Detection of EWS chimeric transcripts by nested RT-PCR to allow reinfusion of uncontaminated peripheral blood stem cells in high-risk Ewing's tumor in childhood
Montanaro, L.; Pession, A.; Trerè, D.; Vici, M.; Prete, A.; Paolucci, G.; Derenzini, M.
Haematologica 84(11): 1012-1015
1999
ISSN/ISBN: 0390-6078 PMID: 10553162 Document Number: 500161
Background and Objectives. Ewing's tumor (ET) are primary malignancies of bone and soft tissues characterized in at least 96% of cases by specific fusion transcripts originating from recurrent chromosomal translocations. Clinical protocols for high-risk metastatic ETs include high-dose radiation/chemotherapy followed by autologous peripheral blood stem cell (PBSC) reinfusion. We used nested reverse transcriptase polymerase chain reaction (RT-PCR) to search for the presence of ET-specific transcripts in PBSC collections from patients with high-risk ET in order to collect harvests free from neoplastic cells but still sufficient to obtain early stable engraftment. Design and Methods. Thirty-seven harvest samples from 15 ET patients treated with mobilizing chemotherapy were analyzed. Nested RT-PCR was performed to detect ET-specific transcripts in RNA extracted from the PBSC collections. Results. A total of 30 harvests was performed. On average, 2 harvests (range 1-4) were sufficient to collect the minimum required number of mononuclear cells (2.5X106/kg). Nested RT-PCR revealed neoplastic cells in 4/30 (13%) harvests, which were derived from 3/15 patients (20%). After further cytoreductive/mobilizing chemotherapy, a total of 7 additional harvests taken from these 3 patients were all free from neoplastic cells. Interpretation and Conclusions. PBSC collections from ET patients undergoing autologous stem cell transplantation are at risk of neoplastic contamination. Additional harvests following a further cycle of cytoreductive/mobilizing therapy may be sufficient to obtain non-contaminated material for reinfusion.