Molecular Monitoring of Minimal Residual Disease in Follicular and Mantle Cell Non-Hodgkin's Lymphomas Treated With High-Dose Chemotherapy and Peripheral Blood Progenitor Cell Autografting

The optimal time and clinical implications of measurable residual disease detection in mantle cell lymphoma

Recent advances in measurable residual disease (MRD) technology have significantly enhanced predictive accuracy for outcomes in various hematologic malignancies, serving as a crucial surrogate endpoint. However, in mantle cell lymphoma (MCL), identifying the optimal timing for MRD assessment and understanding the prognostic implications of MRD dynamics remain challenging, primarily due to limited extensive MRD data. Our study encompassed 102 patients with MCL, all presenting with clonal B-cell involvement in bone marrow as determined by multiparametric flow cytometry (MFC). MRD evaluations were conducted every two cycles. 75.5% (77/102) achieved MRD negativity during induction therapy. We found the MRD status at the end of four cycles treatment had the best predictive ability for survival (HR = 3.2, C-index = 0.664). 32 of 77 patients (41.6%) had a rapid tumor burden reduction and achieved MRD negativity within two cycles treatment. Notably, this swift shift to MRD negativity was observed more frequently in patients classified as MIPI high-risk. However, this rapid clearance of MRD did not confer any prognostic benefit to these patients. Subgroup analyses revealed that MRD negativity held prognostic value in almost all categories, except for those with blastoid/pleomorphic morphology. MRD assessment serves as a valuable complement to the traditional response evaluation, particularly benefiting for patients attaining partial remission. These findings highlighted the importance of MRD detection during response evaluation of MCL therapy and determined that after four treatment cycles is the best MRD detection timepoint.

Minimal residual disease in patients with diffuse large B-cell lymphoma undergoing autologous stem cell transplantation

Improved biomarkers are required to guide the optimal use of autologous stem cell transplantation (ASCT) in patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL). We hypothesized that minimal residual disease (MRD) identified using immunoglobulin high-throughput sequencing in apheresis stem cell (ASC) samples, post-ASCT peripheral blood mononuclear cell (PBMC), and plasma samples could predict relapse. We studied 159 patients with R/R DLBCL who underwent ASCT, of whom 98 had an ASC sample and 60 had post-ASCT surveillance samples. After a median post-ASCT follow-up of 60 months, the 5-year progression-free survival (PFS) was 48%. MRD was detected in of 23/98 (23%) ASC samples and was associated with very poor PFS (5-year PFS 13% vs 53%, P < .001) and inferior overall survival (52% vs 68%, P = .05). The sensitivity and specificity of ASC MRD positivity for progression and death were 36% and 93%, respectively. Positive ASC MRD remained a significant predictor of PFS in multivariable analysis (hazard ratio [HR], 3.7; P < .001). Post-ASCT surveillance MRD testing of plasma, but not PBMC samples, reliably identified patients with an impending relapse. A positive plasma MRD result was associated with inferior PFS (HR, 3.0; P = .016) in a multivariable analysis. The median lead time from MRD detection to relapse was 62 days (range, 0-518 days). In conclusion, the detection of MRD in ASC samples is associated with a very high risk of relapse, justifying alternative treatment strategies or trials of novel consolidation options in these patients. Furthermore, post-ASCT MRD monitoring may facilitate the evaluation of the early initiation of treatment at molecular relapse. This trial has been registered at www.clinicaltrials.gov as #NCT02362997.

Exploration of residual disease in stem cell products from mantle cell lymphoma using next-generation sequencing

High-dose chemotherapy followed by autologous stem cell transplantation (ASCT) has become a treatment option for fit patients with mantle cell lymphoma (MCL). However, these patients often relapse within few years, potentially caused by contaminating lymphoma cells within the reinfused stem cell product (SCP). Studies have shown that measurable residual disease, also termed minimal residual disease (MRD), following ASCT predicts shorter survival. Using next-generation sequencing, we explore whether the diagnostic MCL clonotype is present within the infused SCP. MRD was detected in 4/17 of the SCPs, ranging 4–568 clonal cells/100,000 cells. With a median survival of 17 months, 3/4 of patients with MRD+ graft succumbed from MCL relapse versus 2/13 in the MRD– fraction. Patients receiving MRD+ grafts had increased risk of mortality, and thus screening of SCPs may be important for clinical decision-making.

Advances in Treatment of Follicular Lymphoma

Follicular lymphoma (FL) is a heterogeneous disease with varying prognosis owing to differences in clinical, laboratory, and disease parameters. Although generally considered incurable, prognosis for early and advanced stage disease has improved because of therapeutic advances, several of which have resulted from elucidation of the biologic and molecular basis of the disease. The choice of treatment for FL is highly dependent on patient and disease characteristics. Several tools are available for risk stratification, although limitations in their routine clinical use exist. For limited disease, treatment options include radiotherapy, rituximab monotherapy or combination regimens, and surveillance. Treatment of advanced disease is often determined by tumor burden, with surveillance or rituximab considered for low tumor burden and chemoimmunotherapy for high tumor burden disease. Treatment for relapsed or refractory disease is influenced by initial first-line therapy and the duration and quality of the response. At present, there is no consensus for treatment of patients with early or multiply-relapsed disease; however, numerous agents, combination regimens, and transplant options have demonstrated efficacy. While the number of therapies available to treat FL has increased together with an improved understanding of the underlying biologic basis of disease, the best approach to select the most appropriate treatment strategy for an individual patient at a particular time continues to be elucidated. This chapter considers prognostic factors and the evolving treatment landscape of FL, including recent and emerging therapies, as well as remaining unmet needs.

Stiffness based enrichment of leukemia cells using microfluidics

To improve the survival rate of cancer patients, new diagnosis strategies are necessary to detect lower levels of cancer cells before and after treatment regimens. The scarcity of diseased cells, particularly in residual disease after treatment, demands highly sensitive detection approaches or the ability to enrich the diseased cells in relation to normal cells. We report a label-free microfluidic approach to enrich leukemia cells from healthy cells using inherent differences in cell biophysical properties. The microfluidic device consists of a channel with an array of diagonal ridges that recurrently compress and translate flowing cells in proportion to cell stiffness. Using devices optimized for acute T cell leukemia model Jurkat, the stiffer white blood cells were translated orthogonally to the channel length, while softer leukemia cells followed hydrodynamic flow. The device enriched Jurkat leukemia cells from white blood cells with an enrichment factor of over 760. The sensitivity, specificity, and accuracy of the device were found to be >0.8. The values of sensitivity and specificity could be adjusted by selecting one or multiple outlets for analysis. We demonstrate that low levels of Jurkat leukemia cells (1 in 104 white blood cells) could be more quickly detected using flow cytometry by using the stiffness sorting pre-enrichment. In a second mode of operation, the device was implemented to sort resistive leukemia cells from both drug-sensitive leukemia cells and normal white blood cells. Therefore, microfluidic biomechanical sorting can be a useful tool to enrich leukemia cells that may improve downstream analyses.

The Role of Quantitative Polymerase Chain Reaction in the Management of Follicular Lymphoma Patients

Aims and background

In order to increase the prognostic significance of polymerase chain reaction (PCR) data it has been suggested that quantitative PCR can be used to measure tumor burden. However, this option has not yet been definitely supported or refuted in patients with follicular lymphoma (FL). We decided to evaluate whether knowledge of the quantitative level of minimal residual disease and its variations can be of use in the management of FL patients.

Methods

We used qualitative and competitive PCR to study 11 patients with refractory or relapsed FL harboring the t(14;18) translocation who underwent autologous (nine patients) or allogeneic (two patients) stem cell transplantation (SCT). Competitive PCR was performed with a multiple competitor carrying specific sequences including Bcl2/lgH MBR and mcr, and the β-globin gene.

