Outcomes of autologous and allogeneic blood or marrow transplantation for mantle cell lymphoma

Allogeneic Stem Cell Transplantation in Mantle Cell Lymphoma; Insights into Its Potential Role in the Era of New Immunotherapeutic and Targeted Therapies: The GETH/GELTAMO Experience

Allo-SCT is a curative option for selected patients with relapsed/refractory (R/R) MCL, but with significant NRM. We present the long-term results of patients receiving allo-SCT in Spain from March 1995 to February 2020. The primary endpoints were EFS, OS, and cumulative incidence (CI) of NRM, relapse, and GVHD. We included 135 patients, most (85%) receiving RIC. After a median follow-up of 68 months, 5-year EFS and OS were 47 and 50%, respectively. Overall and CR rates were 86 and 80%. The CI of relapse at 1 and 3 years were 7 and 12%. NRM at day 100 and 1 year were 17 and 32%. Previous ASCT and Grade 3–4 aGVHD were associated with a higher NRM. Grade 3–4 aGVHD, donor type (mismatch non-related), and the time-period 2006–2020 were independently related to worse EFS. Patients from 1995–2005 were younger, most from HLA-identical sibling donors, and were pretreated less. Our data confirmed that allo-SCT may be a curative option in R/R MCL with low a CI of relapse, although NRM is still high, being mainly secondary to aGVHD. The arrival of new, highly effective and low toxic immunotherapeutic or targeted therapies inevitably will relegate allo-SCT to those fit patients who fail these therapies, far away from the optimal timing of treatment.

Cellular Therapies for Mantle Cell Lymphoma

Mantle cell lymphoma (MCL) is a subtype of B cell non-Hodgkin lymphoma characterized by a heterogeneous clinical presentation. Patients who demonstrate an objective response to induction therapy(ies) and are eligible for intensive therapies are offered an autologous hematopoietic cell transplant (HCT) as front-line consolidation followed by rituximab maintenance. Allogeneic HCT is an option for younger and fit patients with high-risk disease or in patients who have relapsed after autologous HCT. Recent advances in T cell engineering brought chimeric antigen receptor T cell (CAR T) therapy from the bench to the bedside, with brexucabtagene autoleucel being the first CAR T product approved by the US Food and Drug Administration for use in relapsed/refractory MCL. In this comprehensive review, we summarize the literature on available cellular therapies for MCL and present a treatment algorithm that incorporates HCT, autologous or allogeneic, and CAR T therapies.

Mantle cell lymphoma

MCL is a well-characterized generally aggressive lymphoma with a poor prognosis. However, patients with a more indolent disease have been reported in whom the initiation of therapy can be delayed without any consequence for the survival. In 2017 the World Health Organization updated the classification of MCL describing two main subtypes with specific molecular characteristics and clinical features, classical and indolent leukaemic nonnodal MCL. Recent research results suggested an improving outcome of this neoplasm. The addition of rituximab to conventional chemotherapy has increased overall response rates, but it did not improve overall survival compared to chemotherapy alone. The use of intensive frontline therapies including rituximab and consolidation with autologous stem cell transplantation ameliorated response rate and prolonged progression-free survival in young fit patients, 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 understanding of pathogenetic pathways in MCL might improve the outcome of conventional chemotherapy and spare the toxicity of intense therapy in most patients. Cases not eligible for intensive regimens, 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 as the first-line strategy in a wide range of patients. Finally, since the optimal approach to the management of MCL is still evolving, it is critical that these patients are enrolled in clinical trials to identify the better treatment options.

