Incidence of transformation to aggressive lymphoma in limited-stage follicular lymphoma treated with radiotherapy

Risk of transformation by frontline management in follicular and marginal zone lymphomas: a US population-based analysis

ABSTRACT

Follicular lymphoma (FL) and marginal zone lymphoma (MZL) often have long overall survival (OS), however, high-grade transformation (HGT) to diffuse large B-cell lymphoma markedly reduces survival. The roles of upfront treatment vs observation on the incidence and outcome of HGT remain unclear. Thus, we analyzed a Surveillance, Epidemiology, and End Results database to address this question. Patients diagnosed with FL grades 1 to 2 or MZL between 2000 and 2020 were included. Fine-Gray models estimated the impact of covariates on HGT cumulative incidence and lymphoma-specific survival (LSS) and Cox regression on OS. HGT occurred in 4.2% of 23 384 patients with FL and 2.5% of 20 530 patients with MZL. The 5- and 10-year HGT cumulative incidence rates were 2.80% and 4.87% for FL, and 1.74% and 2.95% for MZL, respectively, which are notably lower than in earlier studies. The annual HGT incidence rate peaked in the first 2 years, then steadily declined over 2 decades for FL and all MZL subtypes. In FL, upfront observation vs treatment increases HGT risk (sub-distribution hazard ratio [SHR], 1.23; 95% confidence interval [CI], 1.09-1.40; P < .001) and barely affects OS (hazard ratio [HR], 0.95; 95% CI, 0.90-0.99; P = .03). Conversely, upfront observation was associated with lower HGT risk in nodal (SHR, 0.71; 95% CI, 0.53-0.94; P = .01) and extranodal (SHR, 0.64; 95% CI, 0.48-0.86; P = .003) MZL and did not affect survival in extranodal disease (HR, 0.94; 95% CI, 0.97-1.02; P = .15). HGT was associated with decrease in LSS across all histologies. Upfront treatment reduced the risk of HGT only in FL but not MZL.

Risk Factors for and Outcomes of Follicular Lymphoma Histological Transformation at First Progression in the GALLIUM Study

BACKGROUND

Although advanced‑stage follicular lymphoma (FL) is considered incurable, survival has improved with the introduction of the anti-CD20 antibodies, rituximab (R) and obinutuzumab (G). However, FL can undergo histological transformation (HT) to a more aggressive disease, and a validated model for predicting HT risk is not yet available.

PATIENTS AND METHODS

We assessed HT incidence, risk factors and outcomes in the phase III, GALLIUM study evaluating R- or G-chemotherapy in patients with previously untreated, advanced-stage FL (ClinicalTrials.gov NCT01332968). HT rates were assessed by repeat tumour biopsy at disease progression or relapse, at the investigator's discretion.

RESULTS

Of 1202 patients enrolled, 315 (26.2%) experienced progressive disease; 46 (14.6%) had a biopsy at first progression, 40 of whom had biopsy-confirmed HT. HT risk factors were male sex (subdistribution hazard ratio [sHR], 2.21; 95% confidence interval [CI], 1.16-4.20), elevated baseline serum lactate dehydrogenase (sHR, 3.97; 95% CI, 2.03-7.76), and elevated baseline serum β₂-microglobulin (sHR, 1.96; 95% CI, 1.02-3.79). Patients with HT at first progression had poorer post-progression survival than those with relapsed FL (2-year rate: 55.9% vs. 83.1%). Relapse with HT occurred earlier than FL relapse (median time from randomisation: 0.8 vs. 2.3 years).

CONCLUSION

HT was a low-frequency event associated with poor survival outcomes in the GALLIUM study. Male sex and elevated baseline levels of serum LDH and B2M were significant risk factors for HT. Further research is required to develop validated prognostic indices for HT risk and guide treatment decisions.