Results

After a median post-SCT follow-up of 44 months (range, 12-62), overall survival was 91% and disease-free survival 82%. The quantitative PCR data showed that: 1) effective chemotherapy before SCT substantially (1-2 log) reduced the tumor burden in the bone marrow (BM); 2) the increase in rearranged DNA detected in BM was associated with disease progression and relapse; 3) a PCR-negative autograft seemed to lead to lasting molecular remission even when it was performed in patients with a low level of BM infiltration before transplant; and 4) allo-SCT made and maintained the BM PCR negative even in the presence of a greater tumor burden before SCT. Six of the nine patients having CR after SCT (four auto and two allo) are in continuous molecular remission.

Conclusions

In FL patients qualitative and quantitative PCR may provide data that can be helpful for the prognostic evaluation of tumor progression and the early detection of impending relapse by highlighting biological features such as the quality of the infused material, the tumor burden at transplant, and the behavior of tumor cells after transplant.

The Minimal Residual Disease in Non-Hodgkin's Lymphomas: From the Laboratory to the Clinical Practice

Minimal residual disease (MRD) in non-Hodgkin's lymphomas (NHLs) still represents matter of interest and debate: indeed, the new available treatments offer higher rates of complete responses and MRD negativity than in the past, with a positive impact on the long-term survival. Furthermore, the introduction of more sensitive and accurate molecular techniques, such as digital PCR (ddPCR) and the next generation sequencing techniques (NGS), increased the possibility of identifying molecular targets to be followed after therapy (such as rearrangement of immunoglobulins, fusion genes, or mutations). This review focused on how molecular biology can help to detect MRD in different types of NHLs and how MRD can change the clinical practice in 2019. In follicular lymphoma (FL), contamination of the grafts and molecular disease persistence after transplantation represent a negative prognostic factors. The combination of Rituximab or Obinutuzumab with Bendamustine seems to be the most effective way to clear MRD in FL patients receiving chemo-immunotherapy (further studies are in progress), and also ⁹⁰Yttrium-Ibritumomab-Tiuxetan offers a deep clearance of molecular disease. Finally, molecular MRD can further stratify PET-negative cases, with subjects both PET- and MRD-negative presenting the best outcome. In aggressive lymphomas, MRD has a relevant prognostic power and can represent the platform for immunotherapy (such as CAR-T). In diffuse large B-cell lymphoma (DLBCL), the assessment of MRD in the plasma (where cell-free DNA and exosomes circulate) seems to be more predictive than the bone marrow analysis or peripheral blood mononuclear cells. Finally, NGS technologies could be more useful than the classical "patient allele-specific PCR" because they can identify any possible clone emerging during the treatment or follow-up, even if different from that identified at diagnosis, thus predicting relapse. After all, the present available molecular approaches can move MRD from the bench side to the clinical practice.

Total metabolic tumor volume, circulating tumor cells, cell-free DNA: distinct prognostic value in follicular lymphoma

Outcomes for follicular lymphoma (FL) have greatly improved, but most patients will ultimately relapse. High total metabolic tumor volume (TMTV), computed from baseline ¹⁸F-fluorodeoxyglucose-positron emission tomography (PET), is associated with shorter progression-free survival (PFS), but circulating tumor cells (CTCs) and cell-free DNA (cfDNA) may also reflect tumor burden and be of prognostic value. The aim of our study was to correlate CTCs and cfDNA with TMTV in FL at diagnosis and to determine their prognostic values. We retrospectively analyzed 133 patients (with previously untreated FL and a baseline PET) from 2 cohorts with either a baseline plasma sample (n = 61) or a bcl2-JH-informative peripheral blood (PB) sample (n = 68). Quantification of circulating bcl2-JH⁺ cells and cfDNA was performed by droplet digital polymerase chain reaction. A significant correlation was found between TMTV and both CTCs (P < .0001) and cfDNA (P < .0001). With a median 48-month follow-up, 4-year PFS was lower in patients with TMTV > 510 cm³ (P = .0004), CTCs >0.0018 PB cells (P = .03), or cfDNA >2550 equivalent-genome/mL (P = .04). In comparison with TMTV alone, no additional prognostic information was obtained by measuring CTCs. In contrast, Cox multivariate analysis, including cfDNA and TMTV, showed that both cfDNA and TMTV remained predictive of outcome. In conclusion, CTCs and cfDNA correlate with TMTV in FL, and all 3 influence patient outcome. PFS was shorter for patients with high cfDNA and TMTV, suggesting that these parameters provide relevant information for tumor-tailored therapy.

Toward a Risk-Tailored Therapeutic Policy in Mantle Cell Lymphoma

PURPOSE OF REVIEW

Mantle cell lymphoma (MCL) prognosis is strictly related to the characteristics of the disease, which can range from very indolent cases to highly aggressive and refractory ones. Here we will review the current knowledge on MCL biomarkers.

RECENT FINDINGS

Biomarker-informed diagnosis is essential for differentiating MCL from other mature B cell tumors. Diagnosis of MCL relies on the identification of the t(11;14) translocation by FISH or the consequently aberrant expression of cyclin D1 by immunohistochemistry. For the few cases staining negative for cyclin D1, SOX11 may help to define the diagnosis. Prognostic biomarkers have been proposed to stratify MCL patients, including baseline clinical aspects (leukemic non-nodal presentation, in situ presentation, Mantle cell International Prognostic Index-MIPI), pathological aspects (blastoid morphology, Ki-67 proliferation index, SOX11 expression), genetic aspects (immunoglobulin gene mutation status, TP53 deletion or mutation, CDKN2A deletion), and depth of response after treatment (PET imaging, molecular minimal residual disease). Such tools are increasingly used as a guide for therapeutic decisions. Watchful waiting approach is recommended for patients harboring favorable clinico-biological features, such as leukemic non-nodal presentation, low MIPI score, non-blastoid disease, low Ki-67 proliferation rate, mutated immunoglobulin genes, and the lack of SOX11 expression. For patients in need of frontline therapy, the decision of whether to undertake intensive regimens is based upon patient's age and comorbidities. Central nervous system prophylaxis is recommended for cases showing blastoid morphology. The duration of remission is tightly correlated to the depth of response. With the aim of achieving a longer duration of remission and survival, younger patients may pursue more intensive regimens incorporating high-dose cytarabine, followed by myeloablative consolidation chemotherapy, autologous stem cell transplantation, and rituximab maintenance. Older patients could, on the other hand, benefit from lower intensity immunochemotherapy followed or not by a maintenance therapy depending on which frontline regimen is used. Despite the identification of several potential useful biomarkers that may inform the treatment decisions and the design of clinical trials, the treatment choice remains nowadays determined by the patient age and fitness rather than by the individual patient characteristics. Tailoring therapy toward a risk-adapted strategy to accommodate the wide spectrum of disease is an urgent challenge, and clinical trials may explore the feasibility of a biomarker-defined therapeutic policy.

Recommendations for Clinical Trial Development in Mantle Cell Lymphoma

Mantle cell lymphoma (MCL) comprises around 6% of all non-Hodgkin's lymphoma (NHL) diagnoses. In younger patients, age less than 60 to 65 years, aggressive induction often followed by consolidation with autologous stem cell transplant has suggested improved outcomes in this population. Less intensive therapies in older patients often followed by maintenance have been studied or are under active investigation. However, despite recent advances, MCL remains incurable, with a median overall survival of around five years. Patients with high-risk disease have particularly poor outcomes. Treatment varies widely across institutions, and to date no randomized trials comparing intensive vs less intensive approaches have been reported. Although recent data have highlighted the heterogeneity of MCL outcomes, patient assessment for treatment selection has largely been driven by patient age with little regard to fitness, disease biology, or disease risk. One critical advance is the finding that minimal residual disease status (MRD) after induction correlates with long-term outcomes. As such, its use as a potential end point could inform clinical trial design. In order to more rapidly improve the outcomes of MCL patients, clinical trials are needed that prospectively stratify patients on the basis of MCL biology and disease risk, incorporate novel agents, and use MRD to guide the need for additional therapy.

