The U.S. Food and Drug Administration has approved Genzyme’s Mozobil (plerixafor injection), a drug that mobilizes hematopoietic stem cells (HSCs) from the bone marrow into the bloodstream. Mozobil has been approved for non-Hodgkin’s Lymphoma and multiple myeloma.

Mozobil is a small molecule CXCR4 chemokine receptor antagonist. The CXCR4 receptors are responsible for holding HSCs in bone marrow. These stem cells give rise to all blood types and can be used in cancer treatment. CXCR4 antagonists mobilize HSCs in the bloodstream. HSCs are then collected for autologous stem cell transplants, a therapy that treats patients with their own stem cells. The healthy stem cells are then given to the patient after chemotherapy to help the bone marrow produce healthy new cells.

Mozobil is effective when used in combination with cytokine G-CSF. Cytokines are signaling molecules used in cellular communication. Like CXCR4 antagonists, cytokines mobilize HSCs, which can then be collected for transplants.

According to Dr. DiPersio, a professor at Washington University, St. Louis, an autologous transplant is sometimes the only hope for a cure for a cancer patient. However, patients need at least two million stem cells per kilogram of body weight, which is often prohibitory. This process can take from four hours to multiple days. Sometimes, patients cannot mobilize enough cells for a transplant.

Clinical studies have shown that 72 percent of multiple myeloma patients who received Mozobil and G-CSF were able to collect at least six million stem cells per kilogram of body weight in a median number of one day.

In addition to increasing the number of mobilized stem cells, Mozobil also has economic benefits for patients and treatment centers. It can decrease the number of days it takes to remove stem cells from the blood (also known as apheresis). Additionally, the number of patients requiring a second mobilization treatment is significantly reduced.

Some side effects associated with Mozobil and G-CSF combination therapy are the potential for tumor cell mobilization, increased circulating leukocytes, decreased platelet counts, splenic enlargement, and fetal harm in pregnant women. The most common adverse effects in patients who received Mozobil with G-CSF were diarrhea, nausea, fatigue, injection site reactions, headache, arthralgia (severe joint pain), dizziness, and vomiting.

The introduction of Mozobil will improve transplantation therapies for patients with non-Hodgkin’s lymphoma and multiple myeloma. Genezyme is currently investigating other applications for this drug, such as mobilization of hematopoietic stem cells in allogeneic stem cell transplants (which requires stem cells from another donor) and tumor sensitization in oncology treatments.

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