LightCycler-based quantitative real-time PCR monitoring of patients with follicular lymphoma receiving rituximab in combination with conventional or high-dose cytotoxic chemotherapy

OBJECTIVES: Quantitative real-time polymerase chain reaction (qPCR) is a suitable method to measure residual disease in hematological malignancies. Our objective was to assess a LightCycler-based qPCR for t(14;18)(q32;q21)(IgH/bcl-2)-positive cells quantification in the context of clinical and morphopathological characteristics of patients with follicular lymphoma treated with rituximab (R) in combination with conventional or high-dose chemotherapy. METHODS: A total of 270 bone marrow (BM) and peripheral blood (PB) samples collected from 52 patients with follicular lymphoma at diagnosis or at relapse before or sequentially during therapy were examined by qPCR and nested-PCR. RESULTS: A greater amount of t(14;18)-positive cells was observed in BM in comparison with PB in 76% of paired samples. The presence and number of t(14;18)-positive cells in BM and PB correlated with lymphoma activity. Significantly higher numbers of lymphoma cells were found in patients under non-remission compared with patients in clinical remission. During non-remission, 10-fold higher numbers were measured at relapse than at diagnosis. During remission, significantly higher levels were found in partial compared with complete remission. During first-line therapy, R/cyclophosphamide/adriamycin/vincristine/prednisone (CHOP) had higher in vivo purging ability than R/fludarabine/mitoxantrone (FM). After R/high-dose cytosine-arabinoside and mitoxantrone (HAM) or R/carmustine/etoposide/cytarabine/melphalan (BEAM), the level of t(14;18)-positive cells dropped below the detection limit in 80% of patients. CONCLUSIONS: LightCycler qPCR is a reliable method for quantitative molecular monitoring of t(14;18)-positive cells in BM and PB of patients with follicular lymphoma. It reflects the clinical characteristics of patients and allows assessment of response to different treatment regimens on a molecular level.     

Translocation (14;18)-positive cells are present in the circulation of the majority of patients with localized (stage I and II) follicular non- Hodgkin's lymphoma

Stage I and II follicular non-Hodgkin's lymphoma (NHL) is clinically defined as a localized disease. To study the possibility that this disease is in fact disseminated, we used the sensitive polymerase chain reaction (PCR) method using translocation (14;18) as marker. Samples from 21 patients who were clinically diagnosed with stage I or II follicular NHL were analyzed for the presence of t(14;18)-positive cells using PCR. We analyzed (1) the diagnostic lymph node biopsy and (2) the peripheral blood or bone marrow samples from these patients. Translocation (14;18) cells were detected in the diagnostic lymph node biopsies of 12 patients. In 9 of these patients, t(14;18)-positive cells were detected in peripheral blood and/or bone marrow samples at diagnosis and/or after therapy. Thus, in 75% of the follicular NHL patients carrying the t(14;18) as a marker for lymphoma cells, t(14;18)- positive cells were detected in peripheral blood and bone marrow at diagnosis and after therapy. Our results show that t(14;18)-positive cells can be detected in the circulation of patients with stage I and II follicular NHL, indicating that, although diagnosed as localized, the disease is disseminated.     

Polymerase chain reaction detection of cells carrying t(14;18) in bone marrow of patients with follicular and diffuse large B-cell lymphoma: the importance of analysis at diagnosis and significance of long-term follow-up