Addition of Rituximab to Involved-Field Radiation Therapy Prolongs Progression-free Survival in Stage I-II Follicular Lymphoma: Results of a Multicenter Study

PURPOSE

Rituximab (Rit) therapy added to involved-field radiation therapy (RT) has been proposed as an effective treatment for stage I-II follicular lymphoma (FL). The results of an observational multicenter study on the Rit-RT combination in limited-stage FL are here reported.

METHODS AND MATERIALS

Data have been collected from 2 consecutive cohorts of 94 patients with stage I-II FL treated between 1985 and 2011 at 5 Italian institutions. All patients had grade 1-3a FL, a median age of 54 years (range: 25-82). The first 51 patients received RT alone (control group), while the subsequent series of 43 patients received 4 rituximab courses (375 mg/m(2), days 1, 8, 15, 22) before RT (Rit-RT). Molecular disease was evaluated by nested bcl-2/IgH PCR or clonal IgH rearrangement was available in 33 Rit-RT patients.

RESULTS

At a median follow-up of 10.9 years (range: 1.8-22.9), the 10-year progression-free survival (PFS) and overall survival (OS) projections for the whole cohort were 57% and 87.5%, respectively. The 10-year PFS was significantly longer (P<.05) in the Rit-RT group (64.6%) compared to RT alone (50.7%), whereas the 10-year OS projections were not significantly different. On bivariate analysis controlling for stage, there was only a trend toward improved PFS for Rit-RT (HR, 0.55; P=.081). Follicular lymphoma international prognostic index and age were associated with OS but not with PFS on Cox regression analysis. Bone marrow molecular analysis showing PCR positivity at diagnosis was strongly associated with relapse risk upon univariate and multivariate analysis.

CONCLUSIONS

This multicenter observational study suggests a potential benefit of adding rituximab to radiation therapy for stage I-II FL. The results of the currently ongoing randomized studies are required to confirm these results. The study underlines the importance of molecular disease monitoring also for patient with limited-stage disease.

Rituximab for indolent lymphomas before and after allogeneic hematopoietic stem cell transplantation

PURPOSE OF REVIEW

The most substantial advancement in the treatment of indolent B-cell non-Hodgkin lymphoma (NHL), since the advent of combination chemotherapy, has been the introduction of the monoclonal anti-CD20 antibody rituximab. However, the optimal schedule, timing, and duration of rituximab therapy remain controversial.

RECENT FINDINGS

Since its initially reported single-agent activity in 1997, the role of rituximab has greatly expanded and it is now ubiquitously integrated in all treatment phases of indolent NHL. Yet, several questions remain to be addressed: should asymptomatic patients be treated at diagnosis with single-agent rituximab or still kept in watchful waiting, what are the optimal first-line treatments to combine with rituximab, what is the role of maintenance therapy, and is there a benefit in incorporating rituximab in autologous and allogeneic stem cell transplantation schemes for these diseases? Recent and ongoing clinical trials tackling these relevant issues will be presented and critically discussed in this article.

SUMMARY

Excellent outcomes are reported with rituximab therapy in indolent NHL, both early and late in the disease course. Continued study of this most valuable therapeutic agent is warranted to set the optimal treatment approach leading to cure the majority of patients.

Persistence of minimal residual disease in bone marrow predicts outcome in follicular lymphomas treated with a rituximab-intensive program

PCR negativity is a strong outcome predictor after rituximab-intensive immunochemotherapy at multiple posttreatment times. PCR is predictive even when maintenance is delivered, and accumulation of PCR-negative results further reduces the likelihood of relapse.

Clinical implications and prognostic role of minimal residual disease detection in follicular lymphoma

The identification of patients at high risk of relapse is a critical goal of modern translational research in oncohematology. Minimal residual disease (MRD) detection by polymerase chain reaction-based methods is routinely employed in the management of patients with acute lymphoblastic leukemia. Current knowledge indicates that it is also a useful prognostic tool in several mature lymphoproliferative disorders and particularly in follicular lymphoma (FL). Based on this evidence clinical trials employing MRD-based risk stratification are currently ongoing in FL. In this review the 'state of the art' of MRD evaluation in FL is discussed. A short description of technical issues and recent methodological advances is provided. Then, the bulk of the review focuses on critical take-home messages for clinicians working in the field. Finally, we discuss future perspectives of MRD detection and more generally outcome prediction in FL.

Minimal residual disease detection in mantle cell lymphoma: technical aspects and clinical relevance

The prognostic impact of minimal residual disease (MRD) has been demonstrated for several hematologic malignancies. While in acute lymphoblastic leukemias MRD assessment by polymerase chain reaction (PCR)-based methods has been established as an important tool for clinical risk assessment and is part of clinical management, data demonstrating a prognostic value of MRD in mantle cell lymphoma (MCL) were sparse and results from randomized trials have been published only recently. In the present review technical aspects of different MRD detection methods are discussed, as well as the prognostic relevance of MRD in the context of clinical trials in patients with MCL. Furthermore, recommendations are given for workflow and useful implication of MRD in future clinical trials design.

Mantle cell lymphoma

MCL is a well-characterized clinically aggressive lymphoma with a poor prognosis. Recent research findings have slightly improved the outcome of this neoplasm. The addition of rituximab to conventional chemotherapy has increased overall response rates, but it does not improve overall survival with respect to chemotherapy alone. The use of intensive frontline therapies including rituximab and consolidated by ASCT ameliorates response rate and prolongs progression-free survival, but any impact on survival remains to be proven. Furthermore, the optimal timing, cytoreductive regimen and conditioning regimen, and the clinical implications of achieving a disease remission even at molecular level remain to be elucidated. The development of targeted therapies as the consequence of better dissection of pathogenetic pathways in MCL might improve the outcome of conventional chemotherapy in most patients and spare the toxicity of intense therapy in a minority of MCL patients characterized by a relatively indolent disease. Patients not eligible for intensive regimens, such as hyperC-VAD, may be considered for less demanding therapies, such as the combination of rituximab either with CHOP or with purine analogues, or bendamustine. Allogeneic SCT can be an effective option for relapsed disease in patients who are fit enough and have a compatible donor. Maintenance rituximab may be considered after response to immunochemotherapy for relapsed disease, although there are currently no data to recommend this approach as the first-line strategy. As the optimal approach to the management of MCL is still evolving, it is critical that these patients be enrolled in clinical trials to identify better treatment options.

BCL-2/IgH polymerase chain reaction status at the end of induction treatment is not predictive for progression-free survival in relapsed/resistant follicular lymphoma: results of a prospective randomized EORTC 20981 phase III intergroup study

PURPOSE

The prognostic value of residual BCL2/immunoglobulin heavy chain (BCL2/IgH) -positive cells in peripheral blood (PB) or bone marrow (BM) after induction treatment in follicular lymphoma (FL) is still controversial. In a prospective randomized phase III intergroup trial of 465 patients with relapsed/resistant follicular lymphoma (FL), we showed that addition of rituximab to cyclophosphamide, doxorubicin, vincristine, and prednisone induction results in increased overall and complete response rates, and that rituximab maintenance strongly improves median progression-free survival (PFS) as well as overall survival. Here, we studied whether BCL2/IgH major break point levels in PB/BM correlated with response rates/quality for the induction phase and PFS for the maintenance phase.

PATIENTS AND METHODS

Samples were obtained before and after induction therapy and at the end of the 2 years maintenance/observation period. BCL2/IgH major break point-positive cells were quantified by genomic quantitative polymerase chain reaction in 792 samples from 238 patients.

