X4 Pharmaceuticals' Drug in the FDA Approval Process
This section highlights FDA-related milestones and regulatory updates for drugs developed by X4 Pharmaceuticals (XFOR).
Over the past two years, X4 Pharmaceuticals has reported clinical trial outcomes, regulatory submissions, approvals, and other FDA events for drugs and therapies such as
Mavorixafor. For definitions of regulatory abbreviations such as NDA, BLA, or PDUFA, see the event status legend.
Mavorixafor FDA Regulatory Timeline and Events
Mavorixafor is a drug developed by X4 Pharmaceuticals for the following indication: In people diagnosed with idiopathic, cyclic, or congenital neutropenia.
This drug is under review by the U.S. Food and Drug Administration (FDA).
Below is a timeline of key regulatory milestones for this therapy.
- Drug:
- Mavorixafor
- Announced Date:
- September 8, 2026
- Indication:
- In people diagnosed with idiopathic, cyclic, or congenital neutropenia.
Announcement
X4 Pharmaceuticals announced the positive outcome of its Type C Meeting with the U.S. Food and Drug Administration (FDA) related to the global 4WARD Phase 3 clinical trial.
Read Announcement- Drug:
- Mavorixafor
- Announced Date:
- June 16, 2025
- Indication:
- In people diagnosed with idiopathic, cyclic, or congenital neutropenia.
Announcement
X4 Pharmaceuticals announced the presentation of positive data from its completed Phase 2 trial of mavorixafor in the treatment of certain chronic neutropenic (CN) conditions at the 30th Annual Congress of the European Hematology Association (EHA) in Milan, Italy.
AI Summary
X4 Pharmaceuticals recently presented positive data from its completed Phase 2 trial of mavorixafor at the 30th Annual Congress of the European Hematology Association in Milan, Italy. The study evaluated the oral treatment for certain chronic neutropenic conditions over a six-month period. Results showed that mavorixafor not only led to durable, meaningful increases in neutrophil counts but also allowed many patients to reduce or even stop the use of injectable granulocyte colony-stimulating factor (G-CSF). These findings suggest that mavorixafor may offer a simpler, oral alternative to the current therapy, which relies on regular injections. The encouraging trial outcomes have built confidence in the potential of mavorixafor and are shaping the design of an ongoing global Phase 3 trial, aimed at confirming its safety and effectiveness for patients with chronic neutropenia.
Read Announcement- Drug:
- Mavorixafor
- Announced Date:
- June 10, 2025
- Indication:
- In people diagnosed with idiopathic, cyclic, or congenital neutropenia.
Announcement
X4 Pharmaceuticals announced that the U.S. Food and Drug Administration (FDA) has granted Fast Track designation to mavorixafor, an oral CXCR4 antagonist, for the treatment of chronic neutropenia (CN).
AI Summary
X4 Pharmaceuticals announced that the FDA has granted Fast Track designation to mavorixafor, an oral CXCR4 antagonist, for treating chronic neutropenia (CN). This designation will help speed up drug development and review by allowing for more frequent communication with the FDA and potentially facilitating an accelerated approval process if the necessary criteria are met.
Mavorixafor works by mobilizing neutrophils from the bone marrow into the bloodstream, offering a potential alternative to the current injectable treatment, G-CSF, which has notable side effects. The company is actively conducting a global, pivotal Phase 3 clinical trial (4WARD) and expects to complete enrollment later this year with top-line data expected in late 2026. The Fast Track designation underscores the FDA’s commitment to addressing the unmet medical needs of the CN community.
Read Announcement- Drug:
- Mavorixafor
- Announced Date:
- February 6, 2025
- Indication:
- In people diagnosed with idiopathic, cyclic, or congenital neutropenia.
Announcement
X4 Pharmaceuticals announced today a restructuring of its workforce and capital spending to focus efforts on advancing mavorixafor to treat those with chronic neutropenia, while also optimizing its U.S. promotion of XOLREMDI® (mavorixafor), approved for the treatment of WHIM syndrome (warts, hypogammaglobulinemia, infections and myelokathexis), a rare immunodeficiency.
AI Summary
X4 Pharmaceuticals has announced a major restructuring focused on advancing its drug mavorixafor for treating chronic neutropenia. The company will reduce overall costs by cutting headcount and capital spending, which includes scaling back some research efforts and closing its Vienna facility. This strategic shift will allow X4 to concentrate on the ongoing global Phase 3 clinical trial for mavorixafor in chronic neutropenia and ensure more efficient use of resources. In addition, X4 is optimizing its U.S. commercial approach for XOLREMDI®, the approved formulation of mavorixafor used to treat WHIM syndrome—a rare immunodeficiency characterized by warts, low antibody levels, infections, and abnormal white blood cell function. These moves are designed to improve operational and capital efficiency while expanding the company’s reach to benefit a larger patient population.
Read Announcement- Drug:
- Mavorixafor
- Announced Date:
- January 24, 2025
- Target Action Date:
- H1 2026
- Estimated Target Date Range:
- January 1, 2026 - June 30, 2026
- Indication:
- In people diagnosed with idiopathic, cyclic, or congenital neutropenia.
Announcement
X4 Pharmaceuticals announced that Decision on MAA expected in 1H 2026
AI Summary
X4 Pharmaceuticals announced that its Marketing Authorization Application (MAA) for mavorixafor in the treatment of WHIM syndrome is now under review by the European Medicines Agency’s Committee for Medicinal Products for Human Use (CHMP). The company expects the decision on the MAA in the first half of 2026, a key milestone in its efforts to bring a much-needed therapy to patients in Europe.
