Introduction to a Special Issue on Low-Grade B Cell Lymphoma in the Spleen

Malignant lymphoproliferative disorders in the spleen may be primary (usually designated as splenic lymphoma) or secondary (due to progression of nodal or extra nodal lymphoid neoplasms) and represent an underestimated cause of splenomegaly, partially due to the decreasing frequency of splenectomy in our era of personalized molecular medicine [...]

Advances in Lymphoma Molecular Diagnostics

Lymphomas encompass a diverse group of malignant lymphoid neoplasms. Over recent years much scientific effort has been undertaken to identify and understand molecular changes in lymphomas, resulting in a wide range of genetic alterations that have been reported across all types of lymphomas. As many of these changes are now incorporated into the World Health Organization’s defined criteria for the diagnostic evaluation of patients with lymphoid neoplasms, their accurate identification is crucial. Even if many alterations are not routinely evaluated in daily clinical practice, they may still have implications in risk stratification, treatment, prognosis or disease monitoring. Moreover, some alterations can be used for targeted treatment. Therefore, these advances in lymphoma molecular diagnostics in some cases have led to changes in treatment algorithms. Here, we give an overview of and discuss advances in molecular techniques in current clinical practice, as well as highlight some of them in a clinical context.

An Overview of Selected Rare B-Cell Lymphoproliferative Disorders: Imaging, Histopathologic, and Clinical Features

Lymphoproliferative disorders (LPD) are conditions characterized by the uncontrolled proliferation of B or T-cell lines. They encompass a wide spectrum of abnormalities, which may be broadly classified as reactive processes or malignant diseases, such as lymphoma, based on their cellular clonality and clinical behavior. While some of these disorders are rare, they may be encountered sporadically in clinical practice, causing diagnostic dilemmas owing to overlap in their clinical and imaging features with more common disorders. The updated 4th edition WHO classification of lymphoid neoplasms was released in 2016 to incorporate the rapid clinical, pathological, molecular biology and cytogenetic advances of some of these disorders. Despite these updates, very little information is presented in the literature from the radiology perspective. The aim of this article is to familiarize radiologists and other physicians with certain rare variants of B-cell lymphoproliferative disorders with a focus on imaging features of these disorders, as well as to provide an overview of some important updates contained within the new WHO classification of lymphoid neoplasms.

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.

Nanopore sequencing for the screening of myeloid and lymphoid neoplasms with eosinophilia and rearrangement of PDGFRα, PDGFRβ, FGFR1 or PCM1-JAK2

Eosinophilia represents a group of diseases with heterogeneous pathobiology and clinical phenotypes. Among the alterations found in primary Eosinophilia, gene fusions involving PDGFRα, PDGFRβ, FGFR1 or JAK2 represent the biomarkers of WHO-defined “myeloid and lymphoid neoplasms with eosinophilia”. The heterogeneous nature of genomic aberrations and the promiscuity of fusion partners, may limit the diagnostic accuracy of current cytogenetics approaches. To address such technical challenges, we exploited a nanopore-based sequencing assay to screen patients with primary Eosinophilia. The comprehensive sequencing approach described here enables the identification of genomic fusion in 60 h, starting from DNA purified from whole blood.

Antibody Response to Vaccination with BNT162b2, mRNA-1273, and ChADOx1 in Patients with Myeloid and Lymphoid Neoplasms