RESULTS

Pretreatment BCL2/IgH levels had no significant prognostic value for overall response or complete remission rates after induction treatment, but pretreatment positive BM results had an adverse prognostic value for PFS from first randomization (P = .023). Importantly, BCL2/IgH levels at the end of induction treatment had no prognostic value for PFS from second randomization. The highly significant improved PFS by rituximab maintenance was observed in both BCL2/IgH PB/BM-positive and -negative groups.

CONCLUSION

Postinduction BCL2/IgH major break point status in BM/PB is not useful for decisions on subsequent therapy for patients with relapsed/resistant FL.

Molecular remission is an independent predictor of clinical outcome in patients with mantle cell lymphoma after combined immunochemotherapy: a European MCL intergroup study

The prognostic impact of minimal residual disease (MRD) was analyzed in 259 patients with mantle cell lymphoma (MCL) treated within 2 randomized trials of the European MCL Network (MCL Younger and MCL Elderly trial). After rituximab-based induction treatment, 106 of 190 evaluable patients (56%) achieved a molecular remission (MR) based on blood and/or bone marrow (BM) analysis. MR resulted in a significantly improved response duration (RD; 87% vs 61% patients in remission at 2 years, P = .004) and emerged to be an independent prognostic factor for RD (hazard ratio = 0.4, 95% confidence interval, 0.1-0.9, P = .028). MR was highly predictive for prolonged RD independent of clinical response (complete response [CR], complete response unconfirmed [CRu], partial response [PR]; RD at 2 years: 94% in BM MRD-negative CR/CRu and 100% in BM MRD-negative PR, compared with 71% in BM MRD-positive CR/CRu and 51% in BM MRD-positive PR, P = .002). Sustained MR during the postinduction period was predictive for outcome in MCL Younger after autologous stem cell transplantation (ASCT; RD at 2 years 100% vs 65%, P = .001) and during maintenance in MCL Elderly (RD at 2 years: 76% vs 36%, P = .015). ASCT increased the proportion of patients in MR from 55% before high-dose therapy to 72% thereafter. Sequential MRD monitoring is a powerful predictor for treatment outcome in MCL. These trials are registered at www.clinicaltrials.gov as #NCT00209222 and #NCT00209209.

Rituximab based therapy followed by autologous stem cell transplantation leads to superior outcome and high rates of PCR negativity in patients with indolent B-cell lymphoproliferative disorders

Autologous stem cell transplantation (ASCT) and rituximab based therapy represent effective treatments of indolent B-cell lymphoproliferative disorders (B-LPDs) that often induce molecular remission (MR). We assessed the impact of MR after treatment on prognosis of 57 patients with indolent B-LPDs. We also evaluated the impact of therapy on patients' outcome. Failure to achieve MR was identified as an independent risk factor regardless of treatment modality. PCR positive patients had shorter progression free survival (PFS) in contrast with patients in MR after rituximab (median 0.75 and 2.5 years respectively; p=0.006) or patients in MR after rituximab followed by ASCT (median 3.3 years; p=0.0032). PCR positive patients had a 5-year overall survival (OS) of only 40% compared to a 5-year OS of 76% for PCR negative patients after rituximab (p=0.0186) and 86% PCR negative patients after rituximab with ASCT (p=0.003). All nine patients transplanted with PCR positive graft relapsed (p=0.0023) with shorter PFS (p=0.0008). Rituximab based therapy induced MR in 25 (64%) compared to 18 (100%) patients after rituximab followed by ASCT (p=0.0025). We observed no difference in PFS between the transplant group (3.3 years) and rituximab based treatment (1.9 years), but the 5-year OS of patients with transplant was 85 and 59% respectively (p=0.0271). Patients with indolent B-LPDs who achieve MR have better prognosis. Rituximab based therapy induces MR in high number of patients, which can be further improved by ASCT and patients have an excellent outcome. PCR positive harvest represents a high risk of relapse after ASCT.

Pre-emptive treatment with rituximab of molecular relapse after autologous stem cell transplantation in mantle cell lymphoma

PURPOSE

Minimal residual disease (MRD) is predictive of clinical progression in mantle-cell lymphoma (MCL). According to the Nordic MCL-2 protocol we prospectively analyzed the efficacy of pre-emptive treatment using rituximab to MCL patients in molecular relapse after autologous stem cell transplantation (ASCT).

PATIENTS AND MATERIALS

MCL patients enrolled onto the study, who had polymerase chain reaction (PCR) detectable molecular markers and underwent ASCT, were followed with serial PCR assessments of MRD in consecutive bone marrow and peripheral blood samples after ASCT. In case of molecular relapse with increasing MRD levels, patients were offered pre-emptive treatment with rituximab 375 mg/m(2) weekly for 4 weeks.

RESULTS

Of 160 MCL patients enrolled, 145 underwent ASCT, of whom 78 had a molecular marker. Of these, 74 were in complete remission (CR) and four had progressive disease after ASCT. Of the CR patients, 36 underwent a molecular relapse up to 6 years (mean, 18.5 months) after ASCT. Ten patients did not receive pre-emptive treatment mainly due to a simultaneous molecular and clinical relapse, while 26 patients underwent pre-emptive treatment leading to reinduction of molecular remission in 92%. Median molecular and clinical relapse-free survival after pre-emptive treatment were 1.5 and 3.7 years, respectively. Of the 38 patients who remain in molecular remission for now for a median of 3.3 years (range, 0.4 to 6.6 years), 33 are still in clinical CR.

CONCLUSION

Molecular relapse may occur many years after ASCT in MCL, and PCR based pre-emptive treatment using rituximab is feasible, reinduce molecular remission, and may prevent clinical relapse.

Autografting followed by rituximab for chemosensitive mantle cell lymphoma: A pilot study and literature review

Mantle cell lymphoma (MCL) is rarely cured with either conventional-dose chemotherapy or autografting. Recent evidence suggests that anti-CD20 monoclonal antibody therapy (rituximab) in combination with chemotherapy may improve the response rate. We report a pilot study of autografting using busulfan-melphalan conditioning followed by rituximab in 9 patients (median age 52 years) with chemosensitive MCL. Rituximab was given for 4 doses of 375 mg/m(2) between 4 and 10 weeks post-transplant. Three of 5 patients autografted after induction therapy remain alive in clinical and molecular complete remission at 33-50 months post-transplant. Only 1 of 4 patients autografted after relapse remains in complete remission. Two of the 3 patients with persistent marrow molecular positivity post-autograft became negative after rituximab therapy. Molecular negativity was first observed in 2 patients only after rituximab therapy. Overall, 2 patients have relapsed and the remaining 3 died of late-onset respiratory failure, probably reflecting infection and/or aggressive conditioning in an older patient population. These preliminary results, together with a review of the literature, suggest that the combination of autografting and rituximab may lead to durable molecular remissions in patients with chemosensitive MCL. Further studies are required to clarify whether the administration of rituximab: (1) is optimal pre- or post-autograft and (2) impacts on the incidence of infection and idiopathic pneumonitis in this context.

Eradication of Minimal Residual Disease with Alemtuzumab in B-Cell Chronic Lymphocytic Leukemia (B-CLL) Patients: The Need for a Standard Method of Detection and the Potential Impact of Bone Marrow Clearance on Disease Outcome

The introduction of new therapeutic agents, such as fludarabine phosphate (Fludara) and alemtuzumab (MabCampath, Campath), has made it possible to treat B-cell chronic lymphocytic leukemia (B-CLL) more effectively, compared with alkylating agents. However, although an increasing number of patients are able to achieve complete remission (CR), relapse is almost inevitable, because of the re-emergence of the malignant clone from small numbers of residual malignant cells. This phenomenon has introduced a need for a more sensitive assessment of low-level disease which, in turn, has encouraged the development of therapies aimed at the eradication of all residual disease in CR patients. The eradication of residual disease is associated with improved remission durability and has great potential in offering the possibility of cure. Alemtuzumab is the foundation of many eradication-based treatment approaches because of its ability to achieve clinical remissions and to successfully purge minimal residual disease (MRD) from both blood and bone marrow in B-CLL patients. This article describes and compares polymerase chain reaction (PCR) and flow cytometric methodologies for the assessment of MRD, and presents data demonstrating that alemtuzumab can eliminate residual malignant cells from blood and bone marrow (whether assessed by PCR or flow cytometry) at the highest levels of sensitivity currently available. The ability to clear MRD from bone marrow in patients achieving clinical CR using alemtuzumab is a significant step forward in the treatment of B-CLL, and supports treatment strategies in which alemtuzumab is used in combination with other agents. Purging of MRD from both blood and bone marrow also enables patients to proceed to autologous hematopoietic stem cell transplantation, a strategy that is able to achieve long-term remission.

