Variability in morphology and cell proliferation in sequential biopsies of mantle cell lymphoma at diagnosis and relapse: clinical correlation and insights into disease progression

Assessment of Ki-67 Proliferative Index in Cytological Samples of Nodal B-Cell Lymphomas

BACKGROUND

The Ki-67 proliferative index (PI) is part of the diagnosis of nodal B-cell lymphoma (nBCL), but its determination in cytological samples is not standardized. We aimed to establish an approach for the accurate determination of the Ki-67 PI in cytological slides to differentiate between indolent and aggressive nBCLs.

METHODS

Patients diagnosed with nBCL by fine-needle aspiration biopsy and subsequent excision biopsy were included. Cell suspensions were prepared from biopsy samples for CD3/Ki-67 double immunocytochemical staining and flow-cytometric verification of lymphoma B-cell counts. The Ki-67 PI was assessed by manual counting and eyeballing in cytology and eyeballing in histology. The cut-off values for the differentiation between aggressive and indolent lymphomas were determined for each method.

RESULTS

A strong correlation between manual and flow-cytometric counting of lymphoma B cells was confirmed (interclass correlation coefficient (IC coef.) = 0.78). The correlation of the Ki-67 PI determined in cytological and histological slides was also strong (IC coef. > 0.80). Histologically, 55 cases were classified as indolent and 31 as aggressive nBCLs. KI-67 PI cut-off values of 28.5%, 27.5%, and 35.5% were established for manual counting and eyeballing in cytology and eyeballing in histology, respectively, with high sensitivity and specificity.

CONCLUSIONS

The Ki-67 PI, assessed by manual counting and eyeballing in cytological samples, accurately differentiates between indolent and aggressive nBCLs.

EBV-Positive Pleomorphic Variant Transformation of CD5-Negative Mantle Cell Lymphoma: A Rare Case Report and Literature Review

Mantle cell lymphoma (MCL) is a mature B-cell lymphoma associated with cyclin D family rearrangements and typically expresses CD5 and cyclin D1. Epstein-Barr virus- (EBV-) positive MCL is rare, and the role of EBV infection and its transformation in MCL remains unclear. We present a case of CD5-negative classic MCL that progressed to an EBV + pleomorphic MCL six years after the initial diagnosis. Molecular studies confirmed the same clonal origin. To the best of our knowledge, the EBV-positive transformation of CD5-negative MCL into a pleomorphic variant has rarely been reported, and its recognition is important for the diagnosis and the management of patients with MCL.

Skin Involvement by Hematological Neoplasms with Blastic Morphology: Lymphoblastic Lymphoma, Blastoid Variant of Mantle Cell Lymphoma and Differential Diagnoses

Hematological neoplasms sharing a blastic morphology may involve the skin. The skin may be either the primary site of occurrence of hematological malignancies with blastic features or cutaneous lesions are the first manifestation of an underlying systemic malignancy. The assessment of skin biopsies of hematological neoplasms with blastic features poses diagnostic problems and requires expert hematopathologists considering a wide range of differential diagnoses. The precise diagnosis of diseases sharing blastic features but with different outcomes and requiring distinct therapies is essential for patient management. The present paper mainly focuses on cutaneous involvement of the blastoid variant of mantle cell lymphoma and lymphoblastic lymphoma of B-cell or T-cell origin. The relevant literature has been reviewed and the clinical aspects, pathological features, prognosis, and therapy of both blastoid mantle cell lymphoma and lymphoblastic lymphoma involving the skin are discussed. A focus on other hematological entities with blastic features, which may involve the skin, to be taken into consideration in differential diagnosis is also given.

Chronic lymphocytic leukaemia/small lymphocytic lymphoma and mantle cell lymphoma: from early lesions to transformation

The International Clinical Advisory Committee reviewed advances in our understanding of the clinicopathologic and biologic features of chronic lymphocytic leukaemia/small lymphocytic lymphoma, B-cell prolymphocytic leukaemia, and mantle cell lymphoma since the revised 4th edition of the WHO Classification of Tumours of the Haematopoietic and Lymphoid Tissues. Discussions amongst pathologists, clinicians, and molecular geneticists around these diseases focussed on incorporating new knowledge into the next classification system. In this manuscript, we review these disease entities and incorporate results of these deliberations, including advances in our understanding of early lesions and transformation.