Reduced-intensity or myeloablative allogeneic hematopoietic cell transplantation for mantle cell lymphoma: a systematic review

Allogeneic hematopoietic cell transplantation (allo-HCT) is the only known treatment that can offer a cure in mantle cell lymphoma, but it is unclear if regimen dose-intensity offers any advantage. We performed a systematic review/meta-analysis to assess efficacy of allo-HCT using myeloablative or reduced-intensity conditioning. We report results according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. On the basis of a relatively lower nonrelapse mortality and a slightly better progression-free survival/event-free survival and overall survival rates, reduced-intensity allo-HCT regimens appear to be the preferred choice when an allo-HCT is being considered for mantle cell lymphoma. The higher rate of relapse when offering reduced-intensity regimens cannot be ignored but certainly highlights opportunities to incorporate post-transplant strategies to mitigate this risk. A prospective comparative study is ultimately needed to generate more conclusive evidence.

Umbilical Cord as Prospective Source for Mesenchymal Stem Cell-Based Therapy

The paper presents current evidence on the properties of human umbilical cord-derived mesenchymal stem cells, including origin, proliferative potential, plasticity, stability of karyotype and phenotype, transcriptome, secretome, and immunomodulatory activity. A review of preclinical studies and clinical trials using this cell type is performed. Prospects for the use of mesenchymal stem cells, derived from the umbilical cord, in cell transplantation are associated with the need for specialized biobanking and transplant standardization criteria.

Long-term sustained disease control in patients with mantle cell lymphoma with or without active disease after treatment with allogeneic hematopoietic cell transplantation after nonmyeloablative conditioning

BACKGROUND

Previously, early results were reported for allogeneic hematopoietic cell transplantation (HCT) after nonmyeloablative conditioning with 2 Gy of total body irradiation with or without fludarabine and/or rituximab in 33 patients with mantle cell lymphoma (MCL).

METHODS

This study examined the outcomes of 70 patients with MCL and included extended follow-up (median, 10 years) for the 33 initial patients. Grafts were obtained from human leukocyte antigen (HLA)-matched, related donors (47%), unrelated donors (41%), and HLA antigen-mismatched donors (11%).

RESULTS

The 5-year incidence of nonrelapse mortality was 28%. The relapse rate was 26%. The 5-year rates of overall survival (OS) and progression-free survival (PFS) were 55% and 46%, respectively. The 10-year rates of OS and PFS were 44% and 41%, respectively. Eighty percent of surviving patients were off immunosuppression at the last follow-up. The presence of relapsed or refractory disease at the time of HCT predicted a higher rate of relapse (hazard ratio [HR], 2.94; P = .05). Despite this, OS rates at 5 (51% vs 58%) and 10 years (43% vs 45%) were comparable between those with relapsed/refractory disease and those undergoing transplantation with partial or complete remission. A high-risk cytomegalovirus (CMV) status was the only independent predictor of worse OS (HR, 2.32; P = .02). A high-risk CMV status and a low CD3 dose predicted PFS (HR, 2.22; P = .03).

CONCLUSIONS

Nonmyeloablative allogeneic HCT provides a long-term survival benefit for patients with relapsed MCL, including those with refractory disease or multiple relapses.

Lifting the mantle: Unveiling new treatment approaches in relapsed or refractory mantle cell lymphoma

The management of relapsed/refractory mantle cell lymphoma (MCL) remains a clinical challenge. A standard second-line treatment for relapsed/refractory MCL does not exist. Management of relapsed/refractory MCL requires an individualized treatment approach, incorporating factors such as: functional status, prior treatments, response to prior therapies, and disease biology. Generally, there are two categories of salvage therapy; the first, non-cross-resistant cytotoxic chemotherapeutic agents and, the second, pathway-targeted agents. For transplant eligible patients, the optimal therapy usually consists of salvage, remission re-induction phase followed, whenever possible, by a consolidation phase. Bendamustine and/or high dose cytarabine plus rituximab based chemotherapy represent the most common salvage therapy with an overall response rate of 70-80%. Consolidation with a reduced intensity conditioning allogeneic stem cell transplantation represents the only potentially curative treatment. Overall survival ranges from 30% to 50% at 5 years with this approach. For transplant ineligible patients, ibrutinib is the most effective treatment with an overall response rate of almost 70% and median response duration of 17.5 months. Lacking an effective consolidation, this approach is not considered curative. In this review we characterize the main therapeutic approaches available in this setting and summarize our preferred clinical treatment approach.

