Clinical Data
Poster #2186: “Oral Administration of Mavorixafor, a CXCR4 Antagonist, Increases Peripheral White Blood Cell Counts Across Different Disease States”Key Poster Takeaways:

• Ongoing studies across a wide variety of diseases, including Waldenström’s macroglobulinemia (WM), clear cell renal cell carcinoma (ccRCC), WHIM (Warts, Hypogammaglobulinemia, Infections, Myelokathexis) syndrome, and chronic idiopathic neutropenia (CN), show that oral administration of mavorixafor increases blood neutrophils, lymphocytes, and monocytes.
• Mavorixafor efficacy has been observed with short-term and long-term treatment both alone and in combination with other therapies, including axitinib, ibrutinib, and granulocyte-colony stimulating factor (G-CSF).
• These results suggest that mavorixafor, through its mechanism of CXCR4 antagonism, has the potential to reduce the prevalence and/or severity of a broader array of immunodeficiencies than previously recognized, regardless of the presence or absence of CXCR4 mutations.
  

Poster #1121: “Mavorixafor, an Oral CXCR4 Antagonist, for Treatment of Patients with WHIM Syndrome: Results from the Long-Term Extension of the Open-Label Phase 2 Study”Key Poster Takeaways:

• Mavorixafor continues to show durable increases in neutrophils, lymphocytes, and monocytes, sustained improvements in infections and warts, and has been well tolerated in the ongoing Phase 2 open-label extension trial in WHIM syndrome (median treatment duration = 148.4 weeks).
• Infection rates decreased with increased doses of mavorixafor.
• Decreases in mean annualized infection rates correlate well with time above threshold for absolute neutrophil count (TAT-ANC), the primary endpoint in X4’s ongoing, fully enrolled, global, Phase 3 registrational trial in WHIM syndrome.
• Standardized patient interviews revealed that long-term treatment with mavorixafor has been well tolerated and continues to demonstrate beneficial treatment effects, including decreased frequency, severity, and duration of infections and fewer hospital/doctor visits.
• Data continue to support the potential of mavorixafor to be a safe, effective, and long-term oral therapy targeting the underlying cause of WHIM syndrome.
• Phase 3 top-line clinical results from the 52-week trial are expected in the fourth quarter of 2022.

Poster #2063: “Comprehensive In Vitro Characterization of CXCR4WHIM Variants to Decipher Genotype–Phenotype Correlations in WHIM Syndrome”Key Poster Takeaways:

• In this study, detailed functional analyses of 14 published CXCR4WHIM mutations were performed.
• Data suggest that CXCR4 internalization and AKT activation may be used as key assays for the prediction of CXCR4 variant pathogenicity in vitro and potentially as in vitro WHIM-related disease biomarkers.
• All tested CXCR4 variant cell lines were sensitive to mavorixafor at clinically relevant concentrations.