Vaccination with autologous tumor-loaded dendritic cells induces clinical and immunologic responses in indolent B-cell lymphoma patients with relapsed and measurable disease: a pilot study

Eighteen relapsed patients with measurable indolent non-Hodgkin lymphoma (NHL) were vaccinated with dendritic cells (DCs) loaded with killed autologous tumor cells. Six patients had objective clinical responses including 3 continuous complete responses (CRs) and 3 partial responses (PRs), with a median follow up of 50.5 months. Eight patients had stable disease, whereas 4 had progressive disease. Clinical responses were significantly associated with a reduction in CD4+CD25+FOXP3+ regulatory T cells, an increase in CD3−CD56dimCD16+ natural killer (NK) cells, and maturation of lymphocytes to the effector memory stage in either postvaccination peripheral blood or tumor specimen samples. In partial responding patients, vaccination significantly boosted the IFN-γ–producing T-cell response to autologous tumor challenge. In one HLA-A*0201+ patient who achieved CR, IL-4 release by circulating T cells in response to tumor-specific IgH-encoded peptides was also documented. Immunohistochemical analysis of tumor biopsies using biotin-conjugated autologous serum samples revealed a tumor-restricted humoral response only in the postvaccination serum from responding patients. Collectively these results demonstrate that vaccination with tumor-loaded DCs may induce both T- and B-cell responses and produces clinical benefits in indolent NHL patients with measurable disease. This study is registered with the Istituto Superiore di Sanità: http://www.iss.it with protocol number 7578-PRE 21-801.

High-Dose Yttrium-90–Ibritumomab Tiuxetan With Tandem Stem-Cell Reinfusion: An Outpatient Preparative Regimen for Autologous Hematopoietic Cell Transplantation

Purpose

To develop high-dose myeloablative therapy for CD20+ non-Hodgkin's lymphoma (NHL) as a safe and widely applicable regimen.

Patients and Methods

Patients with relapsed/refractory (n = 25) or de novo high-risk (n = 5) NHL received one myeloablative dose of yttrium-90 (90Y)–ibritumomab tiuxetan after five chemotherapy courses, including three cycles of anthracycline- or platinum-containing regimens, one cycle of cyclophosphamide (4 to 7 g/m2), and one cycle of cytarabine (12 to 24 g/m2). The only exclusion criteria were CNS lymphoma and Eastern Cooperative Oncology Group performance status of more than 3. Primary end points were overall survival (OS) and event-free survival (EFS). Secondary end points included safety and applicability of high-dose 90Y-ibritumomab tiuxetan. To minimize hematologic toxicity, stem cells were reinfused at days 7 and 14 after 90Y-ibritumomab tiuxetan.

Results

Thirteen patients received 90Y-ibritumomab tiuxetan 0.8 mCi/kg, and 17 patients received 1.2 mCi/kg. At 1.2 mCi/kg, the radiation absorbed by critical nonhematologic organs approached the protocol-defined upper safety limit, defining this as the recommended dose for subsequent studies. Hematologic toxicity was mild to moderate and of short duration. Infections occurred in 27% of patients (none had a severity grade greater than 3). After a median observation time of 30 months (range, 22 to 48 months), no myeloid secondary malignancy or chromosomal abnormality was observed, the OS rate was 87%, and the EFS rate was 69%.

Conclusion

High-dose 90Y-ibritumomab tiuxetan seems to be an innovative myeloablative regimen with unprecedented short-term toxicity and wide applicability. Further studies are required to assess its long-term safety and role in the management of CD20+ NHL.

Rapid and sustained clearance of circulating lymphoma cells after chemotherapy plus rituximab: clinical significance of quantitative t(14;18) PCR monitoring in advanced stage follicular lymphoma patients

This study of first-line treatment in advanced-stage follicular lymphoma patients analysed the effects of MCP (mitoxantrone, chlorambucil and prednisolone) chemotherapy alone or in combination with rituximab (R-MCP) on circulating lymphoma cells (CLC) and assessed the prognostic value of a quantitative monitoring of CLC. CLC numbers were determined by quantitative polymerase chain reaction (PCR) for the t(14;18)-translocation or by allele-specific PCR for rearranged immunoglobulin heavy chain genes. We analysed blood samples from 43 patients treated in a randomized trial comparing eight cycles of MCP versus R-MCP. Clearance of CLC at the end of therapy was achieved in 21/25 patients (84%) treated with R-MCP compared with 0/18 after MCP alone (P < 0.0001). A > or = 2 log CLC reduction was associated with a favourable clinical response (P = 0.0004) and prolonged event-free survival (P = 0.02). In R-MCP patients, stable CLC numbers or consistently PCR-negative blood samples were associated with a continuing clinical remission whereas in two patients a relapse was preceded by a > or = 2 log CLC increase. This study demonstrated that R-MCP led to a rapid and sustained eradication of CLC and a > or = 2 log CLC reduction was associated with a superior quality and duration of the clinical response.

Prospective, multicenter randomized GITMO/IIL trial comparing intensive (R-HDS) versus conventional (CHOP-R) chemoimmunotherapy in high-risk follicular lymphoma at diagnosis: the superior disease control of R-HDS does not translate into an overall survival advantage

In this randomized multicenter study of 136 patients, 6 courses of CHOP (cyclo-phosphamide/doxorubicin/vincristine/prednisone) followed by rituximab (CHOP-R) were compared with rituximab-supplemented high-dose sequential chemotherapy with autografting (R-HDS) to assess the value of intensified chemo-therapy as a first-line treatment for high-risk follicular lymphoma (FL) after the introduction of monoclonal antibodies. The analysis was intention to treat with event-free survival (EFS) as the primary endpoint. Complete remission (CR) was 62% with CHOP-R and 85% with R-HDS (P < .001). At a median follow-up (MFU) of 51 months, the 4-year EFS was 28% and 61%, respectively (P < .001), with no difference in overall survival (OS). Molecular remission (MR) was achieved in 44% of CHOP-R and 80% of R-HDS patients (P < .001), and was the strongest independent outcome predictor. Patients relapsing after CHOP-R underwent salvage R-HDS in 71% of cases. Salvage R-HDS had an 85% CR rate and a 68% 3-year EFS (MFU, 30 months). We conclude that (1) achieving MR is critical for effective disease control, regardless of which treatment is used; (2) R-HDS ensures superior disease control and molecular outcome than CHOP-R, but no OS improvement; and (3) CHOP-R failures have a good outcome after salvage R-HDS, suggesting that relapsed/refractory FL could be the most appropriate setting for R-HDS-like treatments. This trial was registered at www.clinicaltrials.gov as no. NCT00435955.

Molecular genetic analysis of haematological malignancies II: mature lymphoid neoplasms

Molecular genetic techniques have become an integral part of the diagnostic assessment for many lymphomas and other chronic lymphoid neoplasms. The demonstration of a clonal immunoglobulin or T cell receptor gene rearrangement offers a useful diagnostic tool in cases where the diagnosis is equivocal. Molecular genetic detection of other genomic rearrangements may not only assist with the diagnosis but can also provide important prognostic information. Many of these rearrangements can act as molecular markers for the detection of low levels of residual disease. In this review, we discuss the applications of molecular genetic analysis to the chronic lymphoid malignancies. The review concentrates on those disorders for which molecular genetic analysis can offer diagnostic and/or prognostic information.

