[Minimal residual disease in follicular and mantle cell lymphoma. Detection using quantitative molecular monitoring of circulating lymphoma cells]. / Minimale Resterkrankung bei follikulären Lymphomen und Mantellzell-Lymphomen -- Nachweis durch quantitatives molekulares Monitoring zirkulierender Lymphomzellen.

BACKGROUND AND OBJECTIVE: In patients with follicular lymphoma and mantle cell lymphoma circulating lymphoma cells can be detected by quantitative real-time PCR with a high sensitivity and reproducibility. With this study we wanted to ascertain whether a continuous molecular remission achieved in patients with mantle cell lymphoma and follicular lymphoma has an impact on survival of these patients. PATIENT AND METHODS: We conducted these investigations in 32 patients (24 with follicular lymphoma and 8 with mantle cell lymphoma) who were treated in a randomized trial with chemotherapy plus/minus rituximab (MCP, R-MCP). A further ten patients had follicular lymphoma (stage I and II) in long-term complete remission after radiation therapy. RESULTS: Up to 18 years after initial diagnoses of a stage I or II follicular lymphoma circulating t(14;18) positive cells could be detected in the peripheral blood. In advanced stage follicular lymphoma patients molecular remissions could only be achieved when they were treated with combined chemo-immunotherapy (MCP+R). A significantly higher relapse-free survival correlates with sustained molecular remission. In contrast, the frustrating clinical results obtained from the treatment of patients with mantle cell lymphoma corresponded to an achievement of only short molecular remissions in very few patients. CONCLUSIONS: The consequent application of quantitative real-time PCR will further improve current treatment strategies in lymphoma patients. Especially, individual treatment options can be developed for patients who do not respond to a standard chemotherapy or progression of disease is recognized, if results of molecular monitoring will be confirmed in large prospective studies.

Quantitative detection of t(14;18)-positive cells by real-time quantitative PCR using fluorogenic probes.

To detect t(14;18)-positive cells present in human lymphoma tissue, bone marrow aspirates and peripheral blood mononuclear cells (PBMNC), we have established an automated, real-time quantitative PCR using double-labeled fluorogenic probes. In relation to t(14;18)-positive genomic DNA or a cloned t(14;18)-DNA fragment, highly reproducible results can be obtained with initial copy numbers between 10 to 10(5). The detection of single copies has been verified by the stochastic multiple-tube approach. PBMNC cells obtained during clinical follow-up of patients with follicular lymphoma were analyzed by the one-step, real-time quantitative PCR and a two-step, semi-nested PCR combined with a limiting dilution assay. The quantitative results obtained by both assays correlate very well. Real-time quantitative PCR has several advantages: (i) it involves less critical pipetting steps, (ii) is less time-consuming and (iii) UTP, in combination with uracil-N-glycosylase, can be used to control carryover contamination. The higher specificity is due to optimized primer annealing conditions and MgCl2 concentration and the use of AmpliTaq Gold. The sensitivity is at least as high as by the two-step PCR. Real-time quantitative PCR will be very helpful in large epidemiological studies and in research for molecular staging and the detection of minimal residual tumor cells, including the analysis of blood stem-cell preparations to be used for transplantation after myelo-ablative therapy.