Incidence, predictive factors, and outcome of lymphoma transformation in follicular lymphoma patients

Early histological transformation of follicular lymphoma to diffuse large B-cell lymphoma indicating adverse survival: A population-based analysis and validation

INTRODUCTION

The histological transformation (HT) of follicular lymphoma (FL) is a crucial biological event. The study aimed to evaluate the incidence, clinicial characteristics, prognosis and impact of HT time on survival of FL transforming to diffuse large B-cell lymphoma in population-based large-scale cohorts.

METHODS

A retrospective cohort study of FL with HT was performed in the Surveillance, Epidemiology, and End Results database. The Hematological Malignancy Research Network FL cohort and Aristotle study FL cohort were used to assess the external validity.

RESULTS

Among 44,127 FL cases from the Surveillance, Epidemiology, and End Results database, 1311 cases were pathology-proven recorded to transform to diffuse large B-cell lymphoma. The cumulative rates of HT at 5, 10, and 15 years after FL diagnosis were estimated to be 1.19%, 2.93%, and 5.01%, respectively. Significantly worse overall survival and cancer-specific survival were exhibited in patients with HT than those without HT. Early HT (transformation of FL within 48 months after FL diagnosis [TOD48]) was an independent predictor for adverse overall survival of HT patients, regardless of treatment modalities before transformation. The adverse prognostic effect of TOD48 was validated in the Hematological Malignancy Research Network cohort and Aristotle study cohort. Older age (>75 years) and B symptoms within FL at diagnosis were the independent risk factors of TOD48. Furthermore, a novel prognostic model combining TOD48 with Follicular Lymphoma International Prognostic Index (TOD48-FLIPI) was constructed and validated for risk stratification.

CONCLUSION

TOD48 was a risk indicator of HT, and the novel prognostic model "TOD48-FLIPI" for HT patients was proposed.

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.

Advancements in Personalized CAR-T Therapy: Comprehensive Overview of Biomarkers and Therapeutic Targets in Hematological Malignancies

Chimeric antigen receptor T-cell (CAR-T) therapy is a novel anticancer therapy using autologous or allogeneic T-cells. To date, six CAR-T therapies for specific B-cell acute lymphoblastic leukemia (B-ALL), non-Hodgkin lymphomas (NHL), and multiple myeloma (MM) have been approved by the Food and Drug Administration (FDA). Significant barriers to the effectiveness of CAR-T therapy include cytokine release syndrome (CRS), neurotoxicity in the case of Allogeneic Stem Cell Transplantation (Allo-SCT) graft-versus-host-disease (GVHD), antigen escape, modest antitumor activity, restricted trafficking, limited persistence, the immunosuppressive microenvironment, and senescence and exhaustion of CAR-Ts. Furthermore, cancer drug resistance remains a major problem in clinical practice. CAR-T therapy, in combination with checkpoint blockades and bispecific T-cell engagers (BiTEs) or other drugs, appears to be an appealing anticancer strategy. Many of these agents have shown impressive results, combining efficacy with tolerability. Biomarkers like extracellular vesicles (EVs), cell-free DNA (cfDNA), circulating tumor (ctDNA) and miRNAs may play an important role in toxicity, relapse assessment, and efficacy prediction, and can be implicated in clinical applications of CAR-T therapy and in establishing safe and efficacious personalized medicine. However, further research is required to fully comprehend the particular side effects of immunomodulation, to ascertain the best order and combination of this medication with conventional chemotherapy and targeted therapies, and to find reliable predictive biomarkers.

Outcomes of the transformation of follicular lymphoma to diffuse large B-cell lymphoma in the rituximab era: A population-based study

BACKGROUND

Histological transformation (HT) to diffuse large B-cell lymphoma (DLBCL) is a common complication of follicular lymphoma (FL) and is usually associated with a dismal outcome. However, the survival rate of these patients has improved over the last 20 years with the introduction of rituximab. This study aimed to access the outcome of transformation to DLBCL (t-DLBCL) from FL in a retrospective series that began after the widespread use of rituximab use. In addition, we also compared survival between t-DLBCL and primary DLBCL (p-DLBCL) in the same timeframe.

METHODS

We utilized the Surveillance, Epidemiology, and End Results (SEER) database to identify patients with primary FL and patients with p-DLBCL between 2000 and 2020. Patients who had a subsequent diagnosis of DLBCL at least 2 months after FL diagnosis were identified as t-DLBCL.

RESULTS

Finally, we identified 50,332 FL and 95,933 p-DLBCL. With a median follow-up of 119 months, 1631 patients developed t-DLBCL. The median time from FL diagnosis to t-DLBCL was approximately 4 years. The post-transformation survival (PTS) rate at 5 years was 49.6%, with a median PTS of 56 months. Older age, advanced stage, and early transformation were associated with worse PTS. Furthermore, t-DLBCL receiving chemotherapy or combined modality as initial therapy before HT was also associated with worse PTS, while the result was inverse when taking the impact of initial management strategy at HT into account. Taking t-DLBCL and p-DLBCL as a whole, comparable survival was observed between p-DLBCL and t-DLBCL receiving radiation or watch-and-wait as initial therapy prior to HT.

CONCLUSION

The outcome of t-DLBCL in the rituximab era was better than historical series before the rituximab era. Due to the good prognosis, we did not recommend autologous stem cell transplantation for t-DLBCL receiving watch-and-wait or radiation as initial therapy before HT.

AN UNUSUAL CASE OF PRIMARY VITREORETINAL LYMPHOMA: A TRANSFORMED LYMPHOMA

PURPOSE

To report a case of primary vitreoretinal lymphoma (VRL) presenting as diffuse large b-cell lymphoma 19 years after initial systemic follicular lymphoma.

METHOD

A case report.

RESULTS

An 81-year-old male patient presented with a 1-month history of floaters and blurry vision in the left eye. He had a history of follicular non-Hodgkin lymphoma treated with systemic chemotherapy in 2002 and prostate cancer treated surgically in 2004. Ophthalmic examination revealed vitritis, retinal whitening, perivascular sheathing, and a vascularized cream-colored retinal mass in the superonasal periphery of the left eye. Diagnostic vitrectomy with retina and vitreous biopsies demonstrated diffuse large b-cell lymphoma. Positron emission tomography/computed tomography confirmed the isolated lesion in the left eye without systemic involvement. Treatment with systemic and intraocular chemotherapy was planned.

