Leukemic Non-nodal Mantle Cell Lymphoma Research Articles

Optical genomic mapping is a helpful tool for detecting CCND1 rearrangements in CD5-negative small B-cell lymphoma: Two cases of leukemic non-nodal mantle cell lymphoma

Optical genome mapping (OGM) is a new DNA-based technology which provides comprehensive examination of the entire genome. We report two patients who presented with splenomegaly and leukocytosis with lymphocytosis including villous lymphocytes. Neither patient had lymphadenopathy. Bone marrow evaluation showed involvement by small B-cell lymphoma in a sinusoidal and interstitial distribution, and immunophenotypic analysis showed that the neoplastic cells were positive for B-cell markers and cyclin D1 but were negative for SOX11 and CD5. Initially, the clinicopathologic features in both patients were thought to be suspicious for hairy cell leukemia variant or splenic marginal zone lymphoma. However, OGM detected CCND1 rearrangement: t(2;11)/IGK::CCND1 in one case and t(11;14)/IGH::CCND1 in the other case. These cases illustrate the valuable role OGM can play in establishing the diagnosis of MCL. Case 1 also contributes to the paucity of literature on the rare occurrence of IGK::CCND1 in MCL.

Clinical and biological features and prognosis of patients with leukemic non-nodal mantle cell lymphoma

Objective: To investigate the clinical, biological and prognostic characteristics of leukemic non-nodal mantle cell lymphoma (nnMCL). Methods: The clinical data of 14 patients with nnMCL and 238 patients with classical mantle cell lymphoma (cMCL) in Blood Diseases Hospital, Chinese Academy of Medical Sciences from November 2000 to October 2020 were retrospectively analyzed. Among the 14 patients with nnMCL, there were 9 males and 5 females, with the age [M (Q1, Q3)] of 57.5 (52.3, 67.0) years. Among the 238 patients with cMCL, there were 187 males and 51 females, with the age of 58.0 (51.0, 65.3) years. The clinical and biological characteristics of the two groups were recorded and compared. Follow-up and efficacy evaluation were conducted by re-examination during hospital stay and telephone follow-up and so on. Results: The proportion of CD200 expression in nnMCL patients was 8/14, which was higher than that in cMCL patients [14.6% (19/130)] (P=0.001). The proportion of CD23 expression in nnMCL patients was 8/14, which was higher than that in cMCL patients [13.5% (23/171)] (P<0.001). The proportion of CD5 expression in nnMCL patients was 10/14, which was lower than that in cMCL patients [97.4% (184/189)] (P=0.001). The proportion of CD38 expression in nnMCL patients was 4/14, which was lower than that in cMCL patients [69.6% (112/161)] (P=0.005). The expression proportion of sex-determining region of Y chromosome-related high-mobility-group box 11 (SOX11) in nnMCL patients was 1/5, which was lower than that in cMCL patients [77.9% (60/77)] (P=0.014). The proportion of immunoglobulin heavy chain variable region (IGHV) mutations in nnMCL patients was 11/11, which was higher than that in cMCL patients [26.0% (13/50)] (P<0.001). As of April 11, 2021, the follow-up time for nnMCL and cMCL patients was 31 (8-89) months and 48 (0-195) months, respectively. Among the 14 nnMCL patients, 6 patients were still under observation, and 8 patients were treated. The overall response rate (ORR) was 8/8, including 4 patients with complete remission and 4 patients with partial response. The median overall survival and median progression-free survival were not reached in nnMCL patients. In the cMCL group, 50.0% (112/224) patients achieved a complete response, 24.6% (55/224) patients achieved a partial response, and ORR was 74.6% (167/224). There was no statistically significant difference in ORR between the two groups (P=0.205). Conclusions: nnMCL patients have an indolent progression, with higher expression rates of CD23 and CD200 and lower expression rates of SOX11, CD5 and CD38. Most patients have IGHV mutations, with a relatively good prognosis, and"watch and wait"approach is an optional treatment.