Rituximab Induces Effective Clearance of Minimal Residual Disease in Molecular Relapses of Mantle Cell Lymphoma

Molecular remission (MR) is associated with improved outcome in mantle cell lymphoma (MCL). If MR is not achieved, patients are at high risk of relapse. We retrospectively describe the molecular and clinical follow-ups of 4 patients with molecular relapses (M-rels) who were treated with rituximab. The 4 patients received rituximab-supplemented, high-dose sequential chemotherapy and autologous stem cell transplantation as induction treatment and achieved clinical remission and MR. M-rel was defined as polymerase chain reaction (PCR) positivity in 2 consecutive samples in the absence of clinical relapse. M-rels occurred at 3, 6, 39, and 52 months and were always confirmed by direct sequencing of the clonal rearrangement. Minimal residual disease was monitored by qualitative and real-time quantitative PCR. All patients received 4 courses of rituximab, with 2 additional infusions if PCR positivity remained. After 4-6 courses of rituximab, all patients re-entered MR. No clinical relapses were recorded at 3, 6, 18, and 62 months from treatment, although 1 patient had a second M-rel that was sensitive to rituximab. Our results indicate that rituximab is active against residual MCL cells and suggest that molecularly tailored maintenance therapy needs to be investigated in clinical trials.

Prolonged survival and low incidence of late toxic sequelae in advanced follicular lymphoma treated with a TBI-free autografting program: updated results of the multicenter consecutive GITMO trial

This study provides an updated report of the consecutive multicenter Gruppo Italiano Trapianto Midollo Osseo trial employing an intensified, purging-free, total body irradiation-free, high-dose sequential chemotherapy schedule with peripheral blood stem cell autograft (i-HDS) in advanced-stage follicular lymphoma (FL). Special interest has been devoted to late toxicities and outcome in terms of molecular status. Ninety-two untreated FL patients aged <or=60 were enrolled by 20 Italian centers and evaluated on an intention-to-treat basis. Main findings are as follows: (1) 5.5-years overall survival projection of 80% (median follow-up: 68 months), with no differences related to age-adjusted IPI score; (2) 46 (50%) of 92 patients presently in continuous complete remission; (3) projected long-term progression-free survival exceeding 80% for patients collecting PCR-negative stem cell harvests or achieving molecular remission within the first 2 years from the end of therapy; (4) actuarial 5-years risk of developing secondary myelodysplasia and acute myeloid leukemia of 3.7%, with most of these events occurring in patients re-treated for recurrent lymphoma. These results demonstrate that i-HDS is feasible, effective and safe even in terms of long-term outcome. As the HDS schedule can be easily supplemented with Rituximab, it is one of the best options for random comparison with Rituximab-supplemented conventional chemotherapy.

Quantitative assessment of molecular remission after high-dose therapy with autologous stem cell transplantation predicts long-term remission in mantle cell lymphoma

To evaluate the prognostic impact of minimal residual disease (MRD), quantitative real-time polymerase chain reaction (RQ-PCR) of clonal IGH rearrangements was performed in 29 patients with mantle cell lymphoma (MCL) treated with high-dose radiochemotherapy and autologous stem cell transplantation (ASCT). Fourteen of 27 patients evaluable for MRD after ASCT achieved complete clinical and molecular remission, whereas 13 patients had detectable MRD within the first year after ASCT. Molecular remission after ASCT was strongly predictive for improved outcome, with a median progression-free survival (PFS) of 92 months in the MRD-negative group compared with 21 months in the MRD-positive group (P < .001). Median overall survival (OS) was 44 months in the MRD-positive group and has not been reached in the MRD-negative group (P < .003). In multivariate analysis, molecular remission and bulky disease were independent prognostic factors for PFS (P = .001 and P = .021, respectively). While cyclophosphamide, doxorubicin, vincristine, prednisolone (CHOP)–like cytoreduction had only modest influence, ara-C–containing mobilization and myeloablative radiochemotherapy significantly reduced MRD. Quantitative MRD measured in the stem cell products of 27 patients was not predictive for molecular remission. We conclude that sequential quantitative monitoring of residual disease after ASCT is a powerful indicator for treatment outcome in MCL and defines subgroups of patients with a significantly different prognosis.

Pilot study of tandem high-dose chemotherapy and autologous stem cell transplantation with a novel combination of regimens in patients with poor risk lymphoma

In an effort to improve the outcome of poor-risk lymphoma patients, we evaluated a novel regimen of tandem high-dose chemotherapy (THDC) with autologous stem cell transplantation. A total of 41 patients (median age 40 years, range 15-68 years) with poor-risk non-Hodgkin's lymphoma and Hodgkin's disease were enrolled. THDC consisted of melphalan (180 mg/m2) and escalating dose mitoxantrone (30-50 mg/m2) (MMt) for the first conditioning regimen, and thiotepa (500 mg/m2), carboplatin (800 mg/m2), and escalating dose etoposide phosphate (400-850 mg/m2), (ETCb) as the second regimen. In all, 31 patients (76%) completed both transplants, with a median time between transplants of 55 days (range 26-120). The maximum tolerated dose was determined as 40 mg/m2 for mitoxantrone and 550 mg/m2 for etoposide phosphate. The overall toxic death rate was 12%. Following high-dose chemotherapy, 10 of 24 evaluable patients (42%) were in CR. The two-year overall survival and event-free survival is 67% (95% CI, 52-81%) and 45%, (95% CI, 29-61%) for the 41 patients enrolled; and 69% (95% CI, 525-586%) and 48% (95% CI, 30-67%) for the 31 patients completing both transplants. This THDC regimen is feasible but with notable toxicity in heavily pretreated patients; its role in the current treatment of high-risk lymphoma remains to be determined.

Chemotherapy with rituximab followed by high-dose therapy and autologous stem cell transplantation in patients with mantle cell lymphoma

BACKGROUND

The authors evaluated the efficacy of chemotherapy combined with rituximab followed by high-dose therapy (HDT) plus autologous stem cell transplantation in patients with mantle cell lymphoma (MCL).

METHODS

This was a retrospective analysis of 34 patients who were treated in 2 departments of hematology, including 29 patients (85%) who received first-line treatment. Rituximab was administered as 4 injections just before harvest in 25 patients (73%) or simultaneously with chemotherapy in 9 patients (27%). HDT included total body irradiation in 26 patients (77%).

RESULTS

After induction therapy, all patients except one reached a response: There were 14 (41%) complete responses (CR) and 19 (56%) partial responses (PR). Stem cell harvest was successful in all patients but 2, with a median number of 5.9 CD34-positive cells per 10(6)/kg. Three months after transplantation, 24 patients (71%) were in CR, and 7 patients (21%) were in PR. At 3 years from the day of transplantation, the estimated overall survival was 87%. With a median follow-up at 2.6 years, the estimated median time to disease progression was 3.4 years. Rituximab treatment before harvest did not delay hematopoietic reconstitution: The median time it took patients to recover absolute neutrophil count to > 0.5 G/L was 10 days.

CONCLUSIONS

Chemotherapy combined with rituximab followed by HDT improved the overall survival and progression-free survival in patients MCL without adding toxicities.

Detection and monitoring of minimal residual disease by quantitative real-time PCR

BACKGROUND

The detection of malignant cells by quantitative real-time PCR has become state of the art for diagnosis, monitoring response to treatment and detection of minimal residual disease (MRD) in patients with leukemia or lymphoma. In order to be used in high-throughput analyses technical details have to be standardized to improve reproducibility and comparability of quantitative results obtained in different laboratories.

METHODS

Molecular monitoring of disease activity during and after treatment based on the detection of malignant cells in circulation or bone marrow by quantitative real-time PCR will be helpful to develop individualized treatment strategies for every patient.

