A Phase 2 interventional study of Pacritinib and Placebo in VEXAS and VEXAS Syndrome, sponsored by Swedish Orphan Biovitrum. Recruiting at 39 sites in 8 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-10-16.
Sponsored by Swedish Orphan Biovitrum · Phase 2, Interventional, and Treatment
This trial is to assess the effectiveness and safety of pacritinib in patients with VEXAS (i.e., Vacuoles in myeloid progenitors, E1 ubiquitin-activating enzyme, X-linked, autoinflammatory manifestations, and somatic) syndrome. In phase 2a, approximately 78 participants will be randomized to either pacritinib dose A, pacritinib dose B + placebo, or placebo. In Phase 2b, approximately 78 participants will be randomized. Phase 2b participants will initially be randomized to either pacritinib dose A, pacritinib dose B + placebo, or placebo. After dose selection, Phase 2b further participants will be randomized to either the selected pacritinib dose or placebo.
Randomization will be stratified by prescribed GC dose on the day of randomization.
This trial is a randomized, multicenter, double-blind, placebo-controlled phase 2a and 2b trial designed to evaluate the efficacy and safety of pacritinib for the prevention of VEXAS flares after glucocorticoid (GC) taper. The trial will enroll participants ≥18 years with inflammatory VEXAS syndrome receiving ongoing GC therapy for ≥4 consecutive weeks, requiring between 15 and 45 mg daily (of prednisone / prednisolone or equivalent) at the time of enrollment (randomization).
In phase 2a, participants will be randomized 1:1:1 to receive pacritinib dose A (n=26), pacritinib dose B plus placebo (n=26), or placebo (n=26) for up to 24 weeks during a double-blind treatment period, followed by treatment with pacritinib during an open-label treatment period for up to 48 weeks.
In Phase 2b, approximately 78 participants will be randomized (enrollment starts after completion of Phase 2a enrollment). Randomization will initially be conducted in a 1:1:1 ratio to receive pacritinib dose A, pacritinib dose B plus placebo, or placebo, consistent with Phase 2a. Following Phase 2a results, a single pacritinib dose will be selected for continued evaluation. After dose selection, Phase 2b further participants will be randomized in a 2:1 ratio of the selected pacritinib dose to placebo until the total target of 78 participants are randomized.
Randomization will be stratified by prescribed GC dose on the day of randomization. All outcomes will be reported by treatment arm, and comparisons between each pacritinib arm and placebo (Phase 2a) or between the selected pacritinib dose and placebo (Phase 2b) will be performed in the double-blind treatment periods.
Participants who complete the double-blind treatment period at EOW 24 or meet Early Failure criteria at EOW 12 will transition to an open-label pacritinib treatment period through EOW 48. In addition, if a trial arm closes (due to interim futility or safety in Phase 2a or due to dose selection in Phase 2b), all participants currently randomized to the terminated arm will transition to open-label treatment.
Participants who complete the open-label treatment period at End of Week (EOW) 48 and who are benefitting from pacritinib in the opinion of the Investigator may continue to receive treatment for an additional 2 years on the extension period. Participants who discontinue study treatment will have a 30-day post-End of Treatment (EOT) follow-up period.
The trial (including the double-blind and open-label treatment periods, as well as the extension period) is planned to end approximately 3 years from the first dose of the last participant.
1,444 studies on the registry are indexed under Hematologic Neoplasms; 420 are open to participants now.
This study's planned enrollment of 156 is above the median of 46 across 1,044 interventional studies indexed under Hematologic Neoplasms.
Browse Hematologic Neoplasms studies →Swedish Orphan Biovitrum is the lead sponsor of 82 studies on the registry; 6 are open to participants now.
Of its 17 completed or terminated interventional studies of FDA-regulated products, 15 (88%) have results posted.
Counted across the registry records on this site, refreshed daily.
Key Inclusion Criteria:
Adequate organ function, meeting all the following criteria within 30 days prior to enrollment:
Key Exclusion Criteria
History of cardiovascular disease, or clinically significant abnormalities in rhythm or conduction during Screening , including:
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.
A 0–100 scale of how well someone can carry out everyday activities. 100 is no complaints and no signs of illness; 70 is able to look after yourself but not to work or keep up normal activity; 50 is needing considerable help and frequent medical care.
Studies often ask for 60 or 70 and above. Your doctor gives the score.
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
How quickly the kidneys clear creatinine, a waste product, from the blood. A study may estimate it from a blood test with age, weight and sex (often by the Cockcroft–Gault formula), or measure it using blood and urine collected over a set time. Given in mL/min; higher is better.
The number of neutrophils, white blood cells that help fight infection, in a given amount of blood. Too few raises the risk of infection.
It is a count, not a percentage of the white cells. Limits are written in units that mean the same: ≥ 1.5 × 10⁹/L is ≥ 1,500 per mm³ (µL). Each lab has its own reference range.
Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.
Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.
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.
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
The US National Cancer Institute’s scale of how severe an adverse event is — any unwanted medical event during a study, such as a symptom, an illness or an abnormal test result, whether or not a treatment caused it. Whether it did is judged separately.
“Side effects of earlier treatment resolved to grade 1 or less” means they have settled to mild or gone.
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.
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
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.
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.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Karnofsky performance status (KPS)
A 0–100 scale of how well someone can carry out everyday activities. 100 is no complaints and no signs of illness; 70 is able to look after yourself but not to work or keep up normal activity; 50 is needing considerable help and frequent medical care.
