Paula Ragan, PhD, CEO and President, X4 Pharmaceuticals, discusses data presented at The American Society of Hematology Meeting & Exposition (ASH 2021) on a phase 2 open-label extension study of mavorixafor for the treatment of WHIM syndrome.
WHIM syndrome is a primary immunodeficiency disease due to mutations in the CXCR4 receptor gene. The syndrome is named for the characteristic symptoms often present – Warts, Hypogammaglobulinemia, Infections, and Myelokathexis. Due to the nature of the symptoms, it can be years before these patients are properly diagnosed.
As Dr. Ragan notes the results of the phase 2 open-label extension study demonstrated that mavorixafor continues to show durable increases in neutrophils, lymphocytes, and monocytes; sustained improvements in infections and warts; and has been well tolerated.
As of the November 2020 data cutoff, annualized infection rates decreased from 5.6 per year at study baseline to 2.2 per year at 40 months’ treatment, providing evidence of persistent reduction of infections over time. At doses of 300 and 400mg QD, the mean time above threshold for absolute neutrophil count and absolute lymphocytes count were 12.7 hours (SD ± 9.8) and 16.9 hours (SD ± 5.9) compared to 2.1 hours (SD ± 3.3) and 11.5 hours (SD ± 5.9) at doses ≤200 mg QD, respectively. One patient experienced a 79% reduction in warts.
Safety data review at May 2021 showed that there were 12 minor treatment-emergent adverse events (grade 1) with long-term treatment (46 months). This review also showed that there were no treatment-related infections of grade 3 or higher, no treatment-related serious adverse events, and no clinically significant laboratory abnormalities with mavorixafor treatment.
Top-line results from the 52-week phase 3 trial of mavorixafor in WHIM syndrome patients are expected later this year.
To learn more about WHIM syndrome, visit checkrare.com/whim-syndrome/