Randomised comparison of two B-cell purging protocols for patients with B-cell non-Hodgkin lymphoma: in vivo purging with rituximab versus ex vivo purging with CliniMACS CD34 cell enrichment device

Efficacy of ex vivo purging with CD34+ selection to maximize the effects of autologous stem cell transplantation in peripheral T-cell lymphoma patients

BACKGROUND AIMS

Peripheral T-cell lymphomas (PTCLs) are rare and aggressive tumors with uncertain optimal treatment. This study investigated the clinical outcomes of high-dose chemotherapy (HDT) followed by autologous stem cell transplantation (ASCT) after CD34+ selective purging in PTCL patients.

METHODS

Retrospective analysis included 67 PTCL patients who achieved remission and underwent HDT/ASCT. CD34+ selective purging was performed using CliniMACS® (Miltenyi Biotec, Bergisch Gladbach, Germany). Survival outcomes, engraftment, lymphocyte subsets and viral infections were evaluated.

RESULTS

CD34+ selective purged autografts were associated with significantly improved overall survival (OS) and disease-free survival (DFS) compared with unpurged autografts (5-year OS, 73.3% versus 37.8%, 5-year DFS, 73.8% versus 33.4%). The cumulative incidence of relapse was also lower in the purged group (31.5% versus 73.3%). Subgroup analysis revealed significant survival benefits in the high-risk group receiving purged autografts. Lymphocyte subset analysis showed increased natural killer (NK) cell counts in the purged group after ASCT. Higher post-ASCT lymphocyte-to-monocyte ratio (LMR) was associated with improved OS and DFS.

CONCLUSIONS

CD34+ selective purging in PTCL patients undergoing HDT/ASCT improved survival outcomes and reduced relapse risk. The procedure increased NK cell counts and post-ASCT LMR. CD34+ selective purging may minimize autograft tumor cell contamination and enhance efficacy in T-cell lymphomas.

CD34+ selected versus unselected autologous stem cell transplantation in patients with advanced-stage mantle cell and diffuse large B-cell lymphoma

Novel strategies aiming to increase survival rates in patients with advanced-stage mantle cell lymphoma (MCL) and relapsing diffuse large B-cell lymphoma (DLBCL) are a clinical need. High-dose chemotherapy (HDCT) with autologous stem cell transplantation (ASCT) has improved progression-free (PFS) and overall survival (OS) in MCL and relapsed DLBCL. However, the role of CD34+ cell selection before ASCT in MCL and DLBCL is unclear. We retrospectively analyzed the outcome of 62 consecutive patients with advanced-stage MCL or relapsed DLBCL undergoing ASCT with (n=31) or without (n=31) prior CD34+ selection. All patients had stage III or IV disease, with 47% having DLBCL and 53% MCL. The median duration for neutrophil and platelet recovery was 12 and 16 days in CD34+ selected patients, and 11 (P<.001) and 14 days (P=.012) in the group without selection, respectively. No differences in toxicities were observed. The 5-year PFS for CD34+ selected versus not selected patients was 67% and 39% (P=.016), and the 5-year OS was 86% and 54% (P=.007). Our data suggest that using CD34+ selected autografts for ASCT in advanced stage MCL and DLBCL is associated with longer PFS and OS without increased toxicity.

Monoclonal antibodies in conditioning regimens for hematopoietic cell transplantation

Monoclonal antibodies are increasingly being incorporated in conditioning regimens for autologous or allogeneic hematopoietic cell transplantation (HCT). The benefit of adding rituximab to autologous HCT regimens is purportedly related to in vivo purging of clonal B cells. Randomized trials comparing the addition (or not) of rituximab to high-dose therapy regimens are lacking. No benefit of standard-dose radioimmunotherapy-based regimens for autografting in aggressive lymphomas was seen in a randomized controlled study. The incorporation of rituximab into allogeneic HCT regimens aims to improve responses while reducing nonrelapse mortality resulting from acute graft-versus-host disease. The optimal dose and administration schedule of rituximab in this setting are unknown, and potentially serious complications from increased infections owing to prolonged (and profound) cytopenias or persistent hypogammaglobulinemia are of concern. Radioimmunotherapy-based conditioning for allografting holds promise as a modality to optimize tumor control and synergize adoptive immunotherapy effects, but it remains experimental at this time. The addition of alemtuzumab to allogeneic HCT regimens is associated with prolonged lymphopenia and impaired immune reconstitution, high relapse rates, and serious infections. The optimal dose and schedule of alemtuzumab to avoid prolonged immune paresis remain elusive. It is anticipated that additional monoclonal antibodies will soon become available that can be incorporated into HCT regimens after safety and clinical efficacy are demonstrated.