Successful PD-1 inhibitor treatment in a patient with refractory transformed follicular lymphoma who failed to respond to CAR-T cell therapy: a case report and literature review

Follicular lymphoma (FL) accounts for approximately 35% of all non-Hodgkin lymphomas and can progress to diffuse large B cell lymphoma (DLBCL) at a rate of 2% per year. Here, we present a 56-year-old female patient who was diagnosed with grade 3a FL. Further pathological investigation revealed that the lymphoma had transformed into DLBCL following six courses of R-CHOP regimen, and further disease progression was observed after two courses of R2-GemOx. We ultimately failed to collect hematopoietic stem cells after two courses of R2-ICE. CD-22 CAR-T cell therapy salvaged the patient; however, a new soft tissue mass of 4.8 × 4.1 cm rapidly emerged in the patient's right lung. Following the observation of strong tissue staining of PD-L1 (90%), the patient was administered PD-1 inhibitor and 26 Gy of radiotherapy and has maintained progression-free survival at more than 15 months of follow-up. Transformed FL with strong PD-L1 expression showed a poor response to standard immunochemotherapy. Our findings support the potential benefit of PD-1 inhibitor and combination therapies in this type of transformed FL.

Long-term outcomes for patients with limited-stage follicular lymphoma: update of a population-based study

With a median follow-up of 16.6 years, Lo and colleagues report excellent long-term outcomes with primary radiotherapy for limited-stage follicular lymphoma in this month’s CME article.

The role of local radiotherapy following rituximab-containing chemotherapy in patients with transformed indolent B-cell lymphoma

Objectives

This study aimed to evaluate the outcomes of local radiotherapy (LRT) in patients with histologic transformation (HT) following rituximab‐containing chemotherapy.

Methods

We retrospectively analysed 92 patients with biopsy‐confirmed HT undergoing rituximab‐containing chemotherapy at our institution between 2003 and 2015.

Results

Of the 36 patients with limited‐stage disease at diagnosis of HT, 29 (78%) received LRT. The estimated 5‐year progression‐free survival (PFS) rate was significantly better in patients who underwent LRT than in those who did not (93% and 42%, respectively; P < 0.05). Multivariate analyses employing age, sex, performance status, LRT and treatment response demonstrated that LRT was an independent prognostic factor for PFS (hazard ratio [HR]: 11.8; 95% confidence interval [CI]: 1.28‐108.1; P < 0.05). Of the 32 patients who underwent LRT for HT lesion treatment, 31 (97%) did not show disease progression within radiation fields; among them, 27 patients (84%) survived without disease progression during the follow‐up period. One patient developed hypothyroidism due to LRT; the others had no acute or late‐onset complications of LRT.

Conclusions

Our data support the recommendation of LRT for HT lesion treatment following rituximab‐containing chemotherapy in select patients with localised HT, as a rational treatment approach with potentially limited toxicity.

How to manage early-stage follicular lymphoma

INTRODUCTION

Early-stage follicular lymphoma (FL) is characterized by good prognosis and can be cured with involved-field radiotherapy (IF-RT) in most cases. PET scan is a milestone of diagnostic work-up, with the aim of identifying a truly localized disease; however, staging in most of the studies was without PET.

AREAS COVERED

We have searched in MEDLINE (inclusive dates 1994-2020) data about localized FL management. While high-quality evidence is lacking, current guidelines recommend IFRT or involved-site RT as first-line treatment in limited stages FL. Since a significant proportion of disease relapse occurred in non-irradiated areas, it has been hypothesized that occult disease could be present at diagnosis and could persist after RT, contributing to relapse. Available treatment options include watch-and-wait, chemotherapy, RT plus chemo- or chemo-immunotherapy, and RT combined with rituximab (R).

EXPERT OPINION

RT combined with chemotherapy could increase PFS, but a clear OS benefit is lacking and toxic effects could be unacceptable. A promising strategy is represented by R combined with IF-RT, with low relapse rate outside the radiation fields and without the toxicity reported with chemotherapy. The study of prognostic factors in PET-staged patients, the reduction of RT fields and doses, and a response-adapted strategy represent new perspectives to investigate.