Updates in the treatment of mantle cell lymphoma: A Canadian expert framework

Mantle cell lymphoma (MCL) is a B cell Non-Hodgkin Lymphoma that develops in the mantle zone of the lymph node. It is more common in men and is usually diagnosed at an advanced stage with involvement of lymph nodes, bone marrow, and potentially the gastrointestinal tract. MCL accounts for 5–10% of all new NHL cases per year in Canada, which is estimated at 11,400 for 2022. While most patients respond to initial treatment, relapses occur early and MCL generally shows a variable response to subsequent treatments, often with limited duration of benefit. Two main subtypes of MCL can be distinguished that arise from in situ MCL lesions. The most common subtype, classic MCL, arises from these cells with limited or no immunoglobulin heavy chain variable region (IGHV) mutations. Cells from this subtype express SOX11, are genetically unstable, and have naïve B cell-like characteristics. Classic MCL is more often nodal and extranodal and may eventually progress to aggressive blastoid or pleomorphic MCL. The other subtype, leukemic non-nodal MCL, arises from cells that have undergone IGHV somatic hypermutations, do not express SOX11, and exhibit characteristics of memory B cells. This subtype can have an indolent clinical behavior for a long time, often several years, but frequently acquires TP53 and other mutations and progresses to a more aggressive subtype. Treatment options have expanded significantly over the past decades, with improvements in both overall survival (OS) and progression-free survival (PFS) compared to earlier treatment eras. This Canadian expert framework aims to discuss the management considerations for patients with MCL, and will present both front-line treatment options as well as those for relapsed and refractory disease.

Whole-Genome Analysis of Histone Modifications Reveals New Insights into the Biology and Clinical Behavior of Mantle Cell Lymphoma Subtypes

Introduction: Mantle cell lymphoma (MCL) is a mature B-cell neoplasm characterized by the t(11;14)(q13;q32) leading to cyclin D1 overexpression. Two major clinico-biological subtypes of MCL have been recognized, conventional (cMCL) and leukemic non-nodal MCL (nnMCL), being the former clinically more aggressive than the latter. Although these subtypes have been well characterized at the genomic level, the genome-wide landscape of histone modifications is widely unknown. Aim: To explore whether an integrative multiomic analysis of chromatin marks and gene expression may help us to better understand the biology and clinical behavior of cMCL and nnMCL. Methods: We carried out 2 profiling strategies. On the one hand, we performed ChIP-seq for H3K27ac, which marks active regulatory elements, in a series of 52 MCL cases, and we also profiled chromatin accessibility by ATAC-seq in 28 of these cases. On the other hand, we performed ChIP-seq for 6 histone modifications with complementary functions (H3K4me1, H3K4me3, H3K27ac, H3K36me3, H3K27me3 and H3K9me3) in purified neoplastic cells of 3 cMCL and 3 nnMCL, and we mined ChIP-seq data from normal B cell subpopulations. Additionally, we analyzed previously published expression data from 44 MCL profiled by Affymetrix U219 microarrays. Clinical data were available for most cases. Data were analyzed using a battery of computational and statistical approaches. Results: An initial unsupervised principal component analyses of the H3K27ac and ATAC-seq data revealed 2 main clusters corresponding to cMCL and nnMCL, indicating that the chromatin landscape is markedly different between the 2 MCL subtypes. A supervised differential analysis of H3K27ac data between cMCL and nnMCL showed extensive differences, mostly associated with increased H3K27ac in cMCL. Putting the data in the context of normal B cell subpopulations, we identified 746 de novo active regions in cMCL and 126 in nnMCL (LFC>1, FDR ≤0.05). Interestingly, more than 60% of these regions were enhancers according to the chromatin states analysis (derived from the integration of 6 histone modifications), and the majority of them presented an open chromatin configuration. This chromatin activation patterns correlated with transcriptional differences between cMCL and nnMCL. Analyzing the target genes of these regions, we identified 167 and 20 upregulated genes in cMCL and nnMCL, respectively. Upregulated genes in cMCL were linked to cellular processes related to cell cycle and cell proliferation according to gene ontology analysis. Analyzing the transcription factor binding motifs present in the ATAC-seq peaks among the de novo active H3K27ac regions in cMCL, we observed an enrichment in specific transcription factor families such as Krüppel-like family (KLF) and E2F. However, there was no significant enrichment in any transcription factor family among nnMCL de novo active regions. Moreover, although the cMCL-associated de novo H3K27ac signature was common to all cMCL cases, we did observe varying H3K27ac levels among cases. We then explored whether H3K27ac levels could be associated with clinical features in cMCL. In fact, we identified 100 specific regions whose increased H3K27ac levels were significantly associated with shorter overall survival, leading to the identification of two subgroups of cMCL with markedly different clinical behavior. Conclusions: The results obtained with this multilayer chromatin analysis confirm that MCL is a heterogeneous disease showing widespread differences between the 2 subtypes. cMCL present a clear de novo chromatin activation associated with upregulation of key genes involved in cMCL pathogenesis, while nnMCL cases seem to be characterized by the absence of this signature and an overall chromatin profile more similar to normal B cells. Moreover, the level of activation in regulatory regions in cMCL seems to be related with the clinical outcome of the patients, with more activation associated with shorter overall survival.