CONCLUSION

To the best of our knowledge, this is the first reported case of primary vitreoretinal lymphoma of diffuse large b-cell lymphoma transformed from follicular lymphoma. Intravitreal and systemic chemotherapy, including rituximab, should be considered in the management of patients with transformed vitreoretinal lymphoma.

High monocytic MDSC signature predicts multi-drug resistance and cancer relapse in non-Hodgkin lymphoma patients treated with R-CHOP

Introduction

Non-Hodgkin Lymphoma (NHL) is a heterogeneous lymphoproliferative malignancy with B cell origin. Combinatorial treatment of rituximab, cyclophsphamide, hydroxydaunorubicin, oncovin, prednisone (R-CHOP) is the standard treatment regimen for NHL, yielding a complete remission (CR) rate of 40-50%. Unfortunately, considerable patients undergo relapse after CR or initial treatment, resulting in poor clinical implications. Patient's response to chemotherapy varies widely from static disease to cancer recurrence and later is primarily associated with the development of multi-drug resistance (MDR). The immunosuppressive cells within the tumor microenvironment (TME) have become a crucial target for improving the therapy efficacy. However, a better understanding of their involvement is needed for distinctive response of NHL patients after receiving chemotherapy to design more effective front-line treatment algorithms based on reliable predictive biomarkers.

Methods

Peripheral blood from 61 CD20+ NHL patients before and after chemotherapy was utilized for immunophenotyping by flow-cytometry at different phases of treatment. In-vivo and in-vitro doxorubicin (Dox) resistance models were developed with murine Dalton's lymphoma and Jurkat/Raji cell-lines respectively and impact of responsible immune cells on generation of drug resistance was studied by RT-PCR, flow-cytometry and colorimetric assays. Gene silencing, ChIP and western blot were performed to explore the involved signaling pathways.

Results

We observed a strong positive correlation between elevated level of CD33+CD11b+CD14+CD15- monocytic MDSCs (M-MDSC) and MDR in NHL relapse cohorts. We executed the role of M-MDSCs in fostering drug resistance phenomenon in doxorubicin-resistant cancer cells in both in-vitro, in-vivo models. Moreover, in-vitro supplementation of MDSCs in murine and human lymphoma culture augments early expression of MDR phenotypes than culture without MDSCs, correlated well with in-vitro drug efflux and tumor progression. We found that MDSC secreted cytokines IL-6, IL-10, IL-1β are the dominant factors elevating MDR expression in cancer cells, neutralization of MDSC secreted IL-6, IL-10, IL-1β reversed the MDR trait. Moreover, we identified MDSC secreted IL-6/IL-10/IL-1β induced STAT1/STAT3/NF-κβ signaling axis as a targeted cascade to promote early drug resistance in cancer cells.

Conclusion

Our data suggests that screening patients for high titre of M-MDSCs might be considered as a new potential biomarker and treatment modality in overcoming chemo-resistance in NHL patients.

Noncoding mutations cause super-enhancer retargeting resulting in protein synthesis dysregulation during B cell lymphoma progression

Whole-genome sequencing of longitudinal tumor pairs representing transformation of follicular lymphoma to high-grade B cell lymphoma with MYC and BCL2 rearrangements (double-hit lymphoma) identified coding and noncoding genomic alterations acquired during lymphoma progression. Many of these transformation-associated alterations recurrently and focally occur at topologically associating domain resident regulatory DNA elements, including H3K4me3 promoter marks located within H3K27ac super-enhancer clusters in B cell non-Hodgkin lymphoma. One region found to undergo recurrent alteration upon transformation overlaps a super-enhancer affecting the expression of the PAX5/ZCCHC7 gene pair. ZCCHC7 encodes a subunit of the Trf4/5-Air1/2-Mtr4 polyadenylation-like complex and demonstrated copy number gain, chromosomal translocation and enhancer retargeting-mediated transcriptional upregulation upon lymphoma transformation. Consequently, lymphoma cells demonstrate nucleolar dysregulation via altered noncoding 5.8S ribosomal RNA processing. We find that a noncoding mutation acquired during lymphoma progression affects noncoding rRNA processing, thereby rewiring protein synthesis leading to oncogenic changes in the lymphoma proteome.

Investigating and modeling positron emission tomography factors associated with large cell transformation from low-grade lymphomas

Low-grade lymphomas have a 1%-3% annual risk of transformation to a high-grade histology, and prognostic factors remain undefined. We set to investigate the role of positron emission tomography (PET) metrics in identification of transformation in a retrospective case-control series of patients matched by histology and follow-up time. We measured PET parameters including maximum standard uptake value (SUV-max) and total lesion glycolysis (TLG), and developed a PET feature and lactate dehydrogenase (LDH)-based model to identify transformation status within discovery and validation cohorts. For our discovery cohort, we identified 53 patients with transformation and 53 controls with a similar distribution of follicular lymphoma (FL). Time to transformation and control follow-up time was similar. We observed a significant incremental increase in SUV-max and TLG between control, pretransformation and post-transformation groups (P < 0.05). By multivariable analysis, we identified a significant interaction between SUV-max and TLG such that SUV-max had highest significance for low volume cases (P = 0.04). We developed a scoring model incorporating SUV-max, TLG, and serum LDH with improved identification of transformation (area under the curve [AUC] = 0.91). Our model performed similarly for our validation cohort of 23 patients (AUC = 0.90). With external and prospective validation, our scoring model may provide a specific and noninvasive tool for risk stratification for patients with low-grade lymphoma.