Treatment of Histologic Transformation

Histologic transformation from follicular lymphoma to aggressive lymphoma historically had a poor prognosis. Routine use of anti-CD20 antibody rituximab has changed the landscape of follicular lymphoma (FL) such that outcomes are improved in select patients, similar to de-novo diffuse large B-cell lymphoma. Several biological and clinical biomarkers can predict risk of transformation, and ongoing research is improving understanding of the biology surrounding the transformation process. This review provides an overview of risk factors, prognosis, and treatment of histologic transformation of FL.

Risk Factors for Transformation to Higher-Grade Lymphoma and Its Impact on Survival in a Large Cohort of Patients With Marginal Zone Lymphoma From a Single Institution

PURPOSE

Given the paucity of data on higher-grade transformation (HGT) to aggressive lymphoma in patients with marginal zone lymphoma (MZL), we report on a large cohort of patients, identify risk factors, and determine HGT impact on overall survival (OS).

METHODS

We analyzed 453 patients with biopsy-proven MZL seen at our institution between 1995 and 2016. Kaplan-Meier, Cox proportional hazards regression, and competing risk methods were used in analyses of time-to-event outcomes.

RESULTS

Thirty-four patients (7.5%) had biopsy-proven HGT to diffuse large B-cell lymphoma, including seven (21%) diagnosed at the time of initial MZL diagnosis. Among 27 incident patients, median time to HGT was 29 months (range, 1.3 to 135 months). Higher risk of HGT was observed in those with nodal/splenic MZL (subdistribution hazard ratio [SHR], 2.60; P = .023). On multivariable competing risk analysis, elevated lactate dehydrogenase (SHR, 2.71), more than four nodal sites (SHR, 2.97), and failure to achieve complete remission (CR) after initial treatment (SHR, 3.76) conveyed significantly higher risk for HGT ( P < .02). International Prognostic Index (IPI), Follicular Lymphoma IPI, and Mucosa-Associated Lymphoid Tissue Lymphoma IPI were only significant predictors of HGT univariably. Patients with HGT had shorter OS (5-year rate, 65% v 86%; P < .001). Patients who presented with HGT within 12 months since MZL diagnosis had shorter OS than those with HGT at MZL diagnosis combined with those with HGT more than 12 months later (4-year rate, 43% v 81%, P < .001). Non-CR and higher scores of IPI, Follicular Lymphoma IPI, and Mucosa-Associated Lymphoid Tissue Lymphoma IPI were the main significant predictors for shorter progression-free survival and OS.

CONCLUSION

Failure to achieve CR after initial treatment, elevated lactate dehydrogenase, and more than four nodal sites at the time of MZL diagnosis are the main predictors of increased risk of HGT. Patients with HGT have shorter OS.

Randomized Trial of Systemic Therapy After Involved-Field Radiotherapy in Patients With Early-Stage Follicular Lymphoma: TROG 99.03

Purpose

Follicular lymphoma (FL) is curable by involved-field radiotherapy (IFRT) in < 50% of patients with stage I to II disease. We hypothesized that adding systemic therapy to IFRT would improve long-term progression-free survival (PFS).

Patients and Methods

A multicenter randomized controlled trial enrolled patients with stage I to II low-grade FL after staging computed tomography scans and bone marrow biopsies. 18F-labeled fluorodeoxyglucose–positron emission tomography (PET) was not mandatory. Patients were randomly assigned to either arm A (30 Gy IFRT alone) or arm B (IFRT plus six cycles of cyclophosphamide, vincristine, and prednisolone [CVP]). From 2006, rituximab was added to arm B (R-CVP).