Background: In general, patients with hematological diseases are predisposed to develop infections. Severe COVID-19 infection associated with high mortality is more likely in these patient cohorts compared to the general population. Due to immune defects related to the primary disease and/or to immunosuppressive treatment regimes, vaccination efficacy may be reduced in patients with hematological diseases. So far, data on this area are limited. Aim: To evaluate vaccination-related antibody response to BNT162b2, mRNA-1273, and ChADOx1 in patients with hematological disorders. Patients and methods: In this interim analysis of a prospective, observational single-center study, we report antibody levels at least 2 weeks after COVID-19 vaccination. A FDA/CE approved electrochemiluminescent assay (ECLIA) (Elecsys®, Roche, Mannheim, Germany) was used to quantify antibodies, pan Ig (including IgG) against the receptor binding domain (RBD) of the SARS-CoV-2 spike protein. The assay has a measurement range of 0.4 to 250 U/mL, with a concentration ≥0.8 U/ml considered as positive. Data were analyzed for patients without detection of anti-N (nucleocapsid) SARS-CoV-2 antibody (i.e., without having passed SARS-CoV-2 infection). All tests were performed according to the manufacturer's instructions in an accredited laboratory at the University Hospital Mannheim. Results: Between February 2021 and July 2021, a total of 175 patients with hematological diseases were included in this study. The median age was 66 years (range 21-90 years), and 81 (46.3%) were female. The antibody levels were measured at least 14 days (median, 58 days) after the 2 nd vaccination. The patients were vaccinated with BNT162b2 (BioNTech, n=134), mRNA-1273 (Moderna, n=19), ChADOx1 (AstraZeneca, n=12), or got the first vaccination with BNT162b2 and the second with ChADOx1 (n=10). Overall, 145/175 (82.9%) were diagnosed with a malignant hematological disease (myeloid neoplasms, n=108; lymphoid neoplasms, n=37) and 30/175 with a non-malignant hematological disease (autoimmune disease, n=24; benign, n=6). 124 patients (70.1%) were on active therapy, and 51 patients (29.1%) were previously treated or treatment naïve. Correlation to specific therapies is ongoing and will be presented. In general, vaccination-related antibody response was positive (≥0.8 U/mL) in 148/175 (84.6%) patients with a median level of 208.6 U/mL (range 0.8-250.00) and negative (<0.8 U/mL) in 27/175 (15.4%) patients. The distribution of the negative cohort regarding the disease subgroups were as followed: myeloid neoplasms 7/27 (25.9%), lymphoid neoplasms 16/27 (59.3%), non-malignant hematological disease 4/27 (14.8%). Within the negative cohort, 21/27 (77.8%) were treated on active therapy, 6/27 (22.2%) were previously treated or treatment naïve. In myeloid neoplasms, patients with classical myeloproliferative neoplasm (MPN) had the highest negative result for antibodies with 4/7 (57.1%) followed by myelodysplastic syndrome (MDS) 2/7 (28.6%). Interestingly, all patients with chronic myeloid leukemia (CML) had a measurable immune response. In lymphoid neoplasms, patients with low-grade non-hodgkin lymphoma (NHL) (predominately chronic lymphocytic leukemia, CLL) had the highest negative antibody result 13/16 (81.3%) followed by high-grade NHL 4/8 (50%; predominately diffuse large b-cell lymphoma, DLBCL). In non-malignant hematological diseases, only patients with autoimmune diseases had a negative result. Conclusion: A remarkable group of patients with hematological disease were measured with no or low immune response after 2 nd COVID-vaccination, especially those with low-grade NHL, MDS and autoimmune disease. It seems that the percentage of patients with MPN and low response is less critical. No problems appeared in CML patients. Further explorations are needed with focus on potential risk of COVID infections despite full vaccination: The potential of 3 rd booster vaccination should be explored within clinical trials. Disclosures Reiter: AOP Orphan Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel expenses, Research Funding; Celgene/BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support; Incyte: Membership on an entity's Board of Directors or advisory committees, Other: Travel expenses; Blueprint Medicines: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel expenses; Abbvie: Membership on an entity's Board of Directors or advisory committees; Deciphera: Membership on an entity's Board of Directors or advisory committees, Other: Travel expenses. Kreil: Novartis: Research Funding. Hofmann: Amgen: Honoraria; BMS: Honoraria; Novartis: Honoraria. Jawhar: Takeda: Honoraria, Other: Travel support; Blueprint Medicines: Honoraria; Stemline: Consultancy, Honoraria; Celgene: Other: Travel support; Novartis: Consultancy, Honoraria, Other: Travel support, Speakers Bureau. Saussele: Roche: Honoraria; Pfizer: Honoraria; Incyte: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Novartis: Honoraria, Research Funding.

