Gene expression profiling reveals a close relationship between follicular lymphoma grade 3A and 3B, but distinct profiles of follicular lymphoma grade 1 and 2

The clinical and molecular taxonomy of t(14;18)-negative follicular lymphomas

Follicular lymphoma (FL) is a neoplasm derived from germinal center B cells, composed of centrocytes and centroblasts, with at least a focal follicular growth pattern. The t(14;18) translocation together with epigenetic deregulation through recurrent genetic alterations are now recognized as the hallmark of FL. Nevertheless, FL is a heterogeneous disease, clinically, morphologically, and biologically. The existence of FL lacking the t(14;18) chromosomal alteration highlights the complex pathogenesis of FL, and indicates that there are alternative pathogenetic mechanisms that can induce a neoplasm with follicular center B-cell phenotype. Based on their clinical presentation, t(14;18)-negative FLs can be divided into 3 broad groups: nodal presentation, extranodal presentation, and those affecting predominantly children and young adults. Recent studies have shed some light into the genetic alterations of t(14;18)-negative FL. Within the group of t(14;18)-negative FL with nodal presentation, cases with STAT6 mutations are increasingly recognized as a distinctive molecular subgroup, often cooccurring with CREBBP and/or TNFRSF14 mutations. FL with BCL6 rearrangement shows clinicopathological similarities to its t(14;18)-positive counterpart. In contrast, t(14;18)-negative FL in extranodal sites is characterized mainly by TNFRSF14 mutations in the absence of chromatin modifying gene mutations. FL in children have a unique molecular landscape when compared with those in adults. Pediatric-type FL (PTFL) is characterized by MAP2K1, TNFRSF14, and/or IRF8 mutations, whereas large B-cell lymphoma with IRF4 rearrangement is now recognized as a distinct entity, different from PTFL. Ultimately, a better understanding of FL biology and heterogeneity should help to understand the clinical differences and help guide patient management and treatment decisions.

Outcomes in grade 3B follicular lymphoma: an international study led by the Australasian Lymphoma Alliance

Grade (G) 3B follicular lymphoma (FL) is a rare FL subtype which exists on a histological continuum between 'lowgrade' (Grade 1, 2 and 3A FL) and diffuse large B-cell lymphoma (DLBCL) appearing to share features with each. Clinical characteristics and outcomes are poorly understood due to lack of adequate representation in prospective trials and large-scale analyses. We analyzed 157 G3BFL cases from 18 international centers, and two comparator groups; G3AFL (n=302) and DLBCL (n=548). Composite histology with DLBCL or low-grade FL occurred in approximately half of the G3BFL cases. With a median of 5 years follow-up, the overall survival and progression-free survival of G3BFL patients was better than that of DLBCL patients (P<0.001 and P<0.001, respectively); however, G3BFL patients were younger (P<0.001) with better performance status (P<0.001), less extranodal disease (P<0.001) and more frequently had normal lactate dehydrogenase (P<0.001) at baseline. The overall and progression-free survival of patients with G3BFL and G3AFL were similar (P=0.83 and P=0.80, respectively). After frontline immunochemotherapy, 24% of G3BFL relapsed; relapse rates were 63% in the DLBCL cohort and 19% in the low-grade FL cohort. Eight percent of relapses occurred beyond 5 years. In this G3BFL cohort, the revised International Prognostic Index successfully delineated risk groups, but the Follicular Lymphoma International Prognostic Index did not. We conclude that patients with immunochemotherapy-treated G3BFL have similar survival outcomes to those with G3AFL, yet a favorable baseline profile and distinctly superior prognosis compared to patients with DLBCL.

Follicular lymphoma grade 3B: low grade, high grade or should we skip the grade?

Not available.

An overview and a roadmap for artificial intelligence in hematology and oncology

BACKGROUND

Artificial intelligence (AI) is influencing our society on many levels and has broad implications for the future practice of hematology and oncology. However, for many medical professionals and researchers, it often remains unclear what AI can and cannot do, and what are promising areas for a sensible application of AI in hematology and oncology. Finally, the limits and perils of using AI in oncology are not obvious to many healthcare professionals.

METHODS

In this article, we provide an expert-based consensus statement by the joint Working Group on "Artificial Intelligence in Hematology and Oncology" by the German Society of Hematology and Oncology (DGHO), the German Association for Medical Informatics, Biometry and Epidemiology (GMDS), and the Special Interest Group Digital Health of the German Informatics Society (GI). We provide a conceptual framework for AI in hematology and oncology.

RESULTS

First, we propose a technological definition, which we deliberately set in a narrow frame to mainly include the technical developments of the last ten years. Second, we present a taxonomy of clinically relevant AI systems, structured according to the type of clinical data they are used to analyze. Third, we show an overview of potential applications, including clinical, research, and educational environments with a focus on hematology and oncology.

CONCLUSION

Thus, this article provides a point of reference for hematologists and oncologists, and at the same time sets forth a framework for the further development and clinical deployment of AI in hematology and oncology in the future.