Results

Between 2000 and 2012, 150 patients were enrolled, 75 per arm. In arm B, 44 patients were allocated to receive CVP and 31 were allocated to receive R-CVP. At randomization, 75% had stage I, the median age was 57 years, 52% were male, and 48% were PET staged. With a median follow-up of 9.6 years (range, 3.1 to 15.8 years), PFS was superior in arm B (hazard ratio, 0.57; 95% CI, 0.34 to 0.95; P = .033). Ten-year PFS rates were 59% (95% CI, 46% to 74%) and 41% (95% CI, 30% to 57%) for arms B and A, respectively. Patients in arm B who received R-CVP had markedly superior PFS compared with contemporaneous patients in arm A (hazard ratio, 0.26; 95% CI, 0.07 to 0.97; P = .045). Fewer involved regions ( P = .047) and PET staging ( P = .056) were associated with better PFS. Histologic transformation occurred in four and 10 patients in arms B and A, respectively ( P = .1). Ten deaths occurred in arm A versus five in arm B, but overall survival was not significantly different ( P = .40; 87% and 95% at 10 years, respectively).

Conclusion

Systemic therapy with R-CVP after IFRT reduced relapse outside radiation fields and significantly improved PFS. IFRT followed by immunochemotherapy is more effective than IFRT in early-stage FL.

An update in treating transformed lymphoma

Indolent lymphomas typically have a prolonged course and favorable prognosis. Recent data support survival times that can reach several decades, even if periodic treatment is needed to manage symptoms or stabilize disease. However, all indolent lymphomas have the potential to undergo transformation to an aggressive phenotype, clinically characterized by a rapid progression of adenopathy, new-onset constitutional symptoms, or laboratory abnormalities, and the immediate need for therapeutic intervention. The most common scenario is transformation of follicular lymphoma to either diffuse large B-cell lymphoma or high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 translocations; however, other indolent subtypes such as marginal zone lymphoma, lymphoplasmacytic lymphoma, small lymphocytic lymphoma/chronic lymphocytic leukemia, or even nodular lymphocyte predominant Hodgkin lymphoma, can undergo similar histologic transformation. The prognosis of transformed lymphomas has historically been quite poor, but there is ample evidence this is changing in the rituximab era. This article will provide a review of transformed lymphomas with an emphasis on treatment and the nuances of diagnosis and clinical management. Unless otherwise specified, all discussion in this review pertains to transformed follicular lymphoma which is the more common scenario and the subtype with the most robust data. In many cases, this information can be extrapolated and applied to other indolent histologies (i.e. transformed marginal zone lymphoma); however, several other clinical scenarios, such as Richter's transformation and "double hit" transformations, warrant a distinct discussion and will be reviewed separately.

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.

Treatment of localized-stage follicular lymphoma

Follicular lymphoma (FL) is the most common indolent lymphoma, and it most frequently presents in an advanced stage. Therapeutic considerations for advanced stage are different from those of localized-stage FL, in which radiotherapy (RT) is generally recommended. However, the available evidence suffers from shortcomings that are relatively specific to this clinical entity due to its rarity and long survival with all available treatment modalities, including that most of the existing evidence originated at a time when diagnostic classifications, staging procedures and radiotherapeutic standards were different from those available today and when anti-CD20 monoclonal antibodies were not available. Available treatment modalities include observation, systemic therapy only, RT only and RT in combination with systemic therapy. We review the evidence available with each of them and the data from present-day clinical practice studies as well as briefly discuss what diagnostic and therapeutic developments may take place in the next few years.

Novel acquisitions on biology and management of transformed follicular lymphoma

Follicular lymphoma (FL) generally has an indolent clinical course, but in some patients, a histological transformation (HT) into aggressive entities may take place and often lead to a poorer survival. The rituximab era has seen an improved outcome of FL, including those with HT. The current treatment strategies for transformed FL are based on immunochemotherapy for the cases with HT at the time of diagnosis or as the first event after watchful waiting. Patients transforming after prior treatment of FL usually benefit from autologous stem cell transplant. Unfortunately, early assessment of the transformation risk remains elusive. Recent studies delved the mechanisms of HT, showing that this is a complex process, resulting from a number of epigenetic and genetic lesions occurring in the tumour cell population as well as progressive changes in the tumour microenvironment. This novel knowledge has prompted clinical investigations on a variety of new therapeutic strategies.