Microbial contamination of hematopoietic progenitor and other regenerative cells used in transplantation and regenerative medicine

BACKGROUND

Microbial contamination of hematopoietic progenitor cells (HPCs) and other regenerative cells used in transplantation and regenerative medicine can occur during collection and after in vitro manipulation, including purging, cryopreservation, thawing, and infusion.

STUDY DESIGN AND METHODS

Microbiologic culture findings on consecutive HPCs and other cell preparations at a single institution derived from peripheral blood, marrow, cord blood, and mesenchymal stromal cells during all phases of manipulation were retrospectively examined from 2005 through 2011. Results were classified as confirmed positive, false positive, and indeterminate.

RESULTS

During the 6-year surveillance period, 365 patients underwent 912 procedures involving HPC or other cell-based transfusion. True positive microbial contamination was found in five of 663 (0.8%) peripheral blood and two of 34 (5.9%) marrow preparations (p = 0.04), while no contamination was found in 118 preparations from other sources. True-positive microbial contaminants included coagulase-negative staphylococci in autologous HPC products derived from peripheral blood from two patients with asymptomatic central venous catheter infections at time of apheresis and Propionibacterium acnes in one apheresis and two marrow products. Organism loads were low in all cases (≤500 colony-forming units/mL), and no adverse sequelae occurred in four patients that received contaminated products.

CONCLUSION

The incidence of microbial contamination of progenitor cell products in our institution over a 6-year period was low (0.8% overall), with contaminants originating from infected central venous catheters or from skin flora. All contaminants were bacterial species of low virulence, present in low titers and, if transfused, did not result in adverse reactions.

Hematopoietic stem cell therapy for multiple sclerosis: top 10 lessons learned

Reports from more than 600 hematopoietic stem cell transplants (HSCT) have appeared in the medical literature for the last 1 and one-half decades. The patient's own stem cells are harvested and stored temporarily while high doses of chemotherapy and biologics are used to destroy the auto-destructive immune system. The immune system is regenerated from the infused autologous hematopoietic stem cells. Increasing clinical experience has refined patient selection criteria and management in the peri-transplant period leading to a reduction in treatment-related complications. HSCT, when used to treat patients with aggressive highly active multiple sclerosis, can reduce or eliminate ongoing clinical relapses, halt further progression, and reduce the burden of disability in some patients, in the absence of chronic treatment with disease-modifying agents. The top 10 lessons learned from the growing experience using HSCT for the treatment of multiple sclerosis are discussed.

Adverse effects of biologics: a network meta-analysis and Cochrane overview

BACKGROUND

Biologics are used for the treatment of rheumatoid arthritis and many other conditions. While the efficacy of biologics has been established, there is uncertainty regarding the adverse effects of this treatment. Since serious risks such as tuberculosis (TB) reactivation, serious infections, and lymphomas may be common to the biologics but occur in small numbers across the various indications, we planned to combine the results from biologics used in many conditions to obtain the much needed risk estimates.

OBJECTIVES

To compare the adverse effects of tumor necrosis factor blocker (etanercept, adalimumab, infliximab, golimumab, certolizumab), interleukin (IL)-1 antagonist (anakinra), IL-6 antagonist (tocilizumab), anti-CD28 (abatacept), and anti-B cell (rituximab) therapy in patients with any disease condition except human immunodeficiency disease (HIV/AIDS).

METHODS

Randomized controlled trials (RCTs), controlled clinical trials (CCTs) and open-label extension (OLE) studies that studied one of the nine biologics for use in any indication (with the exception of HIV/AIDS) and that reported our pre-specified adverse outcomes were considered for inclusion. We searched The Cochrane Library, MEDLINE, and EMBASE (to January 2010). Identifying search results and data extraction were performed independently and in duplicate. For the network meta-analysis, we performed mixed-effects logistic regression using an arm-based, random-effects model within an empirical Bayes framework.