Ki67 proliferation index in follicular lymphoma is associated with favorable outcome in patients treated with R-CHOP

Follicular lymphoma (FL) is a common, indolent small B-cell lymphoma. While the Follicular Lymphoma International Prognostic Index is widely used, reliable prognostic and predictive biomarkers are needed. A recent study suggested that architectural patterns of CD10, BCL6, and Ki67 expression may correlate with progression-free survival (PFS) in FL patients treated with chemotherapy-free regimens. We examined the prognostic and predictive utility of architectural patterns of CD10, BCL6, Ki67, and FOXP1 in 90 patients treated with immunochemotherapy (bendamustine-rituximab [BR] and R-cyclophosphamide, doxorubicin, vincristine, prednisone [CHOP]). We found that high follicular Ki67 (≥30%) was associated with longer PFS in the subgroup of patients treated with R-CHOP but not among those treated with BR. Validation of this biomarker may support routine use of Ki67 as a predictive marker in FL.

Navigating the Heterogeneity of Follicular Lymphoma and its Many Variants: An Updated Approach to Diagnosis and Classification

Follicular lymphoma (FL) is a lymphoid neoplasm composed of follicle center (germinal center) B cells, with varying proportions of centrocytes and centroblasts, that usually has a predominantly follicular architectural pattern. Over the past decade, our understanding of FL has evolved significantly, with new recognition of several recently defined FL variants characterized by distinct clinical presentations, behaviors, genetic alterations, and biology. This manuscript aims to review the heterogeneity of FL and its variants, to provide an updated guide on their diagnosis and classification, and to describe how approaches to the histologic subclassification of classic FL have evolved in current classification schemes.

Exploration of Tumor Biopsy Gene Signatures to Understand the Role of the Tumor Microenvironment in Outcomes to Lisocabtagene Maraleucel

In the TRANSCEND NHL 001 study, 53% of patients with relapsed/refractory large B-cell lymphoma (LBCL) treated with lisocabtagene maraleucel (liso-cel) achieved a complete response (CR). To determine characteristics of patients who did and did not achieve a CR, we examined the tumor biology and microenvironment from lymph node tumor biopsies. LBCL biopsies from liso-cel-treated patients were taken pretreatment and ∼11 days posttreatment for RNA sequencing (RNA-seq) and multiplex immunofluorescence (mIF). We analyzed gene expression data from pretreatment biopsies (N = 78) to identify gene sets enriched in patients who achieved a CR to those with progressive disease. Pretreatment biopsies from month-3 CR patients displayed higher expression levels of T-cell and stroma-associated genes, and lower expression of cell-cycle genes. To interpret whether LBCL samples were "follicular lymphoma (FL)-like," we constructed an independent gene expression signature and found that patients with a higher "FL-like" gene expression score had longer progression-free survival (PFS). Cell of origin was not associated with response or PFS, but double-hit gene expression was associated with shorter PFS. The day 11 posttreatment samples (RNA-seq, N = 73; mIF, N = 53) had higher levels of chimeric antigen receptor (CAR) T-cell densities and CAR gene expression, general immune infiltration, and immune activation in patients with CR. Further, the majority of T cells in the day 11 samples were endogenous. Gene expression signatures in liso-cel-treated patients with LBCL can inform the development of combination therapies and next-generation CAR T-cell therapies.

Genetic subgroups inform on pathobiology in adult and pediatric Burkitt lymphoma

Burkitt lymphoma (BL) accounts for most pediatric non-Hodgkin lymphomas, being less common but significantly more lethal when diagnosed in adults. Much of the knowledge of the genetics of BL thus far has originated from the study of pediatric BL (pBL), leaving its relationship to adult BL (aBL) and other adult lymphomas not fully explored. We sought to more thoroughly identify the somatic changes that underlie lymphomagenesis in aBL and any molecular features that associate with clinical disparities within and between pBL and aBL. Through comprehensive whole-genome sequencing of 230 BL and 295 diffuse large B-cell lymphoma (DLBCL) tumors, we identified additional significantly mutated genes, including more genetic features that associate with tumor Epstein-Barr virus status, and unraveled new distinct subgroupings within BL and DLBCL with 3 predominantly comprising BLs: DGG-BL (DDX3X, GNA13, and GNAI2), IC-BL (ID3 and CCND3), and Q53-BL (quiet TP53). Each BL subgroup is characterized by combinations of common driver and noncoding mutations caused by aberrant somatic hypermutation. The largest subgroups of BL cases, IC-BL and DGG-BL, are further characterized by distinct biological and gene expression differences. IC-BL and DGG-BL and their prototypical genetic features (ID3 and TP53) had significant associations with patient outcomes that were different among aBL and pBL cohorts. These findings highlight shared pathogenesis between aBL and pBL, and establish genetic subtypes within BL that serve to delineate tumors with distinct molecular features, providing a new framework for epidemiologic, diagnostic, and therapeutic strategies.

Differences in clinical characteristics and outcomes between patients with grade 3a and grades 1-2 follicular lymphoma: a real-world multicenter study

BACKGROUND

The difference between clinical characteristics and outcomes between follicular lymphoma grade 1-2 (FL1-2) and FL3a defined pathologically remains unclear, resulting in uncertainty how to treat FL3a. However, it may be crucial for clinicians to discriminate grade 3a and grade 1-2 for predicting prognosis and thus making treatment decisions.

METHODS

We compared 1403 patients with FL1-2 and 765 patients with FL3a diagnosed between January 2000 and December 2020 from fifteen centers nationwide in China to describe differences in clinical characteristics and outcomes.