Studies often ask for 60 or 70 and above. Your doctor gives the score.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Bilirubin
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Creatinine clearance (CrCl)
How quickly the kidneys clear creatinine, a waste product, from the blood. A study may estimate it from a blood test with age, weight and sex (often by the Cockcroft–Gault formula), or measure it using blood and urine collected over a set time. Given in mL/min; higher is better.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Absolute neutrophil count (ANC)
The number of neutrophils, white blood cells that help fight infection, in a given amount of blood. Too few raises the risk of infection.
It is a count, not a percentage of the white cells. Limits are written in units that mean the same: ≥ 1.5 × 10⁹/L is ≥ 1,500 per mm³ (µL). Each lab has its own reference range.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
INR, PT and aPTT (clotting tests)
Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.
Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Platelets
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
QT and QTc
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
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.
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.
CYP3A (CYP3A4) inhibitors and inducers
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
CTCAE grade
The US National Cancer Institute’s scale of how severe an adverse event is — any unwanted medical event during a study, such as a symptom, an illness or an abnormal test result, whether or not a treatment caused it. Whether it did is judged separately.
“Side effects of earlier treatment resolved to grade 1 or less” means they have settled to mild or gone.
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.
ECG (electrocardiogram)
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
TIA (transient ischaemic attack)
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
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.
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.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
To receive oral administration of pacritinib dose A for up to 24 weeks.
Drug: Pacritinib
To receive oral administration of pacritinib dose B plus placebo for up to 24 weeks
Drug: Pacritinib · Drug: Placebo
To receive oral administration of placebo for up to 24 weeks.
Drug: Placebo
Supplied in hard capsules.
Supplied in hard capsules.
Overall Response Rate (ORR), defined as achieving Partial Clinical Response or better at any time during the double-blind treatment period.
Difference in the proportion of participants achieving ORR for the pairwise comparison of pacritinib dose A vs. placebo and pacritinib dose B plus placebo vs. placebo (Phase 2a) and selected pacritinib dose compared to placebo (Phase 2b)
Time frame: up to End of Week 24
Overall Clinical Response (OCR), defined as achieving Clinical Response or better at any time during the double-blind treatment period
Difference in the proportion of participants achieving OCR for the pairwise comparison of pacritinib dose A vs. placebo and pacritinib dose B plus placebo vs. placebo (Phase 2a) and selected pacritinib dose compared to placebo (Phase 2b)
Time frame: up to End of Week 24
Number of flare-free days with GC dose ≤10 mg
Time frame: up to End of Week 24
Proportion of participants on each arm achieving each Best Response category (Clinical Biochemical Response, Clinical Response, Partial Clinical Response, Stable Disease, or Non-response).
Time frame: up to End of Week 24
Hematologic Improvement - Erythroid
Erythroid (HI-E) at any time among participants with baseline hemoglobin \<10 g/dL per modified International Working Group (IWG) criteria
Time frame: up to End of Week 24
Hematologic Improvement - Platelets
Platelets (HI-P) at any time among participants with baseline platelet count \<100 × 10\^9/L per modified IWG criteria
Time frame: up to End of Week 24
Change in health-related quality of life (QOL) as measured by Patient-Reported Outcomes Measurement Information Systems (PROMIS) fatigue short form
The PROMIS short form domains of fatigue 4a will be summarized, raw score from 4 to 20 (T-score from 33.7 to 75.8). A higher score is associated with more fatigue.
Time frame: up to End of Week 24
Change in health-related QOL as measured by PROMIS physical function short form
The PROMIS short form domains of physical function 4a will be summarized, raw score from 4 to 20 (T-score from 22.5 to 57.0). A higher score is associated with better physical function.
Time frame: up to End of Week 24
Change in health-related QOL as measured by PROMIS sleep disturbance short form
The PROMIS short form domains of sleep disturbance 4a will be summarized, raw score from 4 to 20 (T-score from 32.0 to 73.3). A higher score is associated with more sleep disturbance.
Time frame: up to End of Week 24
Change in health-related QOL as measured by the 36-item short form (SF) Survey
The SF-36 Survey measures eight domains of health status; physical functioning, role limitations due to physical health, role limitations due to emotional problems, energy/fatigue, emotional well-being, social functioning, pain, and general health. The values for each domain range from 0 to 100, with the higher score indicating a better health status.
Time frame: up to End of Week 24
Change in health-related QOL as measured by Patient's Global Impression of Change (PGIC) response
The number and percentage of participants achieving PGIC response (reporting symptoms as "much" or "very much" improved).
Time frame: up to End of Week 24
Mean plasma concentration of pacritinib
Mean plasma concentrations (pre-dose and post-dose) will be determined for each pharmacokinetic sampling timepoint.
Time frame: up to Week 24 (pre-dose only)
Change in pharmacodynamic (PD) inflammatory biomarker: C-reactive protein (CRP)
Time frame: up to 30-day Post-End of Trial
Change in PD inflammatory biomarker: erythrocyte sedimentation rate (ESR)
Time frame: up to 30-day Post-End of Trial
Change in PD inflammatory biomarker: ferritin
Time frame: up to 30-day Post-End of Trial
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Plan to share: Yes — Qualified researchers may request access to patient level data and related trial documents. Patient level data will be anonymized and trial documents, if applicable will be redacted to protect the privacy of trial participants.
Data sharing details ↗ · www.sobi.com
Started May 2025 (actual). Primary completion is estimated for Dec 2026, 19 months after the start.
Of 136 phase 2 interventional studies under Hematologic Neoplasms, half reached primary completion within 57 months of starting (the median), counting those still running; a quarter within 40 and three quarters within 94. This study's planned 19 months is below that.
How these figures are worked out, and which studies are left out of them.
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 ↗
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
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Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Studies of the drug tested here: Pacritinib