The t(14;18) is the most frequent chromosomal aberration observed in follicular lymphoma (FL), and is less frequent in diffuse large cell lymphoma (DLCL). The bcl-2/IgH rearrangement constitutes good target for polymerase chain reaction (PCR) detection that allows to find out one tumor cell in 100,000 normal cells. The PCR assay was used to detect bcl-2-rearranged cells in blood and bone marrow (BM) in 63 previously untreated patients with DLCL and in 53 patients with FL. Twenty five FL patients (47%) and 9 DLCL patients (14%) had PCR-detectable lymphoma cells in BM and peripheral blood. Minimal residual disease (MRD) was evaluated in 17 FL and 5 DLCL patients undergoing first-line chemotherapy. Three DLCL patients (60%) but only 1 FL (6%) patient achieved molecular response (PCR-negative status in BM). Two PCR bcl-2/IgH positive patients with FL were treated with rituximab (anti-CD20 antibody) and had no PCR-detectable lymphoma cells in BM after the therapy. Peripheral blood stem cells (PBSC) were harvested in 5 FL (1 PCR-negative) and in 2 DLCL (1 PCR-negative) patients. PCR-positive lymphoma cells contamined PBSC in all patients with BM PCR-positivity before harvesting. Five FL patients underwent autologous transplantation (AT). No bcl-2/IgH positive cells were detected in 4 patients (80%) at any point after AT. One patient achieved molecular response after rituximab treatment. All the patients are in CR 6, 22, 30, 31 and 42 months respectively, after AT. On the other hand, 4 FL patients in clinical complete remission, but with persistent PCR positivity in BM relapsed with median of 21 months (interval, 14-28 months) from the end of a first-line chemotherapy. Thus, the results show that PCR detection of the bcl-2/IgH rearrangement is a very useful method in evaluating the BM infiltration by lymphoma cells especially in the situation of MRD. Conventional chemotherapy did not eradicate bcl-2 positive cells in BM in most of lymphoma patients, but autologous transplantation or rituximab immunotherapy can induce molecular response in a significant proportion of them. Our results support the previous observations of the molecular response importance in view of better disease free and probably also overall survival.     

Lack of correlation between numbers of circulating t(14;18)-positive cells and response to first-line treatment in follicular lymphoma

In follicular lymphoma, the t(14;18) status of the peripheral blood and bone marrow analyzed by polymerase chain reaction (PCR) is assumed to correlate with disease activity in patients with relapsed disease. The clinical significance of quantitating circulating lymphoma cells by real-time PCR is reported in patients on first-line treatment. Thirty-four consecutive patients with previously untreated follicular lymphoma and detectable t(14;18)-positive cells in pretreatment peripheral blood samples were monitored. All patients were treated with standard chemotherapy in combination with interferon alfa-2b. Before and after induction therapy, blood samples were taken for quantitative analysis of t(14;18). At presentation, a median of 262 t(14;18)-positive cells per 75,000 normal cells was found (range, 1-75 000). Patients with lower numbers of circulating tumor cells more frequently had bulky disease (P =.02). Seventy-nine percent of the patients responded clinically to treatment. In 22 of 28 patients, including 4 patients in whom treatment had failed clinically, the number of circulating t(14;18)-positive cells decreased to undetectable or low levels after therapy. In the remaining responding patients, circulating tumor cells persisted after therapy. These quantitative data on circulating t(14;18)-positive cells call into question the usefulness of molecular monitoring of the blood in a group of patients with follicular lymphoma uniformly treated with a noncurative first-line regimen. T(14;18)-positive cells decreased in peripheral blood after treatment, irrespective of the clinical response. Therefore, the significance of so-called molecular remission should be reconsidered in follicular lymphoma. (Blood. 2001;98:940-944)     

Detection of residual lymphoma cells by polymerase chain reaction in peripheral blood is significantly less predictive for relapse than detection in bone marrow

Polymerase chain reaction (PCR) amplification of the t(14;18) has been shown to be a highly sensitive method to detect minimal residual disease in patients with non-Hodgkin's lymphoma (NHL) whose tumors bear this translocation. The ideal tissue source to detect residual lymphoma would be from a previously involved lymph node. However, lymphoid tissue is rarely available once patients achieve complete remission. Although PCR amplification has been used to detect residual lymphoma cells in both bone marrow (BM) and peripheral blood (PB) of patients in complete remission, it is presently unknown whether BM and PB are equivalent tissue sources to detect residual disease. In the present study, we compared the clinical utility of the detection of residual lymphoma in both the BM and the PB of patients with advanced-stage non- Hodgkin's lymphoma before, at the time of, and after high-dose therapy and autologous BM transplantation (ABMT). The detection of residual lymphoma in either the BM or PB was associated with decreased disease- free survival. However, in the present study, 44% of patients who relapsed had no evidence of circulating lymphoma cells in their PB. At the time of BM harvest, PCR-detectable residual lymphoma cells were detected in 211 of 212 patients; although, in a subset of these patients analyzed, lymphoma cells were detected in the peripheral blood of only 49% of patients. When residual lymphoma cells within the autologous BM are infused into the patient these cells are rapidly detectable circulating in the PB in the patient. These cells continue to circulate during the immediate posttransplant period and be detectable in the PB in the majority of patients who are infused with marrow containing residual lymphoma. We conclude that BM is a more informative tissue source than PB in detecting minimal residual disease at the time of and after ABMT, and that contamination of PB early after ABMT appears to be the consequence of reinfusion of lymphoma cells within autologous marrow.     

