely with the FDA as we accelerate the clinical evaluation of pacritinib and continue to work towards approval for patients with VEXAS syndrome.”

VEXAS syndrome (Vacuoles in blood-cell precursors, E1 enzyme, X-linked, Autoinflammatory, Somatic) is a systemic disorder characterized by an overlap of hematologic and inflammatory features. VEXAS syndrome was first described in 2020.¹ It can be progressive and debilitating, with patients experiencing involvement of multiple organ systems and potentially life-threatening complications. Treatment poses a challenge as most immunomodulators fail to control the disease, resulting in a requirement for moderate to high doses of glucocorticoids. There are currently no approved treatment options for VEXAS.

Since 2024, Sobi has been evaluating pacritinib in VEXAS with the PAXIS study, the first randomized trial for this condition. PAXIS (NCT06782373) is a Phase II, randomized, multicenter, double-blind, placebo-controlled, dose-finding trial followed by an open-label period, designed to evaluate the efficacy and safety of pacritinib in preventing disease flares in patients with VEXAS syndrome following glucocorticoid tapering. For more information about this trial, please visit the PAXIS website and clinicaltrials.gov.²

Topline data is expected in 2027.

Contacts
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About Vonjo (pacritinib)

VONJO (pacritinib) is a kinase inhibitor that is indicated in the US for the treatment of adults with intermediate or high-risk primary or secondary (post-polycythemia vera or post-essential thrombocythemia) myelofibrosis with a platelet count below 50 × 10⁹/L. This indication is approved under accelerated approval based on spleen volume reduction. Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial(s).

Indication and Important Safety Information

VONJO is a prescription medicine used to treat adults with certain types of myelofibrosis (MF) who have a platelet count below 50 x 10⁹/L.

This indication is approved under accelerated approval based on spleen volume reduction. Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial(s).

Important Safety Information
VONJO can cause serious side effects, including:

Bleeding. VONJO may cause severe bleeding, which can be serious and, in some cases, may lead to death. Avoid taking VONJO if you are bleeding. If you develop bleeding, stop VONJO and call your healthcare provider. Your healthcare provider will do a blood test to check your blood cell counts before you start VONJO and regularly during your treatment with VONJO. Tell your healthcare provider right away if you develop any of these symptoms: unusual bleeding, bruising, and fever. You will need to stop taking VONJO 7 days before any planned surgery or invasive procedure (such as a heart catheterization, stent placement in a coronary artery in your heart, or a procedure for varicose veins). Your healthcare provider should tell you when you can start taking VONJO again.

Diarrhea. Diarrhea is common with VONJO, but can also be severe, and cause loss of too much body fluid (dehydration). Tell your healthcare provider if you have diarrhea and follow instructions for what to do to help treat diarrhea. Drink plenty of fluids to help prevent dehydration. Your healthcare provider may change your dose of VONJO if you have severe diarrhea. If you notice any change in how often you have bowel movements, if they become softer or you have diarrhea, start taking an antidiarrheal medicine (for example, loperamide) as soon as you notice changes, as directed by your healthcare provider.

Worsening low platelet counts. Your healthcare provider will do blood tests to check your blood counts before you start taking VONJO and during treatment with VONJO.

Changes in the electrical activity of your heart called QTc prolongation. QTc prolongation can cause irregular heartbeats that can be life-threatening. Your healthcare provider will check the electrical activity of your heart with a test called an electrocardiogram (ECG) before you start VONJO and during treatment with VONJO, as needed. If you have a history of low blood potassium, it is important that you get your blood tests done as ordered by your healthcare provider to monitor your body salts (electrolytes) in your blood. Tell your healthcare provider right away if you feel dizzy, lightheaded, or faint.

Increased risk of major cardiovascular events such as heart attack, stroke, or death in people who have cardiovascular risk factors and who are current or past smokers have happened in some people taking another Janus associated kinase (JAK) inhibitor to treat rheumatoid arthritis. Get emergency help right away if you have any symptoms of a heart attack or stroke while taking VONJO, including: discomfort in the center of your chest that lasts for more than a few minutes, or that goes away and comes back; severe tightness, pain, pressure, or heaviness in your chest, throat, neck, or jaw; pain or discomfort in your arms, back, neck, jaw, or stomach; shortness of breath with or without chest discomfort; breaking out in a cold sweat; nausea or vomiting; feeling lightheaded; weakness in one part or on one side of your body; or slurred speech.

