Histologic conversion in the non-Hodgkin's lymphomas

Significance of initial, interim and end-of-therapy 18F-FDG PET/CT for predicting transformation risk in follicular lymphoma

Background

Histological transformation (HT) of follicular lymphoma to a more aggressive lymphoma is a serious event affecting patients’ outcomes. To date, no strong clinical HT predictors present at diagnosis have yet been identified. The fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) is highlighted as a non-invasive diagnostic tool for the detection of HT, but its ability to predict HT at early stage of disease has not been clear. Therefore, this study investigated the predictive values of the pre-transformation standardized uptake value (SUV_max) for the risk of transformation in FL.

Methods

This retrospective study involved 219 patients with FL between June 2008 and October 2019 who had undergone ¹⁸F-FDG PET/CT scan. One hundred and thirty-two, 64, and 78 patients underwent PET at baseline (PET_baseline), interim (PET_interim) and end-of-induction therapy (PET_end), respectively. Qualitative assessment was performed using the 5-point Deauville scale. Statistical analysis was done using Cox regression models, receiver operating characteristic (ROC) analysis, and Kaplan–Meir survival curves.

Results

Of the 219 patients included, 128 had low-grade FL (grade 1–2) and 91 had high-grade FL (grade 3a). HT eventually occurred in 30 patients. The median time to HT was 13.6 months. Among clinical indicators, advance pathological grade was shown as the most significant predictor of HT (HR = 4.561, 95% CI 1.604–12.965). We further assessed the relationship between PET and HT risk in FL. Univariate Cox regression determined that SUV_baseline and SUV_end were significant predictors for HT, while neither SUV_interim nor qualitative assessment of Deauville score has predictive value for HT. Due to the noticeable impact of high pathological grade on the HT risk, we conducted the subgroup analysis in patients with low/high pathological grade, and found SUV_baseline could still predict HT risk in both low-grade and high-grade subgroups. Multivariate analysis adjusted by FLIPI2 score showed the SUV_baseline (HR 1.065, 95% CI 1.020–1.111) and SUV_end (HR 1.261, 95% CI 1.076–1.478) remained as significant predictors independently of the FLIPI2 score. According to the cut-off determined from the ROC analysis, increased SUV_baseline with a cutoff value of 14.3 and higher SUV_end with a cutoff value of 7.3 were highly predictive of a shorter time to HT.

Conclusions

In follicular lymphoma, quantitative assessment used SUV_max at the pre-treatment and end-of-treatment PET/CT scan may be helpful for early screen out patients at high risk of transformation and guide treatment decisions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02094-5.

Incidence Patterns of Sequential or Composite Lymphoma: A Population-Based Cancer Registry Study

The development of multiple histologic types of lymphoma in a single patient has been sporadically reported as sequential or composite lymphoma. However, the incidence pattern of such patients has been rarely evaluated in a large population-based setting. We investigated the incidence of sequential or composite lymphoma based on 11,174 lymphoma records from a population-based cancer registry between 1985-2012 in Nagasaki Prefecture, Japan. We identified 99 lymphoma records were of 49 independent patients other than relapse. The prevalence of the sequential or composite lymphomas in a single patient was 0.44% (95% confidence interval [95% CI], 0.32-0.56%) without sex difference. Among the 49 patients, five (10.2%) were composite/discordant lymphoma. The most frequent "composite lymphoma" was a combination of diffuse large B-cell lymphomas (DLBCL) and adult T-cell leukemia (n = 3). A case of "discordant lymphoma" was a combination of follicular lymphoma on spleen and Waldenström macroglobulinemia on bone marrow. The rest of the patients (n = 44, 89.8% of all composite lymphoma) were "sequential lymphoma" with various combination of lymphoma subtypes on different dates. The major combination of the sequential lymphoma was DLBCL after marginal zone lymphomas (n = 4). In the era of improved survival of lymphoma patients, hematologists should be aware of the development of additional lymphomas.

The ion channels and transporters gene expression profile indicates a shift in excitability and metabolisms during malignant progression of Follicular Lymphoma

The definition of the gene expression profile of genes encoding Ion Channels and Transporters (ICT-GEP) represents a novel and attracting aspect in cancer. We determined the ICT-GEP of Follicular Lymphoma (FL), and compared it with that of the more aggressive Diffuse Large B Cell Lymphoma (DLBCL). cDNA microarray data were collected both from patients enrolled for this study, and from public datasets. In FL the ICT-GEP indicated the overexpression of both the K⁺ channel encoding gene KCNN4, and SLC2A1, which encodes the Glut1 glucose transporter. SLC2A1 turned out to represent the hub of a functional network, connecting channels and transporters in FL. Relapsed FL patients were characterised by 38 differentially expressed ICT genes, among which ATP9A, SLC2A1 and KCNN4 were under-expressed, indicating a down-regulation of both excitability and glycolysis. A completely different profile of K⁺ channel encoding genes emerged in DLBCL accompanied by the over-expression of the fatty acid transporter-encoding gene SLC27A1 as well as of the metabolism regulator NCoR1. This indicates a change in excitability and a shift towards an oxidative metabolism in DLBCL. Overall, the ICT-GEP may contribute to identifying novel lymphoma biomarkers related to excitability and metabolic pathways, with particular relevance for drug resistant, relapsed FL.

Rituximab and the risk of transformation of follicular lymphoma: a retrospective pooled analysis

BACKGROUND

Histological transformation of follicular lymphoma to aggressive lymphoma is a serious event with a substantial effect on patient outcome. The aim of the Aristotle study was to assess the effect of rituximab on the risk of histological transformation and its outcome.

METHODS

11 cooperative groups or institutions across Europe contributed data to this study. Eligible patients (≥18 years) had histologically confirmed follicular lymphoma grade 1, 2, or 3a, diagnosed between Jan 2, 1997, and Dec 20, 2013. Histological transformation was defined as a biopsy-proven aggressive lymphoma that occurred as a first event after first-line therapy. The primary endpoints were the cumulative hazard of histological transformation and survival after transformation.

FINDINGS

Information was available for 10 001 patients with follicular lymphoma, 8116 of whom were eligible for analysis. 509 histological transformations were reported. After a median follow-up of 87 months (range 1-221; 2·5-97·5th percentile 5-160), the 10-year cumulative hazard of histological transformation was 7·7% (95% CI 6·9-8·5). The 10-year cumulative hazard of histological transformation was 5·2% (95% CI 4·5-6·2) in patients who received rituximab and 8·7% (7·2-10·6) in those who did not (hazard ratio [HR] 0·73, 95% CI 0·58-0·90; p=0·004). The 10-year cumulative hazard of histological transformation was 5·9% (95% CI 5·0-7·0) for patients who received induction rituximab only and 3·6% (95% CI 2·3-5·5) for those treated with induction and maintenance rituximab (HR 0·55, 95% CI 0·37-0·81; p=0·003). This finding was confirmed in a multivariate analysis (p=0·016). 287 deaths were recorded in 509 patients with histological transformation, resulting in a 10-year survival after transformation of 32% (95% CI 26-38). Survival after transformation did not differ between patients not exposed to rituximab and those who received rituximab in induction only (HR 0·94, 95% CI 0·69-1·28; p=0·70), and those who received rituximab in induction and maintenance (0·96, 0·58-1·61; p=0·88).

