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.     

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.     

Quantitative PCR of bone marrow BCL2/IgH+ cells at diagnosis predicts treatment response and long-term outcome in follicular non-Hodgkin lymphoma

By real-time quantitative polymerase chain reaction (RQ-PCR), we evaluated BCL2/IgH(+) cells in the bone marrow (BM) and peripheral blood (PB) from 86 patients with follicular lymphoma treated with the sequential administration of CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) and rituximab. At diagnosis, the amount of BCL2/IgH(+) cells in the BM was low (1 BCL2/IgH(+) cell in 1000-100 000 normal cells) in 43% of patients, intermediate (1 in 100-1000) in 34%, and high (> 1 in 100) in 23%. A 2 log decrease of BCL2/IgH(+) cells was achieved after CHOP and an additional 2 log reduction following rituximab. By multivariate analysis, a low level of BCL2/IgH(+) cells in the BM at diagnosis was the best predictor for the achievement of a complete clinical and molecular response. At 5 years, the event-free survival rates of patients with a low/intermediate or high tumor infiltration in the BM were 59% and 32%, respectively. The freedom from recurrence of patients who achieved a molecular response in the BM, no matter whether after CHOP alone or CHOP and rituximab, was 64% as compared to 32% for patients who did not (P < .006). RQ-PCR performed at presentation on BM samples predicts treatment response and long-term clinical outcome in patients with follicular lymphoma.     

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.     

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.     

Reliable detection of clonal IgH/Bcl2 MBR rearrangement in follicular lymphoma: methodology and clinical significance

The prognostic significance of IgH/Bcl2 rearrangement in follicular lymphoma (FL) remains contentious; polymerase chain reaction (PCR) methodology and tissue source variability may account for some inconsistencies. As IgH/Bcl2 major breakpoint region (MBR) sequences may be found in normal blood, an MBR+ result by conventional PCR in blood/bone marrow may not indicate FL. To establish tumour MBR status, 190 lymphoid tissue samples with histologically evident FL (and therefore >1% tumour cells) were examined by real-time quantifiable PCR; 50% (95/190) had clonal MBR IgH/Bcl2 (MBR was considered clonal when >1%). Overall survival (median = 11.5 years) of MBR+ and MBR- patients was not significantly different.     

JH probe real-time quantitative polymerase chain reaction assay for Bcl-2/IgH rearrangements

Follicular lymphoma (FL) characteristically bears the t(14;18)(q32;q21). However, only approximately 75% of the consequent Bcl-2 breakpoints lie within the major breakpoint region (MBR) or the minor cluster region (mcr). While these can be quantified by cluster region-specific real-time quantitative polymerase chain reaction (RQ-PCR), a significant proportion of cases are left requiring a customized approach. Therefore, an RQ-PCR assay for the quantification of Bcl-2/IgH breakpoints has been developed that uses germline JH TaqMan probes and germline JH primers in combination with customized forward primers. Validation of this approach by comparison with an established MBR RQ-PCR showed both techniques to be concordant across a wide range of copy numbers with a sensitivity of five copies per 10(5) cells. In addition, to generate standard curves equating to diverse Bcl-2/IgH rearrangements, a strategy for using placental DNA as a surrogate standard was devised. The performance of the assay in detecting molecular evidence of disease in sequential biopsies from five patients (three with atypical Bcl-2/IgH breakpoints identified by long-range or inverse PCR, one MBR+ and one mcr+) was tested. This alternative approach represents a sensitive and specific means of quantifying common and atypical Bcl-2/IgH rearrangements and maximizes the number of patients with FL suitable for molecular monitoring.     

Recurrence of Bcl-2/IgH polymerase chain reaction positivity following a prolonged molecular remission can be unrelated to the original follicular lymphoma clone

OBJECTIVE: The aim of this study was to evaluate whether reappearance of polymerase chain reaction (PCR) positivity for the Bcl-2/IgH translocation following a phase of molecular remission in autografted follicular lymphoma (FL) patients is always associated with reappearance of the original neoplastic clone. PATIENTS AND METHODS: The molecular follow-up of 119 autografted Bcl-2/IgH positive patients was evaluated by nested PCR. In case of molecular recurrence, direct sequencing of involved rearrangements has been performed both at diagnosis and at the time of recurrence. The two sequences then were compared in terms of breakpoints, N insertions, and JH usage. RESULTS: Seventy-five patients achieving molecular remission were identified in our patient sample (63%). Of these patients, eight (10.6%) experienced molecular recurrence. Direct sequencing of the Bcl-2/IgH translocation performed at diagnosis and recurrence showed identical rearrangements in six subjects and unrelated rearrangements in two. As opposed to most true molecular relapses, unrelated rearrangements always occurred several years after transplantation. To date, the two subjects carrying unrelated rearrangements show no signs of active lymphoproliferative disease. CONCLUSIONS: This report is the first evidence that Bcl-2/IgH rearrangements unrelated to the original tumor clone can lead to false-positive results during the molecular follow-up of autografted FL patients. Based on these results, we recommend confirmation by direct sequencing, at least for patients experiencing molecular relapse 2 or more years after the end of treatment. This will be particularly important for patients enrolled in clinical trials that schedule additional treatment in case of molecular evidence of persistent disease activity.     

