A new commercial player for rare diseases has entered the market with the approval of X4 Pharmaceuticals’ first medicine, mavorixafor. Xolremdi is now the first medication approved by the FDA to treat WHIM, a rare condition characterized by a combination of primary immunodeficiency and chronic neutropenic disease brought on by an over-signaling of the CXCR4 pathway.
After a decade-long development process, the FDA authorized mavorixafor’s use in patients aged 12 and above who suffer from WHIM syndrome, which includes warts, hypogammaglobulinemia, infections, and myelokathexis.
According to a securities filing, the oral medication, which will be marketed under the trade name Xolremdi, will be sold for $496,400 annually for patients who weigh more than 50 kg and around $372,300 for patients who weigh less than or equal to 50 kg.
The illness stops white blood cells from circulating and defending the body against infection by causing them to become lodged in the patient’s bone marrow.
Warts, hypogammaglobulinemia (low antibody levels), infections, and myelokathexis (low white blood cell count) are the four basic signs of the condition that gave rise to its name. WHIM patients frequently suffer from severe infections because they typically have low blood levels of neutrophils and lymphocytes. Patients with WHIM who experience recurrent infections may experience hearing loss and lung function deterioration.
Because it inhibits CXCR4, Xolremdi aims to suppress the over-signaling pathway, which in turn allows white blood cells to leave the bone marrow and enter the circulation. According to Ragan, this allows the white blood cells to circulate, check for infection, and maybe stop it early. Furthermore, she said, X4 believes that Xolremdi may improve patients’ immunological memory over the long run, which might benefit them both immediately and over time.
The phase 3 4WHIM study demonstrated that Xolremdi reduced infection rates and increased patients’ neutrophil and lymphocyte counts.
According to X4, there are presently about 1,000 WHIM sufferers in the United States. However, Ragan stated that “if you build it, they will come” and that “we will ultimately know what the true prevalence is once the drug is approved over many years” due to the extremely rare nature of the condition and the likelihood that it is underdiagnosed.
In addition to WHIM, Ragan stated that X4 is testing mavorixafor in persistent neutropenia, with intentions to begin a late-stage trial in the disease later this year. The FDA has also granted X4 a priority review voucher in connection with the Xolremdi approval, which the business may utilize to expedite the FDA’s assessment of an additional regulatory submission or to sell to another pharmaceutical company.