INTERPRETATION

The risk of histological transformation as a first event can be significantly reduced by the use of rituximab. These findings support the need to inform patients using rituximab nowadays that the risk of transformation is lower than it was before the introduction of rituxumab.

FUNDING

Associazione Angela Serra per la Ricerca sul Cancro, European Lymphoma Institute, European Hematology Association Lymphoma Group, Fondazione Italiana Linfomi, Spanish Group of Lymphoma and Bone Marrow Transplantation.

Indolent lymphoma with composite histology and simultaneous transformation at initial diagnosis exhibit clinical features similar to de novo diffuse large B-cell lymphoma

While various studies characterized clinical and prognostic properties of de novo diffuse large B-Cell lymphoma (DLBCL) and transformed indolent lymphomas, the clinicopathological features of indolent lymphoma and simultaneous secondary transformation upon initial diagnosis (ssDLBCL) are insufficiently established.

Between 2010 and 2017, 247 consecutive patients admitted to our institution and treated for DLBCL were investigated for composite histology of ssDLBCL-type. Upon systematical histopathological evaluation composite histology was identified in 22/247 cases (8.9%).

The predominant histology of the underlying indolent lymphoma was follicular lymphoma of variable grading (I-IIIA; 81.8%) whereas marginal zone lymphoma represented a minor sub group (18.2%). Clinicopathological investigation revealed a high degree of concordance between ssDLBCL and de novo DLBCL upon initial diagnosis and clinical courses were shown to be strikingly similar. The predominant fraction of ssDLBCL were germinal center derived lymphomas (GCB-type) with a trend towards a superior outcome compared with non-GCB-type ssDLBCL. Additionally, we demonstrate a significant adverse prognostic impact of an underlying indolent lymphoma component other than follicular-type lymphoma (e.g. marginal zone lymphoma). Moreover, the frequency of double-hit (DHL) or double-expressor lymphomas (DEL) appears to be low.

Our findings provide substantial insight into the behavior of ssDLBCL, highlight the ramifications of the concurrent high-grade fraction within indolent lymphomas and underline therapeutic efficacy of R-CHOP type immunochemotherapy in the majority of ssDLBCL patients.

Follicular lymphomas and their transformation: Past and current research

INTRODUCTION

Follicular lymphoma (FL) is the second most common type of non-Hodgkin lymphoma (NHL). Histological transformation (HT) refers to the evolution of a clinically indolent NHL to a clinically aggressive one, defined as those lymphomas in which survival is limited to a few months when untreated. Areas covered: HT is associated with rapid progression of lymphadenopathy, infiltration of extranodal sites, development of systemic symptoms, and elevated serum level of lactate dehydrogenase (LDH). It is frequently related to a poor prognosis, and the median survival after transformation is less than 2 years. Transformation to diffuse large B cell lymphoma (DLBCL) in patients with FL occurs at an annual rate of approximately 3% for the first 15 years, after which the risk of HT falls for reasons that remain unclear. Expert commentary: Although it has long been assumed that transformation reflects the emergence of an aggressive subclone of cells from the primary FL, recent studies suggest that FL transformation might also arise by divergent evolution from a more immature common progenitor cell. Studies on genomic changes and DNA sequencing have shed some light onto the process of transformation. Nowadays, we know that HT is a complex process where several molecular pathways are involved.

Risk Factors and Outcomes for Patients With Follicular Lymphoma Who Had Histologic Transformation After Response to First-Line Immunochemotherapy in the PRIMA Trial

Purpose

To study the outcome of histologic transformation (HT) in a large prospective cohort of patients with follicular lymphoma (FL) who previously responded to immunochemotherapy.

Patients and Methods

After a median 6-year follow-up of 1,018 randomly assigned patients from the PRIMA trial, disease progression was observed in 463 patients, 194 of whom had histologic documentation.

Results

Forty patients had histology consistent with HT, and 154 had untransformed FL (median time to recurrence, 9.6 v 22.8 months, respectively; P = .018). Thirty-seven percent of biopsies performed during the first year of follow-up showed HT corresponding to 58% of all HTs. Altered performance status, anemia, high lactate dehydrogenase level, “B” symptoms, histologic grade 3a, and high Follicular Lymphoma International Prognostic Index scores at diagnosis were identified as HT risk factors. Response (complete v partial) to immunochemotherapy or rituximab maintenance had no impact on the risk of HT. After salvage treatment, patients with HT had less frequent complete response (50.3% v 67.4%; P = .03) and more disease progression (28.2% v 9.6%; P < .001) than patients without HT. Estimated overall survival for the patients with HT was poorer (median, 3.8 v 6.4 years; hazard ratio, 3.9; 95% CI, 2.2 to 6.9). Autologous stem cell transplantation improved the outcomes of patients with HT (median overall survival, not reached v 1.7 years) but not of patients with persistent FL histology.

Conclusion

HT in patients with FL who previously responded to immunochemotherapy is an early event associated with a poor outcome that may deserve intensive salvage with autologous stem cell transplantation. These data emphasize the necessity for biopsy at the first recurrence of FL.

Impact of prior treatment on outcome of transformed follicular lymphoma and relapsed de novo diffuse large B cell lymphoma: a retrospective multicentre analysis

Transformation of follicular lymphoma (FL) into aggressive disease and relapse of de novo diffuse large B cell lymphoma (DLBCL) are considered highly unfavourable events. However, most published data were acquired when rituximab was not routinely used. We retrospectively analysed 50 patients with transformed FL (tFL) in a multicenter study and compared them to 50 individuals with relapsed DLBCL (rDLBCL) who all obtained rituximab for the treatment of their disease. Our goal was to identify factors that predict a more favourable prognosis. After a median follow-up of 5.4 years from diagnosis, there was no significant difference in median overall survival (OS) from the date of transformation (tFL) or date of the first relapse (rDLBCL) (1.9 versus 3.9 years, P = .542). Of note, 5-year OS of patients with tFL was 46 %. Follicular lymphoma patients, treatment naïve prior to transformation, fared significantly better than pretreated patients (median not reached versus 1.4 years, P = .014). Regarding rDLBCL, female gender (13.9 versus 1.8 years, P = .019) and absence of rituximab prior to the first relapse (14.0 versus 1.8 years, P = .035) were favourable prognostic factors in a uni- and multivariate analysis. Only a proportion of patients received high-dose chemotherapy with autologous stem cell transplantation (HDT-ASCT), i.e. 38 and 52 % of patients with tFL and rDLBCL, respectively. Our data indicate that a favourable prognosis is conferred by treatment naivety in tFL and by rituximab naivety in rDLBCL. In contrast, we did not find a prognostic impact of HDT-ASCT in our series.