Initial therapy of mantle cell lymphoma

Mantle cell lymphoma is a well-recognized distinct clinicopathologic subtype of B-cell non-Hodgkin lymphoma. The current World Health Organization (WHO) classification subdivides this entity into aggressive and other variants. The disease has a predilection for older males, and patients typically present at an advanced stage with frequent splenomegaly and extranodal involvement including bone marrow, peripheral blood, gastrointestinal, and occasional central nervous system involvement. Early studies of therapy outcomes in this disease revealed that while response rates where high, relapse was expected after a limited period of time. Prolonged survival was uncommon, with initial median survival rates typically in the 3-4-year range. Those with a high proliferative rate, blastoid morphology, and selected clinical features were recognized as having a worse prognosis. Therapeutic approaches have diverged into aggressive therapies with high response rates and promising progression free survival rates, which may be applied to younger healthy patients, and less aggressive approaches. Aggressive therapies include intensive chemotherapy alone or chemotherapy followed by autologous stem cell transplant, which has been shown to be most effective when applied in first remission. Whether these more intense therapies result in improved survival as compared with less aggressive therapies is not well established. Allogeneic transplant has also been investigated, although high treatment-related mortality and the risk of chronic graft versus host disease and the relatively advanced age of this patient population have tempered enthusiasm for this approach. A number of less aggressive therapies have been shown to produce promising results. Consolidation and maintenance strategies are an active area of investigation. A number of newer agents have shown promising activity in relapsed disease, and are being investigated in the front-line setting. Overall survival rates are improving in this disease, with current studies suggesting a median survival of 5 or more years.

ESMO Consensus conferences: guidelines on malignant lymphoma. part 2: marginal zone lymphoma, mantle cell lymphoma, peripheral T-cell lymphoma

To complement the existing treatment guidelines for all tumour types, ESMO organizes consensus conferences to focus on specific issues in each type of tumour. In this setting, a consensus conference on the management of lymphoma was held on 18 June 2011 in Lugano, next to the 11th International Conference on Malignant Lymphoma. The conference convened ∼30 experts from all around Europe, and selected six lymphoma entities to be addressed; for each of them, three to five open questions were to be addressed by the experts. For each question, a recommendation should be given by the panel, referring to the strength of the recommendation based on the level of evidence. This consensus report focuses on the three less common lymphoproliferative malignancies: marginal zone lymphoma, mantle cell lymphoma, and peripheral T-cell lymphomas. A first report had focused on diffuse large B-cell lymphoma, follicular lymphoma, and chronic lymphocytic leukaemia.

Open questions in the management of mantle cell lymphoma

Mantle cell lymphoma (MCL) is one of the lymphomas with the worse prognosis (median survival 3-5years) as it has an aggressive evolution and at the same time is incurable. Biologically it is characterized by the t(11;14)(q13;q32) translocation leading to overexpression of cyclin D1. This review focuses on a number of controversial issues in the management of this disease, as how to stage patients with a disease which often has extranodal localizations, how to recognize the small subgroup of cases with an indolent course, which treatment is suggested for the young and fit or for the elderly, the role of CNS prophylaxis, rituximab maintenance and radiotherapy, the indications to allogeneic transplantation and the place of new active anti-lymphoma drugs.