The incidence of biopsy-proven transformation in follicular lymphoma in the rituximab era. A retrospective analysis from the Czech Lymphoma Study Group (CLSG) database

The aim of this study is to assess the incidence, risk factors, and outcome of biopsy-proven transformation in follicular lymphoma (FL) patients in the rituximab era. Transformation was analyzed in 1233 patients with initially diagnosed FL grades 1-3A, identified between 2002 and 2012 in the prospectively maintained Czech Lymphoma Study Group database. Only patients with histologically proven transformation (HT) were included. HT occurred in 58 cases at a median of 3.0 years from the initial FL diagnosis; the HT rate was 4% at 5 years. Transformation occurred most frequently at the first relapse (84% patients). Median OS from the HT was 2.5 years (95% CI 0.4-4.6) and 6-year OS with HT was shorter compared to all FLs (60 vs. 83.9%; 95% CI). A bulky tumor (≥ 10 cm), increased lactate dehydrogenase, age ≥ 60 years, and International Prognostic Index (intermediate/high risk), but not Follicular Lymphoma International Prognostic Index, were associated with transformation (p < 0.05). In the first line, 70% of patients received rituximab (including 36% rituximab maintenance), 57% CHOP-like regimens, and 2.6% of patients were treated with fludarabine-based therapy, whereas 11% of patients were watched only. The patients treated with R-CHOP in the first line (n = 591) showed the transformation rate at 5 years of 4.23% (95% CI 2.52-5.93); subsequent rituximab maintenance (n = 276) vs. observation (n = 153) was associated with a lower transformation rate (p.033; HR 3.29; CI 1.10-9.82). The transformation rate seems to be lower than in previous series, which may be influenced by broad use of rituximab, but prognosis of HT developed during therapy continues to be poor.

Transformed follicular lymphoma

Follicular Lymphoma (FL) is the second most common type of non-Hodgkin lymphoma and is considered to be the prototype of indolent lymphomas. Histologic transformation into an aggressive lymphoma, which is expected to occur at a rate of 2 to 3% each year, is associated with rapid progression, treatment resistance, and poor prognosis. Recent modifications to the physiopathologic mechanism of transformed follicular lymphoma (t-FL) have been proposed, including genetic and epigenetic mechanisms as well as a role for the microenvironment. Although t-FL is considered a devastating complication, as it is associated with treatment-refractory disease and a dismal outcome, recent data in the rituximab era have suggested that not only is the prognosis less severe than reported in the previous literature but the risk of transformation is also lower. Thus, this study aimed to review the most recent research on t-FL in an attempt to better understand the clinical meaning of transformation from FL to diffuse large B cell lymphoma (DLBCL) and the impact of current treatment strategies on the curability of this intriguing subentity of lymphoma.

Patterns of use and survival outcomes of positron emission tomography for initial staging in elderly follicular lymphoma patients

The role of positron emission tomography (PET) in the initial assessment of follicular lymphoma (FL) has been a topic of debate. We examined the patterns of utilization of PET staging in FL and assessed the association of PET with survival. Using the SEER-Medicare database, we identified 5712 patients diagnosed with first primary FL between 2000 and 2009. Older age, African-American race, poor performance status, B-symptoms and history of anemia were negatively associated with PET staging. Receipt of PET staging was positively associated with treatment at institutions affiliated with research networks and with residence in areas with higher concentrations of nuclear medicine specialists. PET was associated with improved lymphoma-related (HR 0.69, 95% CI: 0.58-0.82) and overall (HR 0.75, 95% CI: 0.68-0.83) survival. Our findings substantiate the use of PET as the standard of care for imaging in FL patients. Further investigation is warranted to identify mechanisms underlying the apparent survival advantage associated with PET staging in FL.

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.

