15 October 2018 - - The US Food and Drug Administration has granted Orphan Drug Designation for US-based biotechnology company X4 Pharmaceuticals' drug candidate, X4P-001-RD for the treatment of WHIM syndrome, a primary immunodeficiency disease for which there are currently no approved treatments for patients, the company said.

X4P-001-RD is currently in a Phase 2/3 clinical trial in patients with WHIM syndrome, and positive interim results from the Phase 2 portion of the study were announced at the European Hematology Association Congress in June 2018.

Orphan Drug Designation is granted by the FDA to drugs and biologics that are defined as those intended for the safe and effective treatment, diagnosis or prevention of rare diseases or conditions that affect fewer than 200,000 people in the United States.

Orphan Drug Designation provides certain incentives which may include tax credits towards the cost of clinical trials and prescription drug user fee waivers.

If a product that has Orphan Drug Designation subsequently receives the first FDA approval for the disease for which it has such designation, the product is entitled to orphan product exclusivity.

WHIM syndrome is a primary immunodeficiency disease caused by genetic mutations in the CXCR4 receptor gene resulting in susceptibility to certain types of infections. WHIM is an abbreviation for the characteristic clinical symptoms of the syndrome: Warts, Hypogammaglobulinemia, Infections, and Myelokathexis.

Within the overall category of primary immunodeficiencies, there are between 15,000 and 100,000 patients in the US that are classified with primary immunodeficiency disease of unknown origin of which WHIM is one.

WHIM syndrome is a rare disorder and the precise prevalence or incidence of patients that have the genetic mutation responsible for WHIM syndrome is unknown. Individuals with WHIM syndrome are more susceptible to potentially life-threatening bacterial infections.

Additionally, WHIM syndrome is associated with significant morbidity beginning in early childhood and continuing throughout life.

Current therapy is limited to treatment of acute infections with antibiotics or prevention through the use of intravenous immunoglobulin or G-CSF.

There is no approved therapy for the treatment of WHIM syndrome.

X4 Pharmaceuticals is developing novel therapeutics designed to improve immune cell trafficking to treat rare diseases and cancer.

The company's oral small molecule drug candidates antagonize the CXCR4 pathway, which plays a central role in immune surveillance. X4's most advanced product candidate is in a Phase 2/3 clinical trial in patients with WHIM syndrome, a rare genetic, primary immunodeficiency disease, and is currently under investigation in multiple clinical trials in solid tumors.

X4 was founded and is led by a team with deep product development and commercialization expertise, including several former members of the Genzyme leadership team, and is located in Cambridge, MA.