RESULTS

Compared with FL1-2 patients, FL3a subgroup had a higher percentage of elderly patients (P = 0.003), and relatively more FL3a patients presented with increased levels of LDH (P < 0.0001) and higher Ki-67 indexs greater than 30% (P < 0.001). More FL3a patients were treated with CHOP ± R (P < 0.0001), and fewer were treated with the watchful-waiting approach (P < 0.0001). The results showed a higher incidence of relapse among FL3a patients, in which more patients underwent histological transformation (HT) when compared to FL1-2 (P = 0.003). 1470 (76.2%) patients of the entire cohort received R-CHOP therapy; survival analysis revealed that FL3a patients had a worse progression-free survival (PFS) rate than FL1-2 patients. Survival of FL3a patients with respect to FLIPI showed an inferior PFS in the intermediate and high-risk groups than FL1-2 patients. FL3a patients had a much worse prognosis than FL1-2 with or without progression of disease within 24 months (POD24). FL3a patients had higher likelihood of lymphoma-related death (LRD, P < 0.05), whereas the rates for non-LRD were comparable.

CONCLUSION

In conclusion, this study demonstrates a marked difference in clinical features and outcomes in FL3a patients compared with FL1-2 patients. The results highlight the need for applying therapeutic approaches distinct from FL1-2 when treating FL3a patients.

Follicular Lymphoma in the 5th Edition of the WHO-Classification of Haematolymphoid Neoplasms-Updated Classification and New Biological Data

The conceptual description of Follicular lymphoma (FL) in the 5th edition of the World Health Organization (WHO) classification of haematolymphoid tumors (WHO-HAEM5) has undergone significant revision. The vast majority of FL (85%) with a follicular growth pattern are composed of centrocytes and centroblasts, harbor the t(14;18)(q32;q21) translocation and are now termed classic FL (cFL). They are set apart from three related subtypes, FL with predominantly follicular growth pattern, FL with unusual cytological features (uFL) and follicular large B-cell lymphoma (FLBCL). In contrast to the revised 4th edition of the WHO classification of haematolymphoid tumors (WHO-HAEM4R), grading of cFL is no longer mandatory. FL with a predominantly diffuse growth pattern had been previously recognized in WHO-HAEM4R. It frequently occurs as a large tumor in the inguinal region and is associated with CD23 expression. An absence of the IGH::BCL2 fusion and frequent STAT6 mutations along with 1p36 deletion or TNFRSF14 mutation is typical. The newly introduced subtype of uFL includes two subsets that significantly diverge from cFL: one with "blastoid" and one with "large centrocyte" variant cytological features. uFL more frequently displays variant immunophenotypic and genotypic features. FLBCL is largely identical to WHO-HAEM4R FL grade 3B and renaming was done for reasons of consistency throughout the classification. In-situ follicular B-cell neoplasm, pediatric-type FL, duodenal-type FL and primary cutaneous follicle center lymphoma are categorized as discrete entities. In addition, novel findings concerning underlying biological mechanisms in the pathogenesis of early and systemic follicular lymphoma will be presented.

Application of circulating tumour DNA in terms of prognosis prediction in Chinese follicular lymphoma patients

Background: Follicular lymphoma (FL), an indolent non-Hodgkin lymphoma (NHL), is generally incurable. Favourable prognosis and durable remission are crucial for FL patients. The genetic mutation spectrum provides novel biomarkers for determining the prognosis of FL patients, but its detection is easily affected by the collection of tumour tissue biopsies. In this study, we aimed to describe the mutational landscape of FL using circulating tumour DNA (ctDNA) samples and to explore the relationship between mutations and prognostic indicators of clinical outcome in patients with newly diagnosed follicular lymphoma and the prognostic value of such mutations. Methods: A total of 28 patients with newly diagnosed FL were included in this study. A targeted NGS-based 59-gene panel was used to assess the ctDNA mutation profiles. Differences in clinical factors between patients carrying mutations and those without mutations were analysed. We also explored the relationship between gene mutation status, mean VAFs (variant allele frequencies) and clinical factors. The Kaplan‒Meier method was applied to analyse the overall survival (OS) and progression-free survival (PFS) of patients carrying mutations and those without mutations. Results: ctDNA mutations were detectable in 21 (75%) patients. The most commonly mutated genes were CREBBP (54%, 15/28), KMT2D (50%, 14/28), STAT6 (29%, 8/28), CARD11 (18%, 5/28), PCLO (14%, 4/28), EP300 (14%, 4/28), BCL2 (11%, 3/28), and TNFAIP3 (11%, 3/28), with a mutation frequency of >10%. Patients with detectable ctDNA mutation tended to present with advanced Ann Arbor stage (III-IV) (p = 0.009), high FLIPI risk (3-5) (p = 0.023) and severe lymph node involvement (No. of involved areas ≥5) (p = 0.02). In addition, we found that the mean VAF was significantly higher in patients with advanced Ann Arbor stage, high-risk FLIPI, elevated lactate dehydrogenase (LDH: 0-248U/L), advanced pathology grade, bone marrow involvement (BMI) and lymph node involvement. Additionally, KMT2D, EP300, and STAT6 mutations were associated with inferior PFS (p < 0.05). Conclusion: We described the ctDNA mutation landscapes in Chinese patients with newly diagnosed FL and found that ctDNA VAF means reflect tumour burden. Moreover, PFS was shorter in patients with KMT2D, EP300 and STAT6 mutations.

