Stem cell sources Ancestim (recombinant human stem cell factor, SCF) in association with filgrastim does not enhance chemotherapy and/or growth factor-induced peripheral blood progenitor cell (PBPC) mobilization in patients with a prior insufficient PBPC collection MG da Silva 1 , P Pimentel 2 , A Carvalhais 2 , I Barbosa 2 , A Machado 1 , F Campilho 2 , SR Sousa 2 , N Miranda 1 , F Leal da Costa 1 , A Campos 2 , CP Vaz 2 , J Antas 3 and JL Passos-Coelho 1 1 Bone Marrow Transplantation Unit, Instituto Portugueˆs de Oncologia de Francisco Gentil, Lisboa, Portugal; 2 Bone Marrow Transplantation Unit, Instituto Portugueˆs de Oncologia de Francisco Gentil, Porto, Portugal; and 3 AMGEN, Portugal Summary: Up to a third of autologous transplantation candidates fail to mobilize hematopoietic progenitors into the peripheral blood with chemotherapy and/or growth factor treatment, thusrequiringinnovativemobilizationstrategies.Intotal,20 cancer patients unable to provide adequate PBPC products after a previous mobilization attempt were treated with ancestim (20 lg/kg/day s.c.) and filgrastim (10 lg/kg/day s.c.). In 16 patients, the pre-study mobilization was with filgrastim alone. Eight patients underwent single large volume leukapheresis (LVL) and 12 multiple standard volumeleukaphereses(SVL)inbothmobilizations.Pairwise comparison of peripheral blood CD34 þ cell concentrations on the day of first leukapheresis failed to document synergism – median CD34 þ /ll of 3.2 (o0.1 to 15.4) and 4.5 (1–28.56) for the pre-study and on-study mobilizations (P ¼ 0.79, sign test), and 4.2 (o0.1–15.4) and 5 (1–28.56), respectively, for the 16 patients previously mobilized with filgrastim alone (P ¼ 1, sign test). The number of CD34 þ cells/kg collected per unit of blood volume (BV) processed wassimilarinbothmobilizations–median0.1  10 6 /kg/BV and0.09  10 6 /kg/BV,respectively(P ¼ 1,signtest).Inthis phase II study, the combination of ancestim and filgrastim did not allow adequate PBPC mobilization and collection in patients with a previous suboptimal PBPC collection. Bone Marrow Transplantation (2004) 34, 683–691. doi:10.1038/sj.bmt.1704602 Published online 23 August 2004 Keywords: ancestim; PBPC mobilization; hematopoietic transplantation High-dose chemoradiotherapy, with autologous or allo- geneic hematopoietic support, is increasingly used to treat hematological malignancies and selected solid tumors. 1–3 In thelastdecade,peripheralbloodhasreplacedbonemarrow as the preferred source of hematopoietic progenitors to achieve hematological reconstitution. Peripheral blood progenitor cell (PBPC) transplants were shown to result in a faster hematological reconstitution when compared to bone marrow infusions, in randomized and nonrandomized studies. 4–7 PBPC harvesting has the additional advantage of being performed in the outpatient setting, avoiding general anesthesia. However, in the majority of patients multiple leukaphereses are needed to collect a PBPC product. 7–9 To overcome the inconvenience and cost of multiple proce- dures, large volume leukaphereses (LVL), defined as the processing of more than three blood volumes (BVs) or 15l of blood in a single session, have been used as a way of processing a high number of patients’ BVs in a single session. 10–14 LVLcanalsorecruitPBPCintothecirculatory compartment, allowing the continuous harvest of large numbers of progenitors throughout the procedure. 10–12,14 Similar recruitment of PBPC has been reported by some 15 butnotothers 16 with standard volume leukapheresis (SVL). The group in Lisboa 10 and others 11–14 have shown that LVL is safe and at least as efficient as SVL for PBPC harvesting, allowing the collection of an adequate PBPC product in the majority of cancer patients in a single session. Regardless of the type of apheresis procedure used, hematopoietic progenitors need to be mobilized into the peripheral blood by the administration of chemotherapy, hematopoietic growth factors (mostly G-CSF) or their combination. 4,5,17 Such mobilization increases the concen- tration of hematopoietic progenitors in the circulation, thus reducing the number of leukaphereses required to collect a PBPC product capable of hematopoietic reconstitution. Prior therapy, bone marrow involvement by the tumor and cancer diagnosis can influence the ability to mobilize Received 6 January 2004; accepted 6 May 2004 Published online 23 August 2004 Correspondence: Dr MG da Silva, Servic ¸o de Hematologia, Instituto Portugueˆs de Oncologia de Francisco Gentil, Rua Prof. Lima Basto, 1093 Lisboa Codex, Portugal; E-mail: jcoelho@ipolisboa.min-saude.pt Bone Marrow Transplantation (2004) 34, 683–691 & 2004 Nature Publishing Group All rights reserved 0268-3369/04 $30.00 www.nature.com/bmt