Copy-Neutral Loss-of-Heterozygosity Adds Diagnostic and Prognostic Information to the Molecular Profiling of Hematological Malignancies

Background: Copy-neutral loss-of-heterozygosity (CN-LOH) - not detectable by chromosome banding analysis - is gaining importance as a prognostic factor and can either cause the duplication of an activating mutation in an oncogene, the deletion of a tumor suppressor gene or the gain/loss of specific methylated regions. However, examination for possible CN-LOH in hematological diagnostics is at present not routinely performed and, hence, data regarding the occurrence of CN-LOH across different entities as well as the association of relevant genes is limited. Aim: (1) Frequency assessment of CN-LOH by target enrichment sequencing (TES) in a diagnostic setting, (2) evaluation of whole genome sequencing (WGS) data to estimate the prevalence of CN-LOH in a larger cohort, to pinpoint relevant genes for CN-LOHs with so far unknown associations, and to determine cross-entity variability. Patients and Methods: 1196 patients (507 female, 689 male, median age: 66 years), sent between 04/2021-07/2021 for diagnostic work-up, were analyzed by TES with a median coverage of 1765x for the gene panel and 52x for the CNV spike-in panel (IDT, Coralville, IA). Amplification-free WGS libraries of 3851 different patients were sequenced with a median coverage of 102x. Reads were aligned to the human reference genome (GRCh37, Ensembl annotation, Isaac aligner). Cnvkit (v 0.9.9) was used to call copy number variations (CNVs) and CN-LOH for TES and HadoopCNV (Yang et al. 2017) was used to call CN-LOH for WGS. Results: 1196 patients were analyzed by TES. For 10% of the patients at least one CN-LOH event was detected without any association to age or gender but a slightly higher incidence in myeloid compared to lymphoid neoplasms (10% vs 6%). In 14 patients, CN-LOH affected more than one chromosome arm. CN-LOH occurred most frequently in 4q (n = 15), 7q (n = 16), 9p (n = 25) and 11q (n = 10). As expected, 4q CN-LOH co-occurred with high variant allele frequencies (VAF) of TET2. Based on WGS data, 4q CN-LOH occurred predominately in AML (35%), CMML (22%), and MDS (20%). In rare cases, 4q CN-LOH was associated with FBXW7 variants in T-ALL. 7q CN-LOH occurred nearly exclusively in myeloid neoplasms (95%) and was associated with high VAFs in EZH2 in 69% of TES and 82% of WGS cases. CUX1 variants with high VAFs were detected in 80% (TES) and 45% (WGS) of the remaining cases, respectively. The well-known 9p CN-LOH led to JAK2V617F homozygosity in all myeloid neoplasms and occurred most often in MPNs. In T-ALL, regions of 9p CN-LOH harbored CDKN2A/B deletions. 11q CN-LOH occurred more often in myeloid than lymphoid neoplasms (79% vs 21%) and was associated with CBL variants in 61% and KMT2A-PTD in 19% of the cases. In contrast, ATM was the relevant gene in all lymphoid cases with 11q CN-LOH. CN-LOH in 11p was detected less frequently and only in 25% of cases an association with WT1 variants could be identified. Our WGS data confirmed the known associations between 1p CN-LOH and high allele burden in MPL, CSF3R and NRAS, 2p CN-LOH and DNMT3A variants, 13q CN-LOH and FLT3-ITD, the near exclusive occurrence of 16p CN-LOH in follicular lymphoma (FL, 98%) with high CREBBP-mutant allele burden , 17p CN-LOH and TP53 homozygosity, and the exclusive occurrence of 21q CN-LOH in AML and its association with RUNX1 mutations. Besides, 12q CN-LOH was associated with KMT2D in FL, with SH2B3 in MDS/MPN overlaps and in rare cases with KDM2B. For 17q CN-LOH the relevant gene was not unequivocally identifiable with high mutant allele variants in SRSF2, STAT5B, and NF1. 18q CN-LOH was a very rare event but consistently associated with a high VAF of MBD2, which presumably influences cell proliferation (Cheng et al. 2018). 19q CN-LOH was mostly (63%) associated with a high VAF of CEBPA variants, except for patients with hairy cell leukemia: in these cases nonsense mutations in CIC (VAF > 90%) were detected. CN-LOH in 22q was more common in myeloid malignancies (65% vs 35%) and associated with PRR14L mutations in the majority of myeloid cases (62%). Of note, this association occurred neither in AML samples nor in lymphoid neoplasms. No recurrent mutations were found for 6p and 14q CN-LOHs. For all other chromosomes, CN-LOH events were very rare. Conclusions: By using a CNV spike-in panel, TES adds additional diagnostic and prognostic information by enabling simultaneous detection of selected gene mutations and genome-wide CNVs, as well as CN-LOH, without increase in sequencing costs and turn-around times. Figure 1 Figure 1. Disclosures Haferlach: MLL Munich Leukemia Laboratory: Other: Part ownership. Kern: MLL Munich Leukemia Laboratory: Other: Part ownership. Haferlach: MLL Munich Leukemia Laboratory: Other: Part ownership.