Pathology of follicular lymphoma

Follicular lymphoma (FL) is a heterogeneous disease, and there are many different subgroups, such as in terms of age of onset, involved organ (especially extranodal sites such as gastrointestinal tract) and genetic abnormality. Grade 3B is currently regarded as a distinct entity by molecular genetic analyses, but the independence of Grade 3A remains unclear. Variations of clinical course are known in FL. Some cases are very indolent, but others are not. The latter cases show histological transformation to diffuse large B-cell lymphoma (DLBCL) (high-grade transformation) and an aggressive course. Histological transformation to DLBCL is reported to occur in about 30-40% of patients, at a rate of about 3% each year. However, it reaches a plateau at about 16 years, so the stratification of patients in whom transformation would or would not occur is very important for the therapeutic strategy. From genome-wide analysis by next-generation sequencing, EZH2, CREBBP and MLL2, which are histone-modifying genes, have been shown to be frequently mutated in FL and to have an important role in lymphomagenesis. IGH-BCL2 translocation and CREBBP mutations are early events, whereas MLL2 and TNFSFR14 mutations represent late events during disease evolution. In the 2008 WHO classification, three new variants: (1) pediatric follicular lymphoma, (2) primary intestinal follicular lymphoma and (3) in situ follicular lymphoma, are included. Pathologists and clinicians should consider these new developments when deciding on the diagnostic and therapeutic strategy.

BCL2 mutations are associated with increased risk of transformation and shortened survival in follicular lymphoma

Follicular lymphoma (FL), an indolent neoplasm caused by a t(14;18) chromosomal translocation that juxtaposes the BCL2 gene and immunoglobulin locus, has a variable clinical course and frequently undergoes transformation to an aggressive lymphoma. Although BCL2 mutations have been previously described, their relationship to FL progression remains unclear. In this study, we evaluated the frequency and nature of BCL2 mutations in 2 independent cohorts of grade 1 and 2 FLs, along with the correlation between BCL2 mutations, transformation risk, and survival. The prevalence of BCL2 coding sequence mutations was 12% in FL at diagnosis and 53% at transformation (P < .0001). The presence of these BCL2 mutations at diagnosis correlated with an increased risk of transformation (hazard ratio 3.6; 95% CI, 2.0-6.2; P < .0001) and increased risk of death due to lymphoma (median survival of 9.5 years with BCL2 mutations vs 20.4 years without; P = .012). In a multivariate analysis, BCL2 mutations and high FL international prognostic index were independent risk factors for transformation and death due to lymphoma. Some mutant Bcl-2 proteins exhibited enhanced antiapoptotic capacity in vitro. Accordingly, BCL2 mutations can affect antiapoptotic Bcl-2 function, are associated with increased activation-induced cytidine deaminase expression, and correlate with increased risk of transformation and death due to lymphoma.

Pattern of CD14+ follicular dendritic cells and PD1+ T cells independently predicts time to transformation in follicular lymphoma

PURPOSE

Transformation of follicular lymphoma is a critical event associated with a poor prognosis. The role of the tumor microenvironment in previous transformation studies has yielded conflicting results.

EXPERIMENTAL DESIGN

To define cell subtypes associated with transformation, we examined tissue specimens at diagnosis from patients with follicular lymphoma that later transformed and, using immunohistochemistry (IHC), stained for CD68, CD11c, CD21, CXCL13, FOXP3, PD1, and CD14. Cell content and the pattern of expression were evaluated. Those identified as significantly associated with time to transformation (TTT) and overall survival (OS) were further characterized by flow cytometry and multicolor IHC.

RESULTS

Of note, 58 patients were analyzed with median TTT of 4.7 years. The pattern of PD1(+) and CD14(+) cells rather than the quantity of cells was predictive of clinical outcomes. On multivariate analysis, including the follicular lymphoma international prognostic index score, CD14(+) cells localized in the follicle were associated with a shorter TTT (HR, 3.0; P = 0.004). PD1(+) cells with diffuse staining were associated with a shorter TTT (HR, 1.9; P = 0.045) and inferior OS (HR, 2.5; P = 0.012). Multicolor IHC and flow cytometry identified CD14(+) cells as follicular dendritic cells (FDC), whereas PD1(+) cells represented two separate populations, TFH and exhausted T cells.

CONCLUSION

These results identify the presence of PD1(+) T cells and CD14(+) FDC as independent predictors of transformation in follicular lymphoma. Clin Cancer Res; 20(11); 2862-72. ©2014 AACR.

Rates and outcomes of follicular lymphoma transformation in the immunochemotherapy era: a report from the University of Iowa/MayoClinic Specialized Program of Research Excellence Molecular Epidemiology Resource

PURPOSE

This study sought to characterize transformation incidence and outcome for patients with follicular lymphoma (FL) in a prospective observational series begun after diffusion of rituximab use.

PATIENTS AND METHODS

Patients with newly diagnosed FL were prospectively enrolled onto the University of Iowa/Mayo Clinic Specialized Program of Research Excellence Molecular Epidemiology Resource from 2002 to 2009. Patients were actively followed for re-treatment, clinical or pathologic transformation, and death. Risk of transformation was analyzed via time to transformation by using death as a competing risk.

RESULTS

In all, there were 631 patients with newly diagnosed grade 1 to 3a FL who had a median age at enrollment of 60 years. At a median follow-up of 60 months (range, 11 to 110 months), 79 patients had died, and 60 patients developed transformed lymphoma, of which 51 were biopsy proven. The overall transformation rate at 5 years was 10.7%, with an estimated rate of 2% per year. Increased lactate dehydrogenase was associated with increased risk of transformation. Transformation rate at 5 years was highest in patients who were initially observed and lowest in patients who initially received rituximab monotherapy (14.4% v 3.2%; P = .021). Median overall survival following transformation was 50 months and was superior in patients with transformation greater than 18 months after FL diagnosis compared with patients with earlier transformation (5-year overall survival, 66% v 22%; P < .001).

CONCLUSION

Follicular transformation rates in the immunochemotherapy era are similar to risk of death without transformation and may be lower than reported in older series. Post-transformation prognosis is substantially better than described in older series. Initial management strategies may influence the risk of transformation.