Genetics of Transformed Follicular Lymphoma

Histological transformation (HT) to a more aggressive disease–mostly diffuse large B-cell lymphoma–is considered one of the most dismal events in the clinical course of follicular lymphoma (FL). Current knowledge has not found a single biological event specific for HT, although different studies have highlighted common genetic alterations, such as TP53 and CDKN2A/B loss, and MYC translocations, among others. Together, they increase genomic complexity and mutational burden at HT. A better knowledge of HT pathogenesis would presumably help to find diagnostic biomarkers allowing the identification of patients at high-risk of transformation, as well as the discrimination from patients with FL recurrence, and those who remain in remission. This would also help to identify new drug targets and the design of clinical trials for the treatment of transformation. In the present review we provide a comprehensive overview of the genetic events frequently identified in transformed FL contributing to the switch towards aggressive behaviour, and we will discuss current open questions in the field of HT.

Follicular lymphoma and macrophages: impact of approved and novel therapies

The survival and proliferation of follicular lymphoma (FL) cells are strongly dependent on macrophages, because their presence is necessary for the propagation of FL cells in vitro. To this regard, as also shown for the majority of solid tumors, a high tissue content of tumor-associated macrophages (TAMs), particularly if showing a protumoral phenotype (also called M2), is strongly associated with a poor outcome among patients with FL treated with chemotherapy. The introduction of rituximab, an anti-CD20 antibody that can be used by TAMs to facilitate antibody-dependent cellular cytotoxicity and antibody-dependent cellular phagocytosis, has challenged this paradigm. In the rituximab era, clinical studies have yielded conflicting results in FL, showing variable outcomes based on the type of regimen used. This highlighted, for the first time, that the impact of TAMs on the prognosis of patients with FL may depend on the administered treatment, emphasizing the need to better understand how currently available therapies affect macrophage function in FL. We summarize the impact of approved and novel therapies for FL, including radiation therapy, chemotherapy, anti-CD20 monoclonal antibodies, lenalidomide, and targeted agents, on the biology of TAMs and describe their effects on macrophage phagocytosis, polarization, and function. Although novel agents targeting the CD47/SIRPα axis are being developed and show promising activity in FL, a deeper understanding of macrophage biology and their complex pathways will help to develop novel and safer therapeutic strategies for patients with this type of lymphoma.

Single-Center Analysis of Characteristics and Outcomes of De Novo, Concurrent, and Transformed Diffuse Large B-Cell Lymphoma

Outcomes of diffuse large B-cell lymphoma (DLBCL), either concurrent with or transformed from indolent lymphoma, treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone are described in retrospective studies. The efficacy of other regimens in transformed or concurrent DLBCL is largely unknown. In this single-center retrospective study, we present characteristics of concurrent and transformed DLBCL and outcomes after dose-adjusted etoposide, vincristine, cyclophosphamide, prednisone, and doxorubicin with rituximab (DA-EPOCH-R) comparative with de novo DLBCL. Of 170 patients with DLBCL, 136 were de novo, 17 were concurrent, and 17 were transformed. Transformed DLBCL had significantly lower complete response rates and progression-free survival (PFS) but similar overall survival (OS) compared with de novo counterpart. There was no significant difference between de novo and concurrent DLBCL regarding response rates, PFS, and OS. DA-EPOCH-R was associated with inferior OS. Thus, intensified treatment with DA-EPOCH-R might not improve outcomes of transformed DLBCL.

CHN1 is a Novel Prognostic Marker for Diffuse Large B-Cell Lymphoma

Purpose

Diffuse large B-cell lymphoma (DLBCL) is the most common B-cell malignancy. Thirty to forty percent of DLBCL patients still experience relapse or develop refractory disease even with standard immunochemotherapy, leading to a poor prognosis. Currently, although several gene-based classification methods can be used to predict the prognosis of DLBCL, some patients are still unable to be classified. This study was performed to identify a novel prognostic biomarker for DLBCL.

Patients and Methods

A total of 1850 B-cell non-Hodgkin lymphoma (B-NHL) patients in 8 independent datasets with microarray gene expression profiles were retrieved from the Gene Expression Omnibus (GEO) database and Lymphoma/Leukemia Molecular Profiling Project (LLMPP). The candidate genes were selected through three filters in a strict pipeline. Survival analysis was performed in two independent datasets of patients with both gene expression data and clinical information. Gene set enrichment analysis (GSEA) and the CIBERSORT algorithm were used to explore the biological functions of the genes.

Results

We identified 6 candidate genes associated with the clinical outcome of DLBCL patients: CHN1, CD3D, CLU, ICOS, KLRB1 and LAT. Unlike the other five genes, CHN1 has not been previously reported to be implicated in lymphoma. We also observed that CHN1 had prognostic significance in important clinical subgroups; in particular, high CHN1 expression was significantly related to good outcomes in DLBCL patients with the germinal center B-cell-like (GCB) subtype, stage III–IV, or an International Prognostic Index (IPI) score > 2. Multivariate Cox regression analysis of the two datasets showed that CHN1 was an independent prognostic factor for DLBCL. Additionally, GSEA and CIBERSORT indicated that CHN1 was correlated with cell adhesion and T cell immune infiltration.

Conclusion

Our data indicate for the first time that high CHN1 expression is associated with favorable outcomes in DLBCL patients, suggesting its potential utility as a prognostic marker in DLBCL.

Rituximab maintenance improves outcomes of transformed diffuse large B-cell lymphoma: a retrospective study of 519 cases with de novo diffuse large B-cell lymphoma and 62 cases with concurrent diffuse large B-cell lymphoma and follicular lymphoma

Although outcomes of transformed diffuse large B-cell lymphoma (DLBCL) from follicular lymphoma (FL) were improved using rituximab-combined immunochemotherapy, the efficacy of subsequent rituximab maintenance (RM) remains unclear. We retrospectively analyzed the prognoses of 519 patients with de novo DLBCL and 62 patients with concurrent DLBCL and FL (concurrent-DLBCL/FL). Progression-free survival (PFS) was shorter in patients with concurrent-DLBCL/FL than in de novo DLBCL (p=.030). Twenty-four patients with concurrent-DLBCL/FL received RM after induction therapy, and they achieved better OS and PFS (p=.010 and p<.001, respectively) with lower risk of relapse (p<.001) than the non-RM group. Moreover, concurrent-DLBCL/FL showed better subsequent OS and PFS after recurrence than de novo DLBCL (p=.0083 and p=.0044, respectively). Our study indicates that in the face of a high relapse rate, concurrent-DLBCL/FL is manageable and benefits from RM.