The impact of histological grade on outcomes in follicular lymphoma: An analysis of patients in the SEER database in the context of evolving disease classification and treatment

Currently, there is no convincing evidence that the grade of follicular lymphoma (FL) impacts patient outcome. We correlated grades in 33 925 patients with nodal FL during 1992-2018 in the SEER database with disease-specific survival (DSS) and overall survival (OS). Patients with FL grade 3 had lower DSS and OS as compared to FL grades 1-2. During 1992-2005, the 10-year DSS for patients with FL grades 3 and grades 1-2 were 68.6%, and 71.4%, respectively, and in 2006-2018, they were 77.7% and 82.6%, respectively. The 10-year OS estimates in 1992-2005 were 49.9% and 54.2% for grade 3 and grades 1-2 respectively, and in 2006-2018, they were 59.1% and 63.5% for grade 3 and grades 1-2, respectively. After adjustment for stage and age, the hazard ratios for death due to FL and death from any cause for patients with FL grade 3 during 1992-2005 were 1.09 (1.02-1.16) and 1.07 (1.02-1.12), respectively, compared to FL grades 1-2; and during 2006-2018, the hazard ratios for death due to FL and death from any cause for patients with FL grade 3 were 1.34 (1.22-1.45) and 1.16 (1.10-1.23), respectively compared to FL grades 1-2. The grade of FL is an important determinant of disease biology.

The prognostic nutritional index, an independent predictor of overall survival for newly diagnosed follicular lymphoma in China

Objective

The prognostic nutritional index (PNI) is an important prognostic factor for survival outcomes in various hematological malignancies. The current study focused on exploring the predictive value of the PNI in newly diagnosed follicular lymphoma (FL) in China.

Materials and methods

The clinical indicators and follow-up data of 176 patients who received chemotherapy or immunotherapy combined with chemotherapy with FL in our hospital from January 2016 to March 2022 were retrospectively analyzed. Cox proportional hazard model was used for univariate and multivariate analyses. Kaplan–Meier curves were used to calculate survival rates and draw survival curves. The log-rank test was applied to compare differences between groups.

Results

The optimal cut-off value of PNI was 44.3. All patients were divided into a high PNI group (>44.3) and a low PNI group (≤44.3). The low PNI group had a low CR rate and a high risk of death, with a tendency toward POD24, and Both OS and PFS were worse than those in the high PNI group. PNI was able to predict OS and PFS in FL patients and was the only independent predictor of OS (P = 0.014 HR 5.024; 95%CI 1.388∼18.178) in multivariate analysis. PNI could re-stratify patients into groups of high FLIPI score, high FLIPI2 score, no POD24, and rituximab combined with chemotherapy. Moreover, integrating PNI into the FLIPI and FLIPI2 models improved the area under the curve (AUC) for more accurate survival prediction and prognosis.

Conclusion

PNI is a significant prognostic indicator for newly diagnosed FL in China that can early identify patients with poor prognosis and guide clinical treatment decisions.

Clinical features and outcomes of patients with follicular lymphoma: A real-world study of 926 patients in China

Background

The data about the clinical features and outcomes of Chinese patients with follicular lymphoma (FL) are limited. Here, we conducted a retrospective study to explore the initial treatment strategies and clinical outcomes of Chinese patients with FL in the real world.

Method

This study included FL patients who were newly diagnosed in Tianjin Medical University Cancer Institute and Hospital from March 2002 to August 2020.

Results

A total of 926 FL patients were enrolled. The median age was 54 years old, and the majority of the Chinese FL patients had advanced-stage disease and Eastern Cooperative Oncology Group(ECOG) <1 but less frequently infiltrated bone marrow. After a median of 38-month follow-up, the 5-year progressive-free survival (PFS) and overall survival (OS) of grade1-3a were 57.8% and 88.7%, respectively, which both are similar to those reported in previous Chinese and Western studies. The co-existence at diagnosis of FL and diffuse large B-cell lymphoma (DLBCL) components (FL/DLBCL) was associated with poor outcomes. The FL grades and proportion of DLBCL component in FL/DLBCL did not have an impact on PFS and OS. The most common regimen with great efficacy and risk-benefit was RCHOP-like followed by R maintenance regimen. The 5-year cumulative hazard of histological transformation (HT) was 4.7% (95% CI, 3.5-5.9); median time to transformation was 23.5 months (range, 2-146 months) after diagnosis. Three-year survival following transformation was 55% (95% CI, 40-70). Patients with stage III-IV, elevated β2 microglobulin (β2-MG), and B symptoms seemed to be more prone to progress within 24 months of frontline therapy (POD24). The FLIPI-2 showed the highest specificity to predict POD24, reflecting the prediction of correctly classifying as low-risk patients, but the FLIPI had the highest sensitivity to predict the risk of progression for critical patients.

Conclusions

We revealed the clinical characteristics and outcomes of FL patients in the real world in China, which may provide novel data on prognostic factors and primary treatment of FL, applicable to routine clinical practice.

