Allogeneic Stem Cell Transplantation in a Pediatric Patient with Whim Syndrome

WHIM syndrome (warts, hypogammaglobulinemia, infections, and myelokathexis) is a rare autosomal dominant immunodeficiency disorder that is caused by a gain in function in cysteine-X-cysteine chemokine receptor 4 (CXCR4) gene. Affected individuals have recurrent infections of the respiratory tract and soft tissues, and marked susceptibility to warts caused by human papilloma viruses (HPV). Patients have an increased risk of malignancy (lymphoma) and HPV-associated cancers. The optimal therapy for WHIM syndrome has not been defined and treatment has been with supportive care using intravenous immunoglobulin (IVIG) and granulocyte colony stimulating factor (G-CSF). New CXCR4 antagonist therapies are still in either phase I trials (plerixafor) or considered experimental (Chlacone-4).

A successful umbilical cord blood transplant has been reported by Kriven et al. Here we describe a successful matched unrelated allogeneic stem cell transplant (SCT) in a girl with WHIM syndrome caused by a known mutation in the CXCR4 gene.

This patient was diagnosed at birth with familial congenital neutropenia as findings were similar to those for the patient's mother and maternal grandmother. A complete blood count showed pancytopenia (WBC= 1.03 x10³/µL, hemoglobin= 9.2 g/dL, platelet count= 74,000/µL, ANC= 70). Despite G-CSF and IVIG therapy, the patient had recurrent infections with sinusitis and pneumonia, along with progressive organomegaly with progressive pancytopenia.

At the age of 4, the patient underwent matched unrelated SCT with a fully ablative regimen [busulfan 0.8 mg/kg/dose for 16 doses (days -9, -8, -7, and -6), cyclophosphamide 50 mg/kg/dose for 4 doses (days -5, -4, -3, and -2) and alemtuzumab 5 mg/day (weight-based dosage) for 3 doses (days -5, -4, and -3)]. Tacrolimus and mini methotrexate (on days +1, +3, +6 and +11) were given for GVHD prophylaxis. Neutrophil and platelet engraftment occurred on days + 21 and + 45, respectively. The patient is 100% donor chimeric. Post-transplant course has been complicated by grade II skin GVHD treated successfully with oral and topical steroids. The patient also developed adenovirus, BK virus and HHV-6 viral reactivations but without disease. The patient is now approximately 2 years post SCT with durable engraftment, normal humoral immune reconstitution and no chronic GVHD.

Thus, stem cell transplant following myeloablative conditioning can be accomplished for patients with WHIM syndrome. Furthermore, transplantation performed at the patient's young age likely prevented complications of recurrent infections and warts.