Comparative analysis between RQ‐PCR and digital droplet PCR of BCL2/IGH gene rearrangement in the peripheral blood and bone marrow of early stage follicular lymphoma

BCL2/IGH rearrangements were analysed by polymerase chain reaction (PCR) at diagnosis in paired peripheral blood (PB) and bone marrow (BM) samples from 67 patients with stage I/II follicular lymphoma (FL). Real time quantitative PCR (RQ‐PCR) and digital droplet PCR (ddPCR) were performed in cases with a major breakpoint region (MBR+) at diagnosis and after localized radiotherapy and rituximab administration in order to investigate the applicability of ddPCR. The overall ddPCR/RQ‐PCR concordance was 81·9% (113/138 samples) and 97·5% in the 40/138 with quantifiable disease (RQ‐PCR≥10⁻⁵). At baseline, ddPCR allowed the recovery of a MBR+ marker in 8/18 (44·4%) samples that resulted MBR‐negative/minor cluster region‐negative/minor BCL2‐negative by qualitative PCR. Moreover, the tumour burden at diagnosis significantly predicted progression‐free survival (PSF) only when quantified by ddPCR. Paired PB and BM samples analysis demonstrated a high concordance in the detection of BCL2/IGH+ cells by qualitative and quantitative methods; in particular, 40/62 samples were positive by ddPCR (25 PB+/BM+; 9 PB+/BM−; 6 PB−/BM+), with 34/40 (85%) identified by the study of PB only. In conclusion, in localized FL, ddPCR is a promising tool for monitoring minimal residual disease (MRD) that is at least comparable to RQ‐PCR and potentially more accurate. PB is a suitable source for serial BCL2/IGH MRD assessments, regardless of the methodology utilized.     

Dynamics of circulating t(14;18)-positive cells during first-line and subsequent lines of treatment in follicular lymphoma

In follicular lymphoma the t(14;18) might be useful as a tumor marker in predicting the quality of the response to treatment. We investigated whether analyzing numbers of t(14;18)-positive cells in peripheral blood correlated with remission status in individual patients receiving a variety of treatments. Numbers of circulating t(14;18)-positive cells were determined by real-time polymerase chain reaction (PCR) technique. Disease parameters and response to treatment were related to the pre- and post-treatment numbers of circulating t(14;18)-positive cells for 53 follicular lymphoma patients. In these 53 patients, 70 treatment episodes were investigated. A content of more than 328 t(14;18)-positive cells per 75,000 cells prior to therapy correlated with the more advanced stage IV disease (P=0.01), bone marrow involvement (P<0.01), and overt leukemic lymphoma (P=0.04). Therapy episodes that cleared circulation from t(14;18)-positive cells with more than one log resulted in a significantly longer progression-free survival than treatment episodes with less than one log decline (26 versus 12 months, respectively) (P<0.01). After first-line treatment episodes, numbers of circulating t(14;18)-positive cells declined in fairly all cases, irrespective of the clinical response. However, for second or later lines of treatment, declining numbers of lymphoma cells correlated with a clinical remission, whereas increasing numbers of lymphoma cells were associated with clinically stable or progressive disease. From this, we conclude that quantitation of circulating t(14;18)-positive cells in peripheral blood is of only limited clinical significance in predicting treatment efficacy for the individual follicular lymphoma patient.Supported by an unrestrictive grant from Schering-Plough (JMMR)     

Detection by polymerase chain reaction of residual cells with the bcl-2 translocation is associated with increased risk of relapse after autologous bone marrow transplantation for B-cell lymphoma