Follicular Lymphoma Microenvironment Characteristics Associated with Tumor Cell Mutations and MHC Class II Expression

Follicular lymphoma (FL) is a B-cell malignancy with a complex tumor microenvironment that is rich in nonmalignant immune cells. We applied single-cell RNA sequencing to characterize the diverse tumor and immune cell populations of FL and identified major phenotypic subsets of FL T cells, including a cytotoxic CD4 T-cell population. We characterized four major FL subtypes with differential representation or relative depletion of distinct T-cell subsets. By integrating exome sequencing, we observed that somatic mutations are associated with, but not definitive for, reduced MHC expression on FL cells. In turn, expression of MHCII genes by FL cells was associated with significant differences in the proportions and targetable immunophenotypic characteristics of T cells. This provides a classification framework of the FL microenvironment in association with FL genotypes and MHC expression, and informs different potential immunotherapeutic strategies based upon tumor cell MHCII expression.

SIGNIFICANCE

We have characterized the FL-infiltrating T cells, identified cytotoxic CD4 T cells as an important component that is associated with tumor cell-intrinsic characteristics, and identified sets of targetable immune checkpoints on T cells that differed from FLs with normal versus low MHC expression. See related commentary by Melnick, p. 374. This article is highlighted in the In This Issue feature, p. 369.

Risk factors for POD24 in patients with previously untreated follicular lymphoma: a systematic review and meta-analysis

Progression of disease within 24 months (POD24) is strongly associated with a poor outcome in patients with follicular lymphoma (FL). Our study aimed to identify the potential risk factors for POD24 in patients with FL. Medline, EMBASE and the Cochrane Library were systematically searched from the earliest record to September 2020. Studies investigating the prognostic factors for POD24 in patients with newly diagnosed grade 1-3a FL were included. Among 10,014 pieces of literature, a total of 90 studies investigating 82 risk factors were included for qualitative analysis. Meta-analyses were performed in 31 studies with 11 factors. Results showed that elevated sIL-2R, β2m and LDH, total metabolic tumour volume > 510 cm³, vitamin D < 20 ng/mL, grade 3a and lymphoma-associated macrophages/high-power field ≥ 15 were significantly associated with an increased risk of POD24. No significant association was found between POD24 and the ALC/AMC ratio, sex, T effector signature or EZH2 genetic alteration. Additionally, minimal residual disease, Ki-67, PD-1 and TP53 were analysed narratively. Overall, this is the first study that comprehensively analysed the prognostic factors associated with POD24 in FL patients. We have confirmed the significance value of several common prognostic factors as well as others not commonly included in clinical study, helping to construct an integrated and more efficient model.

Prediction of prognosis and pathologic grade in follicular lymphoma using 18F-FDG PET/CT

Purpose

We investigated the utility of a new baseline PET parameter expressing lesion dissemination and metabolic parameters for predicting progression-free survival (PFS) and pathologic grade in follicular lymphoma (FL).

Methods

The baseline ¹⁸F-FDG PET/CT images of 126 patients with grade 1–3A FL were retrospectively analyzed. A novel PET/CT parameter characterizing lesion dissemination, the distance between two lesions that were furthest apart (D_max), was calculated. The total metabolic tumor volume and total lesion glycolysis (TLG) were computed by using 41% of the maximum standardized uptake value (SUV_max) thresholding method.

Results

The 5-year PFS rate was 51.9% for all patients. In the multivariate analysis, high D_max [P = 0.046; hazard ratio (HR) = 2.877], high TLG (P = 0.004; HR = 3.612), and elevated serum lactate dehydrogenase (P = 0.041; HR = 2.287) were independent predictors of PFS. A scoring system for prognostic stratification was established based on these three adverse factors, and the patients were classified into three risk categories: low risk (zero to one factor, n = 75), intermediate risk (two adverse factors, n = 29), and high risk (three adverse factors, n = 22). Patients in the high-risk group had a shorter 3-year PFS (21.7%) than those in the low- and intermediate-risk groups (90.6 and 44.6%, respectively) (P < 0.001). The C-index of our scoring system for PFS (0.785) was superior to the predictive capability of the Follicular Lymphoma International Prognostic Index (FLIPI), FLIPI2, and PRIMA-Prognostic Index (C-index: 0.628–0.701). The receiver operating characteristic curves and decision curve analysis demonstrated that the scoring system had better differentiation and clinical utility than these existing indices. In addition, the median SUV_max was significantly higher in grade 3A (36 cases) than in grades 1 and 2 FL (90 cases) (median: 13.63 vs. 11.45, P = 0.013), but a substantial overlap existed (range: 2.25–39.62 vs. 3.17–39.80).

Conclusion

TLG and D_max represent two complementary aspects of the disease, capturing the tumor burden and lesion dissemination. TLG and D_max are promising metrics for identifying patients at a high risk of progression or relapse. Additionally, SUV_max seems to have some value for distinguishing grade 3A from low-grade FL but cannot substitute for biopsy.