Allogeneic hematopoietic cell transplantation in mantle cell lymphoma

Mantle cell lymphoma (MCL) is a high-risk non-Hodgkin lymphoma that is considered incurable with standard chemotherapy. While autologous hematopoietic cell transplantation (autoHCT) can provide lengthy disease-free survival in select patients, cure generally is not an expected outcome with this approach. Allogeneic hematopoietic cell transplantation (alloHCT), which can exploit the potential benefits of graft-versus-lymphoma (GVL) effect, has been shown in multiple studies to yield a small but reproducible portion of patients with long-term remission more suggestive of cure. Historically, alloHCT for MCL was administered after myeloablative conditioning, but this approach was limited by early non-relapse mortality. Development of reduced-intensity (RI)-alloHCT has abrogated some of the early post-transplant risks, allowing this potentially effective therapy to be offered to a larger number of affected individuals. The trends in published data reflect a preference toward using RI-alloHCT for MCL, often because patients in whom alloHCT is being considered have relapsed disease following myeloablative autoHCT. Further efforts to spare the effects of graft-versus-host disease (GVHD) while still evoking GVL remain a focus of investigation in this area. In this review, we will discuss the application of alloHCT in the management of MCL, the factors associated with outcome, the different methods in which it can be performed, and the strategies that can be employed in post-alloHCT relapse.

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.

NCI First International Workshop on the Biology, Prevention, and Treatment of Relapse after Allogeneic Hematopoietic Stem Cell Transplantation: report from the Committee on the Epidemiology and Natural History of Relapse following Allogeneic Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (alloHSCT) is increasingly being used for treatment of hematologic malignancies, and the immunologic graft-versus-tumor effect (GVT) provides its therapeutic effectiveness. Disease relapse remains a cause of treatment failure in a significant proportion of patients undergoing alloHSCT without improvements over the last 2-3 decades. We summarize here current data and outline future research regarding the epidemiology, risk factors, and outcomes of relapse after alloHSCT. Although some factors (eg, disease status at alloHSCT or graft-versus-host disease [GVHD] effects) are common, other disease-specific factors may be unique. The impact of reduced-intensity regimens on relapse and survival still need to be assessed using contemporary supportive care and comparable patient populations. The outcome of patients relapsing after an alloHSCT generally remains poor even though interventions including donor leukocyte infusions can benefit some patients. Trials examining targeted therapies along with improved safety of alloHSCT may result in improved outcomes, yet selection bias necessitates prospective assessment to gauge the real contribution of any new therapies. Ongoing chronic GVHD (cGVHD) or other residual post-alloHSCT morbidities may limit the applicability of new therapies. Developing strategies to promptly identify patients as alloHSCT candidates, while malignancy is in a more treatable stage, could decrease relapses rates after alloHSCT. Better understanding and monitoring of minimal residual disease posttransplant could lead to novel preemptive treatments of relapse. Analyses of larger cohorts through multicenter collaborations or registries remain essential to probe questions not amenable to single center or prospective studies. Studies need to provide data with detail on disease status, prior treatments, biologic markers, and posttransplant events. Stringent statistical methods to study relapse remain an important area of research. The opportunities for improvement in prevention and management of post-alloHSCT relapse are apparent, but clinical discipline in their careful study remains important.

Autologous and allogeneic stem cell transplantation: rising therapeutic promise for mantle cell lymphoma

Mantle cell lymphoma (MCL) is currently an incurable neoplasm with a median survival duration of 3-5 years. The clinical results of therapy with cyclophosphamide, doxorubicin, vincristine, and prednisone or similar regimens are inadequate,leading to widespread exploration of the use of autologous stem cell transplantation (ASCT) during the first remission. In the pre-rituximab era, early ASCT extended the median remission duration by 1-2 years, but most patients eventually experienced relapse. With the advent of rituximab and its incorporation into stem cell mobilization and conditioning regimens, several research groups have reported improved outcomes, including the emergence of early survival curve plateaus that suggest a cured fraction. Intensive chemoimmunotherapy with rituximab and hyperfractionated cyclophosphamide,vincristine, doxorubicin, and dexamethasone has been reported to have similarly favorable results. Therefore, the addition of rituximab to intensive chemotherapy or ASCT regimens may be curative in patients undergoing frontline treatment for MCL. In the relapsed or refractory disease setting, the clinical results of ASCT remain inadequate. However, the increasing safety and high efficacy of non-myeloablative stem cell transplantation (SCT) suggests that it is the most appropriate transplantation modality in patients with relapsed or refractory MCL when a suitable donor is available.