Mutations of ATM Confer a Risk of Inferior Survival in Patients with TP53-wild Type Mantle Cell Lymphoma

Background: Despite improved approaches to prognostication in mantle cell lymphoma (MCL), the impact of specific genomic aberrations is not well-described beyond TP53, which is well recognized as a high-risk marker across malignancies and widely assessed at time of diagnosis. However, since outcomes in patients without TP53 aberrations can be highly variable and difficult to predict, additional molecular markers are needed to identify patients who are at high risk for early relapse and inferior OS (Bond et al, Blood Adv 2021). In this study, we used comprehensive whole exome and transcriptome sequencing to genomically assess the prognostic impact of recurrent abnormalities in patients with MCL with and without TP53 aberrations. Methods: The Atlas of Blood Cancer Genomes (ABCG) project is a worldwide effort to systematically profile the genetic alterations and expression changes in all blood cancers. We recruited MCL patients with detailed clinical data available and subjected their tumors to whole exome and transcriptome sequencing. TP53-aberrant cases were identified from the genomic and diagnostic data. Progression-free survival (PFS) and overall survival (OS) were measured from the date of diagnosis until date of progression/relapse or death (PFS) or death (OS) using the Kaplan-Meier method and statistical comparisons by the logrank test. Results: Whole exome and whole transcriptome sequencing was performed successfully for 252 patients with MCL. Consistent with previous descriptions of the disease, median age at diagnosis was 65 years (range: 32-96), and 73% of patients were male. Seventy-five percent of patients had stage IV disease, and MIPI score was high, intermediate, or low in 34%, 34%, and 32% of patients, respectively. Ki67 proliferative index was ≥30% in 48% of patients with available data (n=115). Most patients received commonly used MCL therapies. Of the 185 patients for whom first-line treatment was known, 28% received bendamustine-containing regimens, 42% received cytarabine-containing regimens, and the remaining 30% received other regimens. Twenty-one percent of patients underwent autologous stem cell transplant consolidation as part of first-line therapy. Seventeen percent of patients had blastoid or pleomorphic histology, and 3% had leukemic non-nodal type MCL. Median PFS for the entire cohort was 41 months, and median OS was 138 months. As expected, patients with a confirmed TP53 abnormality (n=39) had inferior median OS compared to TP53-WT patients (n=84; 39 months vs 138 months, p<0.001). Recurrent mutations identified in TP53-aberrant and TP53-WT patients are presented in Figure 1. Among TP53-WT patients, the following genes were mutated in ≥10% of cases: ATM (45%), KMT2D (23%), PTPN13 (13%), NOTCH1 (13%), NSD2 (11%), and SPEN (10%). Incidence of ATM mutations in TP53-aberrant patients was 21% and was less common in patients with TP53 mutations (14%) rather than deletions (30%). Presence of an ATM mutation (median variant allele frequency 43%; range 15-96%) in TP53-WT patients was associated with inferior median PFS (38 months vs 138 months for ATM WT, p=0.023) (Figure 2); median OS was also shorter in patients with ATM mutations (104 vs 138 months, p=0.035). Although the incidence of ATM mutations was lower in TP53-aberrant patients, there was no significant association between ATM mutation and PFS or OS in that subgroup. Conclusions: To our knowledge, this study represents the largest genomic characterization of clinical outcomes in MCL patients. These findings suggest a pathogenic role for ATM mutations in patients with TP53-WT MCL and provide molecular insights into their heterogeneous outcomes. Although ATM mutations have been previously shown to be mutually exclusive with TP53 mutations (Mareckova et al, Leukemia & Lymphoma 2019), to our knowledge this is the first study that shows prognostic differences by ATM mutation status among TP53-WT patients. Our data indicate that ATM mutations are a significant prognostic factor and should be assessed at diagnosis along with TP53. Further clinical investigation of ATM mutations in TP53-WT MCL patients will be important to determine how this molecular marker may inform risk stratification and treatment approaches. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Concurrent JAK2 V617F Acute Myeloid Leukemia (AML) and Leukemic non-nodal Mantle Cell Lymphoma (LN-MCL): Case study

