Mozobil is a new drug designed to mobilize stem cells from the bone marrow into the bloodstream, where they can be collected. Previous alkylation therapy, radiotherapy and low collection day platelet count are predictive of poor collection yields. Neupogen, which is commonly given prior to stem cell harvesting, stimulates the body to make white blood cells. When given together, Mozobil and Neupogen have been shown to increase harvest efficiency prior to autologous peripheral stem cell transplantation.
I assume that the trial of Neupogen is to assess whether sufficient numbers of stem cells can be harvested without using Mozobil. I am not aware of any datat that Neupogen alone can be used to predict response to the combinaiton of Mozobil and Neupogen.
The original trial was a Phase III study which randomly allocated patients with NHL scheduled to receive an autologous transplant to have stem cells collected after Neupogen alone or Neupogen plus Mozobil. They reported that 59% of patients receiving Neupogen plus Mozobil achieved the goal of harvesting 6 million CD34+ cells/kg from the peripheral blood in 4 or fewer aphereses compared to 20% for the Neupogen alone group. In addition, 87% of patients receiving Neupogen plus Mozobil achieved the minimum quantity of CD34+ cells required for transplantation (2 million/kg) compared to 47% in the Neupogen alone group. It was also reported that combination therapy was also more successful in achieving secondary endpoints such as: number of days to achieve target CD 34+ cell numbers, success of engraftment, number of days needed to engraft and durability of engraftment for the first 100 days. Other studies also suggest that Mozobil is an effective agent for mobilization of stem cells when administered as a single agent. A recent study also suggests that Mozobil and Neupogen mobilizes more lymphocytes than Neupogen alone which may decrease post-transplant relapses. This was also confirmed in myeloma patients.
Considering marked superirotiy of combined therapy to Neupogen alone, I do not consider a trial fo Neupogen alone to be clinically appropraite if Mozobil and Meupogen are available.