Prediction of target CD34 positive cells following leukopheresis in children with neuroblastoma.

BACKGROUND: Myeloablative chemotherapy followed by autologous stem cell transplantation (ASCT) may improve long-term survival in children with disseminated neuroblastoma. In children it is important to be able to ascertain when to start the leukopheresis in order to keep the number of procedures to a minimum.

PROCEDURE: Twenty-three children with high-risk neuroblastoma with a median weight of 13 kg (range 8-16 kg). Stem cell collection was planned to start at day 14 after the start of the preceding induction standard chemotherapy and after 4 days of G-CSF treatment at 10 microg/kg body weight once daily subcutaneously. Normal volume leukopheresis (median 2.2 times the blood volume of the child) was carried out using a CS-3000 Plus Blood Cell Separator. A pre-collection peripheral blood CD34+ count of >20/microl was a prerequisite for initiating the stem cell collection.

RESULTS: Timely leukopheresis was carried out in 19/23 patients. In 17 (74%) of the patients the target number of CD34+ cells/kg body weight was obtained in one procedure; in the remaining the target number of stem cells was obtained after leukopheresis on the following day. A highly significant correlation was found between the pre-harvest CD34+ count from the peripheral blood and the total number of collected CD34+ cells/kg (r = 0.79, P < 0.001).

CONCLUSION: When the pre-harvest CD34+ count was >40/microl, a sufficient number of CD34+ stem cells was collected in a single procedure in 15 out of 16 cases.