A Phase I Study of Mozobil in the Treatment of Patients With WHIMS

Description

Mozobil (TM) (plerixafor injection, Genzyme/Sanofi) is a Food and Drug Administration approved medication to mobilize CD34+ hematopoietic stem cells prior to apheresis and use in autologous transplantation in non-Hodgkin lymphoma and multiple myeloma when used in conjunction with granulocyte-colony stimulating factor (G-CSF). The drug s mechanism of action is the specific and reversible inhibition of the chemokine receptor, CXCR4, expressed on CD34+ cells and other leukocytes. This inhibition interferes with the binding of stromal cell derived factor-1 (SDF-1), which is constitutively expressed on bone marrow stromal cells and appears to cause direct and indirect cellular adhesive interactions. Severe congenital neutropenia is a rare inherited disorder in which the affected individuals develop chronic or cyclical neutropenia with circulating counts below 500 cells/microliter blood. This disorder may result from a variety of genetic defects in progenitor- or neutrophil-expressed genes such as elastase, CXCR4, G6PC3, etc. Myelokathexis is the abnormal retention of mature leukocytes in the bone marrow and is seen in some types of severe chronic neutropenia such as warts, hypogammaglobulinemia, infections, and myelokathexis syndrome (WHIMS). WHIMS is a rare primary immunodeficiency, which is known to be caused by mutations that enhance CXCR4 signaling. Our hypothesis is that Mozobil(TM) can be used safely to partially block CXCR4 and treat neutropenia resulting from myelokathexis at doses considerably lower than that being used for CD34+ cell mobilization. This new treatment could also improve other aspects of the disease such as frequent infections, warts, and hypogammaglobulinemia. To test this hypothesis, we propose this trial of Mozobil (TM) in adults with WHIMS, examining safety and absolute neutrophil count as the primary endpoint. Mozobil is injected subcutaneously and will be injected via syringes (up to 84 months) or via an infusion pump (pilot trial of up to 10 subjects for a 24-month period).