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.

Transformation Scoring System (TSS): A new assessment index for clinical transformation of follicular lymphoma

Although histologic analysis is the gold standard for diagnosing follicular lymphoma (FL) transformation, many patients are diagnosed with transformation by clinical factors as biopsy specimens often cannot be obtained. Despite the frequency of clinical diagnosis, no clinical assessment tool has yet been established for FL transformation in the rituximab era. We derived and validated a transformation scoring system (TSS) based on retrospective analyses of 126 patients with biopsy‐proven FL and histologic transformation (HT) at two hospitals of the National Cancer Center of Japan. In the derivation set (76 patients), the detailed analyses of the clinical characteristics at disease progression showed that lactate dehydrogenase (LDH) elevation, focal lymph nodal (LN) enlargement, hemoglobin <12 g/dl, and poor performance status (PS) (2‐4) were associated with HT. The weights of these variables were decided based on the regression coefficients. Next, we constructed a TSS encompassing the above four factors: LDH, (> upper limit of normal [ULN], ≤ULN ×2) (1 point), (≥ULN ×2) (2 points); focal LN enlargement, (≥3 cm, <7 cm) (1 point), (≥7 cm) (2 points); hemoglobin <12 g/dl (1 point); poor PS (2 points). We identified a high positive predictive value (PPV) (96.4%) and negative predictive value (NPV) (85.4%) for diagnosing HT when a cutoff score of 2 was selected for our TSS. In an external validation set (50 patients), the probability of HT was high with scores ≥2 (PPV, 93.3%; NPV, 82.9%). We developed a TSS that offers a simple, yet, valuable tool, for diagnosing HT, especially in patients who cannot undergo biopsy.

The Biological Basis of Histologic Transformation

Histologic transformation of follicular lymphoma remains the leading cause of follicular lymphoma-related mortality in the rituximab era. Both the diverse timing of transformation and heterogeneity in associated genomic events suggest that histologic transformation may itself comprise distinct disease entities. Successive indolent and transformation episodes occur by divergent clonal evolution from an inferred common progenitor cell, representing a potential therapeutic target. Existing biological knowledge largely pre-dates anti-CD20 therapy, and further prospective validation is essential. Inclusion of transformation cases in clinical trials incorporating biomarker discovery, and an integrated understanding of the genetic and microenvironmental factors underpinning transformation, may unearth renewed clinical opportunities.

Follicular lymphoma in the modern era: survival, treatment outcomes, and identification of high-risk subgroups

Patients with follicular lymphoma (FL) frequently require multiple treatments during their disease course; however, survival based on lines of treatment remains poorly described in the post-rituximab era. Also, the Follicular Lymphoma International Prognostic Index (FLIPI) score was developed to predict survival at diagnosis, yet it remains unknown whether increase in FLIPI score following an initial observation period is associated with less-favorable outcomes. To address these knowledge gaps, we retrospectively studied 1088 patients with FL grade 1–3A managed between 1998 and 2009 at our institution. Median overall survival (OS) and progression-free survival (PFS) after first-line treatment were not reached and 4.73 years, respectively. Following successive lines of treatment, years of median OS and PFS were, respectively: after second-line, 11.7 and 1.5; third-line, 8.8 and 1.1; fourth-line, 5.3 and 0.9; fifth-line, 3.1 and 0.6; sixth-line, 1.9 and 0.5. In initially observed, subsequently treated patients, FLIPI score increase after observation was associated with inferior survival following first-line treatment. The reduced survival we observed after second-line and later therapy supports the development of new treatments for relapsed patients and benchmarks historical targets for clinical endpoints. This study also highlights the utility of changes in FLIPI score at diagnosis and after observation in identifying patients likely to have worse outcomes.

Putative role of marginal zone B cells in pathophysiological processes

The maintenance of inner integrity of an organism is founded on the proper performance of two immunity branches, innate and adaptive immune responses. Recently, it became apparent that subset of splenic B cells named marginal zone B cells (MZB cells) exhibits unique developmental and functional features that bridge these two immunity branches. Strategically positioned at the site where blood and lymph are filtered, MZB cells represent a population of sentinels that rapidly proliferate and differentiate into IgM plasmablast cells when encountered with blood-borne, thymus-independent (TI) Ags. Moreover, MZB cells have intrinsic capability to induce potent CD4⁺ helper T cell response and cytokine production upon stimulation with soluble antigens. Due to their ability to overcome a time gap prior the establishment of the full adaptive response towards pathogens, MZB cells connect and direct innate and adaptive immunity. An additional interesting characteristic of MZB cells is capacity to function as regulatory cells in autoimmune processes. MZB cells may also contribute to the control of autoimmunity via the induction of tolerance by apoptotic cells. Importantly, in the clear association with inflammation and autoimmunity, MZB cells may transform into MALT lymphoma, representing a concurrence point for the infection, immunity and malignancy. This paper presents an insight into the complex biology of marginal zone B cells and their role in intertwining and directing innate and adaptive immune processes at the physiological and pathological level.

Quantitative Analysis and Monitoring of EZH2 Mutations Using Liquid Biopsy in Follicular Lymphoma

Recent advances in molecular technologies enable sensitive and quantitative assessment of circulating tumor DNA, offering a noninvasive disease monitoring tool for patients with malignant disorders. Here, we demonstrated on four follicular lymphoma cases that circulating tumor DNA based EZH2 mutation analysis performed by a highly sensitive droplet digital PCR method may be a valuable treatment monitoring approach in EZH2 mutant follicular lymphoma. EZH2 variant allele frequencies changed in parallel with the volume of metabolically active tumor sites observed on 18F-fluorodeoxyglucose positron emission tomography combined with computer tomography (PET-CT) scans. Variant allele frequencies of EZH2 mutations decreased or were eliminated rapidly upon successful treatment, with treatment failure being associated with elevated EZH2 variant allele frequencies. We also demonstrated spatial heterogeneity in a patient with two different EZH2 mutations in distinct anatomical sites, with both mutations simultaneously detected in the liquid biopsy specimen. In summary, circulating tumor DNA based EZH2 mutation analysis offers a rapid, real-time, radiation-free monitoring tool for sensitive detection of EZH2 mutations deriving from different anatomical sites in follicular lymphoma patients receiving immunochemotherapy.