Although molecular biologic techniques can now detect minimal numbers of residual cancer cells in patients in complete clinical remission, the clinical significance of minimal residual disease has never been conclusively established. If the detection of minimal residual disease predicts which patients will relapse, then therapy could be altered based upon the detection of these cells. The t(14;18) can be detected by polymerase chain reaction (PCR) amplification in 50% of patients with B-cell non-Hodgkin's lymphoma and allows detection of one lymphoma cell in up to 1 million normal cells. To determine the clinical significance of the detection of minimal residual lymphoma cells in the bone marrow (BM) PCR amplification was used to detect the presence of residual lymphoma cells after autologous BM transplantation (ABMT) in serial BM samples from 134 patients with B-cell lymphoma in whom a bcl- 2 translocation could be detected. PCR analysis was performed on a total of 542 BM samples obtained while these patients were in complete remission. Disease-free survival was markedly increased in patients with no PCR-detectable lymphoma cells in the marrow compared with those in whom residual lymphoma cells were detected (P < .00001), and the presence of detectable lymphoma cells was associated with a 48-fold increase in the risk of relapse. Of the 77 patients (57%) with no PCR- detectable lymphoma cells in their most recent BM sample, none have relapsed. In contrast, all 33 patients (25%) who have relapsed had PCR- detectable lymphoma cells detected in their BM before clinical relapse occurred. In 19 patients (14%), residual lymphoma cells in the BM were detected early following transplantation and subsequently were no longer detectable, although these patients received no further therapy. In these patients, residual lymphoma cells may already have been irreversibly damaged by the high-dose therapy or an endogenous immune mechanism may be capable of eliminating residual lymphoma cells in some patients. Therefore, although the detection of minimal residual disease by PCR following ABMT in patients with lymphoma identifies those patients at high risk of relapse, the presence of residual minimal disease early after transplantation may not be associated with poor prognosis in a small subset of patients. Confirmatory studies will be required to determine more definitively the role of minimal disease detection to identify which patients require additional therapy.     

Fate of contaminating t(14; 18)+ lymphoma cells during ex vivo expansion of CD34-selected hematopoietic progenitor cells

The use of ex vivo expanded CD34-selected hematopoietic progenitor cells (HPCs) for autologous stem cell support or gene therapy is a major area of research and is likely to increase in the future. At present, little is known about the fate of contaminating malignant cells during ex vivo expansion of CD34-selected HPCs. We established a competitive polymerase chain reaction (PCR) titration assay to determine the number of residual lymphoma cells before and after selection and ex vivo expansion of CD34-selected HPCs in patients with t(14; 18) translocation carrying non-Hodgkin's lymphoma. Seven bone marrow (BM) and 2 mobilized peripheral blood progenitor cell samples from 8 patients without histologic BM involvement at the time of the harvest were analyzed by competitive PCR titration assay and determined to contain between < or = 10 and 4,000 lymphoma cells/ 10(6) mononuclear cells (MNCs). Immunoadsorption enriched CD34+ cells from a mean of 5% (range, 1% to 9%) to a mean of 88% (range, 76% to 94%) of MNCs and resulted in a 1 to 4 log depletion of contaminating tumor cells. Two HPC samples became PCR negative after CD34 selection, whereas 7 samples still contained < or = 10 to 200 residual lymphoma cells/10(5) MNCs. CD34-selected cells were consecutively expanded in suspension culture in the presence of stem cell factor, interleukin-1 beta (IL-1 beta), IL-3, and IL-6. The mean increase of cells was 13- fold (range, 4- to 22-fold) at day 7 and 65-fold (range, 43- to 110- fold) at day 14 of culture. Expansion resulted predominantly in myelomonocytic differentiation, whereas B-cell antigen-expressing cells became undetectable. Six of the seven PCR-positive CD34-selected samples became PCR-negative for the t(14; 18) translocation at day 7 and/or 14 of expansion. One PCR-positive and one PCR-negative CD34- selected sample were PCR-positive after ex vivo expansion, but the number of residual lymphoma cells remained at the limit of detection. We conclude that CD34-selection does not eliminate contaminating lymphoma cells in the majority of t(14; 18)+ HPC harvests. However, during ex vivo expansion of CD34-selected HPCs, residual t(14; 18)+ lymphoma cells do not proliferate and become undetectable by PCR in the majority of cases.     

