Comparison of different strategies of molecular genetic monitoring following autologous stem cell transplantation in patients with follicular lymphoma

Current and future therapeutic approaches for the treatment of follicular lymphoma

INTRODUCTION

Recent advances in prognostication as well as management of Follicular Lymphoma (FL) are moving to personalized approach. Areas covered: Prognostic scores as well as consolidated and innovative therapeutic approaches are evaluated according to the various presentation modalities. For asymptomatic, low-tumor burden FL, a 'watch and wait' policy is currently the first-choice approach, although possible alternatives are discussed. Early stage FL may be treated with local radiotherapy although the role of minimal residual disease in possible additional agents should be determined. The first line treatment for symptomatic FL is chemo-immunotherapy followed by two years maintenance therapy with anti-CD20 monoclonal antibodies. A deeper knowledge of FL biology has opened new perspectives regarding the timing of therapy and has offered new targets for the development of novel agents that aim to change the therapeutic scenario of FL management. Expert commentary: The introduction of novel agents could question the incurability of FL and change the therapeutic goal from prolonging the complete remission state to eradicating the disease in young/fit patients, as well as improving quality of life in elderly/unfit patients. In the near future, combining new biologic agents and adoptive cell therapies could help in achieving these aims.

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.

Minimal residual disease after conventional treatment significantly impacts on progression-free survival of patients with follicular lymphoma: the FIL FOLL05 trial

PURPOSE

The role of the minimal residual disease (MRD) in follicular lymphoma is still debated. In this study, we assessed whether the BCL2/IGH rearrangement could have a prognostic role in patients receiving R-CHOP, R-FM, or R-CVP.

EXPERIMENTAL DESIGN

DNAs from 415 patients among the 504 cases enrolled in the FOLL05 trial (NCT00774826) were centralized and assessed for the BCL2/IGH at diagnosis, at the end of treatment, and after 12 and 24 months.

RESULTS

At diagnosis, the molecular marker was detected in 53% of cases. Patients without molecular marker or with a low molecular tumor burden (<1 × 10(-4) copies) showed higher complete remission (CR) rate and longer progression-free survival (PFS; 3-year PFS 80% vs. 59%; P = 0.015). PFS was significantly conditioned by the PCR status at 12 and 24 months, with 3-year PFS of 66% for MRD(-) cases versus 41% for those MRD(+) at 12 months (P = 0.015), and 84% versus 50% at 24 months (P = 0.014). The MRD negativity at 12 and 24 months resulted in an improved PFS both in CR and in partial remission (PR) patients (3-year PFS = 72% for cases CR/PCR(-) vs. 32% for those CR/PCR(+) vs. 62% for those PR/PCR(-) and 25% for patients in PR/PCR(+); P = 0.001). The prognostic value of MRD at 12 and 24 months of follow-up was confirmed also in multivariate analysis.

CONCLUSIONS

In this study, standardized molecular techniques have been adopted and applied on bone marrow samples from a large cohort. Data reported show that the MRD detection is a powerful independent predictor of PFS in patients with follicular lymphoma receiving conventional chemoimmunotherapy.

Minimal residual disease detection in lymphoma and multiple myeloma: impact on therapeutic paradigms

Early identification of patients at high risk of relapse is a major goal of current translational research in oncohematology. Minimal residual disease (MRD) detection by polymerase chain reaction-based methods is currently part of the routine clinical management of patients with acute lymphoblastic leukemia. However, the current knowledge indicates that it is also a useful prognostic tool in several mature lymphoproliferative disorders. Its utility is currently well established in follicular lymphoma, mantle cell lymphoma, and multiple myeloma. In some of these entities, clinical trials employing MRD as a decision-making tool are currently ongoing. In the present review, we will discuss the 'state of the art' of MRD evaluation in these three neoplasms with the ultimate aim of providing critical take-home messages for clinicians working in the field. Moreover, we will outline the role of MRD detection in the design of future clinical trials.

Commercial LightCycler-based quantitative real-time PCR compared to nested PCR for monitoring of Bcl-2/IgH rearrangement in patients with follicular lymphoma

Translocation of chromosomes 14 and 18 [t(14;18)] for detection of minimal residual disease in follicular lymphoma patients can be analyzed by nested polymerase chain reaction (PCR) or by quantitative PCR like LightCycler-based assays. We have compared both methods in blood and bone marrow samples of 28 patients enrolled in a clinical study on immunochemotherapy. In 42% of samples, the bcl2-IgH rearrangement was detectable by nested PCR, but not by LightCycler PCR. Nested PCR was able to reveal a significant drop in positive bone marrow or peripheral blood samples after therapy. In contrast, with LightCycler PCR, the detected drop in t(14;18)-positive cells did not reach statistical significance. The majority of patients showed positive results with nested PCR of peripheral blood or bone marrow without any associations to presence or absence of histological bone marrow (BM) infiltration by lymphoma cells. With LightCycler PCR, the numbers of positive cells were higher in samples from patients with BM infiltration of lymphoma cells (1.9 x 10(-2)) compared to samples from patients without involvement (4.08 x 10(-5)). A similar trend was seen in samples derived from the peripheral blood. Positivity for t(14;18) after therapy in two patients correlated with clinical relapse 6 months later. The data shown here demonstrate a lower sensitivity of LightCycler vs. nested PCR for detection of t(14;18). The usefulness of nested PCR for t(14;18) for risk stratification after primary therapy has to be validated in larger trials.