POT1 mutations are frequent and associated with Ki-67 index in canine diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) represents one of the most frequent and deadliest neoplasia in dogs worldwide and is characterized by a remarkable degree of clinical heterogeneity, with poor chances to anticipate the outcome. Even if in the last years some recurrently mutated genes have been identified, the genetic origin of canine DLBCL (cDLBCL) is not yet completely understood. The aim of the present study was to assess the prevalence of POT1 mutations in cDLBCL and to elucidate the role of such gene in the pathogenesis of this tumor. Mutations in POT1 were retrieved in 34% of cases, in line with previous reports, but no significant associations with any clinico-pathological variable were identified. Likewise, POT1 mutations are not predictive of worse prognosis. Interestingly, Ki-67 index was significantly higher in dogs harboring POT1 mutations compared to wild-type ones. These results suggest that POT1 mutations may exert their pathogenic role in cDLBCL by promoting cellular proliferation.

Progress in molecular feature of smoldering mantle cell lymphoma

Mantle cell lymphoma (MCL) is considered one of the most aggressive lymphoid tumors. However, it sometimes displays indolent behavior in patients and might not necessitate treatment at diagnosis; this has been described as "smoldering MCL" (SMCL). There are significant differences in the diagnosis, prognosis, molecular mechanisms and treatments of indolent MCL and classical MCL. In this review, we discuss the progress in understanding the molecular mechanism of indolent MCL to provide insights into the genomic nature of this entity. Reported findings of molecular features of indolent MCL include a low Ki-67 index, CD200 positivity, a low frequency of mutations in TP53, a lack of SOX11, normal arrangement and expression of MYC, IGHV mutations, differences from classical MCL by L-MCL16 assays and MCL35 assays, an unmutated P16 status, few defects in ATM, no NOTCH1/2 mutation, Amp 11q gene mutation, no chr9 deletion, microRNA upregulation/downregulation, and low expression of several genes that have been valued in recent years (SPEN, SMARCA4, RANBP2, KMT2C, NSD2, CARD11, FBXW7, BIRC3, KMT2D, CELSR3, TRAF2, MAP3K14, HNRNPH1, Del 9p and/or Del 9q, SP140 and PCDH10). Based on the above molecular characteristics, we may distinguish indolent MCL from classical MCL. If so, indolent MCL will not be overtreated, whereas the treatment of classical MCL will not be delayed.

Mantle Cell Lymphoma With Mantle Zone Growth Pattern

OBJECTIVES

To characterize the clinical and pathologic features of mantle cell lymphoma with mantle zone growth pattern (MCL-MZGP).

METHODS

The clinicopathologic data from 35 cases of MCL-MZGP obtained in 12 centers were analyzed.

RESULTS

The patients with MCL-MZGP typically sought treatment at high clinical stages (81%). Intriguingly, 40% (14/35) of cases were incidentally noted. The lymph nodes with MCL-MZGP showed preserved architecture and expanded mantles containing lymphoma cells with classic or small cell cytology. MCL-MZGP was positive for BCL2 (96%, bright), CD5 (82%, moderate), cyclin D1 (100%), and SOX11 (89%). Clinically, our study revealed no significant difference in the overall survival between patients managed with observation alone and those who received chemotherapy.

CONCLUSIONS

MCL-MZGP was often incidentally identified and resembled reactive mantles. Therefore, recognition of this unusual morphology emphasizes the utility of cyclin D1 immunostain in the cases with suspicious morphology. However, the clinical significance of these findings is still unclear.

Blastoid and pleomorphic mantle cell lymphoma: still a diagnostic and therapeutic challenge!

