Results of a recent Polish study show that the drug Mozobil may help multiple myeloma patients who previously had a stem cell transplant collect enough stem cells for a second transplant.

However, the results also showed that previously transplanted patients collected fewer stem cells than patients who had not received a stem cell transplant before.

According to the study authors, these results showed for the first time that Mozobil (plerixafor) is highly effective for previously transplanted myeloma patients.

Autologous stem cell transplantation, a common treatment option for younger, newly diagnosed myeloma patients, is the process of collecting a patient’s own stem cells and returning them to the body after the patient receives high doses of chemotherapy, which destroy myeloma cells as well as healthy stem cells.

For most patients, stem cells are mobilized from the bone marrow to the bloodstream for collection. A minimum of 2 million stem cells/kg body weight must be collected for transplantation. However, 5 percent to 10 percent of myeloma patients are unable to collect this minimum number of stem cells.

Mozobil is a drug that is used to mobilize stem cells from the bone marrow into the blood stream. Past studies have shown that Mozobil combined with Neupogen (filgrastim), a drug that increases the production of white blood cells, enhances stem cell mobilization in myeloma patients, allowing more patients to collect the minimum number of stem cells required for transplantation (see related Beacon news).

A second autologous stem cell transplant may be beneficial for myeloma patients who are unable to achieve a complete response or a very good partial response after the first transplant. These patients, however, experience a greater risk for poor mobilization and collection of stem cells than patients receiving an autologous stem cell transplant for the first time.

The goal of the Polish study was to assess whether a combination of Mozobil with Neupogen can help previously transplanted myeloma patients collect enough stem cells for a second transplant.

The Polish researchers examined the medical records of 76 myeloma patients from the registry of the Central and Eastern European Leukemia Group. The patients had a median age of 59 years and had received a median of 10 previous chemotherapy cycles. Of the 76 patients included in the analysis, 30 had previously received at least one autologous stem cell transplant.

All patients received 100 µg/kg Neupogen daily for five consecutive days as well as 240 µg/kg Mozobil on the fourth day.  Stem cells were collected on the fifth day.

They repeated this process until either the minimum number of stem cells for transplantation was collected or until they were determined unable to mobilize enough stem cells for collection.

The researchers found that the previously transplanted patients had a lower median concentration of stem cells than previously non-transplanted patients both on the fourth day of the treatment regimen after receiving Neupogen (5.5 stem cells/µL compared to 12 stem cells/µL) and on the fifth day of the treatment regimen after receiving Mozobil (19.5 stem cells/µL compared to 30.0 stem cells/µL)

The researchers found that 70 percent of the previously transplanted patients and 82.6 percent of the previously non-transplanted patients collected enough stem cells for transplantation.

The previously transplanted patients required a median of two sessions to collect enough stem cells for transplantation, compared to one session for previously non-transplanted patients.

The previously transplanted patients collected a median of 2.8 million stem cells/kg body weight, compared to a median of 4.2 million stem cells/kg body weight for the previously non-transplanted patients.

For more information, please see the article in the European Journal of Hematology (abstract).