Clinical Trials

X4 Pharmaceuticals is working to bring new therapies to the treatment of rare primary immunodeficiency diseases, such as WHIM syndrome, and the immune-targeted treatment of multiple cancers.

X4 Pharmaceuticals has clinical studies on-going with our investigational products. You can find more information about each of these studies at, a US government sponsored website that lists ongoing and completed trials.

WHIM syndrome

WHIM syndrome is a type of primary immunodeficiency where the body’s immune system does not function properly. WHIM is an abbreviation for the characteristic symptoms of the syndrome: Warts, Hypogammaglobulinemia, Infections, and Myelokathexis. WHIM syndrome is a rare primary immunodeficiency with an estimated incidence of 0.23 per million births.1 The exact prevalence of the disease is not known. Patients with WHIM syndrome have low white blood cell counts and, because patients are highly susceptible to severe recurrent infections, WHIM syndrome is associated with significant chronic morbidity. Current therapy is limited to treatment of acute infections with antibiotics or preventive treatments, such as intravenous immunoglobulins. There is no approved therapy for the treatment of WHIM syndrome.


Phase 2/3 Study of X4P-001-RD in Patients with WHIM Syndrome


Advanced clear cell renal cell carcinoma (ccRCC)

Kidney cancer is among the ten most common cancers in both men and women with more than 60,000 new diagnoses each year in the United States.2 Clear cell renal cell carcinoma (ccRCC) is the most common form of kidney cancer, and advanced ccRCC accounts for approximately 20% of the patient population. Therapies approved for advanced ccRCC include immunotherapies, mammalian target of rapamycin (mTOR) kinase inhibitors, and vascular endothelial growth factor (VEGF) inhibitors. 3 Despite these advances, there is no cure for ccRCC and newer treatments are needed to improve the efficacy of these therapies and help extend patients’ lives.


Phase 1b Study of X4P-001-IO in Combination with Opdivo for Patients with Advanced ccRCC

Phase 1/2 Study of X4P-001-IO in Patients with Advanced ccRCC


Malignant melanoma

Melanoma is the fifth most common cancer in men and the sixth most common cancer in women in the United States. When discovered early, melanoma is highly curable.4 However, the 10-year survival rate for stage III and stage IV melanoma is 10-25%.5 Adjuvant therapies approved for patients with resectable stage III melanoma include immunomodulating drugs, such as high dose interferon-α therapy and anti-CTLA-4 antibody therapy. Nevertheless, not all patients respond and if they do, many develop resistance to these therapies. Unmet needs remain to improve the efficacy of current therapies and help extend patients’ lives.


X4P-001-IO and Pembrolizumab in Patients with Advanced Melanoma (X4P-001-MELA)


  1. Beaussant-Cohen S, Fenneteau O, Plouvier E, et al. Description and outcome of a cohort of 8 patients with WHIM syndrome from the French Severe Chronic Neutropenia Registry. Orphanet J Rare Dis. 2012;7:71.
  2. Guo F., et. al., “CXCL12/CXCR4: a symbiotic bridge linking cancer cells and their stromal neighbors to oncogenic communication networks,” Oncogene, May 11, 2015.
  3. National Cancer Institute, “Surveillance, Epidemiology, and End Results Program,”
  4. National Cancer Institute, “SEER Stat Fact Sheets: Melanoma of the Skin,”
  5. National Cancer Institute, “What are the survival rates for melanoma skin cancer, by stage?,”