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Mavorixafor

Phase 3

Neutropenia | Small molecule | Hematology |X4 Pharmaceuticals, Inc.|Last Updated: Aug 6, 2026

Success Probability

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Trial Design

RandomizedDouble-BlindPLACEBO_CONTROLLEDDMC
Total Trials2
Total Enrollment208

FDA Designations

BREAKTHROUGH_THERAPYFAST_TRACKRARE_PEDIATRIC_DISEASEPRIORITY_REVIEW

Clinical trial landscape

Mavorixafor · 6 trials · 5 indications

Phase 3 2Phase 1 4
NCT06056297A Study of Mavorixafor in Participants With Congenital and Acquired Primary Autoimmune and Idiopathic Chronic Neutropenic Disorders Who Are Experiencing Recurrent and/or Serious InfectionsNeutropenia
RECRUITING176 Analytics
NCT03995108Efficacy and Safety Study of Mavorixafor in Participants With Warts, Hypogammaglobulinemia, Infections, and Myelokathexis (WHIM) SyndromeWHIM Syndrome
COMPLETED31 Analytics
PHASE3RECRUITING
A Study of Mavorixafor in Participants With Congenital and Acquired Primary Autoimmune and Idiopathic Chronic Neutropenic Disorders Who Are Experiencing Recurrent and/or Serious Infections
Neutropenia
NCT06056297176
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PHASE3COMPLETED
Efficacy and Safety Study of Mavorixafor in Participants With Warts, Hypogammaglobulinemia, Infections, and Myelokathexis (WHIM) Syndrome
WHIM Syndrome
NCT0399510831
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Study Endpoints

Primary Endpoints

Co-primary Endpoint: Annualized Infection Rate Based on Infections Adjudicated by Blinded Infection Adjudication Committee (BIAC) During the Treatment Period
Up to 52 Weeks
Co-primary Endpoint: Number of Participants Meeting the Definition of a Positive Absolute Neutrophil Count (ANC) Response
Up to 52 weeks

Positive ANC response: Increase of ANC \>500 cells/microliter (µL) from baseline.