Increased risk of blood clots. Blood clots in the veins of your legs (deep vein thrombosis, DVT) or lungs (pulmonary embolism, PE) have happened in some people taking another JAK inhibitor and may be life-threatening. Tell your healthcare provider if you have had blood clots in the veins of your legs or lungs in the past. Tell your healthcare provider right away if you have any signs and symptoms of blood clots during treatment with VONJO, including: swelling, pain, or tenderness in one or both legs; sudden, unexplained chest pain; or shortness of breath/difficulty breathing.

Possible increased risk of new (secondary) cancers. People who take another JAK inhibitor for rheumatoid arthritis have an increased risk of new (secondary) cancers, including lymphoma and other cancers, except non-melanoma skin cancer. The risk of new cancers is further increased in people who smoke or who smoked in the past.

Risk of infection. People who have certain blood cancers and take another JAK inhibitor have an increased risk of serious infections. Infections are common with VONJO, but people who take VONJO may also develop serious infections, including bacterial, mycobacterial, fungal, and viral infections. If you have a serious infection, your healthcare provider may not start you on VONJO until your infection is gone. Your healthcare provider will monitor you and treat you for any infections that you get during treatment with VONJO. Tell your healthcare provider right away if you develop any of the following symptoms of infection: chills, aches, fever, nausea, vomiting, weakness, painful skin rash, or blisters.

The most common side effects of VONJO include: nausea, vomiting, low red blood cell count (anemia), and swelling of your ankles, legs, and feet.

VONJO may affect fertility in males. You may have problems fathering a child. Talk to your healthcare provider if this is a concern for you.

These are not all the possible side effects with VONJO. Call your doctor for medical advice about side effects.

Before taking VONJO, tell your healthcare provider if you: 

• smoke or were a smoker in the past
• have had previous medical conditions such as any other cancers, blood clot, heart attack, other heart problems, stroke, infection, diarrhea, commonly loose stools, nausea, vomiting, liver problems, or kidney problems
• have active bleeding, have had severe bleeding, or plan to have surgery. You should stop taking VONJO 7 days before any planned surgery or invasive procedures (such as a heart catheterization, stent placement in a coronary artery in your heart, or a procedure for varicose veins)
• are pregnant, plan to become pregnant, are breastfeeding, or plan to breastfeed. It is not known if VONJO will harm your unborn baby or if it passes into breast milk. You should not breastfeed during treatment and for 2 weeks after your last dose of VONJO
  

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements. Taking VONJO with certain other medicines may affect the amount of VONJO in your blood and may increase your risk of side effects or affect how well VONJO works. Know the medicines you take. Keep a list of the medicines you take to show your healthcare provider and pharmacist when you get a new medicine.

Take VONJO exactly as your healthcare provider tells you to take it. Do not change your dose or stop taking VONJO without first talking to your healthcare provider. If you take other kinase inhibitors, carefully follow your healthcare provider’s instructions about how to slowly decrease (taper) your dose and stop the other kinase inhibitor medicines before you begin taking VONJO. Take VONJO two times daily, with or without food, at about the same time of day. Swallow VONJO capsules whole—do not open, break, or chew capsules. If you take too much VONJO, call your healthcare provider or go to the nearest emergency room right away and take your bottle of VONJO with you. If you miss a dose, skip it, and take your next dose at your regular time—do not take 2 doses at the same time to make up for the missed dose. Your healthcare provider may change your dose or how often you take it, temporarily stop, or permanently stop treatment if you have certain side effects.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch or call 1-800-FDA-1088.

Please see full Prescribing Information.

Sobi^®

Sobi is a global biopharma company unlocking the potential of breakthrough innovations, transforming everyday life for people living with rare diseases. Sobi has approximately 2,000 employees across Europe, North America, the Middle East, Asia and Australia. In 2025, revenue amounted to SEK 28 billion. Sobi’s share (STO:SOBI) is listed on Nasdaq Stockholm. More about Sobi at sobi.com and LinkedIn.

References

1. Beck DB, Heiblig M, Savic S, et al. PAXIS: A Randomized, Double-Blind, Placebo-Controlled, Dose-Finding Phase 2 Study (Part 1) Followed by an Open-Label Period (Part 2) to Assess the Efficacy and Safety of Pacritinib in Patients with VEXAS Syndrome. J Clin Med. 2026;15(4):1426.
   
2. ClinicalTrials.gov. National Library of Medicine (US). Identifier NCT06782373, PAXIS: A Randomized, Double-blind, Placebo-controlled Dose-finding Phase 2 Study (Part 1) Followed by an Open-label Period (Part 2) to Assess the Efficacy and Safety of Pacritinib in Patients With VEXAS Syndrome. Available at: https://clinicaltrials.gov/study/NCT06782373.