Abstract Introduction/Objective We report a unique case of concurrently occurring Acute Myeloid Leukemia (AML) and Leukemic non-nodal Mantle Cell Lymphoma (LN-MCL) in an 86-year-old male. To the best of our knowledge, this is the first report of AML occurring in the background of LN-MCL, with no known history of any malignancy or chemotherapy. Methods/Case Report An 86-year old Caucasian male with unremarkable past medical history presented with pancytopenia, fatigue and generalized weakness. Abdominal CT scan was negative for lymphadenopathy or hepatosplenomegaly. Peripheral blood showed 2% blasts with atypical lymphocytes 89%. Bone marrow aspirate showed 30% myeloblasts expressing CD34, CD117, CD13, CD33, HLA-DR and CD56 (dim) by flow cytometry (FC). Lymphocytes accounted for 40% of bone marrow cellularity. FC identified a population of CD5+ kappa restricted clonal B cells 2%, consistent with a concurrent CD5+ B-lymphoproliferative disorder/lymphoma. The bone marrow biopsy was inadequate for further evaluation of the B- cell lymphoma. Chromosomal analysis revealed a normal male karyotype. FISH analysis was positive for t(11:14) CCND1::IGH rearrangement (in 3.5% of interphase cells) supporting involvement by MCL. Myeloid panel next generation sequencing (51 genes) was positive for JAK2 V617F (VAF, 38%) and ASXL1 P920Tfs*4 (VAF, 22%) variants Results (if a Case Study enter NA) NA Conclusion Concurrent presence of LN-MCL and AML as seen in our patient in the absence of prior history of malignancy or chemotherapy is rare. Presence of JAK2V617F mutation in de-novo AML is extremely rare (&amp;lt;5%). There is no prior history of myeloproliferative neoplasm (MPN) or CBC data to suggest that this may have progressed from an MPN. While the absence of lymphadenopathy suggests that the CD5+ B-LPD likely represents LN-MCL, it is also likely that the CD5+, IgH/CCND1 rearranged B-cells may represent prior undetected circulating cells without overt LN-MCL development, similar to those reported in otherwise healthy individuals. It is unclear but tempting to speculate that the two co-occurring hematologic malignancies may have a common cell of origin

A novel diagnostic approach for the classification of small B-cell lymphoid neoplasms based on the NanoString platform

Small B-cell lymphoid neoplasms (SBCLNs) are a heterogeneous group of diseases characterized by malignant clonal proliferation of mature B-cells. However, the classification of SBCLNs remains a challenge, especially in cases where histopathological analysis is unavailable or those with atypical laboratory findings or equivocal pathologic data. In this study, gene expression profiling of 1039 samples from 27 gene expression omnibus (GEO) datasets was first investigated to select highly and differentially expressed genes among SBCLNs. Samples from 57 SBCLN cases and 102 nonmalignant control samples were used to train a classifier using the NanoString platform. The classifier was built by employing a cascade binary classification method based on the random forest algorithm with 35 refined gene signatures. Cases were successively classified as chronic lymphocytic leukemia/small lymphocytic lymphoma, conventional mantle cell lymphoma, follicular lymphoma, leukemic non-nodal mantle cell lymphoma, marginal zone lymphoma, lymphoplasmacytic lymphoma/Waldenström's macroglobulinemia, and other undetermined. The classifier algorithm was then validated using an independent cohort of 197 patients with SBCLNs. Under the distribution of our validation cohort, the overall sensitivity and specificity of proposed algorithm model were >95%, respectively, for all the cases with tumor cell content greater than 0.72. Combined with additional genetic aberrations including IGH-BCL2 translocation, MYD88 L265P mutation, and BRAF V600E mutation, the optimal sensitivity and specificity were respectively found at 0.88 and 0.98. In conclusion, the established algorithm demonstrated to be an effective and valuable ancillary diagnostic approach for the sub-classification and pathologic investigation of SBCLN in daily practice.

The pathologic diagnosis of mantle cell lymphoma.