Randomized Placebo-Controlled Period: Time (in Hours) Above Threshold-Absolute Neutrophil Count (TAT-ANC in hours) of ≥ 500 Cells/Microliter (µL) over a 24-hour period
Time 0 (pre-dose, up to 15 minutes prior), 30, 60, and 90 min (each ± 5 min) and 2, 3, 4, 8, 12, 16, and 24 hours (each ± 15 min) post-dose at Baseline, Weeks 13, 26, 39, and 52
Open-Label Period: Percentage of Participants With Adverse Events (AEs)
From Day 1 (end of randomized period) up to end of study (30 days post-treatment in open-label period [Week 56 of open-label period])
Maximum Observed Plasma Concentration (Cmax) of Mavorixafor
Predose up to 192 hours postdose (Day 1 up to Day 9)
Area Under the Serum Concentration Curve From Time Zero to the Last Measurable Concentration (AUC0-last) of Mavorixafor
Predose up to 192 hours postdose (Day 1 up to Day 9)
Cohort 1: Maximum Observed Plasma Concentration (Cmax) of Mavorixafor Without (Day 1) and With (Day 18) Coadministration With Carbamazepine
Predose up to 120 hours postdose on Days 1 and 18
Cohort 1: Area Under the Concentration-time Curve From Time Zero to the Last Quantifiable Concentration (AUC0-last) of Mavorixafor Without (Day 1) and With (Day 18) Coadministration With Carbamazepine
Predose up to 120 hours postdose on Days 1 and 18
Cohort 2: Cmax of Mavorixafor Without (Day 1) and With (Day 18) Coadministration With Efavirenz
Predose up to 120 hours postdose on Days 1 and 18
Cohort 2: AUC0-last of Mavorixafor Without (Day 1) and With (Day 18) Coadministration With Efavirenz
Predose up to 120 hours postdose on Days 1 and 18
Number of Participants With Treatment-Emergent Adverse Events (TEAEs) After a Single Dose of Mavorixafor
Baseline through Day 1 and 7 days follow-up
Number of Participants With Treatment-Emergent Adverse Events (TEAEs) After Multiple Doses of Mavorixafor
Baseline through Month 6 and 30 days follow-up
Change From Baseline in Absolute Neutrophil Count (ANC) to 8 hours Post-dose On Day 1
Baseline, 8 hours Post-dose On Day 1
Change From Baseline in ANC to Month 6
Baseline, Month 6
Number of Participants With DLTs
Cycle 1 (28 days)
Percent Change From Baseline in Immunoglobulin M (IgM) at Cycle 1
Baseline, at the end of Cycle 1 (cycle length = 28 days)
Percent Change From Baseline in IgM at Cycle 2
Baseline, at the end of Cycle 2 (cycle length = 28 days)
Percent Change From Baseline in IgM at Cycle 3
Baseline, at the end of Cycle 3 (cycle length = 28 days)
Percent Change From Baseline in Hemoglobin (Hgb) at Cycle 1
Baseline, at the end of Cycle 1 (cycle length = 28 days)
Percent Change From Baseline in Hgb at Cycle 2
Baseline, at the end of Cycle 2 (cycle length = 28 days)
Percent Change From Baseline in Hgb at Cycle 3
Baseline, at the end of Cycle 3 (cycle length = 28 days)
Cmax of Ibrutinib
Pre-dose, 0.5, 1, 2, 4, 6, and 8 to 10 hours post-dose on Day 1 and Day 21 of Cycle 1, 2, and 3 (each cycle length = 28 days)
Time to Reach Cmax (Tmax) of Mavorixafor
Pre-dose, 0.5, 1, 2, 4, 6, and 8 to 10 hours post-dose on Day 1 and Day 21 of Cycle 1, 2, and 3 (each cycle length = 28 days)
Tmax of Ibrutinib
Pre-dose, 0.5, 1, 2, 4, 6, and 8 to 10 hours post-dose on Day 1 and Day 21 of Cycle 1, 2, and 3 (each cycle length = 28 days)
Half-Life (t1/2) of Mavorixafor
Pre-dose, 0.5, 1, 2, 4, 6, and 8 to 10 hours post-dose on Day 1 and Day 21 of Cycle 1, 2, and 3 (each cycle length = 28 days)
t1/2 of Ibrutinib
Pre-dose, 0.5, 1, 2, 4, 6, and 8 to 10 hours post-dose on Day 1 and Day 21 of Cycle 1, 2, and 3 (each cycle length = 28 days)
Accumulation Ratio of Mavorixafor
Pre-dose, 0.5, 1, 2, 4, 6, and 8 to 10 hours post-dose on Day 1 and Day 21 of Cycle 1, 2, and 3 (each cycle length = 28 days)
Accumulation Ratio of Ibrutinib
Pre-dose, 0.5, 1, 2, 4, 6, and 8 to 10 hours post-dose on Day 1 and Day 21 of Cycle 1, 2, and 3 (each cycle length = 28 days)
Area Under the Concentration-Time Curve (AUC) of Mavorixafor
Pre-dose, 0.5, 1, 2, 4, 6, and 8 to 10 hours post-dose on Day 1 and Day 21 of Cycle 1, 2, and 3 (each cycle length = 28 days)
AUC of Ibrutinib
Pre-dose, 0.5, 1, 2, 4, 6, and 8 to 10 hours post-dose on Day 1 and Day 21 of Cycle 1, 2, and 3 (each cycle length = 28 days)
Clearance of Mavorixafor
Pre-dose, 0.5, 1, 2, 4, 6, and 8 to 10 hours post-dose on Day 1 and Day 21 of Cycle 1, 2, and 3 (each cycle length = 28 days)
Clearance of Ibrutinib
Pre-dose, 0.5, 1, 2, 4, 6, and 8 to 10 hours post-dose on Day 1 and Day 21 of Cycle 1, 2, and 3 (each cycle length = 28 days)
Volume of Distribution (Vd) of Mavorixafor
Pre-dose, 0.5, 1, 2, 4, 6, and 8 to 10 hours post-dose on Day 1 and Day 21 of Cycle 1, 2, and 3 (each cycle length = 28 days)
Vd of Ibrutinib
Pre-dose, 0.5, 1, 2, 4, 6, and 8 to 10 hours post-dose on Day 1 and Day 21 of Cycle 1, 2, and 3 (each cycle length = 28 days)
Change From Baseline in AUC of Absolute Neutrophil Count (ANC) at Cycle 1
Baseline, at the end of Cycle 1 (cycle length = 28 days)
Change From Baseline in AUC of ANC at Cycle 2
Baseline, at the end of Cycle 2 (cycle length = 28 days)
Change From Baseline in AUC of ANC at Cycle 3
Baseline, at the end of Cycle 3 (cycle length = 28 days)
Maximal Change From Baseline in ANC Count at Cycle 1
Baseline, at the end of Cycle 1 (cycle length = 28 days)
Maximal Change From Baseline in ANC Count at Cycle 2
Baseline, at the end of Cycle 2 (cycle length = 28 days)
Maximal Change From Baseline in ANC Count at Cycle 3
Baseline, at the end of Cycle 3 (cycle length = 28 days)