Clinical and Biological Prognostic Factors in Follicular Lymphoma

Follicular lymphoma comprises approximately 20-30% of all cases of B-cell lymphomas. Median survival has improved significantly in the modern era. Prognostic factors include histologic grade, cytogenetics, molecular mutations, the tumor microenvironment, and tumor burden. Clinical prognostic indices are available and increasingly incorporate genetic information. Prognostic factors also arise during the course of treatment. Early progression within 24 months of initial chemoimmunotherapy is an adverse prognostic marker of inferior survival. Other high-risk populations include those with double refractory disease or those with high risk of transformation to diffuse large B-cell lymphoma.

Real world data on histological transformation in patients with follicular lymphoma: incidence, clinico-pathological risk factors and outcome in a nationwide Danish cohort

We investigated incidence, risk factors and outcome for follicular lymphoma (FL) patients with histologic transformation (HT) found at primary diagnosis (discordant/composite, dc-tFL) or sequentially (s-tFL). Between 2000 and 2015, 2773 patients were identified. The majority of patients (2252, 81%) did not experience HT (nt-FL), while 224 (8%) had dc-tFL and 297 (11%) s-tFL. The risk of HT was 2.2% per year and 9.6% at 5 years. Age ≥60, a high FLIPI risk score and LDH-elevation were associated with increased risk of HT. Calculated from primary diagnosis and compared with nt-FL, 5-year overall survival (OS) was inferior in both s-tFL and dc-tFL (nt-FL: 82%, s-tFL: 68%, dc-tFL: 68%; p = .001), whereas 5-year progression-free survival (PFS) was worse only in s-tFL (s-tFL: 18%, dc-tFL: 58%, nt-FL: 60%). Calculated from time of HT, s-tFL had inferior outcome compared to dc-tFL for both OS (s-tFL: 47%, dc-tFL: 68%, p = .001) and PFS (s-tFL: 35%, dc-tFL: 58%, p = .001).

Follicular lymphoma transforming to DLBCL and reverting back to follicular lymphoma at relapse-a case report

BACKGROUND

Transformation of low-grade follicular lymphoma to high-grade diffuse large B cell lymphoma (DLBCL) is known. However, the opposite is not commonly reported. In this report, we present a case of follicular lymphoma that underwent transformation to DLBCL. Three years after treatment for histologic transformation, the patient presented again with low-grade follicular lymphoma at the same site which is unusual in the natural history of follicular lymphoma.

CASE PRESENTATION

A 50-year-old female patient presented to us with complaints of slowly progressing swelling in the neck on the left side for a duration of 1 year. Past history of the patient revealed a diagnosis of follicular lymphoma in 2004 for which the patient had taken prednisolone and chlorambucil. Details of staging were not available with the patient. After a complete work-up, she was diagnosed as DLBCL, stage IIIE. She was treated with 6 cycles of CHOP regimen. She had very good response to chemotherapy. However, she defaulted and was lost to follow-up. She presented again after 3 years with history of painless progressive swelling in the right side of the neck for the last 1 year. Examination revealed cervical lymph nodes and ascites. This time, a repeat biopsy and immunohistochemistry was suggestive of follicular lymphoma. In view of significant ascites, she was started on chemotherapy with CVP regimen. After 6 cycles, she has good partial response and resolution of ascites. She is currently on follow-up.

CONCLUSIONS

We have presented a case of FL that has transformed to DLBCL after 10 years of diagnosis. After HT, she was treated with CHOP chemotherapy and the patient relapsed again after 3 years with follicular lymphoma histology. This case highlights the unique and varied natural history of follicular lymphoma that may be attributed to different subclones of malignant cells that may have arisen from a common progenitor FL cell and differential effect of chemotherapy on these subclones.

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.

Positron-emission tomography-based staging reduces the prognostic impact of early disease progression in patients with follicular lymphoma

BACKGROUND

Previous studies reported that early progression of disease (POD) after initial therapy predicted poor overall survival (OS) in patients with follicular lymphoma (FL). Here, we investigated whether pre-treatment imaging modality had an impact on prognostic significance of POD.

METHODS

In this retrospective study, we identified 1088 patients with grade I-IIIA FL; of whom, 238 patients with stage II-IV disease were initially treated with rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP), and 346 patients were treated with rituximab-based chemotherapy. Patients (N = 484) from the FOLL05 study served as an independent validation cohort. We risk-stratified patients based on pre-treatment radiographic imaging (positron-emission tomography [PET] versus computed tomography [CT]) and early POD status using event-defining and landmark analyses. A competing risk analysis evaluated the association between early POD and histologic transformation.

RESULTS

In the discovery cohort, patients with POD within 24 months (PFS24) of initiating R-CHOP therapy had a 5-year OS of 57.6% for CT-staged patients compared with 70.6% for PET-staged patients. In the validation cohort, the 5-year OS for patients with early POD was 53.9% and 100% in CT- and PET-staged patients, respectively. The risk of histologic transformation in patients whose disease progressed within one year of initiating therapy was higher in CT-staged patients than in PET-staged patients (16.7% versus 6.3%, respectively), which was associated with a 9.7-fold higher risk of death.

CONCLUSION

In FL, pre-treatment PET staging reduced the prognostic impact of early POD compared with CT staging. Patients with early POD and no histologic transformation have an extended OS with standard therapy.

