The Utility of Phosphohistone H3 (PHH3) in Follicular Lymphoma Grading: A Comparative Study With Ki-67 and H&E Mitotic Count

Personalised therapy in follicular lymphoma - is the dial turning?

Follicular lymphoma is the most common indolent lymphoma accounting for approximately 20%-25% of all new non-Hodgkin lymphoma diagnoses in western countries. Whilst outcomes are mostly favorable, the spectrum of clinical phenotypes includes high-risk groups with significantly inferior outcomes. This review discusses recent updates in risk stratification and treatment approaches from upfront treatment for limited and advanced stage follicular lymphoma to the growing options for relapsed, refractory disease with perspectives on how to approach this from a personalized lens. Notable gaps remain on how one can precisely and prospectively select optimal treatment for patients based on varying risks, with an anticipation that an increased understanding of the biology of these different phenotypes and increasing refinement of imaging- and biomarker-based tools will, in time, allow these gaps to be closed.

Diagnostic and prognostic assessments of adrenocortical carcinomas by pathological features, immunohistochemical markers and reticular histochemistry staining

BACKGROUND

Current diagnostic criteria of adrenocortical neoplasms are mostly based on morphology. The utility of immunohistochemistry (IHC) and histochemistry is limited.

MATERIALS AND METHODS

To evaluate the diagnostic and prognostic utility of clinicopathological features, morphology, ancillary biomarkers, and reticular histochemistry in adrenocortical neoplasms. We examined 28 adrenocortical carcinomas (ACCs) and 50 adrenocortical adenomas (ACAs) obtained from pathology archives. Clinical data were retrieved from medical records. Two pathologists independently assessed hematoxylin and eosin-stained slides, employing modified Weiss criteria for all tumors and Lin-Weiss-Bisceglia criteria for oncocytic variants. Immunohistochemical markers (Calretinin, alpha-inhibin, MelanA, SF-1, Ki-67, PHH3, IGF-2, β-catenin, P53, CYP11B1, CYP11B2, MLH1, MSH2, MSH6, PMS2, EPCAM) and Gomori's Silver histochemistry were applied. Statistical analysis utilized SPSS Statistics 26.

RESULTS

ACCs exhibited larger tumor sizes (P<0.001) and symptomatic presentations (P = 0.031) compared to ACAs. Parameters of modified Weiss criteria and angioinvasion demonstrated diagnostic value for ACCs. Six immunohistochemical antibodies((MelanA, Ki-67, IGF-2, β-catenin, P53 and CYP11B1) and reticulin framework alterations showed diagnostic value. Notably, Ki-67 and reticulin staining were most recommended. Evident reticulin staining was frequently present in ACCs (P<0.001). Ki-67 was significantly higher in ACCs (P<0.001). Twenty-one conventional and seven oncocytic entities showed different necrosis frequencies. Symptoms and Ki-67 index ≥ 30% were prognostic for ACCs, correlating with shorter survival.

CONCLUSIONS

This study emphasizes the diagnostic value of reticulin framework alterations and a high Ki-67 index. Markers such as CYP11B1, IGF2, P53, β-catenin and MelanA also contribute to the diagnosis of ACCs. Symptoms and Ki-67 index ≥ 30% predict shorter survival. These findings encourges the use of ancillary markers such as reticulin histochemistry and Ki-67 in the workup of evaluations of adrenocortical neoplasms.

Investigation of Ki67 and Phospho-Histone H3 Expressions in Urothelial Carcinoma of the Bladder by Immunohistochemical Method

BACKGROUND

In our study, it is aimed to investigate the relationship between Ki67 and phospho-histone H3 (pHH3) expressions in bladder urothelial carcinomas, with clinicopathological parameters and survival, which have prognostic value.

METHODS

The study included 44 cases of high-grade urothelial carcinoma (HGUC), 37 cases of low-grade urothelial carcinoma (LGUC), and 11 nontumoral bladder cases. Ki67 and pHH3 were applied to the paraffin blocks of the tissues of 81 urothelial carcinoma and 11 nontumoral bladder cases by immunohistochemical method. Percentages of Ki67 and pHH3 expressions were evaluated by digital imaging analysis method. Expression percentages were compared with various clinicopathological parameters, and the relationship between them was evaluated.