Mantle cell lymphoma (MCL) is a mature B-cell non-Hodgkin lymphoma usually characterized by t(11;14) (q13;q32), or CCND1 translocation and Cyclin D1 over expression. A very small subset of MCL may lack the t(11;14) (q13;q32) translocation and Cyclin D1 over expression, but show alternative translocations involving CCND2 and CCND3, and over expression of SOX11. In general, MCL has been considered a very aggressive and incurable lymphoma and patients with MCL usually have a poor prognosis. However, indolent variants, including in situ mantle cell neoplasm and the recently recognized leukemic non-nodal MCL do exist. In recent years, genome-wide molecular genetic studies have revealed a characteristic MCL genetic profile. This review will focus on the pathologic diagnosis of MCL using the traditional morphological and immunophenotypic strategies combined with cytogenetic characteristics and recently identified molecular profile. Morphological subtypes, immunophenotypic variants, recently recognized indolent variants, as well as MCL risk stratification will also be discussed.

Pathology and Diagnosis of Mantle Cell Lymphoma

Mantle Cell Lymphoma (MCL) is a rare type of B-cell non-Hodgkin lymphoma (NHL), characterised by an aggressive clinical course and a poor prognosis that remains incurable for the majority of patients. Cyclin D1 overexpression, which results from t(11; 14)(q13; q32), is the pathogenic hallmark in MCL disease and causing cell cycle disruption. MCL has been categorized based on lymphoid malignancies in the WHO update into two significant subgroups, nodal and leukemic non-nodal MCL; each type has a particular clinical presentation and distinct molecular features. SOX11 is overexpressed in nodal MCL subtype, while the leukemic non-nodal sub-type is associated with SOX11 negativity. MCL has a wide range of differential diagnoses, including other types of low-grade lymphoma, most notably chronic lymphocytic leukaemia (CLL), follicular lymphoma (FL), marginal zone lymphoma (MZL), and lymphoblastic lymphoma (LBL). Therefore, accurate histological biopsy diagnosis is paramount in this rare subtype of NHL. MCL has a distinctive clinical presentation and particular morphological and immunophenotypic features with specific cytogenetic abnormalities. The recent advances in molecular and cytogenetic analysis have improved the accuracy of MCL diagnosis and enhanced disease prognosis. Furthermore, B cell receptor inhibitors have revolutionized MCL treatment. Therefore, an accurate diagnosis of MCL is very important since this may require an aggressive and novel targeted therapy.

Leukemic Non-nodal Mantle Cell Lymphoma: Diagnosis and Treatment.

Mantle cell lymphoma (MCL) encompasses nearly 6% of all the non-Hodgkin lymphomas. It is considered an incurable neoplastic process arising from B cells. The cytogenetic abnormality t(11;14) (q13; q32) leading to cyclin D1 overexpression is the sentinel genetic event and provides an exceptional marker for diagnosis. MCL is generally considered to have an aggressive course as compared with other indolent lymphomas with traditionally reported median survival of 3-5years. According to the 2016 WHO classification, there are two major known variants of MCL: classical which affects the lymph nodes and extra nodal sites and leukemic non-nodal MCL (L-NN-MCL) which characteristically involves the bone marrow, peripheral blood, and the spleen. It is important to distinguish between classical and leukemic non-nodal MCL since the latter variant of MCL follows a rather indolent course with a wait and watch approach in order to avoid overtreatment. However, a subset of patients with L-NN-MCL can transform into a more aggressive course requiring treatment. Current evidence suggests those patients with alteration in TP53 gene do not respond to standard chemotherapy agents and may need targeted therapy. In this review, we describe the characteristics of L-NN-MCL, its diagnosis, and management.

Highly sensitive and specific in situ hybridization assay for quantification of SOX11 mRNA in mantle cell lymphoma reveals association of TP53 mutations with negative and low SOX11 expression.

SOX11 is a valuable marker to identify biologically and clinically relevant groups of mantle cell lymphoma such as cyclin D1 negative and leukemic non-nodal mantle cell lymphoma (MCL). We aimed to establish a sensitive in situ hybridization analysis of SOX11 mRNA allowing its quantification within the histopathological context and compare it with immunohistochemistry and real-time quantitative reverse transcription-PCR (RT-qPCR). Furthermore, TP53 status was correlated with SOX11 mRNA levels. Sixty-six cases were investigated; 58 conventional mantle cell lymphomas (cMCL), including six cyclin D1 negative (46 classic, 12 blas-toid) and eight leukemic non-nodal mantle cell lymphomas (nnMCL). RNAscope was used for the in situ hybridization and the results scored as 0 to 4. MCL cases with SOX11 positivity by immunohistochemistry (IHC) were positive by RNA in situ hybridization (RNAscope) but with different scores. RT-qPCR showed a good correlation with the median of the grouped scores but had a wide variation in individual cases. The SOX11 negative leukemic non-nodal mantle cell lymphomas were also negative by RNAscope. TP53 was mutated in 13/63 (21%) cases, including 5/7 (71%) leukemic non-nodal and 8/56 (14%) cMCL. Interestingly, of the TP53 mutated cases, nine were in the RNAscope negative/low SOX11 group (9/15; 60%) and four in the high SOX11 group (4/36; 11%) (P=0.0007). In conclusion, RNAscope is a reliable method to evaluate SOX11 mRNA levels. This study demonstrates the broad range of SOX11 mRNA levels in MCL. An important finding is the significant correlation of TP53 mutations with negative/low SOX11 mRNA level both in leukemic nnMCL and cMCL.