CONCLUSIONS

The effectiveness of any kind of innovative treatment with specific antibodies, cellular immunotherapy or molecules designed for specific targets of tumor cells can be controlled at a very high level of sensitivity and accuracy. Based on quantitative results indicative for success or treatment failure, therapeutic changes upon the detection of progressive disease at the molecular level can be made even before symptoms or signs of clinical relapse occur. Hopefully, this will lead to higher cure rates and improved long-term survival.

Detection of BCL2-IGH Using Single-Round PCR Assays

The translocation t(14;18) resulting in fusion of the BCL2 and the immunoglobulin heavy chain genes (BCL2-IGH) is present in 80% to 90% of follicular lymphomas and 20% to 30% of diffuse large B-cell lymphomas. Polymerase chain reaction (PCR) analysis for the translocation products suffers from low analytic specificity. As a result, either nested PCR or probe hybridization is required to aid in the identification of the specific translocation products. These added procedures are undesirable in clinical laboratories because nested procedures increase the possibility of contamination and probe hybridization increases assay turnaround time. To simplify the BCL2-IGH assay procedure, we attempted to eliminate the nonspecific PCR products by optimizing the annealing temperatures of the PCR assays using a gradient thermocycler. We showed that gradually increasing the annealing temperature from 55 degrees C to 67 degrees C significantly enhanced the intensity of the specific PCR products while eliminating the nonspecific ones. We compared the simplified procedure with a PCR-probe hybridization method on 68 patient specimens. The simplified procedure had increased analytic and diagnostic specificities with comparable sensitivities. With significantly improved analytic specificity, one round of PCR is sufficient to detect the BCL2-IGH gene rearrangements without further confirmation.

Successful Salvage with High-Dose Sequential Chemotherapy Coupled with In Vivo Purging and Autologous Stem Cell Transplantation in 2 Patients with Primary Refractory Mantle Cell Lymphoma Presenting in the Leukemic Phase

We report the results of an aggressive salvage regimen in 2 patients with advanced-stage leukemic-phase mantle cell lymphoma who were refractory to previous conventional therapies. We combined multiple phases of a cytoreductive regimen including rituximab and sequential high-dose treatment with autologous stem cell transplantation (ASCT). The regimen consisted of a debulking phase with fludarabine, idarubicin, high-dose cytarabine, and high-dose methotrexate; a mobilization and in vivo purging phase with rituximab, cyclophosphamide, and granulocyte colony-stimulating factor; high-dose sequential chemotherapy with etoposide, mitoxantrone, and melphalan followed by ASCT; and, finally, posttransplantation consolidation with rituximab for treatment of minimal residual disease. With this regimen, these 2 refractory patients with multiple poor prognostic factors are in complete remission at 41 and 42 months following transplantation. Although the fact that these 2 patients are still in remission beyond 3 years after ASCT is encouraging, we need a longer follow-up to comment on their long-term survival.

B-cell purging in autologous stem-cell transplantation for non-Hodgkin lymphoma

Autologous stem-cell transplantation is a common therapy for B-cell non-Hodgkin lymphoma. However, a concern with the procedure is the potential of malignant cells to reinfuse with the stem-cell graft. Thus attempts have been made to purge, or eliminate, malignant cells from the graft. The oldest, and most well studied, method for prevention of reinfusion is in vitro use of antibodies against B cells that bind or lyse malignant B cells and healthy cells, while leaving T cells and stem cells to be reinfused. In the past 5 years, investigators have used rituximab, an antibody against CD20, to purge malignant cells in vivo without any manipulation in vitro. Both conventional and new techniques have shown promise, but their exact role remains to be defined. We analysed data on the purging of B cells by use of antibodies in the setting of autologous transplantation, with emphasis on the emerging technique of in vivo purging.

Rituximab consolidation after high-dose chemotherapy and autologous blood stem cell transplantation in follicular and mantle cell lymphoma: a prospective, multicenter phase II study

BACKGROUND

Patients with follicular (FL) or mantle cell lymphoma (MCL) are incurable with conventional therapy. We investigated the safety and efficacy of rituximab consolidation after autologous stem cell transplantation (ASCT) in order to prevent relapse by clearance of minimal residual disease (MRD).

METHODS

Rituximab was given approximately 8 weeks after CD34+ cell enriched ASCT at 375 mg/m2, weekly for 4 weeks. Monitoring of MRD was performed by repetitive PCR analyses.

RESULTS

Thirty-one patients were included; one died early after ASCT before rituximab administration. Thirty patients (20 FL, 10 MCL) were evaluable after rituximab consolidation, and 27 of these were assessable for MRD detection. Rituximab consolidation post-ASCT was safe, the most common toxicity being infection. At a median follow-up of 42 months (range 13-96) after ASCT, 25 patients were censored with an actuarial event-free survival (EFS) of 81% at 4 and 5 years. Four patients (two FL, two MCL) relapsed, and one additional MCL patient died unexpectedly in complete remission. PCR-negativity was observed in 22% of the patients before ASCT, 53% post-ASCT (P=0.0547), 72% after rituximab (P=0.0018) and 100% at 6 months post-transplant (P < 0.001).

CONCLUSIONS

One single course of rituximab consolidation given after ASCT is safe, may help to eliminate MRD and may translate into improved EFS in both FL and MCL patients.

The role of molecular studies in lymphoma diagnosis: a review

Lymphoma classification is based on a multiparametric approach to diagnosis, in which clinical features, morphology, immunophenotype, karyotype and molecular characteristics are important to varying degrees. While in most cases, a diagnosis can be confidently established on the basis of morphology and immunophenotype alone, a small proportion of diagnostically difficult cases will rely on molecular studies to enable a definitive diagnosis. This review discusses the various molecular techniques available including Southern blotting (SB), polymerase chain reaction (PCR), fluorescence in situ hybridisation (FISH)--including multicolour-FISH/spectral karyotyping and comparative genomic hybridisation--and also gene expression profiling using cDNA microarray technology. Emphasis is given to the analysis of antigen receptor gene rearrangements and chromosomal translocations as they relate to lymphoma diagnosis and also in the setting of minimal residual disease (MRD) detection and monitoring. Laboratories performing these tests need to have expertise in these areas of testing, and there is a need for greater standardisation of molecular tests. It is important to know the sensitivity and specificity of each test as well as its limitations and the pitfalls in the interpretation of results. Above all, results of molecular testing should never be considered in isolation, and must always be interpreted in the context of clinical and other laboratory data.

Long-term follow-up of indolent lymphoma patients treated with high-dose sequential chemotherapy and autografting: evidence that durable molecular and clinical remission frequently can be attained only in follicular subtypes

PURPOSE

To evaluate the prognostic relevance of molecular monitoring of minimal residual disease in indolent lymphomas receiving high-dose sequential chemotherapy and autografting.

PATIENTS, MATERIALS, AND METHODS

A polymerase chain reaction- (PCR-)based strategy was used to evaluate the presence of residual tumor cells in a panel of 70 indolent lymphoma patients: 40 with follicular (FCL), 14 with small lymphocytic (SLL), and 16 with mantle-cell (MCL) lymphomas. They were treated either with first-line (n = 61) or second-line (n = 9) therapy with an intensified high-dose chemotherapy program followed by peripheral-blood progenitor cells autografting. The Bcl-1, Bcl-2, and immunoglobulin gene rearrangements were used as lymphoma-specific markers. Overall, a molecular marker was obtained from the diagnostic tissue in 60 of 70 patients (86%). Results The collection of PCR-negative cells and the achievement of posttransplantation molecular remission (MR) were common in patients with FCL subtype (54% and 70%, respectively), whereas they were not frequent among SLL and MCL (25% and 12.5%, respectively) patients. With a median molecular follow-up of 75 months, an 88% incidence of relapse was observed among patients never attaining MR. In contrast, relapse incidence was only 8% among patients attaining a durable MR (P <.005). At present, 26 patients (20 with FCL and six with non-FCL) are long-term survivors in absence of clinical and molecular disease.