Blastoid mantle cell lymphoma is characterized by highly aggressive features and a dismal clinical course. These blastoid and pleomorphic variants are defined by cytomorphological features, but the criteria are somewhat subjective. The diagnosis may be supported by a high cell proliferation based on the Ki-67 labeling index. Recent analyses have shown that the Ki-67 index overrules the prognostic information derived from the cytology subtypes. Nevertheless, genetic analysis suggests that blastoid and pleomorphic variants are distinct from classical mantle cell lymphoma. In clinical cohorts, the frequency of these subsets varies widely but probably represents ∼10% of all cases. Chemotherapy regimens commonly used in mantle cell lymphoma, such as bendamustine, rarely achieve prolonged remissions when given at the dosage developed for classical variants of the disease. Thus, high-dose cytarabine–containing regimens with high-dose consolidation may be generally recommended based on the more aggressive clinical course in these patients. However, even with these intensified regimens, the long-term outcome seems to be impaired. Thus, especially in this patient subset, allogeneic transplantation may be discussed at an early time point in disease management. Accordingly, targeted approaches are warranted in these patients, but clinical data are scarce. Ibrutinib treatment results in high rates of responses, but the median duration of remission is <6 months. Similarly, lenalidomide and temsirolimus result in only short-term remissions. Novel approaches, such as chimeric antigenic receptor T cells, may have the potential to finally improve the dismal long-term outcome of these patients.

Smoldering mantle cell lymphoma

Background

Mantle cell lymphoma (MCL) is an aggressive disease, with poor prognosis and a limited survival. However, some patients with indolent MCL can survive beyond 7~10 years. These patients remain largely asymptomatic and can be in observation for a long time without any treatment. The process of “wait and watch” leaves these patients with the potential risk of evolution to classic, aggressive MCL. On the other hand, early treatment for these patients may not impact overall survival but rather affects the quality of life. Therefore, it is essential to clearly identify this type of indolent MCL at the time of diagnosis.

Results

Reported findings of indolent presentation of MCL include: lack of B symptoms, normal serum lactic dehydrogenase (LDH) and β2-microglobulin levels (β2M), low MCL-International Prognostic Index (MIPI) score, maximum tumor diameter less than 3 cm, spleen size < 20 cm, positron emission tomography/computerized tomography with the Standard Uptake Value max <6, Ki-67 less than 30%, with some particular immunophenotype, such as CD5 and CD38 negative, markedly increased CD23 positive lymphocytes proportions, high expression of CD200, kappa light chain restriction, without C-myc, TP53 and NOTCH1/2 mutations, non-blastoid/pleomorphic histology, and no tumor growth on reevaluation every 2~3 months (followed for at least 6 months). Imaging evaluation may only be performed in the presence of disease-related symptoms or organ involvement. Meanwhile, if novel nodal or extranodal lesion is found, biopsy is mandatory to exclude lymphoma.

Common clinopathological forms of indolent presentations include monoclonal B lymphocytosis with t (11; 14); “indolent leukemic” presentation of MCL with involvement of peripheral blood, bone marrow involvement, splenomegaly, and minimal lymphadenopathies and in situ lymphoma (often found in lymph nodes removed for other reasons, and in gastrointestinal biopsies).

Conclusions

Considering these distinct indolent clinical presentations with particular features in cytology and gene mutational status, we propose to include these MCL clinical presentations under the umbrella of “Smoldering Mantle Cell Lymphoma”.

Mantle Cell Lymphoma: Contemporary Diagnostic and Treatment Perspectives in the Age of Personalized Medicine

Mantle cell lymphoma is a clinically heterogeneous disease occurring within a heterogeneous patient population, highlighting a need for personalized therapy to ensure optimal outcomes. It is therefore critical to understand the benefits and risks associated with both intensive and deintensified approaches. In the following review we provide a therapeutic roadmap to strategically guide treatment for newly diagnosed and relapsed/refractory patients highlighting pivotal and recently published results involving known and novel therapies.

Prognostic Value of Ki-67 Index, Cytology, and Growth Pattern in Mantle-Cell Lymphoma: Results From Randomized Trials of the European Mantle Cell Lymphoma Network

Purpose

Mantle-cell lymphoma (MCL) is a rather aggressive B-cell malignancy whose considerable variability of individual outcome is associated with clinical characteristics (Mantle Cell Lymphoma International Prognostic Index [MIPI]). The Ki-67 index is a strong independent prognostic factor; however, the biologic MIPI (MIPI-b) distinguishes only two groups, which does not appropriately depict the clinical heterogeneity. By using the cohort from the European MCL Younger and MCL Elderly trials, we aimed to evaluate the additional prognostic impact of cytology and growth pattern and to improve risk stratification with the Ki-67 index and MIPI.