Mantle cell lymphoma pathology update in the 2016 WHO classification

Mantle cell lymphoma (MCL) is an aggressive mature B-cell neoplasm genetically characterized by the presence of the t(11;14)(q13;q32) that leads to the constitutive overexpression of cyclin D1. The pathological and biological spectrum of this neoplasm has been expanded in recent years. This improvement in the knowledge of the disease has provided a better understanding of the diverse clinical evolution of the patients. The characterization of cyclin D1-negative MCL has led to the identification of cyclin D2 and D3 translocations as alternative mechanisms in this variant. Two major biological and clinical subtypes of the disease have been recognized, conventional and leukemic non-nodal MCL (nnMCL). MCL derives from CD5+ mature B-cells that have bypassed or experienced the germinal center microenvironment, retain a naive or memory-like epigenetic signature and carry a variable load of somatic mutations in the IGHV region; from truly unmutated to highly mutated, respectively. These two subtypes of tumors also differ in their genomic alterations, and clinical behavior, the conventional MCL (cMCL) being more aggressive than the leukemic nnMCL. This review will focus on the new aspects of the pathology of MCL in the updated 2016 WHO classification and its relevance for the clinical practice.

CSF1R and BTK Inhibitions As Novel Strategies to Disrupt the Dialogue between Mantle Cell Lymphoma and Macrophages

The aggressive clinical behavior of mantle cell lymphoma (MCL) and its short-term response to treatments highlight a need for novel options. The microenvironment strongly controls MCL cell survival, proliferation and chemoresistance, nevertheless little is known regarding the interactions that occur in the tumor niches. Here, we studied the interplay between primary MCL cells (n=55) and macrophages and identified mechanism-based targeted strategies to disrupt this dialogue.Using ex vivo co-cultures of peripheral blood MCL cells and monocytes (healthy donors), we showed that monocytes greatly improved MCL cell survival, whereas MCL cells poorly survived when cultured alone (co-culture, 85.9%; alone, 6.5%; D7; n=17; p<0.001). We also demonstrated that monocytes supported the proliferation of conventional (n=7) and blastoid (n=4), but not leukemic non-nodal MCL subtypes (n=5) (p<0.05).During co-culture, primary MCL cells polarized monocytes into MCL-associated-macrophages (MϕMCL). To define the nature of MϕMCL, we studied their phenotype and function with 12 markers differentially expressed in M1 and M2 macrophages (CD14, CD68, CD163, CD11b, CD86, HLA-DR, CD16, CD23, IL10, IL6, IGF1, BAFF). The analysis showed that even though MϕMCL distinctly clustered from both M1 and M2, they shared more similarities with M2 (CD163high, CD11blow, IL10+, IGF1+).To determine how MCL cells polarized monocytes into CD163high MϕMCL, we analyzed the expression of known M2-polarizing factors and observed that CSF1 and IL10 were overexpressed in MCL cells compared to normal B cells (GEP, p<0.01). CSF1 and IL-10 were detected at the protein level in co-culture (ELISA), and CSF1, but not IL-10, neutralization significantly blocked MϕMCL polarization ex vivo. Previous studies reported modulations of the MCL secretome upon BTK inhibition. Here, we demonstrated that both CSF1 and IL-10 were inhibited upon ibrutinib treatment (0.5 µM) in sensitive MCL cells, whereas no modulation was observed in ibrutinib-resistant cells. Reduction of the CSF1 level by ibrutinib consequently inhibited M2-like polarization and resulted in the inhibition of MϕMCL-dependent tumoral survival (n=8/14) and proliferation (n=4/4). Nevertheless, 6 MCL samples cocultured with MϕMCL appeared resistant to ibrutinib. To test whether targeting the CSF1R could bypass this resistance, we treated MCL/MϕMCL coculture with the inhibitor GW2580. We showed that CSF1R inhibition efficiently reduced the viability of ibrutinib-resistant MCL cells. Moreover, the combination in low concentrations of ibrutinib/GW2580 (125nM) induced a supra-additive effect in ibrutinib-sensitive samples.In vivo, we showed higher levels of CSF1 and IL-10 in the plasma of MCL patients (n=28) compared to match-aged HD (p<0.01). We also showed that CD163 was overexpressed at the surface of circulating monocytes in MCL compared to HD (n=32; p < 0.05), which was consistent with the CD163-inducing properties of CSF1 and IL-10. Taking advantage of a local clinical trial (NCT02558816), we evaluated modulations of CSF1 and IL-10 plasma concentrations as well as CD163 expression on monocytes from 8 patients treated with ibrutinib. We observed a reduction of CSF1 and IL-10 as well as inhibition of CD163 expression in 7/8 patients after 8 days (D8) of treatment (median CD163+ reduction, - 58%). We performed longitudinal follow-up of 4 patients treated with ibrutinib, 3 were characterized by a dramatic reduction in CD163 at D8 and achieved a durable complete response. In contrast, 1 patient who displayed an increase in CD163 at D8, progressed upon treatment.In conclusion, through secretion of IL-10 and CSF1, MCL cells polarized monocytes into M2-like macrophages (MϕMCL), which in turn support tumor survival and proliferation. Ibrutinib counteracts the MCL/MϕMCL dialogue through inhibition of CSF1 production and, consequently, impairs the MϕMCL-dependent expansion of ibrutinib-sensitive MCL cells. Of note, our in vivo retrospective analysis highlights that CSF1, IL-10 and CD163 modulations might be early markers of ibrutinib response. A larger cohort of MCL patients treated with ibrutinib is now necessary to confirm the strength of this soluble and cellular signature. Lastly, targeting the CSF1R is an alternative to disrupt the MCL/MϕMCL pro-tumoral dialogue, especially for ibrutinib-refractory patients for which no therapeutic alternative is available. DisclosuresMoreau:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Le Gouill:Roche: Consultancy, Honoraria; Janssen-Cilag: Consultancy, Honoraria.