Follicular Lymphoma: Refining Prognostic Models and Impact of Pod-24 in Clinical Outcomes

Follicular lymphoma (FL) is the most common indolent lymphoma, accounting for 20%-25% of all non-Hodgkin's lymphomas (NHLs). It is a malignancy with variable biologic presentation and heterogeneous clinical outcomes. Several models incorporating clinical laboratory variables and molecular biomarkers are able to predict its prognosis, allowing to stratify patients into different risk groups. However, these prognostic scores should not be used to indicate first-line treatment or risk-adapted therapeutic recommendations. Over the past 5 years, progression of disease within 24 months (POD-24) of first-line chemo-immunotherapy has emerged as a robust adverse prognostic factor, capable of assessing overall survival and identifying high-risk patients with indication for more aggressive therapeutic approaches, such as consolidation based in autologous stem cell transplantation. It should be reinforced that POD-24 is not a baseline measurement, it is based on a post-treatment strategy, and is usually applied to patients with a high tumor burden. The identification of newly diagnosed patients at high risk for disease progression, particularly those with low tumor volume is still a challenge in the context of FL. Therefore, the primary purpose of this review is to provide an overview of the main prognostic models validated to date for FL. Moreover, using these scores, which incorporate clinical and genetic variables, we aim to identify individuals with newly diagnosed FL, advanced disease, and low tumor burden with a high probability of progression or relapse within 24 months of first treatment. Thus, a decision regarding risk-adapted induction therapy could be better stablished for these subset of patients.

High-grade Follicular Lymphomas Exhibit Clinicopathologic, Cytogenetic, and Molecular Diversity Extending Beyond Grades 3A and 3B

Although follicular lymphoma (FL) is usually graded as FL1-2, FL3A, and FL3B, some borderline cases can be observed and led us to investigate the clinicopathologic diversity of grade 3 FL (FL3). Among 2449 FL patients enrolled in Lymphoma Study Association (LYSA) trials, 1921 cases with sufficient material underwent a central pathologic review. The resulting diagnoses comprised 89.6% FL1-2 (n=1723), 7.2% FL3A (n=138), and 0.5% purely follicular FL3B (n=9). The remaining 51 unclassifiable cases (2.7%) exhibited high-grade features but did not meet WHO criteria for either FL3A or FL3B; and were considered as "unconventional" high-grade FL (FL3U). FL3U morphological pattern consisted of nodular proliferation of large cleaved cells or small-sized to medium-sized blast cells. Compared with FL3A, FL3U exhibited higher MUM1 and Ki67 expression, less BCL2 breaks and more BCL6 rearrangements, together with a higher number of cases without any BCL2, BCL6 or MYC rearrangement. FL3U harbored less frequent mutations in BCL2, KMT2D, KMT2B, and CREBBP than FL3A. MYC and BCL2 were less frequently mutated in FL3U than FL3B. Rituximab cyclophosphamide, doxorubicin, vincristine, and prednisone treated FL3U patients had a worse survival than FL1-2 patients with similar follicular lymphoma international prognostic index and treatment. These results suggest that high-grade FLs encompass a heterogeneous spectrum of tumors with variable morphology and genomic alterations, including FL3U cases that do not strictly fit WHO criteria for either FL3A or FL3B, and display a worse outcome than FL1-2. The distinction of FL3U may be useful to allow a better comprehension of high-grade FLs and to design clinical trials.

Mantle cell lymphoma, malt lymphoma, small lymphocytic lymphoma, and follicular lymphoma of the oral cavity: An update

BACKGROUND

Although uncommon, mature small B-cell lymphomas may arise in the oral/maxillofacial area and oral pathologists must be aware of the key characteristics of these neoplasms to perform an accurate diagnosis. In this manuscript, we attempted to integrate the currently available data on the clinicopathological features of follicular lymphoma (FL), mantle cell lymphoma (MCL), extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT-L), and chronic lymphocytic leukemia/ small lymphocytic lymphoma (CLL/SLL) affecting these anatomical regions.

METHODS

An updated descriptive literature review was carried out and a detailed electronic search was done in multiple databases to gather all cases affecting the oral/maxillofacial region and palatine tonsils.

RESULTS

We observed that MALT-L was the most frequently reported subtype, followed by FL, MCL, and CLL/SLL. The palate was affected in a high proportion of cases and the most usual clinical presentation was an asymptomatic swelling. MALT-L and CLL/SLL neoplastic cells were strongly associated with small salivary glands. FL showed no gender preference, while MCL and CLL/SLL were more prevalent in males and MALT-L in females. Overall, cases were more common in elderly individuals. Patients' treatment and outcome varied, with MCL being the most aggressive neoplasm with a dismal prognosis in comparison to FL and MALT-L.

CONCLUSION

Despite the poor documentation in many of the cases available, especially regarding the microscopic and molecular features of tumors, this review demonstrated that the oral mature small B-cell lymphomas investigated share similar clinical presentation, but carry different prognostic significance, demanding an accurate diagnosis.

The diagnostic and therapeutic challenges of Grade 3B follicular lymphoma

Grade 3B follicular lymphoma (G3B FL) is rare, accounting for only 5-10% of FLs. Not only has it been routinely excluded from clinical trials, but data published on diagnosis, outcomes, choice of therapies and role of imaging are conflicting. With the advent of increasingly diverse treatment options for low-grade (G1-3A) FL, and the molecular subcategorisation of high-grade B-cell lymphomas, characterisation and treatment of G3B FL is ever more important as extrapolation of data becomes more difficult. New data have emerged exploring unique genetic characteristics, specific features on positron emission tomography imaging, choice of therapy, and outcomes of G3B FL in the current era. The present review will summarise and appraise these new data, and offer recommendations based on current evidence.