Quantitation of follicular non-Hodgkin's lymphoma cells carrying t(14;18) by competitive polymerase chain reaction

Summary. A competitive polymerase chain reaction (PCR) technique was developed to quantify residual malignant cells in the peripheral blood and bone marrow of patients with low-grade follicular non-Hodgkin's lymphoma carrying a translocation between chromosomes 14 and 18. Artificial segments were constructed imitating a translocation between chromosome 14 and 18. These artificial translocation segments were used as competitor molecules in the quantitative PCR. Serial dilutions of a known amount of patient-derived translocation segments were coamplified with a fixed number of competitor molecules, and a patient specific calibration curve was constructed. Several patient samples were coamplified with an equal number of competitor molecules and the number of t(14;18) translocations within the samples was calculated by comparison with the calibration curve.
The method was demonstrated on samples of four follicular non-Hodgkin's lymphoma (NHL) patients. In a patient transplanted with allogeneic bone marrow declining numbers of residual lymphoma cells were observed.
We conclude that the method is accurate, relatively fast and the general principle of this method can be applied to all malignancies with characteristic abnormalities on DNA or RNA level that are detectable by PCR.     

The relative role of peripheral blood and bone marrow for monitoring molecular evidence of disease in follicular lymphoma by quantitative real-time polymerase chain reaction

Peripheral blood (PB) and bone marrow (BM) are used interchangeably for t(14;18) (IgH/BCL-2) molecular monitoring in follicular lymphoma (FL) and detection of rearrangement after treatment has been correlated to increased risk of relapse. To determine the relative value of each tissue, MBR t(14;18) was quantified by real-time polymerase chain reaction in 52 simultaneous paired PB and BM samples from 38 FL patients. In total, 79% of sample pairs taken in remission (n = 19) or when no morphological disease was evident in the BM (n = 29) had t(14;18) copy number within one log difference and the median difference was small. These findings suggest that, in remission, PB may be adequately monitored. In general, however, higher copy number was detected in BM than in the corresponding PB sample.     

High-dose therapy and autologous bone marrow transplantation in patients with follicular lymphoma during first remission

We report the results of a study in previously untreated advanced stage patients with follicular lymphoma (FL) who underwent uniform induction chemotherapy with cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP) followed by myeloablative therapy and anti-B-cell monoclonal antibody purged autologous bone marrow transplantation (ABMT). Eighty-three patients with previously untreated, low-grade FL were enrolled. After CHOP induction, only 36% achieved complete remission (CR) and 77 patients underwent ABMT. Before BM harvest, 70 patients had a known t(14;18), as determined by polymerase chain reaction (PCR), and all remained PCR positive in the BM at harvest. After ABMT, the disease-free survival (DFS) and overall survival are estimated to be 63% and 89% at 3 years, respectively, with a median follow-up of 45 months. Patients whose BM was PCR negative after purging experienced significantly longer freedom from recurrence (FFR) than those whose BM remained PCR positive (P = .0006). Continued PCR negativity in follow-up BM samples was also strongly predictive of continued CR. This study suggests that a subset of patients with advanced FL may experience prolonged clinical and molecular remissions following high-dose ablative therapy, although longer follow-up will be necessary to determine potential impact on overall survival.     

Frequency and evaluation of t(14;18) translocation in Sjögren's syndrome

In most cases of follicular lymphoma, t(14;18) chromosomal translocation can be detected in lymphocytes of peripheral blood and bone marrow. Nevertheless, certain other types of diseases can also be characterised by the presence of the translocation. Patients of Sjögren's syndrome have an increased frequency of developing non-Hodgkin's lymphoma, e.g. follicular lymphoma; in turn, they may have translocation-bearing cells. One hundred Sjögren's syndrome patients were screened using a nested polymerase chain reaction technique to identify whether they had the translocation in their peripheral blood lymphocytes. Five percent of that population revealed a temporary or long-lasting presence of the translocation, sometimes even in the lymphocytes from bone marrow. Our results indicate that in addition to the conventional diagnostic methods of lymphoma, there are certain other factors, e.g. the duration of the presence of t (14; 18) translocation and the source of lymphocytes, that should be considered for successful early diagnoses and perhaps for treatment of the lymphoma in the Sjögren's patients.     

Diagnostic usefulness of bone marrow aspiration material for the amplification of IS6110 insertion element in extrapulmonary tuberculosis: comparison of two PCR techniques.

