Breakthrough Therapy Designation Given to Investigative WHIM Syndrome Treatment

WHIM Syndrome

WHIM syndrome is a form of primary immunodeficiency. It is caused by a mutation in the CXCR4 gene. WHIM stands for Warts, Hypogammaglobulinemia, Infections, and Myelokathexis.

Throughout their lives, patients experience an increased risk of infection and certain cancers. By the age of 40, their estimated cancer risk is 30%. Unfortunately, the only current treatment options are G-CSF or immunoglobulin to prevent infection. They also may be prescribed antibiotics to treat infections if they do occur.

Thankfully, a new potential therapy has just received Breakthrough Therapy Designation by the FDA and researchers are hopeful it could become the first FDA approved therapy for adults with the condition.


The new treatment is called Mavorixafor or X4P-001. It was first granted Orphan Drug Designation in 2018 by the FDA and then in 2019 by the European Commission.

In addition to WHIM, it is being investigated as a therapeutic option for clear cell renal cell carcinoma, Waldenstrom’s macroglobulinemia, and severe congenital neutropenia.

The pill is taken orally, once each day. It is a formulation of a small molecule antagonist of the chemokine receptor called CXCR4.

Now, X4P-001 is being studied in a Phase 3 trial for WHIM Syndrome. This global investigation is called 4WHIM.

Breakthrough Therapy Designation

Breakthrough Therapy Designation is given to therapies developed to treat a serious medical condition with a high unmet need. Therapies granted this designation must have already met at least one clinical endpoint in a trial and shown it may be able to provide patients substantial improvements. It allows development to be expedited, hopefully allowing these novel treatments to reach patients sooner.

X4P-001’s designation was based off a Phase 2 trial. This investigation showed clinically significant improvements in absolute neutrophil counts as well as absolute lymphocyte counts. This indicates that infection rates had decreased as did the wart burden for patients. Additionally, the medication was found to be well-tolerated.

X4 Pharmaceuticals, the organization examining this therapy, is excited about the future for this medication. Stay tuned to hear results from the Phase 3 investigation.

You can read more about this investigative therapy here.

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