Association of clinical status of follicular lymphoma patients after autologous stem cell transplant and quantitative assessment of lymphoma in blood and bone marrow as measured by SYBR Green I polymerase chain reaction

Molecular remission in the autograft and bone marrow after transplant are predictive of durable clinical remission in relapsed follicular lymphoma. Thus, a simple reliable method to quantify minimal residual disease (MRD) would improve prognostication in these patients. Fluorescent hybridization probes have been used in real-time quantitative polymerase chain reaction (RQ-PCR) to monitor MRD with a reproducible sensitivity of 0.01%; however, these techniques are expensive and require additional experiments to examine clonality. We describe a SYBR Green I detection method that is more universal, checks clonal identity, yields the same sensitivity for monitoring MRD, and is more economically attractive. Using this method to follow 14 follicular lymphoma patients treated with autologous stem cell transplantation, molecular markers were successfully defined for 12 patients. Median contamination of stem-cell grafts was 0.1% (range, 0 to 13%). Six patients with measurable graft contamination became PCR-negative in blood and bone marrow within 12 months after autologous stem cell transplantation. Three patients free of disease progression (median follow-up of 75 months) are in molecular remission. Increasing fractions of RQ-PCR-positive blood and bone marrow cells reliably predicted morphological and clinical relapse. In one case, both clinical relapse and spontaneous regression were reflected by changes in MRD levels. Thus, our RQ-PCR method reproducibly distinguishes different levels of MRD.

The role of molecular monitoring in autotransplantation for non-Hodgkin's lymphoma

Seventy-two patients with non-Hodgkin's lymphoma were evaluated for the presence of molecular markers (IgH, bcl-1, bcl-2 rearrangement) on bone marrow, at diagnosis and after PBSCT, and on harvests in order to find a possible predictive role of minimal residual disease on treatment outcome. At diagnosis, 41 (59%) out of 69 available bone marrows showed molecular involvement. Fifty-six percent of leukaphereses were involved, mainly indolent lymphoma (P = 0.001) or advanced disease (P = 0.01). Ex vivo purging cleared only one stem collection out of 31 PCR-positive leukaphereses. Aggressive lymphomas showed both a longer overall survival (OS) (P = 0.03) and relapse-free survival RFS (P = 0.02) when transplanted with unpurged stem cells, whereas indolent NHL survival was not influenced by ex vivo purging. Twenty out of 26 samples taken during follow-up had bone marrow involvement at diagnosis. Of these, 15 cleared their bone marrow; both OS and RFS were significantly longer in the PCR-negative cases (P = 0.05 and P = 0.005). At 1 year after PBSCT, 75% of patients were PCR negative, with 50% molecular remissions; the relapse rate was 55% for patients still PCR positive vs 29% for those who were PCR negative. Thus, after high-dose chemotherapy, close molecular monitoring of MRD using qualitative PCR techniques seems to represent a reliable prognostic indicator.

A prospective study of positive/negative ex vivo B-cell depletion in patients with chronic lymphocytic leukemia

OBJECTIVE

Autologous peripheral blood stem cell (PBSC) transplantation is increasingly being used in patients with chronic lymphocytic leukemia (CLL). As the autografts are frequently contaminated with large numbers of tumor cells, we have prospectively investigated the feasibility and efficacy of ex vivo double purging of PBSC grafts in an open, nonrandomized, single-center phase I/II clinical study.

MATERIALS AND METHODS

Twenty consecutive patients with poor-risk CLL underwent uniform stem cell mobilization with chemotherapy and granulocyte colony-stimulating factor (G-CSF). Double B-cell depletion of the harvested PBSC products was performed using immunomagnetic CD34(+) cell selection (Isolex300i Nexell, Irvine, CA) followed by a negative step with anti-CD19/20/23/37-labeled immunomagnetic beads. The purified PBSC were reinfused after myeloablative treatment with TBI/CY.

RESULTS

A total of 25 separation runs was accomplished using collection products containing 3.4% (1.1-8.1) CD34(+) cells and 1.2% (0.1-42) CD19(+)CD5(+) CLL cells. After double selection, 33% (15-67) CD34(+) cells were recovered with a purity of 98.8% (89.1-99. 8). CLL cells were undetectable by high-resolution flow cytometry in 15 of 25 final products; median purging efficacy was 5 (4.1-6) log. The CD34(+) content of the 20 final grafts was 4.6 (2.2-6.5) x 10(6)/kg. Rapid and durable engraftment developed in all cases. With a median follow-up of 20 (6-29) months, 17 patients live in complete clinical remission, two have recurrent disease, and one patient died due to pulmonary embolism five months after transplant. Persistence of the leukemic clone on the molecular level was demonstrated by dot blotting with clone-specific CDR3 probes in an additional five patients. Serious or unexpected infectious complications did not occur.