Secondary Endpoints

Infection Severity Based on Common Terminology Criteria for Adverse Events (CTCAE) Adjudicated by a BIAC During the Treatment Period
Up to 52 Weeks
Infection Duration Based on Duration of Infections Adjudicated by a BIAC During the Treatment Period in Those Participants who Developed Infections
Up to 52 Weeks
Antibiotic Use Due to Infection, Characterized by the Frequency of Antibiotic Use During the Treatment Period
Up to 52 Weeks
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Study Design & Arms

AllocationRANDOMIZED
MaskingQUADRUPLE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
MavorixaforEXPERIMENTALParticipants will receive mavorixafor orally once daily starting from Day 1 through Week 52.
PlaceboPLACEBO_COMPARATORParticipants will receive placebo to match mavorixafor orally once daily starting from Day 1 through Week 52.
Group 1: Child-Pugh AEXPERIMENTALParticipants with mild HI will receive a single dose of mavorixafor orally on an empty stomach, following a minimum 10-hour fasting period.
Group 2: Child-Pugh BEXPERIMENTALParticipants with moderate HI will receive a single dose of mavorixafor orally on an empty stomach, following a minimum 10-hour fasting period.
Group 3: Child-Pugh CEXPERIMENTALParticipants with severe HI will receive a single dose of mavorixafor orally on an empty stomach, following a minimum 10-hour fasting period.
Group 4: HVsEXPERIMENTALHVs matched with the mild HI participants will receive a single dose of mavorixafor orally on an empty stomach, following a minimum 10-hour fasting period.
Group 5: HVsEXPERIMENTALHVs matched with the moderate HI participants will receive a single dose of mavorixafor orally on an empty stomach, following a minimum 10-hour fasting period.
Group 6: HVsEXPERIMENTALHVs matched with the severe HI participants will receive a single dose of mavorixafor orally on an empty stomach, following a minimum 10-hour fasting period.
Cohort 1: Mavorixafor and CarbamazepineEXPERIMENTALParticipants will receive a single dose of mavorixafor administered on Day 1 and a single dose of mavorixafor administered on Day 18 on an empty stomach, after an overnight fast (at least 10 hours). Participants will receive carbamazepine administered orally twice daily (BID) on Days 6 through Day 22, 30 minutes after the end of a meal.
Cohort 2: Mavorixafor and EfavirenzEXPERIMENTALParticipants will receive a single dose of mavorixafor administered on Day 1 and a single dose of mavorixafor administered on Day 18 on an empty stomach, after an overnight fast (at least 10 hours). Participants will receive efavirenz administered once daily (QD) on Days 6 through 22, at bedtime, at least 4 hours after the end of a meal.
Mavorixafor and IbrutinibEXPERIMENTALEach participants will initially receive mavorixafor at Dose Level 1 (200 mg QD) in combination with ibrutinib 420 mg. Cohort A will comprise the first 6 participants enrolled in the study that complete at least their first cycle at Dose Level 2 (400 mg QD). Cohort A participants will start at Dose Level 1 and be allowed to dose escalate after the first cycle to Dose Level 2, if no DLTs are observed during the first cycle of each participant. Cohort B will comprise the next 6 participants enrolled into the study that complete at least their 1st cycle at Dose Level 3 (600 mg QD). Cohort B participants will start at Dose Level 1 and be allowed to dose escalate up to Dose Levels 2 and 3. Cohort C will comprise the remainder of participants enrolled up to the total of 18. Cohort C participants will start at Dose Level 1 and be allowed to escalate to 400 and 600 mg after each dose level has been deemed safe by participants from Cohort A and B.