Patients and Methods

Diagnostic tumor biopsies were reviewed by the European Mantle Cell Lymphoma Pathology Panel to determine Ki-67 index by using published guidelines, cytology, and growth pattern. We evaluated prognostic effects for overall survival (OS) by Cox regression. For the cohort used for MIPI-b development (German Low-Grade Lymphoma Study Group [GLSG] 1996 and GLSG2000), we checked whether the equally weighted combination of Ki-67 index (dichotomized at the validated 30% cutoff) and MIPI risk groups was adequate and compared the prognostic power of this modified combination to MIPI and MIPI-b for the MCL Younger/MCL Elderly cohort.

Results

The Ki-67 index was assessed in 508 of 832 patients (median age, 62 years). Blastoid cytology was associated with inferior OS independently of MIPI but not independently of the Ki-67 index. Growth pattern was not independently prognostic. The modified combination of the Ki-67 index and MIPI separated four groups with 5-year OS: 85%, 72%, 43%, and 17% (P < .001) and was more discriminative than MIPI and MIPI-b.

Conclusion

Using the Ki-67 index is superior to using cytology and growth pattern as prognostic factors in MCL. The modified combination of the Ki-67 index and MIPI showed a refined risk stratification, reflecting their strong complementary prognostic effects while integrating the most relevant prognostic factors available in clinical routine.

Novel agents in mantle cell lymphoma

Mantle cell lymphoma (MCL) is an uncommon B-cell non-Hodgkin lymphoma, comprising approximately 6-8% of all non-Hodgkin lymphomas. MCL is biologically and clinically heterogeneous, and there is no standard treatment for MCL. Although untreated MCL often responds well to frontline combination chemotherapy, relapsed, refractory MCL can be challenging to treat and traditional cytotoxic chemotherapy is typically not highly effective. In recent years, increased insight into the molecular and genomic diversity of MCL and the pathogenesis of the disease has given rise to the development of many new biologically targeted therapies. Ibrutinib was recently FDA approved for relapsed, refractory MCL and will likely have a significant impact on treatment paradigms for MCL. In addition to ibrutinib, there are many classes of novel agents that are currently in development. This review focuses on recent developments in the management of relapsed, refractory MCL, describing the growing armamentarium of novel agents available to combat this disease.

Postibrutinib outcomes in patients with mantle cell lymphoma

Despite unprecedented clinical activity in mantle cell lymphoma (MCL), primary and acquired resistance to ibrutinib is common. The outcomes and ideal management of patients who experience ibrutinib failure are unclear. We performed a retrospective cohort study of all patients with MCL who experienced disease progression while receiving ibrutinib across 15 international sites. Medical records were evaluated for clinical characteristics, pathological and radiological data, and therapies used pre- and postibrutinib. A total of 114 subjects met eligibility criteria. The median number of prior therapies was 3 (range, 0-10). The Mantle Cell Lymphoma International Prognostic Index (MIPI) scores at the start of ibrutinib were low, intermediate, and high in 46%, 31%, and 23% of patients, respectively. Of patients with available data prior to ibrutinib and postibrutinib, 34 of 47 and 11 of 12 had a Ki67 >30%. The median time on ibrutinib was 4.7 months (range 0.7-43.6). The median overall survival (OS) following cessation of ibrutinib was 2.9 months (95% confidence interval [CI], 1.6-4.9). Of the 104 patients with data available, 73 underwent subsequent treatment an average of 0.3 months after stopping ibrutinib with a median OS of 5.8 months (95% CI, 3.7-10.4). Multivariate Cox regression analysis of MIPI before postibrutinib treatment, and subsequent treatment with bendamustine, cytarabine, or lenalidomide failed to reveal any association with OS. Poor clinical outcomes were noted in the majority of patients with primary or secondary ibrutinib resistance. We could not identify treatments that clearly improved outcomes. Future trials should focus on understanding the mechanisms of ibrutinib resistance and on treatment after ibrutinib.