MAIN RESULTS

We included 163 RCTs with 50,010 participants and 46 extension studies with 11,954 participants. The median duration of RCTs was six months and 13 months for OLEs. Data were limited for tuberculosis (TB) reactivation, lymphoma, and congestive heart failure. Adjusted for dose, biologics as a group were associated with a statistically significant higher rate of total adverse events (odds ratio (OR) 1.19, 95% CI 1.09 to 1.30; number needed to treat to harm (NNTH) = 30, 95% CI 21 to 60) and withdrawals due to adverse events (OR 1.32, 95% CI 1.06 to 1.64; NNTH = 37, 95% CI 19 to 190) and an increased risk of TB reactivation (OR 4.68, 95% CI 1.18 to 18.60; NNTH = 681, 95% CI 143 to 14706) compared to control.The rate of serious adverse events, serious infections, lymphoma, and congestive heart failure were not statistically significantly different between biologics and control treatment. Certolizumab pegol was associated with significantly higher risk of serious infections compared to control treatment (OR 3.51, 95% CI 1.59 to 7.79; NNTH = 17, 95% CI 7 to 68). Infliximab was associated with significantly higher risk of withdrawals due to adverse events compared to control (OR 2.04, 95% CI 1.43 to 2.91; NNTH = 12, 95% CI 8 to 28). Indirect comparisons revealed that abatacept and anakinra were associated with a significantly lower risk of serious adverse events compared to most other biologics.  Although the overall numbers are relatively small, certolizumab pegol was associated with significantly higher odds of serious infections compared to etanercept, adalimumab, abatacept, anakinra, golimumab, infliximab, and rituximab; abatacept was significantly less likely than infliximab and tocilizumab to be associated with serious infections.  Abatacept, adalimumab, etanercept and golimumab were significantly less likely than infliximab to result in withdrawals due to adverse events.

AUTHORS' CONCLUSIONS

Overall, in the short term biologics were associated with significantly higher rates of total adverse events, withdrawals due to adverse events and TB reactivation. Some biologics had a statistically higher association with certain adverse outcomes compared to control, but there was no consistency across the outcomes so caution is needed in interpreting these results.There is an urgent need for more research regarding the long-term safety of biologics and the comparative safety of different biologics. National and international registries and other types of large databases are relevant sources for providing complementary evidence regarding the short- and longer-term safety of biologics. 

The role of rituximab in autologous and allogeneic hematopoietic stem cell transplantation for non-Hodgkin's lymphoma

The addition of rituximab to chemotherapy has substantially changed the treatment strategies for patients with B-cell lymphomas. Rituximab, combined with standard chemotherapy regimens, shows consistently improved results compared with chemotherapy alone and has been extensively employed in both newly diagnosed and relapsed patients with B-cell lymphoma. Because of its low toxicity profile and its potent antilymphoma activity mediated through direct apoptotic and indirect effector mechanisms, rituximab also has been actively incorporated into stem cell transplantation (SCT) protocols to attain a state of minimal disease, provide a safe and effective method for in vivo purging prior to autologous SCT, and promote graft-versus-lymphoma effects in allogeneic SCT. This review compiles the still immature but rapidly growing data on this combined modality.

Role of hematopoietic stem cell transplant in the management of follicular lymphoma

Despite decades of published data regarding the application of autologous and allogeneic stem cell transplant in patients with follicular lymphoma, there remain no uniform indications for its use in this disease. Autologous transplant has been shown to lead to longer progression-free survival times in randomized trials when compared with postremission interferon-based chemoimmunotherapy. However, the development of rituximab and its use in frontline, salvage, and maintenance therapy complicates the decision to pursue autologous transplant, a modality developed prior to the advent of anti-CD20 monoclonal antibodies. Allogeneic transplant offers the advantages of lymphoma-free grafts and the immunologic graft-versus-lymphoma effect. These factors may confer the possibility of long-term remission, though historically they have been accompanied by high rates of upfront morbidity and mortality, especially in heavily pretreated patients with a poor performance status or chemotherapy-refractory disease. Advances in patient selection, human leukocyte antigen (HLA) matching, conditioning regimens, and supportive care have reduced transplant-related mortality and the incidence of graft-versus-host disease. Recently published data focus on the incorporation of rituximab and radioimmunoconjugates prior to, during, and following autologous transplant. Furthermore, reduced-intensity allogeneic stem cell transplantation has increasingly been used for relapsed follicular lymphoma patients with comorbidities or advanced age. Several recent reports suggest that reduced-intensity regimens may provide a high likelihood of long-term disease-free survival for patients up to 70 years of age with a good performance status, chemotherapy-sensitive disease, and HLA-matched sibling donors. Such patients with relapsed disease should be referred to a transplant center that can enroll them in one of the forthcoming clinical trials that aim to confirm these outcomes.