Interventions

NameTypeDescription
MavorixaforDRUGMavorixafor will be administered per schedule specified in the arm description.
PlaceboDRUGPlacebo will be administered per schedule specified in the arm description.
CarbamazepineDRUGCarbamazepine will be administered per schedule specified in the arm description.
EfavirenzDRUGEfavirenz will be administered per schedule specified in the arm description.
IbrutinibDRUGIbrutinib capsules will be administered per dose and schedule specified in the arm.
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Eligibility Criteria

Age Range12 Years to N/A
SexALL
Healthy VolunteersNo
Study Sites114

Key Inclusion Criteria: * Diagnosis of congenital or acquired primary autoimmune and idiopathic chronic neutropenic disorder ≥6 months prior to the screening visit that is not attributable to medications, active or recent infections or malignancy. * Congenital Neutropenia, including but not limited...

Countries:United StatesArgentinaAustraliaBelgiumCanadaColombiaCzechiaFranceGeorgiaGermanyGreeceHungaryIndiaIsraelItalyMalaysiaPortugalRomaniaSerbiaSpainSwitzerlandThailandTurkey (Türkiye)UkraineUnited KingdomAustriaDenmarkNetherlandsRussiaSouth Korea
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Recent Changes (Last 90 Days)

MEDIUMAug 6, 2026NCT03995108TRIAL_REMOVED: changed
LOWAug 6, 2026NCT06056297lastUpdatePostDate: changed
MEDIUMAug 6, 2026NCT03995108TRIAL_REMOVED: changed
LOWAug 6, 2026NCT06056297lastUpdatePostDate: changed
MEDIUMAug 6, 2026NCT03995108TRIAL_REMOVED: changed
HIGHJul 15, 2026NCT06858696Status: RECRUITING → COMPLETED
HIGHJul 15, 2026NCT06858696Status: RECRUITING → COMPLETED
HIGHJul 6, 2026NCT03995108Status: ACTIVE_NOT_RECRUITING → COMPLETED
HIGHJul 6, 2026NCT03995108Status: ACTIVE_NOT_RECRUITING → COMPLETED
LOWJun 5, 2026NCT06056297lastUpdatePostDate: changed
LOWJun 5, 2026NCT06056297lastUpdatePostDate: changed
LOWJun 5, 2026NCT06056297lastUpdatePostDate: changed
LOWJun 5, 2026NCT06056297lastUpdatePostDate: changed
LOWMay 26, 2026NCT06858696primaryCompletionDate: changed
LOWMay 26, 2026NCT06056297primaryCompletionDate: changed
LOWMay 26, 2026NCT03995108primaryCompletionDate: changed
LOWMay 24, 2026NCT06858696studyFirstPostDate: changed
LOWMay 24, 2026NCT06056297studyFirstPostDate: changed
LOWMay 24, 2026NCT03995108studyFirstPostDate: changed

Frequently asked questions about Mavorixafor

What is Mavorixafor used for?

Mavorixafor is an investigational small molecule being studied for use in WHIM syndrome, Waldenstrom's macroglobulinemia, hepatic insufficiency, neutropenia, and in healthy participants. It has been evaluated in clinical trials for these conditions, including a Phase 3 study in WHIM syndrome and Phase 1 studies in other settings.

Who makes Mavorixafor?

Mavorixafor is being developed by X4 Pharmaceuticals, Inc., a biopharmaceutical company traded on NASDAQ under the ticker symbol XFOR. The company is conducting clinical trials to evaluate the drug's safety and efficacy across multiple indications.

What phase is Mavorixafor in?

Mavorixafor is in clinical development. It has completed a Phase 3 trial in WHIM syndrome and Phase 1 trials in Waldenstrom's macroglobulinemia, hepatic insufficiency, and healthy participants. The drug is investigational and has not been approved by the FDA.

What clinical trials is Mavorixafor in?

Mavorixafor has been studied in several clinical trials. NCT03995108 was a Phase 3 study in WHIM syndrome with 31 participants. NCT04274738 was a Phase 1 study in Waldenstrom's macroglobulinemia with 16 participants. NCT06858696 and NCT06914869 were Phase 1 studies in hepatic insufficiency and healthy participants, respectively.

What FDA designations has Mavorixafor received?

Mavorixafor has received multiple FDA designations, including Breakthrough Therapy, Fast Track, Rare Pediatric Disease, and Priority Review. These designations are intended to expedite the development and review of the drug for serious conditions.

Is Mavorixafor being studied in combination with other drugs?

Yes, Mavorixafor has been studied in combination with ibrutinib in a Phase 1 trial for Waldenstrom's macroglobulinemia. The trial, NCT04274738, enrolled 16 participants whose tumors expressed mutations in MYD88 and CXCR4.