Anthracycline-containing regimens for treatment of follicular lymphoma in adults

BACKGROUND

Anthracycline-containing regimens (ACR) are the most prevalent regimens in the management of patients with advanced follicular lymphoma (FL). However, there is no proof that they are superior to non-anthracycline-containing regimens (non-ACR).

OBJECTIVES

To compare the efficacy of ACRs to other chemotherapy regimens, in the treatment of FL.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 3), MEDLINE (January 1966 to April 2013), smaller databases, relevant conference proceedings (2004 to 2012) and the National Medical Library (April 2013).

SELECTION CRITERIA

We included randomized controlled trials (RCTs) comparing ACR with non-ACR for adult patients with FL. We excluded trials in which immunotherapy, radiotherapy alone or stem-cell transplantation were used in one arm alone. Our primary outcome was overall survival (OS). Secondary outcomes included disease control, as measured by progression-free survival (PFS) or remission duration (RD).

DATA COLLECTION AND ANALYSIS

Two review authors assessed the quality of trials and extracted data. We contacted study authors for additional information. We analyzed trials separately according to resemblance of the chemotherapeutic regimens in study arms, other than the addition of anthracyclines ('same' versus 'different' chemotherapy). Hazard ratios (HR) and risk ratios (RR) with 95% confidence intervals (CI) were estimated and pooled using the fixed-effect model.

MAIN RESULTS

Eight RCTs, conducted between 1974 and 2011, and involving 2636 patients were included in this meta-analysis. All trials included therapy-naive patients. Rituximab was used in one trial only. Follow-up was between three and five years in most trials (range three to 18 years). All trials were published in peer-reviewed journals.Five trials compared similar chemotherapeutic regimens, except for the anthracycline. In three studies reporting overall survival specifically in FL patients, there was no statistically significant difference between ACR and non-ACR arms (HR 0.99; 95% CI 0.77 to 1.29; I(2) = 0%). ACR significantly improved disease control (HR 0.65; 95% CI 0.52 to 0.81; four trials). Progression or relapse at three years were reduced (RR 0.73; 95% CI 0.63 to 0.85). Anthracyclines did not significantly increase rates of complete response (RR 1.05; 95% CI 0.94 to 1.18) or overall response (RR 1.06; 95% CI 1.00 to 1.12), but heterogeneity was substantial.Overall, ACR were more often associated with cytopenias, but not with serious infections or death related to chemotherapy. Cardiotoxicity, albeit rare, was associated with anthracycline use (RR 4.55; 95% CI 0.92 to 22.49; four trials).Three trials added anthracycline to one arm of two different regimens. None showed benefit to ACR regarding OS, yet there was a trend in favor of anthracyclines for disease control. Results were heterogeneous.We judged the overall quality of these trials as moderate as all are unblinded, some are outdated and are not uniform in outcome definitions.

AUTHORS' CONCLUSIONS

The use of anthracyclines in patients with FL has no demonstrable benefit on overall survival, although it may have been mitigated by the more intense regimens given in the control arms of three of five trials. ACR improved disease control, as measured by PFS and RD with an increased risk for side effects, notably cardiotoxicity. The current evidence on the added value of ACR in the management of FL is limited. Further studies involving immunotherapy during induction and maintenance may change conclusion.

Improvements in observed and relative survival in follicular grade 1-2 lymphoma during 4 decades: the Stanford University experience

Recent studies report an improvement in overall survival (OS) of patients with follicular lymphoma (FL). Previously untreated patients with grade 1 to 2 FL treated at Stanford University from 1960-2003 were identified. Four eras were considered: era 1, pre-anthracycline (1960-1975, n = 180); era 2, anthracycline (1976-1986, n = 426); era 3, aggressive chemotherapy/purine analogs (1987-1996, n = 471); and era 4, rituximab (1997-2003, n = 257). Clinical characteristics, patterns of care, and survival were assessed. Observed OS was compared with the expected OS calculated from Berkeley Mortality Database life tables derived from population matched by gender and age at the time of diagnosis. The median OS was 13.6 years. Age, gender, and stage did not differ across the eras. Although primary treatment varied, event-free survival after the first treatment did not differ between eras (P = .17). Median OS improved from 11 years in eras 1 and 2 to 18.4 years in era 3 and has not yet been reached for era 4 (P < .001), with no suggestion of a plateau in any era. These improvements in OS exceeded improvements in survival in the general population during the same period. Several factors, including better supportive care and effective therapies for relapsed disease, are likely responsible for this improvement.

The miR-17-92 microRNA cluster: a novel diagnostic tool in large B-cell malignancies

Diffuse large B-cell lymphoma (DLBCL) can present as de novo or can arise through the transformation of many indolent lymphomas, including follicular lymphoma (FL). The morphological differentiation between germinal center-DLBCL (GC-DLBCL) and high-grade (grade 3) FL could be challenging; the accurate sub-classification of large B-cell lymphomas is mandatory in order to select the most appropriate among the new-targeted therapies. Recent expression profiling studies reported microRNAs (miRNAs) (and miR-17-92 cluster, in particular) as useful tools in differentiating DLBCL and FL. However, these preliminary results are based on cell line-derived data or did not consider grade 3 FL cases. To investigate this point, 36 cases of GC-DLBCL and 18 cases of grade 3 non-transforming FL were considered. All diagnoses were based on the World Health Organization criteria and were confirmed by clinical, histological, and immunohistochemical data. Six members of the miR-17-92 cluster (ie, miR-18b, miR-19b, miR-20a, miR-92, miR-93, and miR-106a) and two control miRNAs (ie, miR-150 and miR-210) were quantified by quantitative reverse transcription-polymerase chain reaction. All the considered miR-17-92 cluster miRNAs were significantly overexpressed in GC-DLBCL, being miR-20a and miR-106a the most dysregulated (P<0.001). Receiver operating characteristics (ROCs) analysis was used to find the optimal cut-off in distinguishing the two histotypes. The ROC estimated thresholds for miR-18b, miR-19b, miR-20a, miR-92, and miR-106a displayed a sensitivity level higher than 0.80 in achieving the GC-DLBCL diagnosis. The classification tree built on the six thresholds allowed the correct identification of 35/36 GC-DLBCL (97.2%). Profiling the miR-17-92 cluster is a promising investigative method for differentiating GC-DLBCL from high-grade FL. Subject to the validation of these findings in further larger studies; miR-17-92 cluster could represent a reliable, standardizable diagnostic tool for the sub-classification of large B-cell lymphoid neoplasm.