Follicular non-Hodgkin lymphoma: long-term results of stem-cell transplantation

PURPOSE OF REVIEW

Hematopoietic stem-cell transplantation is an effective treatment option for follicular lymphoma. This review summarizes recent updates of the literature focusing on the available long-term follow-up of high-dose therapeutic approaches.

RECENT FINDINGS

Autologous transplantation can prolong overall survival in relapsed disease and can extend progression-free survival in first remission. With more than 10 years of follow-up, the survival curves demonstrate a plateau indicating a potential cure in certain patients. Use of allogeneic transplantation may result in cure as well, but has been plagued by high treatment-related mortality rates when myeloablative conditioning is used. The decreased toxicity of reduced-intensity conditioning is more applicable to the older follicular lymphoma population, but long-term follow-up data are lacking.

SUMMARY

For selected patients, both autologous and allogeneic transplantation offer the possibility of prolonged survival and can result in a cure in up to 25-45% of cases. It is unclear whether to incorporate monoclonal antibody or radioimmunoconjugate therapy. Stem-cell transplantation should at least be considered in patients younger than 60 years, possibly early in the disease course. Late consequences such as an increased risk of second malignancy may compromise this approach and close patient follow-up is essential.

A randomized trial of etoposide and G-CSF with or without rituximab for PBSC mobilization in B-cell non-Hodgkin's lymphoma

Some reports have suggested that rituximab administration before PBSC mobilization may adversely affect PBSC yield. We conducted a prospective randomized trial of PBSC mobilization using etoposide and G-CSF with or without rituximab to determine whether its addition would adversely affect CD34+ cell yield in patients with non-Hodgkin's lymphoma. Twenty seven patients were mobilized with etoposide and G-CSF and 28 with etoposide, G-CSF and rituximab. There were no adverse consequences of rituximab on CD34+ cell yield, or hematopoietic recovery or immunoglobulin levels after transplantation.

Evaluation of 'out-of-specification' CliniMACS CD34-selection procedures of hematopoietic progenitor cell-apheresis products

BACKGROUND

Immunomagnetic selection of CD34(+) hematopoietic progenitor cells (HPC) using CliniMACS CD34 selection technology is widely used to provide high-purity HPC grafts. However, the number of nucleated cells and CD34+ cells recommended by the manufacturer for processing in a single procedure or with 1 vial of CD34 reagent is limited.

METHODS

In this retrospective evaluation of 643 CliniMACS CD34-selection procedures, we validated the capacity of CliniMACS tubing sets and CD34 reagent. Endpoints of this study were the recovery and purity of CD34+ cells, T-cell depletion efficiency and recovery of colony-forming units-granulocyte-macrophage (CFU-GM).

RESULTS

Overloading normal or large-scale tubing sets with excess numbers of total nucleated cells, without exceeding the maximum number of CD34+ cells, had no significant effect on the recovery and purity of CD34+ cells. In contrast, overloading normal or large-scale tubing sets with excess numbers of CD34+ cells resulted in a significantly lower recovery of CD34+ cells. Furthermore, the separation capacity of 1 vial of CD34 reagent could be increased safely from 600 x 10(6) CD34+ cells to 1000 x 10(6) CD34+ cells with similar recovery of CD34(+) cells. Finally, T-cell depletion efficiency and the fraction of CD34+ cells that formed CFU-GM colonies were not affected by out-of-specification procedures.

DISCUSSION

Our validated increase of the capacity of CliniMACS tubing sets and CD34 reagent will reduce the number of selection procedures and thereby processing time for large HPC products. In addition, it results in a significant cost reduction for these procedures.

