Researchers from several U.S. medical centers have reported that the addition of Mozobil® (plerixafor, AMD3100) to Neupogen® (filgrastim) significantly increases the efficiency of autologous peripheral blood stem cell harvests in patients with multiple myeloma. The details of this study appeared in an early online publication in Blood on April 10, 2009.[1]

Single or tandem autologous peripheral blood stem cell transplants are effective treatment for patients with multiple myeloma and other hematologic diseases. Peripheral blood stem cells for autologous stem cell transplantation are usually collected after the administration of Neupogen or Neulasta® (pegfilgrastim) with or without chemotherapy. Patients who receive more than one course of therapy supported by stem cells need relatively large numbers of CD34+ stem cells and often require multiple days of stem cell harvests.

Mozobil was approved by the U.S. Food and Drug Administration in December of 2008 for use with Neupogen for mobilization of peripheral blood stem cells in patients with non-Hodgkin’s lymphoma (NHL) and multiple myeloma. A Phase II study suggested that more stem cells could be collected in fewer apheresis procedures when Mozobil was added to Neupogen compared with Neupogen alone in patients with Hodgkin’s lymphoma.[2] A previous multicenter study showed that adequate numbers of CD34+ cells were collected in 96% of heavily pretreated patients with NHL and myeloma when Mozobil was added to Neupogen.[3] This study suggested that Mozobil significantly increased the number of circulating CD34+ cells compared with Neupogen alone.

Researchers from Genzyme reported data on 115 “poor mobilizers” with NHL, Hodgkin’s lymphoma, or myeloma who were treated with Mozobil plus Neupogen.[4] They reported that over 75% of these “poor mobilizers” in each disease category had successful harvests of CD34+ cells following treatment with Neupogen and Mozobil. Researchers from the University of Oregon reported that 17 of 20 patients who had failed to collect sufficient numbers of CD34+ cells with Neupogen or Neupogen plus chemotherapy had successful stem cell harvests following the addition of Mozobil to Neupogen.[5]

The current study was a multicenter randomized trial that compared the efficiency of stem cell collections following Neupogen and Mozobil versus Neupogen and placebo in 148 patients with multiple myeloma. The primary endpoint of this study was the fraction of patients who achieved at least 6 x 106 CD34+ cells/kg in two or fewer apheresis procedures. Seventy-two percent of patients in the Mozobil group achieved this goal compared with 34% of patients in the Neupogen-plus-placebo group. Fifty-four percent of patients in the Mozobil group achieved the targeted CD34+ cell dose in one collection, while 56% of the placebo group required four apheresis procedures to reach this goal. Transplants were performed in 96% of patients in the Mozobil group and 88% of the placebo group. There were no differences in engraftment between the two groups. These authors concluded: “Plerixafor and G-CSF was well tolerated and significantly more patients collected the optimal CD34+ cell/kg target for transplant earlier compared to G-CSF alone.”

Comments: It would appear from all the studies to date that the combination of Mozobil and Neupogen or Mozobil and Neulasta should be the standard mode of mobilization of peripheral blood stem cells for autologous transplantation.

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