Transformation of follicular lymphoma

Histological transformation of follicular lymphoma (FL) to a more aggressive non-Hodgkin's lymphomas is a pivotal event in the natural history of FL and is associated with poor outcome. While commonly observed in clinical practice and despite multiple studies designed to address its pathogenesis, the biology of this process represents an enigma. In this chapter we present a state of the art review summarizing the definition of histologic transformation, its incidence, pathogenesis, clinical manifestations, treatment and outcome. Furthermore, we specifically emphasize gaps in our knowledge that should be addressed in future studies.

Transformation of Indolent B-Cell Lymphomas

Histologic transformation (HT) to an aggressive lymphoma is a well-described event in the natural history and clinical course of patients with so-called indolent lymphomas. This phenomenon has been studied most extensively in patients with follicular lymphoma and subsequent transformation to a diffuse large B-cell lymphoma, with little literature on HT in nonfollicular lymphomas. Despite a considerable body of information on the pathologic and molecular events associated with HT, its pathogenesis has remained elusive and the molecular information available has not been translated into clinical advances. It remains unclear if there is already a predisposition to HT and whether this can be detected at the time of diagnosis. The rituximab era has been characterized by a significant improvement in the prognosis of patients with B-cell lymphomas, but HT remains one of the most important challenges in the management of patients with indolent lymphoma, the difficulties starting with the diagnosis and definition of HT and ending with the appropriate management and treatment of the event. Going forward, it is crucial to incorporate HT as a major end point in clinical trials and to include patients with HT as subject of such studies if we are to see meaningful progress in the future.

Down-regulation of CD9 expression and its correlation to tumor progression in B lymphomas

Histological transformation, a pivotal event in the natural history of cancers including lymphomas, is typically associated with more aggressive clinical behavior. L3055, a B lymphoma cell line of germinal center (GC) origin, is dependent on follicular dendritic cells (FDCs) for survival and proliferation, similar to GC-B cells. However, L3055 cells become less FDC-dependent after prolonged culture, which is analogous to transformation in vivo. Comparison of two L3055 subclones (i.e., the FDC-dependent indolent clone 12 and the FDC-independent aggressive clone 33) by DNA microarray revealed that CD9 was the most differentially expressed gene (P = 0.05). L3055-12 expresses high levels of CD9 while L3055-33 does not. Reduced levels or loss of CD9 expression is also observed in other CD9-positive B lymphoma cell lines. The resultant CD9-negative cells grow faster than CD9-positive cells due to their greater resistance to apoptosis. Furthermore, CD9-negative cells are less dependent on FDCs for their survival and growth compared with CD9-positive cells. CD9 down-regulation in B lymphomas appears to be controlled epigenetically, mainly through histone modifications. These findings imply that CD9 is inversely correlated with B lymphoma progression, and CD9 inactivation may play an important role in B lymphoma transformation.

Prognostic Factors in Follicular Lymphoma

Follicular lymphoma (FL) is one of the most common types of non-Hodgkin's lymphoma. It is usually diagnosed at an advanced stage, for which many treatment options exist, however, no curative standard therapy has been identified. The outcome is highly variable with a median survival of approximately 10 years. The life expectancy of patients with FL has been extended with the use of rituximab, a monoclonal antibody targeting the CD20 antigen on FL cells, but there remains a group of patients who fail to respond to chemoimmunotherapy and die early of their disease. Transformation of FL to an aggressive histology is an important event with high morbidity and mortality. The Follicular Lymphoma International Prognostic Index has become the clinically useful prognostic tool, but gives only a rough estimate of expected outcome. There is a need for useful biomarkers for prediction of the disease course of single patients to individualize therapy, especially in the new era of chemoimmunotherapy.

Identification of molecular targets associated with transformed diffuse large B cell lymphoma using highly purified tumor cells

Follicular lymphoma (FL) frequently transforms into the more aggressive diffuse large B cell lymphoma (DLBCL-tr), but no protein biomarkers have been identified for predictive or early diagnosis. Gene expression analyses have identified genes changing on transformation but have failed to be reproducible in different studies, reflecting the heterogeneity within the tumor tissue and between tumor samples. Gene expression analyses on Affymetrix Human Genome U133 Plus 2.0 arrays were performed, using flow cytometry sorted tumor cells derived from FL and transformed DLBCL. To identify molecular targets associated with the transformation, subsequent immunohistochemistry (IHC) analyses of the corresponding proteins were performed. Using highly purified cells, this study identified 163 genes, which were significantly deregulated during the transformation in a majority of cases. Among the upregulated transcripts, 13 genes were selected for validation using IHC, based on the availability of commercial antibodies, and galectin-3 and NEK2 proteins specifically identify DLBCL-tr, when compared with FL. We demonstrate that by purifying tumor cells through cell sorting, thereby reducing the heterogeneity due to infiltrating cells, it was possible to identify distinct differences between tumor entities rather than variations due to cellular composition. Galectin-3 and NEK2 both identified a subgroup of DLBCL-tr, and the function of these protein markers also suggests a biological role in the transformation process.

Gene expression profiling in diffuse large B-cell lymphoma

Diffuse Large B cell lymphoma (DLBCL) is characterized by a markedly heterogeneous clinical course and response to therapy that is not appreciated with standard histopathologic and immunophenotypic evaluations. Analysis of global gene expression using DNA microarrays has the potential to improve the classification of lymphomas. Molecular profiling may allow the description of specific disease subtypes with similar clinical behavior and outcome. In addition, gene expression profiling has led to the discovery of new putative genes and a better understanding of aberrant signaling pathways. These insights may lead to the discovery of new targeted therapies. This review describes the progress that has been made in our understanding of DLBCL as a result of gene expression profiling.

The International Prognostic Index predicts outcome after histological transformation of low-grade non-Hodgkin lymphoma

Histological transformation of low-grade non-Hodgkin lymphoma (NHL) to diffuse large cell NHL is well recognized and is associated with a poor prognosis. We sought to determine the overall outcome and the factors that affect survival in patients with histological transformation of low-grade NHL. Between November 1979 and September 2000, 93 patients who developed transformed lymphoma were identified. The median time to transformation was 4.2 years from the original diagnosis. The median age at transformation was 63 years. Seventy-eight percent had stage III or IV disease. Fifty-seven percent had extranodal involvement, including bone marrow; 33% had an elevated lactate dehydrogenase. The International Prognostic Index (IPI) at transformation was termed the transformation IPI (tIPI); 29% had a tIPI of 0-1, 59% had a tIPI of 2-3 and 8% had a tIPI of 4-5. At a median follow-up of 15 months from histological transformation, 20 of 93 patients (22%) were alive. The median survival from transformation was 15 months (4 months to 19.7 years). On univariate analysis, the following factors at the time of histological transformation were associated with an improved survival: low tIPI (P = 0.009), time to transformation > 4 years (P = 0.02), age < or = 60 years (P = 0.02) and stage I or II disease (P = 0.04). On multivariate analysis, factors that remained significant included a low tIPI (P = 0.0001) and a time to transformation > 4 years (P = 0.004). tIPI correlated with overall survival (OS); IPI 0-1, median OS 38 months; IPI 2-3, median OS 12 months; IPI 4-5, median OS 4 months. In conclusion, tIPI at the time of histological transformation is an important predictor of OS. A time to transformation > 4 years from diagnosis is associated with better OS.