Time-dependent effect of non-Hodgkin's lymphoma grade on disease-free survival of relapsed/refractory patients treated with high-dose chemotherapy plus autotransplantation

Evaluation of time to event outcomes usually is examined by the Kaplan-Meier method and Cox proportional hazards models. We developed a modified statistical model based on histologic grade and other variables to describe the time-dependent outcome for autologous stem cell transplant (autotransplant) performed for non-Hodgkin's lymphoma (NHL) based on histologic grade and other variables. One hundred and fourteen relapsed or refractory NHL patients were treated using BCNU 600 mg/m2, etoposide 2400 mg/m2, and cisplatin 200 mg/m2 IV followed by autotransplant. Median age was 53.5 (range: 25-70) years, 78 patients had aggressive NHL and 36 indolent NHL. Seventy-five patients received involved-field radiotherapy just prior to transplant. At a median follow-up of 33 (range: 3 to 118) months, the estimated 5-year Kaplan-Meier probabilities of overall survival and disease-free survival were 61% and 51%, respectively. Cox proportional hazards model analysis showed that proportionality did not hold for lymphoma grade, indicating that the relationship between the grade and disease-free survival differed over time. By piece-wise Cox model, the relative risk for experiencing relapse or death after 1 year in patients with indolent compared with patients with aggressive NHL was 2.81 (p=0.019) with 95% confidence interval (1.19, 6.65). The time-dependent effect of lymphoma grade on disease-free survival suggests the need for early (within first year) incorporation of novel therapeutic approaches in management of patients with indolent NHL undergoing autotransplant.

Rituximab-ESHAP as a mobilization regimen for relapsed or refractory B-cell lymphomas: a comparison with ESHAP

BACKGROUND

It has previously been shown that ESHAP was an effective mobilization regimen for patients with pretreated lymphoma. To extend these observations, the efficacy and feasibility of rituximab plus ESHAP regimen in CD20+ B-cell NHL were assessed.

STUDY DESIGN AND METHODS

The mobilization efficacy and engraftment characteristics were compared in the 22 patients who received the rituximab plus ESHAP (R-ESHAP) with 33 historical controls who received ESHAP.

RESULTS

The two treatment groups were well matched in patient characteristics. In the R-ESHAP group, 62 pheresis procedures were performed. Apheresis procedures were started on median Day 16 (range, Days 13-18). The median number of collected CD34+ cells was 10.6 x 10(6) per kg (range, 4.9 x 10(6)-52.6 x 10(6)/kg). Nineteen (95%) patients achieved optimal peripheral blood hematopoietic progenitor cell (PBPC) collection, defined as at least 5 x 10(6) CD34+ cells per kg. There were no significant differences between the two groups with respect to mobilization efficacy. Sixteen patients in the R-ESHAP group (73%) underwent autologous peripheral blood progenitor cell transplantation (APBPCT). The median time to absolute neutrophil count at least 0.5 x 10(9) per L was 10 days (range, 8-17 days), and the median time to a platelet count of at least 20 x 10(9) per L was 12 days (range, 7-27 days). Lymphocyte recovery was slower in the R-ESHAP group, but the rate of infectious complications was similar in the two groups. In the R-ESHAP group, the 2-year overall survival and progression-free survival after APBPCT were 63.2 and 57.4 percent, respectively.

CONCLUSION

Addition of rituximab to ESHAP chemotherapy did not have any adverse effects on PBPC mobilization. Further studies are needed, however, to determine whether addition of rituximab improves outcomes.

Autotransplant conditioning regimens for aggressive lymphoma: are we on the right road?

High-dose chemotherapy and autologous stem cell transplant (ASCT) is the standard approach for chemosensitive, relapsed aggressive non-Hodgkin's lymphoma (NHL). Various conditioning regimens have been used as treatment before ASCT and disease-free (DFS) and overall survival (OS) rates range from 34 to 60% and 26 to 46%, respectively. To date, few comparative randomized trials have been performed and no regimen has demonstrated superiority to another. Reduction of disease relapse remains the major hurdle for improving patient outcome and in vitro and in vivo purging of lymphoma cells has not necessarily enhanced results. Rituximab pre-mobilization and post-transplant appear to provide better response rates with OS approaching 87-91% at 2-3 years. Newer approaches with radioimmunotherapy may raise DFS to 78% and OS to 93%, albeit with short follow-up. Advances in the conditioning regimens and supportive care have reduced transplant-related mortality to less than 10%. In this review we discuss commonly utilized conditioning regimens, describe their pros and cons and address purging and present conditioning strategies. Owing to the poor outcome with conventional chemotherapy in mantle cell, Burkitt's and T-cell lymphoma, we propose the standard approach of front-line ASCT for these high-risk lymphoma patients. Finally, we will present novel strategies, which can enhance the anti-lymphoma effect, at the same time reducing toxicity, to improve the outcome of ASCT in NHL patients.