RESULTS

Ki67 was expressed in 28% of urothelial carcinoma cases and 1% of nontumoral cases. pHH3 was expressed in 10.32% of urothelial carcinoma cases and 0.16% of nontumoral cases. In our study, we found significantly higher Ki67 and pHH3 expressions in urothelial carcinoma compared to nontumoral cases. There was a statistically significant relationship (p < 0.05) and a positive correlation between Ki67 expression and lymphovascular invasion, pT stage, and histological grade. A statistically significant relationship (p < 0.05) and a positive correlation were found between pHH3 expression and lymphovascular invasion, pT stage, recurrence, and histological grade. In addition, a statistically significant relationship was found between Ki67 and pHH3 expressions. In our study, survival was found to be low in high-grade urothelial carcinoma cases with lymphovascular invasion, advanced age (65 years and older), and high Ki67 and pHH3 expression rates.

CONCLUSIONS

According to our findings, high Ki67 and pHH3 expressions were found to be associated with poor prognostic parameters such as advanced pathologic stage, high histologic grade, and low survival. Our findings suggest that Ki67 and pHH3 may play a role in the differentiation, progression, and aggressive behavior of urothelial carcinoma. However, further studies are needed to confirm our findings and determine the role of these markers in urothelial carcinoma.

Impact of Histone Modifications and Their Therapeutic Targeting in Hematological Malignancies

Hematologic malignancies are a large and heterogeneous group of neoplasms characterized by complex pathogenetic mechanisms. The abnormal regulation of epigenetic mechanisms and specifically, histone modifications, has been demonstrated to play a central role in hematological cancer pathogenesis and progression. A variety of epigenetic enzymes that affect the state of histones have been detected as deregulated, being either over- or underexpressed, which induces changes in chromatin compaction and, subsequently, affects gene expression. Recent advances in the field of epigenetics have revealed novel therapeutic targets, with many epigenetic drugs being investigated in clinical trials. The present review focuses on the biological impact of histone modifications in the pathogenesis of hematologic malignancies, describing a wide range of therapeutic agents that have been discovered to target these alterations and are currently under investigation in clinical trials.

The 5th edition of the World Health Organization Classification of Haematolymphoid Tumours: Lymphoid Neoplasms

We herein present an overview of the upcoming 5^th edition of the World Health Organization Classification of Haematolymphoid Tumours focussing on lymphoid neoplasms. Myeloid and histiocytic neoplasms will be presented in a separate accompanying article. Besides listing the entities of the classification, we highlight and explain changes from the revised 4^th edition. These include reorganization of entities by a hierarchical system as is adopted throughout the 5^th edition of the WHO classification of tumours of all organ systems, modification of nomenclature for some entities, revision of diagnostic criteria or subtypes, deletion of certain entities, and introduction of new entities, as well as inclusion of tumour-like lesions, mesenchymal lesions specific to lymph node and spleen, and germline predisposition syndromes associated with the lymphoid neoplasms.

Tsc2 mutation induces renal tubular cell nonautonomous disease

TSC renal cystic disease is poorly understood and has no approved treatment. In a new principal cell-targeted murine model of Tsc cystic disease, the renal cystic epithelium is mostly composed of type A intercalated cells with an intact Tsc2 gene confirmed by sequencing, although these cells exhibit a Tsc-mutant disease phenotype. We used a newly derived targeted murine model in lineage tracing and extracellular vesicle (EV) characterization experiments and a cell culture model in EV characterization and cellular induction experiments to understand TSC cystogenesis. Using lineage tracing experiments, we found principal cells undergo clonal expansion but contribute very few cells to the cyst. We determined that cystic kidneys contain more interstitial EVs than noncystic kidneys, excrete fewer EVs in urine, and contain EVs in cyst fluid. Moreover, the loss of Tsc2 gene in EV-producing cells greatly changes the effect of EVs on renal tubular epithelium, such that the epithelium develops increased secretory and proliferative pathway activity. We demonstate that the mTORC1 pathway activity is independent form the EV production, and that the EV effects for a single cell line can vary significantly. TSC cystogenesis involves significant contribution from genetically intact cells conscripted to the mutant phenotype by mutant cell derived EVs.

Histone Modifications and Their Targeting in Lymphoid Malignancies

In a wide range of lymphoid neoplasms, the process of malignant transformation is associated with somatic mutations in B cells that affect the epigenetic machinery. Consequential alterations in histone modifications contribute to disease-specific changes in the transcriptional program. Affected genes commonly play important roles in cell cycle regulation, apoptosis-inducing signal transduction, and DNA damage response, thus facilitating the emergence of malignant traits that impair immune surveillance and favor the emergence of different B-cell lymphoma subtypes. In the last two decades, the field has made a major effort to develop therapies that target these epigenetic alterations. In this review, we discuss which epigenetic alterations occur in B-cell non-Hodgkin lymphoma. Furthermore, we aim to present in a close to comprehensive manner the current state-of-the-art in the preclinical and clinical development of epigenetic drugs. We focus on therapeutic strategies interfering with histone methylation and acetylation as these are most advanced in being deployed from the bench-to-bedside and have the greatest potential to improve the prognosis of lymphoma patients.