SETTING: In many cases of extra-pulmonary tuberculosis (EPTB), with the exception of paucibacillary analysed specimens, the suspected site of mycobacterial infection is relatively inaccessible or unknown, making laboratory confirmation of TB laborious and problematic. OBJECTIVE: Two different polymerase chain reaction (PCR) based methods were compared to investigate the validity of bone marrow aspiration material as an easily accessible alternative sample for molecular analysis in EPTB. DESIGN: We amplified the same sequence of IS6110 of Mycobacterium tuberculosis complex in 19 confirmed cases of EPTB using two different nested PCR techniques: one in-house 'classic' PCR and another based on LightCycler technology. RESULTS: Both methods demonstrated the same reliability when performed in samples of infected tissue. However, the LightCycler protocol was superior to the in-house system when applied in bone marrow aspiration material, revealing positivity in 18/19 compared to 13/19 samples of 'classic' PCR. CONCLUSION: The application of an optimised LightCycler nested amplification protocol in bone marrow aspirates may promote diagnostic accuracy in difficult and/or urgent cases of EPTB.     

The detection of minimal lymphoma by molecular and combined culture–molecular methods

Seventy-four patients from a prospective randomized trial comparing autologous bone marrow (ABM) versus blood stem cell (BSC) transplantation after high-dose chemotherapy for intermediate and high grade non-Hodgkin's lymphoma (NHL) were studied for the presence of residual lymphoma prior to transplantation. Pre-transplant bone marrow (BM), peripheral blood (PB) and the ABM or BSC harvest were studied by molecular assays immediately after collection and at weekly intervals after the initiation of in vitro cultures. B-NHLs with t(14;18) at the major breakpoint region (mbr) were monitored by detecting cells with the translocation. Other B-NHLs were monitored with tumour-specific primers and probes to the immunoglobulin heavy chain (IgH) gene complementary determining region (CDR) III. T-NHLs were similarly monitored using the T-cell receptor gamma chain gene V-J junctional region as the tumour-specific marker. Of the 74 patients, seven did not have adequate tumour biopsies for molecular characterization. Of the remaining 67 cases, 35 had identifiable markers for follow-up studies and 20/35 cases (52%) had tumour cells detected in either the pretransplant BM/PB samples or the ABM/BSC harvest. Residual tumours were detected at a high frequency in T-NHL (100%) and t(14;18)⁺ B-NHL (86%) but at a lower frequency in B-NHLs without t(14,18) (44%). In five cases, one or more of the samples were initially negative for residual lymphoma but became positive after a period of culture; additional studies confirmed that in vitro culture enhanced the sensitivity of tumour detection in about half of these samples. Molecular assay for minimal residual disease can be performed in the setting of multicentre prospective clinical trials. The substantial frequency of failure of obtaining tumour-specific IgH CDRIII sequences in paraffin-embedded B-NHLs argues for the storage of frozen tumour samples for possible molecular studies.     

Eradication of polymerase chain reaction detectable immunoglobulin gene rearrangement in non-Hodgkin's lymphoma is associated with decreased relapse after autologous bone marrow transplantation

In B-cell non-Hodgkin's lymphoma (NHL), as in other B-cell malignancies, clonal rearrangement of the third complementarity determining region (CDR III) of the immunoglobulin heavy chain gene (IgH) provides a useful marker for the detection of minimal residual disease (MRD) after treatment. To determine the clinical utility of IgH polymerase chain reaction (PCR), we analyzed peripheral blood (PB) and bone marrow (BM) samples from 25 patients with NHL with no PCR detectable chromosomal rearrangement who have undergone autologous bone marrow transplantation (ABMT). Patients with histologic bone marrow infiltration at the time of bone marrow harvest were selected for study since this provided us with diagnostic tissue samples. As an initial strategy DNA was amplified using consensus variable (VH) and joining (JH) region primers. In those cases failing to amplify using consensus region primers, PCR was performed using a panel of VH family-specific framework region 1 (FR1) primers. The clonal products were directly sequenced. From the V-N-D region nucleotide sequences, clone specific probes were constructed and used for subsequent detection of MRD. A clonal PCR product could be PCR amplified and directly sequenced in 18 (72%, 90% confidence intervals 54%-86%) of these 25 patients, 8 with diffuse and 10 with follicular NHL. Eight of these 18 patients have relapsed after ABMT. All had detectable lymphoma cells before relapse and the sequence of the CDR III region at the time of relapse was identical to that obtained at the time of ABMT. All 10 patients who remain in complete remission from 18 to 36 months after ABMT had eradication of PCR detectable lymphoma cells after ABMT, although in three patients PCR detectable MRD was detected early after ABMT. We conclude that sequencing and the use of patient specific IgH CDR III oligonucleotides probes provides a simple and highly reliable method to determine the specificity of the IgH PCR technique. The clinical utility of this technique is demonstrated by the finding that eradication of PCR detectable lymphoma cells in these patients is associated with decreased relapse after ABMT (P = .0002).     