Prolymphocytoid transformation of follicular lymphoma with coexpression of CD5 and CD10

Histologic transformation of follicular lymphoma is usually to a diffuse large B-cell lymphoma. We present a rare example of a histologic transformation of follicular lymphoma manifested by prolymphocytoid morphology and an unusual immunophenotype characterized by coexpression of CD5 and CD10. The transformed prolymphocytoid lymphoma was positive for CD5 and CD10 antigens by both flow cytometry and immunohistochemistry. The case also expressed bcl-2 and bcl-6 proteins, and exhibited t(14;18), consistent with derivation from a pre-existing follicular lymphoma. Polymerase chain reaction analysis of the immunoglobulin kappa light chain genes derived from the follicular lymphoma and prolymphocytoid lymphoma showed identical rearranged bands, suggesting clonal identity of the two neoplasms. The basis for coexpression of CD5 and CD10 remains unclear. Because the preceding low-grade follicular lymphoma was positive only for CD10 and did not express CD5, CD5 expression appears to be an acquired phenomenon accompanying the process of histologic transformation in this particular case. Prolymphocytoid transformation, similar to other histologic forms of transformation of follicular lymphoma, appears to accompany clinical progression of disease.

The incidence, natural history, biology, and treatment of transformed lymphomas

Treatment of patients with transformed lymphoma presents a significant challenge to the practicing physician. Indeed, the transformation of follicular lymphoma to a more aggressive histology is inherent to the biology of this disease and is often associated with an aggressive clinical course, resulting in a poor prognosis. Recent population-based studies have better defined the incidence of this event, and recent laboratory studies have defined the molecular and immunological processes associated with transformation. These studies will be discussed in this review, as will the treatment options for these patients.

Economic burden of follicular non-Hodgkin's lymphoma

Follicular non-Hodgkin's lymphoma (FNHL), a slow-growing cancer of the immune system, constitutes about 15-30% of all incident non-Hodgkin's lymphoma in developed countries. Its incidence is rising worldwide. Patients can live many years, but FNHL is considered incurable. We systematically reviewed the English-language MEDLINE-indexed and non-indexed economic literature published in the past 10 years on FNHL, identifying 23 primary economic studies. The economic burden of FNHL is significant, but available data are generally limited to retrospective considerations of hospital-based direct treatment costs, with little information available regarding societal cost of illness. Most direct cost information originates from the US, with one estimate of $US36 000 for the per-patient incremental cost of FNHL care during the first year following diagnosis. The most studied treatment is rituximab, which may offer similar overall costs to fludarabine considering higher resource use with fludarabine complications. Nearly all cost-effectiveness models identified by this review evaluated rituximab for relapsed/refractory FNHL responding to chemotherapy induction. Rituximab is supported as a cost-effective addition to standard chemotherapy by two models in the UK and one in the US, as maintenance therapy instead of stem-cell transplant by one UK model, and as maintenance therapy instead of observation alone by one model each in France, Spain and Canada. The UK National Institute for Health and Clinical Excellence updated guidance on rituximab in February 2008, concluding that it is cost effective when added to induction chemotherapy, and when used as maintenance therapy. No studies of per-patient or national indirect costs of illness were identified, with the only study of indirect costs a Canadian survey documenting lost work productivity. Across all study types identified by our review, the most common focus was on the direct costs of rituximab. As new treatments for FNHL come to market, more real-life cost data are imperative to calculate their relative cost effectiveness.

The incidence, natural history, biology, and treatment of transformed lymphomas

Treatment of patients with transformed lymphoma presents a significant challenge to the practicing physician. Indeed, the transformation of follicular lymphoma to a more aggressive histology is inherent to the biology of this disease and is often associated with an aggressive clinical course, resulting in a poor prognosis. Recent population-based studies have better defined the incidence of this event, and recent laboratory studies have defined the molecular and immunological processes associated with transformation. These studies will be discussed in this review, as will the treatment options for these patients.

Follicular lymphoma: clinical features and treatment

Follicular lymphoma (FL) is the second most common subtype of non-Hodgkin's lymphoma (NHL) in the Western world, constituting up to 22% of the total cases of NHL. This article describes the clinical characteristics of FL, its prognostic indicators, and its clinical course, including transformation to an aggressive lymphoma. Primary management and therapies for recurrent FL are detailed.

Population-Based Analysis of Incidence and Outcome of Transformed Non-Hodgkin's Lymphoma

Purpose

To assess the incidence and predictive factors for development of transformed lymphoma in a population-based series of patients with follicular lymphoma (FL).

Patients and Methods

The Lymphoid Cancer Database was used to identify patients with FL diagnosed and treated in the province of British Columbia, Canada. Transformed lymphoma was defined as the development of aggressive non-Hodgkin's lymphoma (NHL) in patients with FL. Factors present at the time of initial diagnosis of indolent NHL and at transformation were analyzed for their impact on risk of transformation and subsequent outcome.

Results

Between 1986 and 2001, 600 patients with newly diagnosed FL met the inclusion criteria. With a median follow-up of 109 months (range, 10 to 244), 170 (28%) developed transformation, 107 (63%) based on biopsy confirmation. The annual risk of transformation was 3% continuously through 15 years. A multivariate analysis of clinical factors at diagnosis identified advanced stage as the only predictor of future transformation. The median post-transformation survival was 1.7 years. The 5-year survival was superior for patients with limited extent transformation compared with those with advanced cases (66% v 19%, P < .0001). Patients with transformation based on clinical versus histological criteria had an identical median survival of 1.8 years (P = .2).

Conclusion

The annual risk of transformation of FL is 3% continuing without plateau beyond 15 years. Advanced stage at diagnosis is predictive of future transformation. Clinically diagnosed transformation has an equal impact on outcome as biopsy proven transformation.