B Cell Receptor Immunogenetics in B Cell Lymphomas: Immunoglobulin Genes as Key to Ontogeny and Clinical Decision Making

The clonotypic B cell receptor immunoglobulin (BcR IG) plays a seminal role in B cell lymphoma development and evolution. From a clinical perspective, this view is supported by the remarkable therapeutic efficacy of BcR signaling inhibitors, even among heavily pre-treated, relapsed/refractory patients. This clinical development complements immunogenetic evidence for antigen drive in the natural history of these tumors. Indeed, BcR IG gene repertoire biases have been documented in different B cell lymphoma subtypes, alluding to selection of B cell progenitors that express particular BcR IG. Moreover, distinct entities display imprints of somatic hypermutation within the clonotypic BcR IG gene following patterns that strengthen the argument for antigen selection. Of note, at least in certain B cell lymphomas, the BcR IG genes are intraclonally diversified, likely in a context of ongoing interactions with antigen(s). Moreover, BcR IG gene repertoire profiling suggests that unique immune pathways lead to distinct B cell lymphomas through targeting cells at different stages in the B cell differentiation trajectory (e.g., germinal center B cells in follicular lymphoma, FL). Regarding the implicated antigens, although their precise nature remains to be fully elucidated, immunogenetic analysis has offered important hints by revealing similarities between the BcR IG of particular lymphomas and B cell clones with known antigenic specificity: this has paved the way to functional studies that identified relevant antigenic determinants of classes of structurally similar epitopes. Finally, in certain tumors, most notably chronic lymphocytic leukemia (CLL), immunogenetic analysis has also proven instrumental in accurate patient risk stratification since cases with differing BcR IG gene sequence features follow distinct disease courses and respond differently to particular treatment modalities. Overall, delving into the BcR IG gene sequences emerges as key to understanding B cell lymphoma pathophysiology, refining prognostication and assisting in making educated treatment choices.

MYC in Germinal Center-derived lymphomas: Mechanisms and therapeutic opportunities

The rearrangement of immunoglobulin loci during the germinal center reaction is associated with an increased risk of chromosomal translocations that activate oncogenes such as MYC, BCL2 or BCL6, thus contributing to the development of B-cell lymphomas. MYC and BCL2 activation are initiating events in Burkitt's (BL) and Follicular Lymphoma (FL), respectively, but can occur at later stages in other subtypes such as Diffuse Large-B Cell Lymphoma (DLBCL). MYC can also be activated during the progression of FL to the transformed stage. Thus, either DLBCL or FL can give rise to aggressive double-hit lymphomas (DHL) with concurrent activation of MYC and BCL2. Research over the last three decades has improved our understanding of the functions of these oncogenes and the basis for their cooperative action in lymphomagenesis. MYC, in particular, is a transcription factor that contributes to cell activation, growth and proliferation, while concomitantly sensitizing cells to apoptosis, the latter being blocked by BCL2. Here, we review our current knowledge about the role of MYC in germinal center B-cells and lymphomas, discuss MYC-induced dependencies that can sensitize cancer cells to select pharmacological inhibitors, and illustrate their therapeutic potential in aggressive lymphomas-and in particular in DHL, in combination with BCL2 inhibitors.

Treatment Outcome in Patients with Primary or Secondary Transformed Indolent B-Cell Lymphomas

BACKGROUND

Histologic transformation (HT) of indolent B-cell lymphomas into an aggressive form can occur simultaneously (primary HT, pHT) or sequentially after a preceding diagnosis of indolent lymphoma (secondary HT, sHT). The clinical course after diagnosis of HT is variable.

OBJECTIVES

To describe the outcome of treatment in pHT and sHT patients.

METHODS

We retrospectively analyzed HT cases with an underlying follicular lymphoma, nodal marginal zone lymphoma, extranodal marginal zone lymphoma, lymphoplasmacytic lymphoma, or small lymphocytic lymphoma at our institution. Kaplan-Meier estimates were used to calculate progression-free survival (PFS) and overall survival (OS).

RESULTS

Ninety-two HT patients were identified, 38 with pHT and 54 with sHT. In sHT, time-to-transformation was not influenced by the preceding treatment strategy of the indolent lymphoma component. In pHT, median PFS was 61 months (95% CI 27-61), and OS was not reached. In sHT, median PFS and OS was 14 months (95% CI 9-32) and 42 months (95% CI 16-90), respectively. Significant differences between pHT and sHT in PFS (p = 0.002; Hazard ratio [HR] 2.30, 95% CI 1.36-3.91) and OS (p = 0.0001; HR 3.30, 95% CI 1.81-6.03) were observed. Response to treatment for transformation was highly prognostic of PFS and OS (p < 0.0001).

CONCLUSIONS

The outcome in pHT cases is favorable and signifi-cantly better than in sHT cases. Failure to achieve a remission after treatment for transformation confers a dismal pro-gnosis.

Survival outcomes of diffuse large B-cell lymphoma by association with concurrent or antecedent follicular lymphoma and double hit status

Diffuse large B-cell lymphoma (DLBCL) transformed from follicular lymphoma (FL) (tDLBCL) has been traditionally associated with an aggressive course, but more recent studies have shown longer survivals. The clinical significance of concurrent FL at the time of diagnosis of DLBCL (cDLBCL/FL) is less clear. We compared outcomes of tDLBCL, cDLBCL/FL, and de novo DLBCL (dDLBCL) and then evaluated the impact of double hit (DH) rearrangements (MYC with BCL2 and/or BCL6) in these subgroups' outcomes. The progression free survival (PFS) and overall survival (OS) were not significantly different among the three groups (dDLBCL, tDLBCL, and cDLBCL/FL). The effect of DH on survival was then analyzed in two subgroups: (1) dDLBCL and (2) tDLBCL + cDLBCL/FL. PFS and OS were significantly shorter in lymphomas with DH in each of these two subgroups. We conclude that DH status drives outcomes in all DLBCLs, regardless of their transformation status.