Pediatric follicular lymphoma in Japan

Follicular lymphoma (FL) is quite rare in children. There have been only two major reports on pediatric FL. The present retrospective study on pediatric FL in Japan, including FL with diffuse large B cell lymphoma (DLBCL), analyzed data from 1991 to 2014. Twenty-two patients with pediatric FL were analyzed. Sixteen patients were boys and six were girls. Median age of onset was 9 years (range 4-17 years). In 11 patients, DLBCL co-existed with FL. The initial lesions involved cervical lesions in 16 patients, and the abdomen in six. With regard to stage of disease at diagnosis, 17 patients were at stage I or II, four were at stage III, and one was at stage IV. Chemotherapy was administered in 18 patients, and only resection was performed in four patients. Mature B lymphoma regimens were selected for 17 patients who received chemotherapy. Although two patients relapsed, all patients are currently alive and disease free. The median follow-up period was 54.5 months (range 6-126 months). Patients having FL with DLBCL were younger compared with those having FL, and this disease was more frequently observed in female patients. Our data revealed that FL in Japanese children is a tumor with good prognosis, as in reports from the United States and Europe.

Systemic Front Line Therapy of Follicular Lymphoma: When, to Whom and How

The natural history of follicular lymphoma is usually characterized by an indolent course with a high response rate to the first line therapy followed by recurrent relapses, with a time to next treatment becoming shorter after each subsequent treatment line. More than 80% of patients have advanced stage disease at diagnosis. The time of initiation and the nature of the treatment is mainly conditioned by symptoms, tumor burden, lymphoma grading, co-morbidities and patients preference. A number of clinical and biological factors have been determined to be prognostic in this disease, but the majority of them could not show to be predictive of response to treatment, and therefore can’t be used to guide the treatment choice. CD20 expression is the only predictive factor recognized in the treatment of FL and justifies the use of “naked” or “conjugated” anti-CD20 monoclonal antibodies as a single agent or in combination with chemo- or targeted therapy. Nevertheless, as this marker is almost universally found in FL, it has little role in the choice of treatment. The outcome of patients with FL improved significantly in the last years, mainly due to the widespread use of rituximab, autologous and allogeneic transplantation in young and fit relapsed patients, the introduction of new drugs and the improvement in diagnostic accuracy and management of side effects. Agents as new monoclonal antibodies, immuno-modulating drugs, and target therapy have recently been developed and approved for the relapsed setting, while studies to evaluate their role in first line treatment are still ongoing. Here we report our considerations on first line treatment approach and on the potential factors which could help in the choice of therapy.

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.

High-grade Transformation of Low-grade B-cell Lymphoma: Pathology and Molecular Pathogenesis

Patients with low-grade (clinically indolent) lymphomas are at risk to undergo transformation to high-grade (clinically aggressive) lymphoma, although transformation only occurs in a subset of patients. When transformation occurs it is a critical event that determines the course of disease and is associated with unfavorable patient outcomes. Accurate detection of transformation, predictive biomarkers, and identification of specific molecular pathways implicated in the pathobiology of transformation will facilitate personalized therapeutic approaches and underpin advances in clinical outcomes. In this article, we present an update of the clinical and pathologic diagnostic criteria for low-grade B-cell lymphoma transformation and discuss the molecular alterations involved in the pathogenesis of this biological phenomenon.

The role of "watch and wait" in intestinal follicular lymphoma in rituximab era

OBJECTIVE

There is no consensus regarding the best treatment for intestinal follicular lymphoma (FL). We used "watch and wait" for patients with intestinal FL with low-tumor-burden (LTB) criteria and without mass formation causing bowel obstruction. We investigated the overall survival (OS) and time to treatment required (TTR).

METHODS

Thirty-three intestinal FL patients [clinical stage (CS) I:16, II1:0, II2:7, IV:10; median observation period: 45.5 months, range: 13-110 months] were diagnosed via endoscopy. Detailed clinical and pathological examinations were performed, and neoplastic process behavior was monitored.