CONCLUSIONS

Positive/negative purging with the Isolex system allows preparation of highly purified CD34(+) fractions and up to six log of tumor cell depletion in patients with B-CLL and can be safety reinfused after myeloablative therapy without affecting hematopoietic engraftment.

Characterisation of BCL2-JH rearrangements in follicular lymphoma: PCR detection of 3' BCL2 breakpoints and evidence of a new cluster

Follicular lymphomas (FL) are closely associated with a t(14;18)(q32;q21) translocation, leading to a bcl2 protein over-production. This translocation probably constitutes a very early step in the development of the disease. Besides the cytogenetic assay, t(14;18) detection can be achieved using either Southern blot or polymerase chain reaction (PCR). Since 1990, several publications have reported discrepancies between the results of cytogenetic and molecular analysis of t(14;18). Using methods able to explore long DNA fragments, several authors reported breakpoints located outside the usual breakpoint regions. However, these techniques cannot be easily used in routine. The aim of this study was to develop a simple PCR assay to amplify rearrangements usually not detected in FL. We selected a group of 83 patients with a t(14;18) on cytogenetic analysis: using usual probes and primers, 54/83 (65.1%) showed a MBR rearrangement, 7/83 (8.4%) were mcr positive and 22/83 (26.5%) remained negative. Among these 22 rearrangements, nine could be detected using this new PCR assay. Four breakpoints were located in a 20 bp area suggesting a recurrent breakpoint cluster close to an Alu repetitive sequence. Finally, remaining negative cases (13/83, 15.6%) suggest that other breakpoints are located between the MBR and mcr regions.

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 &lt; .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.

Minimal residual disease

Monitoring of residual disease in patients with malignant hematologic disorders has been recognized as an important diagnostic tool for assessment of the response to treatment and the individual risk of relapse. In a number of malignancies, employment of sensitive techniques permitting the identification of tumor cells within a 10(4)-fold or greater excess of normal cells revealed that the presence and persistence of residual disease at this level does not necessarily imply inevitable relapse. Several studies demonstrated that surveillance of persisting neoplastic cells by quantitative techniques can provide prognostically relevant information on the sensitivity of the malignant population to the treatment applied and the biologic behavior of the residual tumor cell clone during and after therapy. It has been shown in different types of leukemia that investigation of the level or the dynamics of residual disease by sensitive and quantitative approaches can provide a basis for clinical decision making.

An advantageous method to evaluate IgH rearrangement and its role in minimal residual disease detection

A sensitive, safe and cheap method to detect minimal residual disease (MRD) is here presented. The PCR-GS technique includes: (a) a fluorescent PCR for the IgH region with CDR3/JH consensus primers; (b) the electrophoresis on an automatic sequencer (ABI PRISM 310); (c) the analysis of results by the GeneScan program. A total of 72 samples were analysed: 34/49 B-cell Non-Hodgkin's Lymphoma (NHL) (69%), six out of seven Multiple Myeloma (MM) (86%), 1/2 Hodgkin's Disease (HD) and 4/4 Acute Lymphoblastic Leukaemia (ALL) were found to be positive, showing a monoclonal IgH rearrangement. The major bias of the PCR-GS method are the 21% of false negatives, but 13/15 negative patients carried t(14;18); consequently, the association of the evaluation by PCR assays of the IgH and BCL2/JH rearrangement allowed to detect a molecular marker of B-neoplasia in more than 94% of tested samples.

Myeloablative radiochemotherapy followed by reinfusion of purged autologous stem cells for Waldenström's macroglobulinaemia

Waldenström's macroglobulinaemia (WM) is an incurable lymphoproliferative disorder. The purpose of this study was to investigate the role of autologous peripheral blood stem cell transplantation (ASCT) for the treatment of WM. Seven patients (untreated or after first-line therapy) with symptomatic WM underwent two or three cycles of Dexa-BEAM chemotherapy + G-CSF with stem cell harvesting and proceeded to total body irradiation and high-dose cyclophosphamide followed by reinfusion of ex-vivo B-cell-depleted stem cells. Engraftment was prompt, and procedure-related deaths did not occur. A strong reduction or normalization of BM infiltration and serum IgM levels occurred in all evaluable patients, but immunofixation electrophoresis revealed persistent paraproteinaemia in five of them. With 3-30 months of follow-up, all patients are alive without clinical or serological signs of disease progression. This pilot trial shows for the first time that high-dose radiochemotherapy with purged stem cells is effective and may improve the course of patients with WM. In the majority of cases, however, complete eradication of the disease does not appear to be possible with ASCT alone.