A validated real-time quantitative PCR approach shows a correlation between tumor burden and successful ex vivo purging in follicular lymphoma patients

Objective. Purging procedures are increasingly used to provide stem cell co llections devoid of contaminating tumor cells, In follicle center lymphoma (FCL), most approaches eradicate polymerase chain reaction (PCR)-detectable disease in only a fraction of harvests undergoing ex vivo manipulation, In this study we evaluated whether there is a relationship between tumor burd en of stem cell harvests and successful clearance of PCR-detectable disease following ex vivo manipulation, Materials and Methods. To address this issue, we developed a real-time PCR approach for quantitative measurement of tumor contamination using the bcl- 2 rearrangement. Real-time PCR was used to evaluate the relationship betwee n tumor burden of stem-cell harvests and purging effectiveness in PCR+ samp les derived from 10 FCL patients, Ex vivo purging was performed using the M axSep cell separator (Baxter Immunotherapy, Deerfield, IL, USA), Results. Our real-time PCR method proved effective, sensitive, accurate, an d reproducible. Four collections were successfully cleared of minimal resid ual disease (MRD) whereas six remained PCR+, Real-time PCR showed that the four collections successfully cleared of MRD had a prepurging tumor burden significantly lower than those remaining PCR+ (p = 0.04), Conclusion, This study provides the first evidence that evaluation of tumor burden in stem-cell harvests by real-time PCR can predict the effectivenes s of therapeutic intervention in non-Hodgkin's lymphoma. Based on these fin dings, we foresee a more widespread use of this technique to evaluate the i mpact of different therapeutic approaches in FCL. (C) 2001 International So ciety for Experimental Hematology, Published by Elsevier Science Inc.