RESULTS

All of the 33 patients were WHO grade 1. FL lesions in the digestive tract were found frequently in the second-fourth portion of the duodenum in 91% of the patients; 87% of those patients had lesions in a broader area including the small intestine. Two patients had an enlargement of the area of the lesions and a worsening of the macroscopic findings. Three patients had CS progression; however, these remained within the indication for "watch and wait." Two patients with transformation into diffuse large B-cell lymphoma received rituximab and chemotherapy, which led to complete remission. The OS was 100%. The time to treatment required (TTR) was 49 months in one patient and 37 months in one patient.

CONCLUSION

Intestinal FL in CS I-IV with broad infiltration of the digestive tract meeting the criteria for LTB had a remarkably slow course. This study suggests that "watch and wait" is appropriate for the treatment of LTB intestinal FL even in the era of rituximab.

Outcomes of transformed follicular lymphoma in the modern era: a report from the National LymphoCare Study (NLCS)

We assessed the incidence, prognostic features, and outcomes associated with transformation of follicular lymphoma (FL) among 2652 evaluable patients prospectively enrolled in the National LymphoCare Study. At a median follow-up of 6.8 years, 379/2652 (14.3%) patients transformed following the initial FL diagnosis, including 147 pathologically confirmed and 232 clinically suspected cases. Eastern Cancer Oncology Group performance status >1, extranodal sites >1, elevated lactate dehydrogenase, and B symptoms at diagnosis were associated with transformation risk. Relative to observation, patients initiating treatment at diagnosis had a reduced risk of transformation (hazard ratio [HR], 0.58; 95% confidence interval [CI], 0.46-0.75). The risk of transformation was similar in patients treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone compared with rituximab, cyclophosphamide, vincristine, and prednisone (adjusted HR, 0.94; 95% CI, 0.62-1.42). Maintenance rituximab was associated with reduced transformation risk (HR, 0.67; 95% CI, 0.46-0.97). Five-year survival from diagnosis was significantly worse for patients with vs without transformation (75%, 95% CI, 70-79 vs 85%, 95% CI, 83-86). The median overall survival post-transformation was 5 years. Forty-seven patients with evidence of transformation at the time of diagnosis shared similar prognostic factors and survival rates to those without transformation. Improved outcomes for transformation in the modern era are suggested by this observational study. This trial is registered at www.clinicaltrials.gov as #NCT00097565.

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.

Radiotherapy with rituximab may be better than radiotherapy alone in first-line treatment of early-stage follicular lymphoma: is it time to change the standard strategy?

Early-stage follicular lymphoma (FL) has traditionally been treated with involved-field radiotherapy (RT). Rituximab (R) is a low-toxic, efficient systemic therapy for FL, but there are no data about its clinical impact in early FL. We retrospectively analyzed 93 patients with stage I-II indolent FL treated with RT (n=65) or RT+R (n=14) or R alone (n=14). Median follow-up was 5.0 years for patients with RT, 2.8 years for the RT+R subgroup and 2.5 years for patients treated with R. The complete response rate was 92%, 100% and 86% (not significant) and the median PFS was 3.3 years, not reached and 4.9 years (p=0.035) for the RT, RT+R and R arms, with no impact on overall survival. R combined with RT seems to give better results in terms of global FL control, but longer follow-up and prospective comparison are needed to verify these results.

Transformed follicular non-Hodgkin lymphoma

Histologic transformation of follicular lymphoma to an aggressive non-Hodgkin lymphoma is a critical biologic event with profound implications on the natural history of this otherwise indolent disease. Recent insights into the genetic and epigenetic basis of transformation have been described, with the recognition of pivotal events governing the initiation and persistence of tumor evolution. Outcomes of patients with transformed lymphoma have historically been poor; however, several studies in the rituximab era suggest that survival may be more favorable than previously recognized. This review highlights our current understanding of transformed follicular lymphoma biology and pathogenesis, current treatment, and future directions.

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.