A Diagnostic Approach to the Identification of Burkitt-like Lymphoma With 11q Aberration in Aggressive B-Cell Lymphomas

Rare cases of aggressive B-cell lymphomas with a morphology similar to Burkitt lymphoma (BL) present with the BL-typical immunophenotype, but lacked MYC translocation (MYC-negative Burkitt-like lymphoma: mnBLL). A proportion of those with an imbalance pattern in chromosome 11q has been designated Burkitt-like lymphoma with 11q aberration in the recent update of the World Health Organization (WHO) classification. Because of the problems in the identification of Burkitt-like lymphoma with 11q aberration, our goal was to retrospectively analyze their frequency in a cohort of "candidate" aggressive lymphomas (cohort 1, n=35) such as mnBLL (n=16), diffuse large B-cell lymphoma with similarities to Burkitt lymphoma (DLBCL-BL; n=3), high-grade B-cell lymphomas, not otherwise specified (NOS) (n=16), as well as in a cohort of MYC-negative diffuse large B-cell lymphoma NOS (cohort 2, n=62). In total, 17/33 cohort 1 cases (52%) harbored the typical 11q aberration pattern, predominantly those that had been classified as mnBLL (12/16, 75%), but also as DLBCL-BL (2/3, 67%) and high-grade B-cell lymphomas, NOS (3/14; 21%). The specimens with this typical 11q aberration pattern were usually negative for the BCL2 protein. Of interest and as a new finding, samples harboring the 11q aberration pattern were often characterized by strikingly coarse apoptotic debris within starry sky macrophages facilitating their recognition. In contrast, only 1 of 62 garden variety DLBCL, NOS was positive for the 11q aberration pattern. In 2 DLBCL-BL, a dual MYC translocation/11q aberration pattern was detected. As a diagnostic algorithm, we, therefore, propose analysis of 11q status in MYC-negative high-grade lymphomas with features of BL, especially showing BCL2 negativity and a conspicuous coarse apoptotic debris in starry sky macrophages.

Prognostic significance of histologic grade and Ki-67 proliferation index in follicular lymphoma

The prognostic value of histologic grading and the Ki-67 proliferation index in follicular lymphoma (FL) is controversial. This study investigated the clinical usefulness of these two factors in Asian FL patients. Four hundred and thirty-three patients diagnosed with FL were retrospectively reviewed with a median follow-up time of 47.0 months (range, 24.0-168.0). The 10-year overall survival (OS) rate and progression-free survival (PFS) rate were 91.0% and 47.1%, respectively. Grade 3B and grade 3B with diffuse large B cell lymphoma (DLBCL) showed a better PFS than grade 1-3A (P < 0.001), and similar findings were noted in patients who received rituximab-containing regimens (P = 0.002). In contrast, no significant differences in terms of OS or PFS were observed between grades 1-2 and 3A. In addition, patients with Ki-67 ≥ 30% had a significantly better PFS than patients with Ki-67 < 30% (P = 0.014), although the difference was eliminated in the multivariate analysis. Both grade and Ki-67 index had no impact on prognosis in patients who did not receive rituximab treatment. In conclusion, grade 3A is closely related to grade 1-2, as reflected by a similar indolent clinical course and a lower PFS rate than grade 3B/3B + DLBCL. In addition, a higher Ki-67 index seems to have a positive effect on PFS in FL patients.

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.

First-line treatment with R-CHOP or rituximab-bendamustine in patients with follicular lymphoma grade 3A-results of a retrospective analysis

Based on centroblast frequency, follicular lymphoma (FL) is subdivided into grades 1-2, 3A, and 3B. Grade FL3A frequently coexists with FL1-2 (FL1-2-3A). Based on clinical trials, FL1-2 is treated with rituximab (R) or obinutuzumab plus bendamustine (B) or CHOP, while FL3B is treated with R-CHOP. In contrast, there are little data guiding therapy in FL3A. We present a retrospective, multicenter analysis of 95 FL3A or FL1-2-3A and 203 FL1-2 patients treated with R-CHOP or R-B first-line. R-CHOP facilitated a higher response rate (95% versus 76%) and longer overall survival (OS) (3-year OS 89% versus 73%, P = 0.008) in FL3A or FL1-2-3A, whereas the difference in progression-free survival (PFS) did not reach statistical significance. While transformation rates into aggressive lymphoma were similar between both groups, there were more additional malignancies after R-B compared with R-CHOP (6 versus 2 cases). In FL1-2, R-B achieved a higher 3-year PFS (79% versus 47%, P < 0.01), while there was no significant difference regarding OS or transformation. With the limitations of a retrospective analysis, these results suggest a benefit for R-CHOP over R-B in FL3A or FL1-2-3A. Confirmatory data from prospective clinical trials are needed.

Grade I, II and III Follicular Lymphomas Express Ig VH Genes with Different Patterns of Somatic Mutation

Follicular lymphoma (FL) is an indolent, B-cell, non-Hodgkin’s lymphoma with varying cytological appearance and clinical behavior. The genetic hallmark of FL is the t(14;18) translocation, and as a germinal center derived entity it is also characterized by somatic hypermutation of the immunoglobulin heavy chain (IgH) gene. In an attempt to correlate this molecular signature with the cytological grading of FL, we have analyzed the IgH variable (IgV_H), regions in all cytological grades of FL. Four FL cases showing t(14;18) translocation were classified into grade I-III categories according to the current WHO guidelines. The IgV_H gene segments were PCR-amplified, sequenced, and compared to their respective germline IgV_H sequences. The neoplastic cells of grade I and II FLs revealed clonally related, but highly divergent IgV_H gene sequences indicating the ongoing nature of somatic hypermutation. Grade III FL also showed extensive presence of somatic hypermutation, but these mutations were not associated with intraclonal divergence. Thus, these results suggest that grade I-II and grade III FL may represent different biological entities. The presence of ongoing somatic hypermutation of IgV_H sequences in grade I and II FLs is compatible with direct follicular origin of these tumor cells, contrasting the homogenous, stable clones of grade III FL resembling a post-follicular stage of B-cell development. Our findings demonstrate that contrary to the three tiered cytological grading, molecular features of IgH genes classify FL into two distinct subcategories. These studies also suggest that with progression FL gains post-follicular–like molecular features and becomes independent of the germinal center microenvironment.