Immunologic recovery following autologous stem-cell transplantation with pre- and posttransplantation rituximab for low-grade or mantle cell lymphoma

BACKGROUND

Rituximab may improve transplant outcomes but may delay immunologic recovery.

PATIENTS AND METHODS

Seventy-seven patients with low-grade or mantle cell lymphoma received autologous stem-cell transplantation (ASCT) on a phase II study. Rituximab 375 mg/m(2) was administered 3 days before mobilization-dose cyclophosphamide, then weekly for four doses after count recovery from ASCT. Immune reconstitution was assessed.

RESULTS

Sixty percent of transplants occurred in first remission. Actuarial event-free survival (EFS) and overall survival (OS) were 60% and 73%, respectively, at 5 years, with 7.2-year median follow-up for OS in surviving patients. Median EFS was 8.3 years. Older age and transformed lymphomas were independently associated with inferior EFS, whereas day 60 lymphocyte counts did not predict EFS or late infections. Early and late transplant-related mortality was 1% and 8%, with secondary leukemia in two patients. B-cell counts recovered by 1-2 years; however, the median IgG level remained low at 2 years. Late-onset idiopathic neutropenia, generally inconsequential, was noted in 43%.

CONCLUSION

ASCT with rituximab can produce durable remissions on follow-up out to 10 years. Major infections do not appear to be significantly increased or to be predicted by immune monitoring.

Mature results of the M. D. Anderson Cancer Center risk-adapted transplantation strategy in mantle cell lymphoma

In this study, we analyzed the long-term outcome of a risk-adapted transplantation strategy for mantle cell lymphoma in 121 patients enrolled in sequential transplantation protocols. Notable developments over the 17-year study period were the addition of rituximab to chemotherapy and preparative regimens and the advent of nonmyeloablative allogeneic stem cell transplantation (NST). In the autologous transplantation group (n = 86), rituximab resulted in a marked improvement in progression-free survival for patients who received a transplant in their first remission (where a plateau emerged at 3-8 years) but did not change the outcomes for patients who received a transplant beyond their first remission. In the NST group, composed entirely of patients who received a transplant beyond their first remission, durable remissions also emerged in progression-free survival at 5 to 9 years. The major determinants of disease control after NST were the use of a peripheral blood stem cell graft and donor chimerism of at least 95%, whereas the major determinant of death was immunosuppression for chronic graft-versus-host disease. Our results show that long-term disease-free survival in mantle cell lymphoma is possible after rituximab-containing autologous transplantation for patients in first remission and after NST for patients with relapsed or refractory disease.

Effect of remission status and induction chemotherapy regimen on outcome of autologous stem cell transplantation for mantle cell lymphoma

We analysed the outcomes of autologous stem cell transplantation (ASCT) following high-dose therapy with respect to remission status at the time of transplantation and induction regimen used in 56 consecutive patients with mantle cell lymphoma (MCL). Twenty-one patients received induction chemotherapy with HyperCVAD with or without rituximab (+/-R) followed by ASCT in first complete or partial remission (CR1/PR1), 15 received CHOP (+/-R) followed by ASCT in CR1/PR1 and 20 received ASCT following disease progression. Estimates of overall and progression-free survival (PFS) at 3 years among patients transplanted in CR1/PR1 were 93% and 63% compared with 46% and 36% for patients transplanted with relapsed/refractory disease, respectively. The hazard of mortality among patients transplanted with relapsed/refractory disease was 6.09 times that of patients transplanted in CR1/PR1 (P = 0.006). Patients in the CHOP (+/-R) group had a higher risk of failure for PFS compared with patients in the HyperCVAD (+/-R) group, though the difference did not reach statistical significance (hazard ratio 3.67, P = 0.11). These results suggest that ASCT in CR1/PR1 leads to improved survival outcomes for patients with MCL compared to ASCT with relapsed/refractory disease, and a HyperCVAD (+/-R) induction regimen may be associated with an improved PFS among patients transplanted in CR1/PR1.