The presence of TP53 mutation at diagnosis of follicular lymphoma identifies a high-risk group of patients with shortened time to disease progression and poorer overall survival

The International Prognostic Index and the Follicular Lymphoma International Prognostic Index are widely used for the risk assessment of follicular lymphoma (FL). Although molecular studies have provided insight into the biology of FL, no molecular marker has impacted on treatment stratification. Because TP53 mutations are associated with poor prognosis in hematologic malignancies, we investigated the prognostic value of TP53 mutation at diagnosis in FL. Heterozygous TP53 mutation was detected in 12 of 185 (6%) analyzed cases. Mutation was associated with older age (P = .02) and higher International Prognostic Index score (P = .04). On multivariate analysis, TP53 mutation correlated with shorter progression-free survival (P < .001) and overall survival (P = .009). TP53 mutation was associated with low expression of the immune-response 1 gene expression signature (P = .016) and with an unfavorable gene expression-based survival predictor score (P < .001), demonstrating for the first time that molecular features of the malignant cell may correlate with the nature of the immune response in FL.

Current results and future applications of radioimmunotherapy management of non-Hodgkin's lymphoma

Monoclonal antibodies labeled with radionuclides have become an important therapeutic tool in the treatment of patients with non-Hodgkin's lymphomas (NHL). At the present time, their use in the US is approved for patients with rituximab-resistant, low-grade, follicular or transformed NHL. Encouraging responses seen in the relapsed and refractory patients have prompted their evaluation in earlier disease or in other histologic sub-types either alone or in combination with conventional chemotherapy. Additionally, they have been included as preparative regimens for stem cell transplant protocols within the context of clinical trials. This review discusses the latest clinical trials and future directions of radioimmunoconjugates in the treatment of NHL, with emphasis on US Food and Drug Administration (FDA) approved radioimmunoconjugates, namely 131I-tositumomab and 90Y-ibritumomab tiuxetan.

Risk and Clinical Implications of Transformation of Follicular Lymphoma to Diffuse Large B-Cell Lymphoma

Purpose

To study the clinical significance of transformation to diffuse large B-cell lymphoma (DLBCL) in patients with follicular lymphoma (FL).

Patients and Methods

From 1972 to 1999, 325 patients were diagnosed with FL at St Bartholomew's Hospital (London, United Kingdom). With a median follow-up of 15 years, progression occurred in 186 patients and biopsy-proven transformation in 88 of the 325. The overall repeat biopsy rate was 70%.

Results

The risk of histologic transformation (HT) by 10 years was 28%, HT not yet having been observed after 16.2 years. The risk was higher in patients with advanced stage (P = .02), high-risk Follicular Lymphoma International Prognostic Index (FLIPI; P = .01), and International Prognostic Index (IPI; P = .04) scores at diagnosis. Expectant management (as opposed to treatment being initiated at diagnosis) also predicted for a higher risk of HT (P = .008). Older age (P = .005), low hemoglobin level (P = .03), high lactate dehydrogenase (P < .0001), and high-risk FLIPI (P = .01) or IPI (P = .003) score at the time of first recurrence were associated with the diagnosis of HT in a biopsy performed at that time. The median survival from transformation was 1.2 years. Patients with HT had a shorter overall survival (P < .0001) and a shorter survival from progression (P < .0001) than did those in whom it was not diagnosed.

Conclusion

Advanced stage and high-risk FLIPI and IPI scores at diagnosis correlate with an increased risk of HT. This event strongly influences the outcome of patients with FL by shortening their survival. There may be a subgroup of patients in whom HT does not occur.

Genome-wide detection of recurring sites of uniparental disomy in follicular and transformed follicular lymphoma

Single-nucleotide polymorphism (SNP) array analysis was performed using the 10K GeneChip array on a series of 26 paired follicular lymphoma (FL) and transformed-FL (t-FL) biopsies and the lymphoma cell lines SCI-1, DoHH2 and RL2261. Regions of acquired homozygosity were detected in 43/52 (83%) primary specimens with a mean of 1.7 and 3.0 aberrations in the FL and t-FL, respectively. A notable feature was the occurrence of recurring sites of acquired uniparental disomy (aUDP) on 6p, 9p, 12q and 17p in cell lines and primary samples. Homozygosity of 9p and 17p arose predominantly in t-FL and in three cases rendered the cell homozygous for a pre-existing mutation of either CDKN2A or TP53. These data suggest that mutation precedes mitotic recombination, which leads to the removal of the remaining wild-type allele. In all, 18 cases exhibited abnormalities in both FL and t-FL samples. In 10 cases blocks of homozygosity were detected in FL that were absent in the subsequent t-FL sample. These differences support the notion that FL and t-FL may arise in a proportion of patients by divergence from a common malignant ancestor cell rather than by clonal evolution from an antecedent FL.

CD8+ T-cell content in diagnostic lymph nodes measured by flow cytometry is a predictor of survival in follicular lymphoma

PURPOSE

Follicular lymphoma is a heterogeneous disease with variable prognosis and clinical course. We hypothesized that the presence of nonmalignant T cells in the microenvironment of the tumor may affect the outcome.

EXPERIMENTAL DESIGN

Using flow cytometry, we evaluated the T-cell subsets in the lymph node microenvironment of follicular lymphoma. All patients in South Stockholm County with indolent follicular lymphoma and with flow cytometry done on a diagnostic lymph node between 1994 and 2004 were included (N = 139). Diagnosis and grade (1, 2, and 3a) were confirmed by re-review. Flow cytometry results were reanalyzed. Lymphocyte subsets, the Follicular Lymphoma International Prognostic Index, grade, and clinical characteristics were evaluated in univariable and multivariable Cox analysis with respect to overall survival (OS) and disease-specific survival (DSS).

RESULTS

Higher CD8+ T-cell levels correlated with longer OS and DSS, independently of the Follicular Lymphoma International Prognostic Index (OS, P = 0.017; DSS, P = 0.020) and independently of all other prognostic factors (OS, P = 0.001; DSS, P = 0.004). Median OS was not reached for patients in the upper quarter of CD8+ T-cell levels (>8.6%), 10.4 years for patients in the middle half (4.2-8.6%), and 6.0 years for patients in the lower quarter (<4.2%). Furthermore, patients who had not required treatment within 6 months from diagnosis had more CD8+ T cells (P = 0.011).

CONCLUSIONS

Higher levels of CD8+ T cells predict a better prognosis, and these data support an important role for nonmalignant immune cells in the biology of follicular lymphoma. Evaluating the CD8+ T cells by flow cytometry at diagnosis may provide prognostic information.