New paradigms in mantle cell lymphoma: is it time to risk-stratify treatment based on the proliferative signature?

The elucidation of crucial biologic pathways of cell survival and proliferation has led to the development of highly effective drugs, some of which have markedly improved mantle cell lymphoma (MCL) therapeutic opportunities in the past 10 years. Moreover, an undeniable clinical heterogeneity in treatment response and disease behavior has become apparent in this neoplasm. Thus, the need for biologic markers stratifying patients with MCL in risk classes deserving different treatment approaches has recently been fervently expressed. Among several newly discovered biomarkers, the dismal predictive value of a high proliferative signature has been broadly recognized in large studies of patients with MCL. Different techniques have been used to assess tumor cell proliferation, including mitotic index, immunostaining with Ki-67 antibody, and gene expression profiling. Ki-67 proliferative index, in particular, has been extensively investigated, and its negative impact on relapse incidence and overall survival has been validated in large prospective clinical trials. However, one important pitfall limiting its widespread use in clinical practice is the reported interobserver variability, due to the previous lack of a standardized approach for quantification among different laboratories. In the present review, we describe some of the major techniques to assess cell proliferation in MCL, focusing in particular on the Ki-67 index and its need for a standardized approach to be used in multicenter clinical trials. The value of MCL biologic prognostic scores (as MIPI-b) is discussed, along with our proposal on how to integrate these scores in the planning of future trials investigating a tailored therapeutic approach for patients with MCL. See all articles in this CCR Focus section, "Paradigm Shifts in Lymphoma."

Ki67 is a promising molecular target in the diagnosis of cancer (review)

The expression of Ki67 is strongly associated with tumor cell proliferation and growth, and is widely used in routine pathological investigation as a proliferation marker. The nuclear protein Ki67 (pKi67) is an established prognostic and predictive indicator for the assessment of biopsies from patients with cancer. Clinically, pKi67 has been shown to correlate with metastasis and the clinical stage of tumors. In addition, it has been shown that Ki67 expression is significantly higher malignant tissues with poorly differentiated tumor cells, as compared with normal tissue. According to its predictive role, pKi67 expression identifies subpopulations of patients who are more likely to respond to a given therapy. The Ki67 labeling index is an independent prognostic factor for survival rate, which includes all stages and grade categories. There is a correlation between the ratio of Ki67‑positive malignant cells and patient survival. It has been shown that blocking of Ki67 either by microinjection of antibodies or through the use of antisense oligonucleotides leads to the arrest of cell proliferation. Specifically, antisense oligonucleotides and antibodies against pKi67 have been shown to inhibit the progression of the cell cycle. The Ki67 protein is well characterized at the molecular level and is extensively used as a prognostic and predictive marker for cancer diagnosis and treatment. Increasing evidence indicates that Ki67 may be an effective target in cancer therapy. It therefore merits further development, including testing in more sophisticated in vitro and appropriate in vivo models. This review provides an overview of recent advances in this field.

No evidence of cell cycle dysregulation in mantle cell lymphoma in vivo

Mantle cell lymphoma (MCL) is characterized by the translocation t(11;14)(q13;q32) leading to an overexpression of cyclin D1, a mediator of G1-S phase transition. Thus MCL is regarded as a paradigm of lymphoma with a dysregulated cell cycle. The proliferation rate of MCL is in fact a strong predictor of outcome. We analyzed proteins that are expressed at defined cell cycle phases, such as Ki67, survivin and phosphorylated histone H3 as well as cyclin D1, p53 and p27, on the cellular level by immunofluorescence double stainings in MCL biopsy specimens. Unexpectedly, we did not detect a shortening of early phases in MCL in vivo. Despite the control of the immunoglobulin enhancer, cyclin D1 was expressed in a cell cycle-dependent manner. However, the proliferating Ki67-positive tumor cells expressed low amounts of cyclin D1. Therefore, the expression of cyclin D1 appears not to be the driving factor behind the total proliferation rate of MCL.