A gene signature that distinguishes conventional and leukemic nonnodal mantle cell lymphoma helps predict outcome

AbstractMantle cell lymphoma (MCL) is an aggressive B-cell malignancy, but some patients have a very indolent evolution. This heterogeneous course is related, in part, to the different biological characteristics of conventional MCL (cMCL) and the distinct subgroup of leukemic nonnodal MCL (nnMCL). Robust criteria to distinguish these MCL subtypes and additional biological parameters that influence their evolution are not well defined. We describe a novel molecular assay that reliably distinguishes cMCL and nnMCL using blood samples. We trained a 16-gene assay (L-MCL16 assay) on the NanoString platform using 19 purified leukemic samples. The locked assay was applied to an independent cohort of 70 MCL patients with leukemic presentation. The assay assigned 37% of cases to nnMCL and 56% to cMCL. nnMCL and cMCL differed in nodal presentation, lactate dehydrogenase, immunoglobulin heavy chain gene mutational status, management options, genomic complexity, and CDKN2A/ATM deletions, but the proportion with 17p/TP53 aberrations was similar in both subgroups. Sequential samples showed that assay prediction was stable over time. nnMCL had a better overall survival (OS) than cMCL (3-year OS 92% vs 69%; P = .006) from the time of diagnosis and longer time to first treatment. Genomic complexity and TP53/CDKN2A aberrations predicted for shorter OS in the entire series and cMCL, whereas only genomic complexity was associated with shorter time to first treatment and OS in nnMCL. In conclusion, the newly developed assay robustly recognizes the 2 molecular subtypes of MCL in leukemic samples. Its combination with genetic alterations improves the prognostic evaluation and may provide useful biological information for management decisions.

SOX11, a key oncogenic factor in mantle cell lymphoma.