Pathology and diagnosis of follicular lymphoma and related entities

Follicular lymphoma (FL) is an indolent, mature B-cell neoplasm classically characterised by the t(14;18)(q32;q21) with constitutive overexpression of the anti-apoptotic protein, BCL2. Most cases present in older adults with slowly progressive lymphadenopathy and follow an indolent clinical course. Typical morphology shows an expansile follicular proliferation with tumour expression of germinal centre markers, and bone marrow involvement at diagnosis is frequent. However, in the recent past, efforts to understand the biological and clinical heterogeneity of FL has effected significant change to the diagnostic approach. While morphological grade, assessed by enumerating large 'centroblasts' in the neoplastic follicles, generally correlates with outcome in systemic nodal FL, variants with high-grade morphology but indolent clinical behaviour have been identified. Given the clinical implications of these FL variants, knowledge of their clinical and histopathological defining features is of paramount importance to the pathologist. Furthermore, as with many areas of diagnostic oncology, precursors to FL have been identified and described with measurable rates of progression to bona fide lymphoma. Accurate diagnosis of these early lesions can often prevent unnecessary therapy and guide appropriate monitoring for disease progression. This review aims to summarise these key pathological and diagnostic features of FL. We further highlight the biological underpinnings of FL that will likely affect the classification, diagnosis, and treatment of patients with lymphoma.

A modular transcriptome map of mature B cell lymphomas

BACKGROUND

Germinal center-derived B cell lymphomas are tumors of the lymphoid tissues representing one of the most heterogeneous malignancies. Here we characterize the variety of transcriptomic phenotypes of this disease based on 873 biopsy specimens collected in the German Cancer Aid MMML (Molecular Mechanisms in Malignant Lymphoma) consortium. They include diffuse large B cell lymphoma (DLBCL), follicular lymphoma (FL), Burkitt's lymphoma, mixed FL/DLBCL lymphomas, primary mediastinal large B cell lymphoma, multiple myeloma, IRF4-rearranged large cell lymphoma, MYC-negative Burkitt-like lymphoma with chr. 11q aberration and mantle cell lymphoma.

METHODS

We apply self-organizing map (SOM) machine learning to microarray-derived expression data to generate a holistic view on the transcriptome landscape of lymphomas, to describe the multidimensional nature of gene regulation and to pursue a modular view on co-expression. Expression data were complemented by pathological, genetic and clinical characteristics.

RESULTS

We present a transcriptome map of B cell lymphomas that allows visual comparison between the SOM portraits of different lymphoma strata and individual cases. It decomposes into one dozen modules of co-expressed genes related to different functional categories, to genetic defects and to the pathogenesis of lymphomas. On a molecular level, this disease rather forms a continuum of expression states than clearly separated phenotypes. We introduced the concept of combinatorial pattern types (PATs) that stratifies the lymphomas into nine PAT groups and, on a coarser level, into five prominent cancer hallmark types with proliferation, inflammation and stroma signatures. Inflammation signatures in combination with healthy B cell and tonsil characteristics associate with better overall survival rates, while proliferation in combination with inflammation and plasma cell characteristics worsens it. A phenotypic similarity tree is presented that reveals possible progression paths along the transcriptional dimensions. Our analysis provided a novel look on the transition range between FL and DLBCL, on DLBCL with poor prognosis showing expression patterns resembling that of Burkitt's lymphoma and particularly on 'double-hit' MYC and BCL2 transformed lymphomas.

CONCLUSIONS

The transcriptome map provides a tool that aggregates, refines and visualizes the data collected in the MMML study and interprets them in the light of previous knowledge to provide orientation and support in current and future studies on lymphomas and on other cancer entities.

Limited stage grade 3 follicular lymphoma patients can experience favorable outcomes with combined modality therapy

Controversy exists regarding the optimal management of limited stage grade 3 follicular lymphoma (FL3). We assessed the treatment outcomes of 190 consecutive patients with stage I-II FL. Fifty two patients had FL3 disease, in whom the median age was 55 years. At a median follow-up of 65 months, 5-year progression-free survival (PFS) and overall survival (OS) rates were 76.6% and 87.6%, respectively. Patients receiving systemic therapy followed by radiation therapy (RT) had a significantly better PFS (p=.003) than those treated with RT alone, but similar OS (p = .476). Patients treated with RT had 100% local control. Compared to 132 patients with grade 1-2 FL, those with FL3 had similar PFS (p = .493) and OS (p  =  .330). Patients with FL3 can experience favorable outcomes when treated with a combination of systemic therapy and RT, comparable to low grade FL.