Up-front rituximab maintenance improves outcome in patients with follicular lymphoma: a collaborative Nordic study

The introduction of the anti-CD20 antibody rituximab in combination with chemotherapy (R-chemo) has improved the prognosis of patients with follicular lymphoma (FL). During the last decade, the addition of a maintenance treatment with rituximab (MR) after R-chemo has been tested with the hope of further improving the outcome of these patients. Using 2 independent population-based cohorts, we investigated the effect of up-front MR on time related end points as well as the risk of histological transformation (HT). FL patients were included if they: (1) completed first-line induction treatment with R-chemo, (2) were alive after induction treatment and eligible for MR, and (3) had no evidence of HT at this time point. The training cohort consisted of 733 Danish patients of whom 364 were consolidated with MR; 369 were not. Patients receiving MR more often had advanced clinical stage (90% vs 78%), high Follicular Lymphoma International Prognostic Index (FLIPI) score (64% vs 55%), and bone marrow infiltration (49% vs 40%). Those consolidated with MR had an improved 5-year overall survival (OS; 89% vs 81%; P = .001) and progression-free survival (PFS; 72% vs 60%; P < .001). In the training cohort, MR was associated with a reduction of HT risk (P = .049). Analyses of an independent validation cohort of 190 Finnish patients confirmed the favorable impact of MR on 5-year OS (89% vs 81%; P = .046) and PFS (70% vs 57%; P = .005) but did not find a reduced risk of HT. The present population-based data suggest that the outcome of patients with FL has improved after consolidation of R-chemo with MR.

Spotlight on copanlisib and its potential in the treatment of relapsed/refractory follicular lymphoma: evidence to date

The importance of the phosphatidylinositol-3-kinase (PI3K) pathway in cell survival and proliferation has made it an attractive target in cancer therapy. The development of small molecule inhibitors for the PI3K pathway continues to provide treatment alternatives across a range of malignancy types. Several agents, including idelalisib, copanlisib and duvelisib, not only inhibit the PI3K pathway, but also have effects on associated mechanisms including the ATK and mTOR pathways. The advent of PI3K-specific small molecular inhibitors has led to increased efficacy with avoidance of an excessive toxicity profile. Key enzymes of the PI3K pathway exhibit differing expression in tissue types and roles in tumor pathogenesis. Copanlisib (BAY 80-6946) is a pan-specific PI3K small molecule inhibitor for four key isoforms with increased activity against PI3Kα and PI3Kδ, both important in B-cell malignancies. Follicular lymphoma is one of the most common indolent B-cell non-Hodgkin lymphomas worldwide. Follicular lymphoma like other indolent B-cell non-Hodgkin lymphomas is beleaguered by high relapse rates and the need for subsequent therapy options. Based on efficacy and a limited toxicity profile, copanlisib received accelerated US Food and Drug Administration approval for the treatment of adult patients with relapsed follicular lymphoma following two lines of therapy. Here, we review the development of copanlisib and the role of this agent in the treatment of follicular lymphoma.

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.

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.

Allogeneic haematopoietic cell transplantation offers the chance of cure for patients with transformed follicular lymphoma

PURPOSE

In patients with follicular lymphoma, secondary transformation to aggressive lymphoma (tFL) implies a poor prognosis. In principle, allogeneic haematopoietic cell transplantation (allo-HCT) offers a chance of cure for tFL but is rarely practiced. Aim of this retrospective multicenter study was to define the actual significance of allo-HCT in treatment of tFL.

METHODS

The database of the German Registry for Stem Cell Transplantation (DRST) was screened for patients who underwent allo-HCT for tFL 1998-2008. Confirmation of tFL-diagnosis by local and/or pathologists of the National NHL Board was mandatory for enrolment. Gaps in reported EBMT Minimum Essential Data datasets (MED-A) were filled by local DRST data managers. Relevant HCT outcome variables were evaluated by uni- and multivariate statistical analysis.

RESULTS

Median age of enrolled 33 patients was 51 years with a post allo-HCT median follow-up of 7.1 years of surviving patients. At time of HCT 24/33 patients had chemosensitive disease. In 24/33 patients reduced intensity conditioning (RIC) was used. Estimated 1, 2, 5-year overall survival (OS) and event-free survival rates were 49/39/33, and 33/30/24%. Cumulative 100 days non-relapse mortality was 25%. Chemosensitive disease, RIC, and limited chronic GvHD were identified as independent prognostic factors for OS.

CONCLUSIONS

Allo-HCT offers the chance of cure for tFL.

From genetics to the clinic: a translational perspective on follicular lymphoma

Follicular lymphoma (FL) is the most frequent indolent B cell lymphoma and is still considered to be incurable. In recent years, whole-exome sequencing studies of large cohorts of patients have greatly improved our knowledge of the FL mutational landscape. Moreover, the prolonged evolution of this disease has enabled some insights regarding the early pre-lymphoma lesions as well as the clonal evolution after treatment, allowing an evolutionary perspective on lymphomagenesis. Deciphering the earliest initiating lesions and identifying the molecular alterations leading to disease progression currently represent important goals; accomplishing these could help identify the most relevant targets for precision therapy.

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.

Bendamustine plus Rituximab Versus R-CHOP as First-Line Treatment for Patients with Follicular Lymphoma Grade 3A: Evidence from a Multicenter, Retrospective Study

BACKGROUND

Rituximab plus bendamustine (R-B) has been demonstrated to improve outcomes and reduce toxicity compared with rituximab, cyclophosphamide, doxorubicin, and prednisone (R-CHOP) in follicular lymphoma (FL). Nevertheless, in clinical practice, many centers still prefer R-CHOP to R-B in patients with FL grade 3A (FL3A). Therefore, we retrospectively assessed patients with FL3A treated with either R-CHOP or R-B in five European cancer centers and compared their outcomes.

MATERIALS AND METHODS

We retrospectively assessed 132 patients affected by FL grade 3A treated with either R-B or R-CHOP in the first line and evaluated outcome and toxicity according to the type of treatment. This study included 101 patients who were a subgroup of a previously published cohort.

RESULTS

R-B was less toxic and achieved a similar percentage of complete remissions compared with R-CHOP (97% vs. 96%, p = .3). During follow-up, 10 (16%) patients relapsed after R-B and 29 (41%) after R-CHOP (p = .001), leading to a median progression-free survival (PFS) of 15 versus 11.7 years, respectively (p = .03). Furthermore, R-B overcame the negative prognostic impact of BCL2 expression (15 vs. 4.8 years; p = .001). However, median overall survival was similar between both groups (not reached for both; p = .8).

CONCLUSION

R-B as a first-line treatment of FL3A is better tolerated than R-CHOP and seems to induce more profound responses, leading to a significantly lower relapse rate and prolonged PFS. Therefore, R-B is a valid treatment option for FL grade 3A.