Therapeutic options in mantle cell lymphoma

Mantle cell lymphoma (MCL) is an aggressive lymphoma requiring intensive chemotherapy +/- autologous stem cell transplantation (SCT) to achieve optimal rates of progression-free survival. Here we review the treatment options for patients with newly-diagnosed or relapsed MCL and discuss recent advances in management, including the role of autologous and allogeneic SCT.

Induction of autologous graft-versus-host disease: results of a randomized prospective clinical trial in patients with poor risk lymphoma

The results of blood or marrow transplantation in patients with chemorefractory aggressive lymphoma, that is, those not responding to conventional-dose chemotherapy at the time of transplant, have been poor. The relapse rate has been high after autologous bone marrow transplant, whereas allogeneic transplantation has been associated with excessive transplant-related toxicity. Administration of cyclosporine after autologous transplantation can induce an autoreactive syndrome that resembles graft-versus-host disease (GVHD). This syndrome, named autologous graft-versus-host disease, has clear antitumor activity in animal models that can be enhanced by the addition of cytokines such as gamma-interferon and interleukin-2. A randomized, prospective study was conducted to evaluate the antitumor effect of autologous graft-versus-host disease induced with cyclosporine, and augmented by the administration of gamma-interferon and interleukin-2 in patients with chemorefractory Hodgkin and aggressive non-Hodgkin lymphomas. Fifty-one patients were randomized, 24 to the autologous GVHD induction arm, and 27 to the noninduction arm after autologous transplant using mobilized peripheral blood stem cell (PBSC) grafts. There were no differences in treatment-related mortality, overall and event-free survival (OS, EFS) between both groups; however, in the induction arm, GVHD developed only in 4 patients. The administration of oral cyclosporine followed by interleukin-2 and gamma-interferon is generally not well tolerated, and does not appear to be an effective method to induce autologous GVHD in patients receiving autologous PBSC grafts.

Risk assessment in haemotopoietic stem cell transplantation: disease and disease stage

This chapter addresses the impact of the disease and disease status on the outcome of stem-cell transplantation. In consideration of the other topics addressed within this volume we have elected to focus on allogeneic rather than autologous transplantation. Furthermore we have not tried to be comprehensive and discuss the role of disease status in all conditions amenable to allografting, but rather to review the evidence that exists for selected haematological malignancies. Where possible we have made some clear recommendations, but where evidence is less clear we have indicated the ongoing controversies.

Blood or marrow transplantation for mantle cell lymphoma

PURPOSE OF REVIEW

Mantle cell lymphoma is a generally incurable disease for which blood or marrow transplantation is frequently considered. This review assesses the more recent literature on high-dose therapeutic approaches for mantle cell lymphoma.

RECENT FINDINGS

The benefit of transplantation is most apparent in first remission. Autologous transplantation can prolong event-free and possibly overall survival, although no plateau has been demonstrated in the survival curve. A randomized controlled trial demonstrated a significant event-free survival advantage to upfront autologous transplantation compared with interferon maintenance. The relative merit of autologous versus allogeneic transplantation remains to be better defined.

SUMMARY

The role of transplantation for mantle cell lymphoma is controversial, as the impact on overall survival is unclear. Transplantation should be considered early in the disease course. Elimination of minimal residual disease through in-vivo purging of stem cells may translate into more durable remissions. Nonmyeloablative allogeneic transplantation and high-dose radioimmunotherapy are topics of ongoing investigation.