SOX11 has emerged as a key transcription factor in the pathogenesis of mantle cell lymphoma (MCL) whereas it is not expressed in normal B cells or virtually in any other mature B-cell neoplasm. This review will examine the role of SOX11 as a biomarker in MCL, the new information on its transcriptional targets, and the mechanisms regulating its expression in MCL. SOX11 is highly expressed in conventional MCL, including cyclin D1-negative cases, but it is not expressed in the indolent leukemic nonnodal MCL subtype. These two MCL subtypes also differ in their cell-of-origin, IGHV mutational status and genomic instability. SOX11 promotes tumor growth of MCL cells in vivo and regulates a broad transcriptional program that includes B-cell differentiation pathways and tumor-microenvironment interactions, among others. The mechanisms upregulating SOX11 in MCL are not well understood but are mediated in part by the three-dimensional reconfiguration of the DNA, bringing together a distant enhancer region and the SOX11 promoter. SOX11 is a relevant element in the pathogenesis of MCL and has been instrumental to identify two distinct clinicobiological subtypes of this tumor. Further studies should clarify the mechanisms mediating its oncogenic potential and leading to its intriguing expression in these tumors.

347 - Aggressive Leukemic Non-Nodal Mantle Cell Lymphoma with P53 Gene Rearrangement/Mutation is Highly Responsive to Rituximab/Ibrutinib Combination Therapy

347 - Aggressive Leukemic Non-Nodal Mantle Cell Lymphoma with P53 Gene Rearrangement/Mutation is Highly Responsive to Rituximab/Ibrutinib Combination Therapy

Reproducibility of SOX-11 detection in decalcified bone marrow tissue in mantle cell lymphoma patients

Mantle cell lymphoma (MCL) usually harbors the t(11;14)(q13;q32) with overexpression of CCND1 mRNA and transcription of the cyclin D1 nuclear protein. Regardless of CCND1 status, most MCLs also express the SOX11 nuclear protein, which is thus helpful in the diagnosis of the rare CCND1-negative MCLs. Recently, SOX11 has been reported to be often negative in MCLs clinically resembling marginal zone lymphoma and recently defined as "leukemic non-nodal" MCL in the incoming revision of the WHO classification of lymphoid tumors, for which the bone marrow biopsy is commonly the first diagnostic approach. Due to the less aggressive clinical behavior of the latter MCLs, the reliable determination of the SOX11 antigen in decalcified tissue is mandatory. To this end, since little data are available in the literature, four commercially available anti-SOX11 antibodies (two polyclonal and two monoclonal) were tested on 21 positive staging bone marrow (BM) biopsies from cyclin D1/SOX11-positive MCL patients (17 fixed in B5, 4 in 10% buffered formalin) and on 9 positive BM biopsies from leukemic non-nodal MCL patients. The results were compared for specificity, sensitivity, staining strength and degree of an additional staining on myeloid precursors, also evaluating possible impact of the different fixatives used. Non-mantle cell lymphomas were also tested to address specificity. All reagents showed high sensitivity but the monoclonal code CMC38221001 provided the highest specificity and the lowest degree of non-lymphoid staining on myeloid cells. Formalin fixation generally improved the performance of most antibodies when compared to B5 fixation.

Leukemic non-nodal mantle cell lymphomas have a distinct phenotype and are associated with deletion of PARP1 and 13q14.

Leukemic non-nodal mantle cell lymphoma (lMCL) is a particular subtype of mantle cell lymphoma (MCL), characterized by leukemic non-nodal disease and slow progression. Recognition of this entity is relevant to avoid overtreatment. Despite indolent clinical behaviour, lMCL might transform to a more aggressive disease. The purpose of this study was to compare lMCL with classical MCL (cMCL) and aggressive MCL (aMCL) using immunohistochemistry, interphase fluorescence in situ hybridization (FISH), and array-based comparative genomic hybridization, in order to identify biomarkers for lMCL diagnosis and prognosis. Seven lMCL patients were included. All had bone marrow involvement without lymphadenopathy. An lMCL phenotype was distinct from that of cMCL and aMCL: SOX11-, ATM+, PARP1+/-, and low KI67 (average 2%). Beyond the t(11;14) translocation, fewer secondary cytogenetic alterations were found in lMCL compared to cMCL and aMCL, including deletion of PARP1 and 13q14. At last follow-up, one patient with lMCL had died of disease and another had progressive disease. These patients were respectively 13q14 deletion- and PARP1-positive. One other case of lMCL harbored a 13q14 deletion associated with PARP1 deletion. This patient had indolent disease. lMCL has a particular phenotype and fewer secondary cytogenetic alterations than cMCL and aMCL. PARP1 protein expression and 13q14 deletion are associated with a progressive clinical course of lMCL and should be included in initial diagnostic studies as predictors of unfavorable outcome. PARP1 deletion is involved in lMCL pathogenesis and might confer advantage.