Mavorixafor, an oral, once-daily antagonist of the CXCR4 receptor, has shown promising results in the global Phase 3 4WHIM clinical trial, where it met its primary endpoint and was well tolerated by patients. If approved, it will be the first treatment indicated for WHIM syndrome in Europe, potentially benefiting around 1,000 patients. The company is working closely with its European partner, Norgine, to ensure timely access to this innovative therapy.
Read Announcement- Drug:
- Mavorixafor
- Announced Date:
- January 24, 2025
- Indication:
- In people diagnosed with idiopathic, cyclic, or congenital neutropenia.
Announcement
X4 Pharmaceuticals announced that its Marketing Authorization Application (MAA) for mavorixafor for the treatment of WHIM syndrome (warts, hypogammaglobulinemia, infections and myelokathexis), a rare primary immunodeficiency, has been validated for review and is now under evaluation with the European Medicines Agency's (EMA) Committee for Medicinal Products for Human Use (CHMP).
AI Summary
X4 Pharmaceuticals announced that its Marketing Authorization Application (MAA) for mavorixafor to treat WHIM syndrome has been validated for review and is now under evaluation by the European Medicines Agency’s Committee for Medicinal Products for Human Use (CHMP). WHIM syndrome is a rare primary immunodeficiency characterized by warts, hypogammaglobulinemia, infections, and myelokathexis. With orphan drug designation already granted by the EMA, this milestone is a key step toward providing the first treatment option for WHIM syndrome patients within the European Union.
The submission, made in collaboration with European partner Norgine, marks an important advancement in X4’s global development strategy. By having its MAA validated for review, X4 Pharmaceuticals demonstrates its commitment to meeting regulatory milestones and delivering innovative therapies to improve patient outcomes in rare immune system disorders.
Read Announcement- Drug:
- Mavorixafor
- Announced Date:
- December 4, 2024
- Indication:
- In people diagnosed with idiopathic, cyclic, or congenital neutropenia.
Announcement
X4 Pharmaceuticals announced its upcoming presentations at the 66th American Society of Hematology (ASH) Annual Meeting and Exposition, including a trial-in-progress poster on the ongoing pivotal Phase 3 clinical trial exploring the use of mavorixafor, an oral CXCR4 antagonist, for the treatment of people with chronic neutropenia (CN).
AI Summary
X4 Pharmaceuticals is set to present at the 66th American Society of Hematology (ASH) Annual Meeting and Exposition in San Diego, focusing on a pivotal Phase 3 clinical trial for chronic neutropenia (CN). At the event, the company will showcase a trial-in-progress poster detailing the study of mavorixafor, an oral CXCR4 antagonist that may offer a new treatment option for people with CN. This trial is particularly significant as it could reduce or replace the current use of injectable G-CSF. The 52-week study is a randomized, double-blind, placebo-controlled trial aiming to enroll about 150 participants from multiple global sites. X4 Pharmaceuticals hopes to connect with clinicians at ASH and share insights into how mavorixafor might address a long-standing treatment gap in CN.
Read Announcement
X4 Pharmaceuticals FDA Events - Frequently Asked Questions
As of now, X4 Pharmaceuticals (XFOR) has not received any FDA approvals for its therapy in the last two years.
In the past two years, X4 Pharmaceuticals (XFOR) has reported FDA regulatory activity for Mavorixafor.
The most recent FDA-related event for X4 Pharmaceuticals occurred on September 8, 2026, involving Mavorixafor. The update was categorized as "positive Outcome," with the company reporting: "X4 Pharmaceuticals announced the positive outcome of its Type C Meeting with the U.S. Food and Drug Administration (FDA) related to the global 4WARD Phase 3 clinical trial."
Currently, X4 Pharmaceuticals has one therapy (Mavorixafor) targeting the following condition: In people diagnosed with idiopathic, cyclic, or congenital neutropenia..
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FDA Event Stage Terminology & Abbreviation Guide
- NDA: New Drug Application
- ANDA: Abbreviated New Drug Application
- sNDA: Supplemental New Drug Application
- BLA: Biologics License Application
- sBLA: Supplemental Biologics License Application
- FDA Approved: Approved by the FDA
- EMA: European Medicines Agency
- CE Mark: European Union Certification
- NMPA: China National Medical Products Administration
- MHLW: Japanese Ministry of Health
- FDA Meeting: Consultation with FDA
- Pre-IND: Pre-Investigational New Drug Meeting
- Breakthrough Therapy: Special FDA designation for promising therapies
- Fast Track: Accelerated FDA approval pathway
- Orphan Drug: Designation for rare disease treatments
- RPD: Rare Pediatric Disease Designation
- RMAT: Regenerative Medicine Advanced Therapy
- DSMB Review: Data Safety Monitoring Board Review
- IDMC Review: Independent Data Monitoring Committee
- MAA: MHRA Marketing Authorization Application
- RTF: Refusal to File (Rejected Application)
- 510(k): FDA Clearance for Medical Devices
- Rolling Submission: Staggered regulatory review process
FDA progress for NASDAQ:XFOR last updated on 9/8/2026 by MarketBeat.com Staff. We continuously monitor for new FDA events and market data.
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