Viral purging of haematological autografts: should we sneeze on the graft?

High-dose cytotoxic chemotherapy followed by autologous haematopoietic stem cell transplantation (ASCT) is extensively used for the treatment of many haematopoietic, as well as several epithelial cancers. Disease relapse may be the result of tumour contamination within autograft as evidenced by gene marking studies. The multiple purging strategies that have been described to date have not proven effective in most ASCT settings. This review addresses the possibility of using oncolytic viruses as a novel purging strategy. DNA viruses such as genetically engineered adenoviral vectors have widely been used to deliver either a prodrug-activating enzyme or express wild-type p53 selectively in tumour cells in ex vivo purging protocols. In addition, conditionally replicating adenoviruses that selectively replicate in tumour cells and herpes simplex virus type 1 are other DNA viruses that have been tested as ex vivo purging agents under laboratory conditions. Vesicular stomatitis virus (VSV) and reovirus are naturally occurring RNA viruses that appear to hold promise as purging agents under ex vivo and in vivo settings. Preclinical data demonstrate reovirus's purging potential against breast, monocytic and myeloma cell lines as well as patient-derived tumours of diffuse large B-cell lymphoma, chronic lymphocytic leukaemia, Waldenstrom macroglobulinemia and small lymphocytic lymphoma. In addition, VSV has shown effective killing of leukaemic cell lines and multiple myeloma patient specimens. Given the increasing interest in the utilization of viruses as purging agents, the following review provides a timely summary of the potential and the challenges of oncolytic viruses as purging modalities during ASCT.

Rituximab does not compromise the mobilization and engraftment of autologous peripheral blood stem cells in diffuse-large B-cell lymphoma

To investigate effects of the preautografting administration of rituximab on the mobilization and engraftment of peripheral blood stem cells (PBSC), we retrospectively analyzed the outcomes of 43 newly diagnosed diffuse-large B-cell lymphoma patients who received CHOP chemotherapy with or without rituximab as a first-line treatment before autologous PBSC transplantation (PBSCT). There was no difference in the number of CD34(+) cells among PBSC between the non-rituximab and the rituximab groups. Although B-cells were completely depleted from PBSC in the rituximab group, we found no difference in the expression of CXCR-4, VLA-4 and c-Kit on PBSC, indicating that rituximab did not affect the expression of these adhesion molecules, which might be involved in the mechanism of mobilization. There was no significant difference in the recovery of neutrophils and platelets, transplant-related toxicity and post-transplant complications between the two groups. Despite the short follow-up, there was no significant difference in progression-free survival between the two groups. These results indicated no adverse effect of rituximab on the mobilization and engraftment of PBSC. Larger studies are required to determine the impact of rituximab on the mobilization and function of PBSC as well as whether a survival advantage exists in patients who undergo auto-PBSCT with rituximab.

Rituximab in lymphoma: a systematic review and consensus practice guideline from Cancer Care Ontario

Rituximab is the first antibody-based therapy approved in cancer. The role of this treatment for non-Hodgkin's lymphoma has evolved significantly since its introduction. We aimed to systematically review the literature on rituximab in non-Hodgkin's lymphoma and provide consensus guidelines as to the rational use of this agent. Validated methodology from the Cancer Care Ontario Program in Evidence-Based Care was applied. A comprehensive literature search was completed by reviewers from the Hematology Disease Site Group of Cancer Care Ontario. Data were abstracted from randomized controlled trials of rituximab-containing regimens for patients with non-Hodgkin's lymphoma. Twenty-three randomized controlled trials (RCTs) of rituximab-based therapy were analyzed. Consistent and clinically important benefits in progression-free and overall survival and were seen in the following settings: (1) addition of rituximab to combination chemotherapy for initial treatment of diffuse large B-cell lymphoma and other aggressive B-cell lymphomas; (2) addition of rituximab to combination chemotherapy for initial and subsequent treatment of follicular lymphoma and other indolent B-cell lymphomas; and (3) use of rituximab alone as extended maintenance therapy in patients with indolent B-cell lymphomas who have responded to initial treatment. The consensus opinion of the Hematology Disease Site Group is that rituximab is recommended for these indications.