IMPLICATIONS FOR PRACTICE

Rituximab plus bendamustine (R-B) has shown to be less toxic and more effective than rituximab, cyclophosphamide, doxorubicin, and prednisone (R-CHOP) in follicular lymphoma grade 3A. Although both regimens can induce a complete remission in >95% of patients, relapses occur more frequently after R-CHOP than R-B, leading to a significantly longer progression-free survival in the latter. R-B is also able to overcome the impact of negative prognosticators, such as BCL2 expression. However, because of the indolent course of this disease and efficient salvage treatments, overall survival was similar in both treatment groups. Therefore, R-B is a valid treatment option in this patient setting.

Clinicopathologic characteristics and outcomes of transformed diffuse large B-cell lymphoma in hepatitis C virus-infected patients

Hepatitis C virus (HCV) causes a chronic but curable infection associated with the development of marginal zone lymphoma (MZL) and diffuse large B-cell lymphoma (DLBCL). Preliminary data have shown frequent transformation of indolent lymphoma to DLBCL in HCV-infected patients. To compare their clinicopathologic characteristics and oncologic outcomes, we reviewed the medical records and pathology reports of HCV-infected and uninfected patients with DLBCL that transformed from indolent lymphoma seen at The University of Texas MD Anderson Cancer Center (June 2004 to May 2015). To identify predictors of DLBCL relapse, patients with relapse after first-line chemotherapy were compared with those without it using univariate and logistic regression analyses. Compared with the uninfected patients (n = 63), HCV-infected patients (n = 21) were younger (median age =54 years [interquartile range= 49-62 years] vs. 62 years [53-66 years]; p = 0.01) and more often had advanced DLBCL (Ann Arbor stage 3-4; 95% vs. 76%; p = 0.05). Immunophenotypically, more HCV-infected than uninfected patients had CD10-negative B cells (76% vs. 43%; p = 0.008), CD5-positive B cells (39% vs. 7%; p = 0.004) and activated B-cell phenotypes (57% vs. 31%; p = 0.07). Comparison of the patients who had relapse after first-line chemotherapy (n = 42) and those who did not (n = 40) revealed that having CD5-positive B cells was the only factor associated with DLBCL relapse in multivariate analysis (odds ratio= 10.7; p = 0.02). HCV-infected patients with transformed DLBCL have unique clinicopathologic characteristics that make their lymphoma difficult to treat, potentially leading to unfavorable outcome. The impact of HCV eradication should be explored in such patients.

Pathogenesis of follicular lymphoma

Follicular lymphoma (FL) is presented as a germinal centre B cell lymphoma that is characterized by an indolent clinical course, but remains - paradoxically - largely incurable to date. The last years have seen significant progress in our understanding of FL lymphomagenesis, which is a multi-step process beginning in the bone marrow with the hallmark t(14;18)(q32;q21) translocation. The pathobiology of FL is complex and combines broad somatic changes at the level of both the genome and the epigenome, the latter evidenced by highly recurrent mutations in chromatin-modifying genes such as KMT2D and CREBBP. While the importance of the FL microenvironment has since long been well understood, it has become evident that somatic lesions within tumour cells re-educate normal immune and stromal cells to their advantage. Enhanced understanding of FL pathogenesis is currently leading to refined therapeutic targeting of perturbed biology, paving the way for precision medicine in this lymphoma subtype.

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.

Risk of, and survival following, histological transformation in follicular lymphoma in the rituximab era. A retrospective multicentre study by the Spanish GELTAMO group

The diagnostic criteria for follicular lymphoma (FL) transformation vary among the largest series, which commonly exclude histologically-documented transformation (HT) mandatorily. The aims of this retrospective observational multicentre study by the Spanish Grupo Español de Linfoma y Transplante Autólogo de Médula Ósea, which recruited 1734 patients (800 males/934 females; median age 59 years), diagnosed with FL grades 1-3A, were, (i) the cumulative incidence of HT (CI-HT); (ii) risk factors associated with HT; and (iii) the role of treatment and response on survival following transformation (SFT). With a median follow-up of 6·2 years, 106 patients developed HT. Ten-year CI-HT was 8%. Considering these 106 patients who developed HT, median time to transformation was 2·5 years. High-risk FL International Prognostic Index [Hazard ratio (HR) 2·6, 95% confidence interval (CI): 1·5-4·5] and non-response to first-line therapy (HR 2·9, 95% CI: 1·3-6·8) were associated with HT. Seventy out of the 106 patients died (5-year SFT, 26%). Response to HT first-line therapy (HR 5·3, 95% CI: 2·4-12·0), autologous stem cell transplantation (HR 3·9, 95% CI: 1·5-10·1), and revised International Prognostic Index (HR 2·2, 95% CI: 1·1-4·2) were significantly associated with SFT. Response to treatment and HT were the variables most significantly associated with survival in the rituximab era. Better therapies are needed to improve response. Inclusion of HT in clinical trials with new agents is mandatory.

Can histologic transformation of follicular lymphoma be predicted and prevented?

Transformation to aggressive lymphoma is a critical event in the clinical course of follicular lymphoma (FL) patients. Yet, it is a challenge to reliably predict transformation at the time of diagnosis. Understanding the risk of transformation would be useful for guiding and monitoring patients, as well as for evaluating novel treatment strategies that could potentially prevent transformation. Herein, we review the contribution of clinical, pathological, and genetic risk factors to transformation. Patients with multiple clinical high-risk factors are at elevated risk of transformation but we are currently lacking a prognostic index that would specifically address transformation rather than disease progression or overall survival. From the biological standpoint, multiple studies have correlated individual biomarkers with transformation. However, accurate prediction of this event is currently hampered by our limited knowledge of the evolutionary pathways leading to transformation, as well as the scarcity of comprehensive, large-scale studies that assess both the genomic landscape of alterations within tumor cells and the composition of the microenvironment. Liquid biopsies hold great promise for achieving precision medicine. Indeed, mutations detected within circulating tumor DNA may be a better reflection of the inherent intratumoral heterogeneity than the biopsy of a single site. Last, we will assess whether evidence exists in the literature that transformation might be prevented altogether, based on the choice of therapy for FL.

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.