Molecular characteristics and prognostic significance of Bcl-2/IgH gene rearrangement in Serbian follicular lymphoma patients

Follicular lymphoma (FL) is characterized by the presence of a t(14;18) chromosomal translocation that results in overexpression of bcl-2 protein. Bcl-2/IgH gene rearrangement is detected in 80-90% of follicular lymphomas in Western countries. The aim of this study was to analyze the bcl-2/IgH rearrangement in FL lymphoma patients in Serbia, by PCR technique, correlate molecular findings with clinical characteristics and outcome and assess the prognostic significance of these rearrangements. One hundred-seven patients (median age, 54 years; male/female ratio:60/47) diagnosed with FL were included in the study. DNA samples were obtained from paraffin embedded lymphoid tissue of patients. Bcl-2/IgH rearrangement was assessed for the major breakpoint region (MBR), 5' MBR and the minor cluster region (mcr) breakpoints by PCR technique. We detected a t(14;18) in 81.3% (87/107) of patients. The distribution of bcl-2-IgH rearrangement was as follows: 88,5% (77/87) in MBR breakpoint, 10,35% (9/87) in 5' MBR, whereas mcr bcl-2-IgH rearrangement was observed in one patient (1.15%). No rearrangements were detected in remaining 20 patients (18.7%). This is the first analyses of the frequency of the bcl-2/IgH gene rearrangement in Serbian FL patients, as well as in Eastern European countries. There was no correlation between presence of bcl-2/IgH gene rearrangement and clinical outcome of disease. Incidence of bcl-2/IgH gene rearrangement in Serbian FL patients is relatively high, and similar to frequency in Western countries. Presence of this rearrangement in tumor tissue is not of prognostic significance.     

High-dose sequential chemoradiotherapy in multiple myeloma: residual tumor cells are detectable in bone marrow and peripheral blood cell harvests and after autografting

Based on preliminary encouraging results in terms of response rate and survival, high-dose chemoradiotherapy has gained considerable interest in the treatment of patients with multiple myeloma (MM). We have evaluated the presence of residual myeloma cells in 15 of 18 patients enrolled in a high-dose sequential (HDS) chemoradiotherapy program followed by autografting. Our analysis has been performed both on bone marrow (BM) and peripheral blood (PB) cell harvests and after autografting. As it has been recently shown that B cells clonally related to malignant plasma cells are detectable in MM patients, we have developed a polymerase chain reaction (PCR)-based strategy to detect both residual B cells and plasma cells using clone-specific sequences derived from the rearrangement of Ig heavy chain (IgH) genes. The complementarity-determining regions (CDR) of IgH genes have been used to generate tumor-specific primers and probes. The constant (C) region usage defined the differentiation stage of residual myeloma cells. We report that plasma cells were detectable in PB and BM cell harvests and after transplantation in all assessable patients, irrespective of disease status. B cells were detectable in a consistent proportion of BM and PB samples at diagnosis, but only in one case at the time of PB and BM cell harvests. These cells became sometimes detectable after transplantation. Whether residual myeloma cells are clonogenic and contribute to relapse is currently unknown, and further investigations are required.     

Autologous stem cell transplantation (ASCT) with immunologically purged progenitor cells in patients with advanced stage follicular lymphoma after early partial or complete remission: toxicity, follow-up of minimal residual disease and survival

The role of autologous stem cell transplant (ASCT) in indolent lymphomas is a controversial issue. From 1994 to 1999, we performed ASCT with immunologically purged progenitor cells in 15 patients with advanced stage follicular lymphoma (FL) after early partial or complete remission. Results of the purging strategy and follow-up of minimal residual disease after transplant were analyzed with PCR amplification of bcl-2/IgH rearrangement for the t(14;18) translocation. A comparison of transplanted patients with a group of controls was carried out to evaluate differences in progression-free survival and overall survival. Eighty percent of patients received one chemotherapy regimen before ASCT and were in first remission. All the patients received cyclophosphamide plus hyperfractionated total body irradiation as the conditioning regimen. Nine patients were transplanted with bone marrow (BM) and six with peripheral blood progenitor cells (PBPC). Engraftment was delayed in one patient transplanted with BM. Two patients died during the transplant procedure. Ten of 12 evaluable patients were PCR positive in the BM for bcl-2 rearrangement at diagnosis. Six of them (60%) were still positive after chemotherapy, and one patient was transplanted with a positive hematopoietic product after purging. With a median follow-up of 27 months, six of eight evaluable patients still remain PCR negative in the BM. With a median follow-up of 4.7 years from diagnosis, progression-free survival was 83% (95% CI: 63-100). The risk of disease progression of non-transplanted patients was 19.2 times higher than that of transplanted patients (P = 0.01), but no differences were found in overall survival. Regarding patients in first remission, the risk of relapse was 12.6 times higher in non-transplanted than in transplanted patients (P = 0.04). This procedure seems to offer a good chance to achieve a PCR-negative state and prolonged freedom from recurrence. According to these results, prospective randomized trials are warranted.     