Quantitation of minimal residual disease in multiple myeloma using an allele-specific real-time PCR assay

OBJECTIVE: To develop a real-time PCR method, based on the 5'nuclease TaqMan technology, for quantitation of clonal cells in multiple myeloma (MM). MATERIALS AND METHODS: The real-time quantitative PCR method incorporates both an allele-specific oligonucleotides (ASO) primer and an ASO dual-labeled fluorogenic probe (ASO TaqMan probe). The ASO primer and probe corresponded to the complementary determining region 3 (CDR3) of the rearranged immunoglobulin heavy chain gene (IgH). With the use of a sequence detector, PCR product accumulation was measured through the ASO TaqMan probe. The real-time PCR method was compared with flow cytometric quantitation of myeloma plasma cells. RESULTS: The application of the real-time quantitative ASO IgH PCR method is illustrated by a sequential analysis of minimal residual disease (MRD) in bone marrow (BM) samples from myeloma patients undergoing peripheral blood stem cell (PBSC) transplantation. The real-time PCR method was able to quantitate residual malignant cells in BM samples from patients who were considered to be in complete remission. Further, it was illustrated that a potential problem in determining tumor cell content in myeloma BM samples is the heterogeneous infiltration of the marrow. CONCLUSION: The application of the real-time PCR method provides a sensitive, highly specific, and reproducible quantitation of myeloma cells.     

A UK multicentre phase II study of rituximab (chimaeric anti-CD20 monoclonal antibody) in patients with follicular lymphoma, with PCR monitoring of molecular response

Follicular lymphoma (FL) cells express CD20 and are associated in most cases with the t(14;18) chromosomal translocation. A multicentre study was undertaken between January 1997 and January 1998 to assess the complete response rate (CR) and overall response rate (RR) to rituximab, a chimaeric anti-CD20 monoclonal antibody. Seventy patients with previously treated FL received rituximab (375 mg/m2/week x4, by intravenous infusion). Restaging studies were performed 1 and 2 months after therapy. Molecular monitoring for the presence of cells harbouring the Bcl-2/JH gene rearrangement in the peripheral blood (PB) and bone marrow (BM) was performed before and after treatment using a two-step semi-nested polymerase chain reaction (PCR) assay. The overall RR was 32/70 (46%), being highest in patients who had received only one previous treatment (12/15, 80%). However, only two patients achieved a CR. The median duration of response was 11 months. Thirteen of 21 evaluable 'PCR-positive' patients (62%) became 'PCR-negative' in PB and/or BM samples 1 month after rituximab, although this did not correlate with clinical response. Treatment was generally well tolerated, although one patient developed Stevens-Johnson syndrome. Rituximab was shown to be active in FL, and in some cases PB and/or BM became PCR negative. Studies in combination with cytotoxic chemotherapy to increase the CR rate are warranted.     

Long-term follow-up of autologous bone marrow transplantation in patients with relapsed follicular lymphoma.

We report the results of high-dose chemoradiotherapy and anti-B-cell monoclonal antibody-purged autologous bone marrow transplantation (ABMT) in patients with relapsed indolent follicular lymphoma. Between March 1985 and May 1995, 153 patients underwent ABMT using a uniform ablative regimen with cyclophosphamide and total body irradiation and bone marrow (BM) purging. All patients received multiple chemotherapy regimens before ABMT. At BM harvest, only 30% of patients were in complete remission, and overt BM infiltration was present in 47%. The disease-free survival (DFS) and overall survival (OS) are estimated to be 42% and 66% at 8 years, respectively. Patients whose BM was negative by polymerase chain reaction (PCR) for bcl2/IgH rearrangement after purging experienced longer freedom from recurrence than those whose BM remained PCR positive (P <.0001). Continued PCR negativity in follow-up BM samples was also strongly predictive of continued complete remission (CR). The 12-year survival from diagnosis for these 153 patients is 69%. Considering that the median survival from diagnosis and first recurrence of patients with advanced follicular lymphoma are 8 and 5 years, respectively, our results provide evidence that myeloablative therapy and ABMT may prolong overall survival.