Transformation of follicular lymphoma – Why does it happen and can it be prevented?

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.

Cost-effectiveness of obinutuzumab plus bendamustine in Chinese patients with relapse and refractory follicular lymphoma

A decision analytic model was constructed to assess the cost-effectiveness of obinutuzumab plus bendamustine followed by obinutuzumab maintenance therapy (O-B-O) in Chinese patients with relapsed and refractory follicular lymphoma (rrFL). O-B-O was associated with a dominant or more favorable cost-effectiveness than the conventional therapies. Survival outcomes, quality of life of progression-free survival, and subsequent treatment costs for progressive disease were the main drivers of the cost-effectiveness of O-B-O. The cost-effectiveness proportions of O-B-O relative to conventional therapies under the recommended cost-effectiveness threshold ranged from 61.0% to 99.9%. Thus, O-B-O was highly cost-effective for treating patients with rrFL in China compared with conventional therapies.

Clinical usefulness of a novel classification of T cell distribution patterns in the tumor microenvironment of follicular lymphoma to detect transformation

The clinical course of follicular lymphoma (FL) is thought to be influenced by the infiltrating immune cells in the tumor microenvironment. Focusing on the distribution patterns of T cells may be a promising approach to estimate the prognosis of FL, especially histological transformation. This study was a retrospectively cohort study in the relationship between the pathological distribution pattern of T cells in the tumor microenvironment and clinical course of FL. One hundred twenty-eight patients with FL initially diagnosed at the University of Tokyo Hospital from January 2008 to January 2017 were evaluated. We classified each patient's specimen at initial diagnosis by the distribution pattern of tumor infiltrating CD3-positive cells, intra-follicle focal (IFF), intra-follicle diffuse (IFD), extra-follicle marginal (EFM), and extra-follicle diffuse (EFD). We analyzed the distribution pattern's correlation with other prognostic factors including overall survival (OS), progression free survival (PFS), and transformation. Among 128 cases, 81 had evaluable pathological specimen. Based on our criteria, in the intra-follicle,17 cases (21%) were classified as IFF. Sixty-four cases (79%) were classified as IFD. In the extra follicle, 25 cases (31%) were classified as EFM. Fifty-six cases (69%) were classified as EFD. There was significant difference in risk of transformation between the EFM and EFD around extra-follicle area in the adjusted model (p < 0.05). Also, cases with IFF and EFM had significantly higher risk of transformation compared to cases with other T cell distribution patterns (p < 0.01). We proposed a new classification of CD3-positive T cell distribution patterns around the follicle lesions in FL and demonstrated its clinical significance.

An approach to small lymph node biopsies: pearls and pitfalls of reporting in the real world

Recent advances in interventional radiology have resulted in the utilization of small lymph node biopsies, including fine-needle aspiration (FNA) and core needle biopsy (CNB) as an initial diagnostic tool in hematopathology. A major challenge to the utilization of FNA and CNB is the limited-to-scant tissue often available. We propose delegation of the task of handling biopsy specimens to the laboratory staff by the biopsy operators, in order to optimize the utilization of the specimen. Furthermore, in order to effectively diagnose hematolymphoid neoplasms a variety of ancillary tests including immunohistochemistry, flow cytometry, molecular analysis, florescence in situ hybridization (FISH) are necessary. We propose morphological evaluation coupled with careful utilization of ancillary studies along with clinical correlation to approach the correct diagnosis. Our morphological assessment considers the types of proliferating cell population: mainly small cells, sheets of large cells, or scattered large cells among small cells. This is followed by employment of the corresponding immunopanel to assess the differential diagnosis in each of the three categories. We also elaborate on the importance for pathologists to become proficient in understanding the limitations of small tissue biopsies as well as the differences in interpretation, and wording their reports to help clinicians and direct them to further investigate and/or to re-biopsy when necessary.

Systematic analysis of the frequently amplified 2p15-p16.1 locus reveals PAPOLG as a potential proto-oncogene in follicular and transformed follicular lymphoma

Transformed follicular lymphoma (tFL) originates from histological transformation of follicular lymphoma (FL), which is the most common indolent non-Hodgkin lymphoma. High-resolution genomic copy-number analysis previously identified frequent amplification of the 2p15-p16.1 locus in FL and tFL cases. The genes (i.e. BCL11A, PAPOLG, PUS10, and USP34) in this amplified locus have not been systematically investigated to date in terms of their role in FL pathogenesis or transformation to tFL. Here we investigated the relationship between amplification and expression of genes in 2p15-p16.1 as well as their expression after histological transformation. NCBI GEO SNP array and gene expression profile (GEP) data of tFL cases were analyzed to evaluate the relationship between amplification and mRNA expression. Moreover, transcript levels of these four genes in FL cases were compared with those of patient-matched tFL cases and normal B-cells. Amplification of the 2p15-p16.1 locus is associated with increased transcription of BCL11A and PAPOLG in tFL cases, of which the latter showed increased expression after histological transformation. Compared with the level in normal B-cells, PAPOLG was significantly overexpressed in FL cases, but expression levels of the other three genes did not show any significant difference. Altogether these results suggest that PAPOLG may be the most critical gene in terms of transformation to tFL.

Novel treatment approaches and future perspectives in follicular lymphoma

Follicular lymphoma (FL) is a common B-cell malignancy characterized by relatively indolent growth and incurability with an expected lifetime course of serial intermittent treatment courses. Many patients with FL have lives shortened by the disease and despite a relatively favorable prognosis relative to other incurable systemic malignancies, optimal management of FL has not been achieved. This review focuses on identifying both patients for whom novel therapies might be most beneficial as well as systematically reviewing novel strategies at various levels of investigation. Prognostic markers incorporating clinical measurements and tumor genetics are discussed, yet at the time of diagnosis do not yet powerfully discriminate patients for whom specific strategies are beneficial. Reassessment of prognosis after evaluating the response to initial therapy is the most powerful identifier of those in need of novel management strategies. For initial therapy of high burden systemic disease, anti-CD20 antibody along with chemotherapy or immunomodulators all offer relatively similar effects on overall survival with subtly different effects on progression-free survival and quality of life. Several new agents currently under investigation in the upfront setting are discussed. Perhaps the best testing ground for novel therapies is in patients with early relapse following initial immunochemotherapy. Ongoing research in multiple therapy classes including, novel monoclonal antibodies, antibody drug conjugates, immunomodulatory agents, intracellular pathway inhibitors, immune checkpoint inhibitors, and epigenetic regulators are discussed herein.