Allogeneic stem cell transplantation with T cell-depleted grafts for lymphoproliferative malignancies

In non-Hodgkin lymphoma allogeneic stem cell transplantation (SCT) can be curative, but with standard dose conditioning patients may have substantial morbidity and mortality from graft-versus-host disease (GVHD); for aggressive malignancies, reduced intensity conditioning may result in higher recurrence. Patients with advanced follicular lymphoma (n = 12), transformed B cell malignancy (n = 11), and non-CD30+T cell lymphomas (n = 17) responsive to chemotherapy who had an HLA-identical sibling were offered T cell depleted (CAMPATH-1 G or H antibodies) SCT. Conditioning was with ablative doses of chemotherapy or radiotherapy. Before SCT, patients with follicular lymphoma had a median of 3 treatment courses, and those with transformed B cell and those diagnosed with T cell non-Hodgkin lymphoma had 2 (range, 1-3). At SCT the median age was 46 years (range, 21-59 years) and the number of CD34+ cells infused was 2.85 x 10(6)/kg. All patients showed engraftment but 7 patients (17.5%) developed GVHD. In total 12 subjects expired of transplant-related causes (n = 6) or from disease recurrence. One-year transplant-related mortality was 15%. There was no difference in survival across diagnostic groups. At a median of 1051 days, 70% survived and 68% are without disease. By reducing the incidence and severity of GVHD, patients can tolerate myeloablative doses of chemotherapy satisfactorily. This has resulted in low treatment-related mortality and adequate protection from disease recurrence.

Non-Hodgkin's lymphomas with Burkitt-like cells are associated with c-Myc amplification and poor prognosis

Out of 344 patients with newly diagnosed non-Hodgkin's lymphoma (NHL), this study identified 16 patients presenting Burkitt-like cells (BLCs) after cytological and/or histological review. Conventional cytogenetic analysis showed at diagnosis complex chromosomal abnormalities in 13 cases and a normal karyotype in three cases. However, neither t(8;14)(q24;q32) nor the variants t(2;8)(p12;q24) or t(8;22)(q24;q11) was detected. FISH studies showed c-MYC amplification in all cases with four to more than seven copies in 10 - 77% metaphase or inter-phase cells. This study did not observe any gene fusion signal for c-MYC/IgH excluding a t(8;14) translocation and partial tri or polysomy of chromosome 8. It also excluded in that cases a break apart for the c-MYC locus. This study also never detected IgL/c-MYC, IgK/c-MYC or X-c-MYC. The BLCs were present whatever the lymphoma sub-type: follicular lymphoma (FL) was diagnosed in six out of 16 patients, mantle cell lymphoma (MCL) in four out of 16 patients, marginal zone lymphoma (MZL) in two out of 16 patients and diffuse large B-cell lymphomas (DLBCL) in three out of 16 patients. One additional patient presented a T-cell lymphoma. The clinical course was aggressive with a poor prognosis, as death occurred in nine patients, within 6 months after diagnosis for eight of them. These data could suggest a sub-group of NHL patients (15 B-NHL, 1 T-NHL) have been identified with a poor prognosis characterized by the association of Burkitt-like cells and c-MYC amplification without t(8;14)(q24;q32) or its variants. The possibility that this profile may represent a distinct morphologic NHL sub-set remains to be determined on a large cohort of patients.

The role of hematopoietic cell transplantation for follicular non-Hodgkin's lymphoma

The overall survival with follicular lymphoma has not significantly changed over the last few decades, and there is no universal agreement as to the optimal first-line or subsequent therapy. High-dose chemotherapy with autologous hematopoietic cell transplantation (HCT) confers high response rates and improved progression-free survival in advanced-stage disease, and more recent data indicate a positive effect on overall survival. Initial results with myeloablative allogeneic HCT unequivocally demonstrated a reduction in relapse/progression compared with autologous HCT, but it is associated with prohibitive nonrelapse mortality. Nonmyeloablative or reduced-intensity regimens have substantially reduced up-front toxicity, and preliminary data seem highly encouraging with regard to efficacy. Novel strategies include the use of rituximab for in vivo purging and maintenance therapy. The incorporation of radioimmunoconjugates into conditioning regimens to deliver targeted radiotherapy also appears promising. This review summarizes current and new developments regarding the role of HCT for patients with follicular lymphoma.

Tositumomab and Iodine-131 Tositumomab Produces Durable Complete Remissions in a Subset of Heavily Pretreated Patients With Low-Grade and Transformed Non-Hodgkin’s Lymphomas

Purpose

This study is an integrated efficacy analysis of the five clinical trials of tositumomab and iodine-131 tositumomab in patients with relapsed or refractory low-grade, follicular, or transformed low-grade non-Hodgkin’s lymphoma (NHL) that resulted in the regulatory approval of the iodine-131 tositumomab by the US Food and Drug Administration.

Patients and Methods

This integrated analysis included 250 patients. Patients received a single course of iodine-131 tositumomab. Responses were assessed by an independent panel of radiologists and oncologists.

Results

Response rates in the five trials ranged from 47% to 68%; complete response rates ranged from 20% to 38%. With a median follow-up of 5.3 years, the 5-year progression-free survival was 17%. Eighty-one (32%) of 250 patients had a time to progression of ≥ 1 year (termed durable response population). For the durable response population, 44% had not progressed at ≥ 2.5 to ≥ 9.5 years and had a median duration of response of 45.8 months. The median duration of complete response was not reached. The durable response population had many poor prognostic characteristics, including bone marrow involvement (41%), bulky disease ≥ 5 cm (49%), and transformed histology (23%). Forty-three percent of the patients had been treated with more than four prior therapies and 36% had not responded to their most recent therapy.

Conclusion

The tositumomab and iodine-131 tositumomab therapeutic regimen produces high response rates in patients with relapsed or refractory low-grade, follicular, and transformed low-grade NHL, with a sizable subgroup of patients achieving long-term durable responses.

Long-term event-free survivors after high-dose therapy and autologous stem-cell transplantation for low-grade follicular lymphoma

Although follicular lymphoma (FL) is generally responsive to conventional-dose chemotherapy, improved survival in patients with this disease has been difficult to demonstrate. High-dose chemo/radiotherapy followed by autologous stem-cell transplantation (ASCT) can improve response rates, although its effects on survival remain controversial. Between 1990 and 2003, we transplanted 49 patients with low-grade FL at our institution. Twenty-two patients (45%) had undergone histologic transformation at the time of ASCT. In all, 44 patients (90%) had relapsed disease and five patients (10%) were resistant to chemotherapy at the time of transplantation. After ASCT, 30 patients (61%) were in complete remission (CR). The median overall survival (OS) has not been reached, while the median event-free survival (EFS) is 2.4 years. At a median follow-up of 5.5 years (longest 12.4 years), a plateau has been reached with 56% of patients remaining alive, and 35% event-free. ASCT was well tolerated except for two (4%) treatment-related deaths. In multivariable analysis, CR after ASCT and age less than 60 years are the best predictors of EFS and OS. ASCT is thus a safe therapeutic approach in FL, resulting in long-term EFS and OS for some patients, even with transformed disease.