CONCLUSION

Our results indicate that among indolent lymphomas, FCL and non-FCL subtypes show a significantly different behavior in terms of MR achievement, and MR after intensive chemotherapy and autografting is predictive for a prolonged disease-free survival, whereas persistent PCR positivity is associated with a high risk of relapse.

Infused CD34+ cell dose, but not tumour cell content of peripheral blood progenitor cell grafts, predicts clinical outcome in patients with diffuse large B-cell lymphoma and follicular lymphoma grade 3 treated with high-dose therapy

Previously, we have shown that patients with diffuse large B-cell lymphoma (DLBCL) transplanted with contaminated bone marrow (BM) generally have a poor outcome. Whether this is also the case when peripheral blood progenitor cell (PBPC) grafts are used is not known. Forty-three patients with chemosensitive DLBCL or follicular lymphoma grade 3 (FLgr3) were treated with high-dose therapy (HDT) and autologous stem cell support. Nine patients received purged grafts. Quantitative real-time polymerase chain reaction (QRT-PCR) for either the BCL2/IgH translocation or allele specific oligonucleotide (ASO) QRT-PCR for the immunoglobulin heavy chain (IgH) complementarity-determining region 3 were used. Nine of 25 (36%) PBPC grafts contained tumour cells as tested by QRT-PCR, including two grafts purged by CD34(+) cell enrichment combined with B-cell depletion. The level of contamination of the PBPC/CD34(+) cells ranged from 0 to 8.28%. No relationship could be shown between the total number of tumour cells infused and relapse. Patients receiving PCR-positive or PCR-negative PBPC grafts had similar progression-free survival (PFS) (P = 0.49). However, a significant difference was seen in PFS and overall survival (OS) for the patients given >/=6.1 x 10(6) CD34(+) cells/kg compared with those given <6.1 x 10(6) CD34(+) cells/kg (P = 0.01 and P < 0.05 respectively).

An update on the role of high-dose therapy with autologous or allogeneic stem cell transplantation in mantle cell lymphoma

PURPOSE OF REVIEW

Early trials of high-dose therapy with autologous stem cell transplantation in mantle cell lymphoma were discouraging, with no clear survival advantage attributable to the procedure. Most early series were plagued by small numbers, retrospective designs, and short follow-up. Also, until recently, allogeneic stem cell transplantation was not an option for most mantle cell lymphoma patients who were too old or infirm to tolerate standard conditioning regimens.

RECENT FINDINGS

New advances in allogeneic transplantation, particularly reduced-intensity conditioning regimens, have increased the availability of this procedure to patients with mantle cell lymphoma. New evidence has emerged during the last several years that suggests autologous stem cell transplantation in first complete remission may provide a survival advantage over conventional chemotherapy in patients with mantle cell lymphoma. Additionally, investigational strategies such as in vivo purging with rituximab and the use of radioimmunotherapy in conditioning regimens may further increase response rates and, hopefully, survival in mantle cell lymphoma patients. Finally, recent studies suggest the existence of a graft-versus-lymphoma effect in mantle cell lymphoma providing strong scientific rationale for the possible curative potential of allogeneic stem cell transplantation in this disease.

SUMMARY

This review focuses on recent advances in allogeneic and autologous transplantation for mantle cell lymphoma. Particular emphasis is placed on the role of autologous transplantation in first complete remission, the role of in vivo purging with rituximab, the utility of radioimmunotherapy and, finally, the evolving strategy of reduced-intensity allogeneic stem cell transplantation.

Intensive chemotherapy and autologous stem-cell transplantation plus rituximab is superior to conventional chemotherapy for newly diagnosed advanced stage mantle-cell lymphoma: a matched pair analysis

BACKGROUND

The outcome of 20 patients with newly diagnosed mantle-cell lymphoma (MCL) treated on a prospective trial of autologous stem-cell transplantation (ASCT) and rituximab immunotherapy was compared with the outcome of 40 matched historical control patients treated with standard combination chemotherapy.

PATIENTS AND METHODS

Control patients with MCL were identified from a lymphoma database, and pairs were matched with patients receiving ASCT-rituximab for stage of disease, gender and age (+/-5 years). Only patients treated with an anthracycline- or cyclophosphamide-fludarabine-based regimen were included.

RESULTS

Seventeen of 20 patients who received ASCT-rituximab remain alive in remission at a median of 30 months from diagnosis; one patient relapsed 2 years post-ASCT, and two died at 7 and 11 months post-ASCT without evidence of lymphoma. Of 40 patients treated with conventional chemotherapy, with a median follow-up of 80 months, 33 have relapsed or progressed and 29 have died. Overall (OS) and progression-free (PFS) survival were superior in patients treated with ASCT-rituximab compared with those treated with conventional chemotherapy (PFS at 3 years, 89% versus 29%, P <0.00001; OS at 3 years, 88% versus 65%, P = 0.052).

CONCLUSIONS

This matched-pair analysis suggests that patients with advanced-stage MCL treated with ASCT-rituximab had statistically significantly better PFS and a trend toward better OS than patients treated with conventional chemotherapy. Longer follow-up will determine response duration and the true impact of this treatment strategy on PFS and OS.

Quantitative assessment of contaminating tumor cells in autologous peripheral blood stem cells of B-cell non-Hodgkin lymphomas using immunoglobulin heavy chain gene allele-specific oligonucleotide real-time quantitative-polymerase chain reaction

A real-time quantitative-polymerase chain reaction (RQ-PCR) targeting the immunoglobulin heavy chain (IgH) gene has been used for the quantification of minimal residual disease (MRD) in B-cell hematological malignancies. In non-Hodgkin lymphoma (NHL), experimental costs are increased, as a large number of primer-probe sets are required because of diversity, due to somatic and ongoing mutations of the IgH gene. We developed an allele-specific oligonucleotide (ASO) combined with a germline consensus probe-based RQ-PCR assay and examined MRD in peripheral blood stem cells (PBSC). The IgH consensus probes were adapted in seven (50%) of 14 amplifiable cases. Patients with heavily contaminating tumor cells in PBSC relapsed after PBSC transplantation. Our strategy will contribute to the development of a cost-efficient, precisely quantitative and systemic detection assay for MRD in NHL.

Development of consensus fluorogenically labeled probes of the immunoglobulin heavy-chain gene for detecting minimal residual disease in B-cell non-Hodgkin lymphomas

We have examined 72 patients with B-cell non-Hodgkin lymphoma (B-NHL) in order to search for consensus sequences of the immunoglobulin heavy chain (IgH) gene, and developed consensus fluorogenically labeled probes for use in an allele-specific oligonucleotide (ASO) real-time quantitative polymerase chain reaction (RQ-PCR) assay of minimal residual disease (MRD). We detected a clonal IgH variable region (VH) sequence in 51 (70.8%) of the 72 B-NHLs, the most frequent VH gene usages being VH3 and VH4 (45/51, 88.2%). It was possible to design three consensus fluorogenic probes for the VH3 gene and one for the VH4 gene avoiding these hypermutations. Our sequencing results suggested that consensus fluorogenic probes would be best based on the 5'-side of the framework region 3 (FR3) because the frequency of somatic hypermutations was significantly lower in the regions on which the probes were based than in the remaining parts of FR3 (P < 0.05). Nineteen (54.3%) of 35 B-NHLs with the VH3 gene and 5 (50%) of 10 with the VH4 gene had sequences identical to at least one of these probes. We found that probes containing one base substitution were still applicable for a MRD study, whereas those containing two or more were not. Therefore, our four probes were applicable for 37 (82.2%) of the 45 patients with VH3 or VH4. This limited number of probes makes a large-scale study of MRD in B-NHL more feasible.