Proliferation Activity in Canine Gastrointestinal Lymphoma

Gastrointestinal lymphomas are uncommon in dogs and little is known about their distinct subtypes or proliferation rate. The aim of this study was to stratify 33 canine gastrointestinal lymphoma samples according to the latest World Health Organization classification and to determine the Ki67 proliferation index by manual counting, digital image analysis and visual estimation. The Ki67 index was then correlated with subtype, immunophenotype, mitotic index, grade and tumour location. The mitotic index correlated positively with the Ki67 index. A significantly higher number of Ki67-positive cells was found in enteropathy-associated T-cell lymphoma type I and in diffuse large B-cell lymphoma compared with enteropathy-associated T-cell lymphoma type II. There was also a significant difference in Ki67 immunolabelled cells between grade 1 and grade 2 lymphomas. Moderate agreement was found between the Ki67 index as obtained by manual counting and visual estimation, but there was strong agreement between manual counting and digital image analysis. The user-friendly digital imaging system used in this study could have potential for future determination of the Ki67 index in lymphoid neoplasms.

The receptor of the colony-stimulating factor-1 (CSF-1R) is a novel prognostic factor and therapeutic target in follicular lymphoma

Microenvironment contributes to follicular lymphoma (FL) pathogenesis and impacts survival with macrophages playing a controversial role. In the present study, using FL primary samples and HK follicular dendritic cells (FDC) to mimic the germinal center, together with mouse models, we have analyzed the three-way crosstalk of FL-FDC-macrophages and derived therapeutic opportunities. Ex vivo primary FL-FDC co-cultures (n = 19) and in vivo mouse co-xenografts demonstrated that FL-FDC crosstalk favors tumor growth and, via the secretion of CCL2 and CSF-1, promotes monocyte recruitment, differentiation, and polarization towards an M2-like protumoral phenotype. Moreover, FL-M2 co-cultures displayed enhanced angiogenesis, dissemination, and immunosuppression. Analysis of the CSF-1/CSF-1R pathway uncovered that CSF-1 was significantly higher in serum from grade 3A FL patients, and that high CSF-1R expression in FL biopsies correlated with grade 3A, reduced overall survival and risk of transformation. Furthermore, CSF-1R inhibition with pexidartinib (PLX3397) preferentially affected M2-macrophage viability and polarization program disrupting FL-M2 positive crosstalk. In vivo CSF1-R inhibition caused M2 reduction and repolarization towards M1 macrophages and antitumor effect cooperating with anti-CD20 rituximab. In summary, these results support the role of macrophages in FL pathogenesis and indicate that CSF-1R may be a relevant prognostic factor and a novel therapeutic target cooperating with anti-CD20 immunotherapy.

Improving precise counting of mitotic cells in mantle cell lymphoma using phosphohistone H3 (PHH3) antibody

AIMS

Mantle cell lymphoma (MCL) has a highly heterogeneous clinical course ranging from indolent, to aggressive and rapidly progressive disease. Proliferation is a strong predictor for disease outcome. In routine clinical practice, Ki-67 expression is used as a measure of proliferation. However, several studies have documented a high degree of inter-laboratory and inter-observer variation with Ki-67 immunohistochemistry. Phosphorylation of histone H3 occurs specifically during mitosis and hence serves as a specific marker for cells in mitosis.

METHODS AND RESULTS

We investigated phosphohistone H3 (PHH3) immunohistochemistry as a proliferation maker in 28 tissue biopsies of MCL and compared the PHH3 results (as evaluated by direct microscopic visualisation and image analysis-aided scoring) with morphological subtyping, mitotic counts and Ki-67 index. We found PHH3-mitotic count was about sixfold higher than H&E-mitotic count (mitoses in 10 high power fields). Furthermore, PHH3-mitotic count in aggressive morphological variants of MCL was significantly higher than in usual MCL. The PHH3-mitotic count showed a strong linear correlation with PHH3-mitotic index (percentage positive cells).

CONCLUSIONS

We found PHH3 immunohistochemistry, a reliable mitosis-specific marker, in MCL. Performing precise counts and evaluating precise proliferation indices is easier with PHH3 immunohistochemistry. This contrasts with the conventional estimation of Ki-67 percentages by 'eye-balling'.