Treatment of mantle cell lymphoma: current approach and future directions

Although mantle cell lymphoma has been described as "moderately aggressive" it has become clear that it carries a worse long-term prognosis than other subtypes of non-Hodgkin's lymphoma. In recent years, this has prompted numerous clinical trials of novel and more aggressive therapies in hopes of impacting these poor outcomes. These include more intensive combination chemotherapy regimens, monoclonal antibody therapy in conjunction with other treatments or conjugated to radioactive isotopes, high-dose chemotherapy followed by autologous or allogeneic stem cell transplantation, and newer targeted therapies based on increasing understanding of the molecular pathways of this malignancy.

Treatment of mantle cell lymphoma: targeting the microenvironment

Mantle cell lymphoma is a distinct entity among the non-Hodgkin's lymphomas characterized by a specific chromosomal translocation, the t(11;14)(q13;q32), overexpression of cyclin-D1 and frequent disease manifestations at extranodal sites. Mantle cell lymphoma remains difficult to treat and belongs to the lymphomas with the poorest long-term outcome. Recent advances in our understanding of lymphoma biology suggest that both alterations of the lymphoma cells themselves and interactions with the microenvironment are important for the growth and survival of the malignant B-cell clone. This novel approach to therapy is being exploited by evaluating drugs such as bortezomib and thalidomide that target interactions between tumor cells and cells of the microenvironment. Thus, with the use of novel therapeutic interventions, it is hoped that clinicians will be able to improve the outcome of patients with mantle cell lymphoma.

Stem cell transplantation for mantle cell lymphoma: if, when and how?

Although the prognosis for mantle cell lymphoma (MCL) patients has improved in recent years, the outlook for those with advanced or recurrent disease remains poor. High-dose chemotherapy and autografting performed early in responding patients appears to be a method to extend progression-free survival (PFS) and overall survival (OS). The use of monoclonal antibody therapy added into the initial therapy and in the peritransplant period may improve on these results. Myeloablative allogeneic transplant appears to be a modality capable of providing curative therapy, but is plagued by a high treatment-related mortality, especially in older patients. Reduced-intensity conditioning allografting have fewer problems associated with the initial phase of transplant and hence may be preferred for those patients for whom an allograft is considered but have comorbid conditions or age issues that preclude a full allograft. Long-term results are lacking and the side effects associated with chronic GVHD may be as significant and debilitating. Trials designed to look at newly diagnosed patients with MCL examining the outcomes after planned autologous and allogeneic transplant as part of the initial management are needed to confirm the role of these various modalities in the overall therapy of this poor-outcome lymphoma.

Current Treatment Approaches for Mantle-Cell Lymphoma

Mantle-cell lymphoma (MCL) is now recognized as a distinct clinicopathologic subtype of B-cell non-Hodgkin's lymphoma. Patients with MCL are typically older adults with a male predominance and usually present with stage IV disease. The cells are characterized as CD20+CD5+CD23−with a t(11;14)(q13;q32) and cyclin D1 overexpression on immunohistochemistry. Response to chemotherapy usually results in a tumor response but unmaintained remissions are short and the median survival is 3 to 4 years. The treatment approach to newly diagnosed patients with MCL depends on the patient's eligibility for stem cell transplantation (SCT). Those who are eligible are usually treated with either rituximab-CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) followed by SCT or rituximab-HyperCVAD (cyclophosphamide, vincristine, doxorubicin, decadron, cytarabine, and methotrexate) followed by observation. The purine nucleoside analogues also have activity as single agents and with rituximab. Unfortunately none of these approaches can definitively cure patients with MCL, and new agents are needed. Recent studies in patients with relapsed MCL have shown substantial antitumor activity of single-agent bortezomib, single-agent temsirolimus, and the combination of thalidomide and rituximab. Studies integrating these novel agents earlier in the disease course or in combination with each other will hopefully produce more durable responses with less toxicity.