DAP-kinase hypermethylation in the bone marrow of patients with follicular lymphoma

We studied whether DAP-kinase hypermethylation plays a role as a prognostic marker in patients with follicular lymphoma (FL). We found that DAP-kinase was frequently hypermethylated in bone marrow (BM) samples of 52 FL patients at diagnosis (71%) and identified patients with worse progression-free survival (p=0.06). In particular, patients with histologically proven BM infiltration and DAP-kinase hypermethylation had a poorer outcome (p=0.037). In a total of 170 BM samples obtained at diagnosis or during follow-up, DAP-kinase hypermethylation and the bcl2/IgH rearrangement gave concordant results in 67% of samples (48% both positive, 19% both negative). Both mrakers were independent predictors of the disease status (p<0.001).     

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.     

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.     

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.     

Morphologic transformation of follicular lymphoma is associated with somatic mutation of the translocated Bcl-2 gene

Follicular lymphoma (FL) is a low-grade B-cell non-Hodgkin's lymphoma (NHL) that frequently transforms into diffuse aggressive NHL. The majority of FLs display a t(14; 18) translocation that places the bcl-2 gene into juxtaposition with the lg heavy-chain (H) gene locus. Morphologically transformed malignant FL cells retain their t(14;18) translocation and may acquire additional genetic abnormalities. We analyzed serial biopsy specimens from eight patients with FL for secondary alterations of the rearranged bcl-2 gene in the breakpoint and open reading frame (ORF) regions. Two cases of FL showed no histologic alteration in the second biopsy, and six cases of FL showed morphologic transformation to diffuse large-cell lymphoma (DLL) in the second biopsy. Polymerase chain reaction (PCR) amplification, cloning, and sequencing of the junctional region of the hybrid bcl-2/IgH genes showed identical nucleotide sequences in multiple biopsy specimens of FL that did not show morphologic transformation. In patients in whom FL cells underwent morphologic transformation, FL and autologous DLL cells displayed identical bcl-2/IgH gene nucleotide sequences in five cases and different sequences in one case. In the case for which FL and DLL cells showed different bcl-2/IgH junctional sequences, DLL cells incorporated larger bcl-2 and Ig-joining (JH) gene fragments than the corresponding FL cells, suggesting that DLL clones developed by a distinct t(14; 18) translocation rather than by alteration of the hybrid bcl-2/IgH gene detected in the FL cells. In all eight cases, neither FL nor DLL cells showed alterations of bcl-2 gene sequences in the breakpoint region, suggesting high conservation of the bcl-2 gene during both t(14; 18) translocation and morphologic transformation of the FL cells. PCR single-strand conformation polymorphism (SSCP) and sequence analyses were performed for identification of structural alterations of the bcl-2 gene in the ORF region corresponding to the 239-amino acid p26-bcl-2 alpha protein. A total of 11 point mutations of the ORF were detected in DLL cells of three transformed NHLs, but no alteration of the ORF was detected in FL cells. Four of 11 mutations, at positions 29, 46, 59, and 106, yielded amino acid replacements. These findings demonstrate that FL and DLL cells may be clonally related or unrelated. They also show that transformation of FL cells may be associated with somatic point mutations of the bcl-2 proto- oncogene ORF sequence resulting in alteration of the p26-bcl-2 alpha gene product.     

A real-time (PCR) for a real life…? Quantitative evaluation of BCL2/IGH in follicular lymphoma and its implications for clinical practice

Follicular lymphoma (FL) is highly associated with the molecular rearrangement BCL2/IGH. Although BCL2/IGH has been studied many times in follicular lymphoma, its real clinical value remains controversial. In this study, we performed quantitative testing by real-time polymerase chain reaction in 56 FL patients with median follow-up of 44 months (range, 9-102 months); chemotherapy was administered in 52 of 56 cases. Pretreatment numbers of BCL2/IGH varied in wide ranges, with a median of 2947 (range, 0-1,261,013) copies/10(6) cellular equivalent in peripheral blood (PB) and 4650 copies/10(6) cellular equivalent (range, 1-1,056,813) in bone marrow (BM), the difference between PB and BM was significant (p?= 0.006). Pretreatment of BCL2/IGH quantities were correlated to clinical parameters (e.g., age, stage, sex, lactate dehydrogenase, B symptoms, grade, bulky disease, chemotherapy regimen) and to progression free-survival. Advanced clinical stage (III and IV) and microscopic BM involvement were significantly associated with higher numbers of BCL2/IGH in PB (p < 0.05) and in BM (p = 0.05), regardless all or newly diagnosed patients were evaluated. High pretreatment burden of BCL2/IGH was associated with significantly shorter progression-free survival; p = 0.003 and p = 0.047 for PB and BM, respectively. In conclusion, pretreatment quantity of BCL2/IGH in PB or BM seems to mirror the extent of disease and can provide an auxiliary prognostic parameter in FL. Our results also support evidence of the negative prognostic value of microscopic BM involvement in FL.     

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).