Upfront Targeted Tyrosine Kinase Inhibitor Therapy Improves Outcome in Patients with Myeloid/Lymphoid Neoplasms with Eosinophilia

Background To recognize the growing list of recurrent genetically defined eosinophilia driven by constitutively active tyrosine kinase fusion genes, the World Health Organization (WHO) created a provisional entity of myeloid/lymphoid neoplasms with eosinophilia (MLN-Eo) with rearrangement of PFGFRA, PDGFRB or FGFR1, or with PCM1- JAK2. These eosinophilic disorders are clinically and genetically heterogeneous. Annotating additional somatic mutations and relevant clinical features may have an impact on treatment selection and refine prognostication. In this study, we aim to describe the clinicopathologic characteristics and outcome with upfront targeted tyrosine kinase inhibitor (TKI) therapy in patients (pts) with MLN-Eo. Methods We retrospectively reviewed clinical and molecular data on 39 pts with newly diagnosed MLN-Eo with PDGFRA, PDGFRB, FGFR1, JAK2 or FLT3 rearrangement at Moffitt Cancer Center, Duke Cancer Center, and the UCSF Comprehensive Cancer Center. Clinical data was abstracted in accordance with institutional review board approved protocol. Pts were divided to two categories based on morphologic classification of the disease at diagnosis or at transformation: chronic phase and blastic phase disease. Each category was then divided into two subgroups: Cohort A) upfront TKI +/- other systemic therapy and Cohort B) no upfront TKI arm. Median time from chronic phase disease to blastic phase and median overall survival (mOS) (in whole cohort) were calculated using Kaplan Meier method and compared with log-rank test. Cox proportional hazards (PH) model was used to calculate hazard ratio (HR) in univariate analyses. Result Among the 39 pts included in the analysis, 22 pts had PDGFRA fusion (20)/activating mutations (2), 4 had PDGFRB, 7 had FGFR1, 2 had JAK2 (PCM1-JAK2 and BCR-JAK2), and 4 had FLT3 (3 ETV6-FLT3 and 1 FLT-3-TRIP11). Median age at first diagnosis of myeloid/lymphoid neoplasm was 54.5 years (range 9-76). Seventy-seven percents (30/39) were male. Chronic eosinophilic leukemia (CEL) was the most common clinical diagnosis and occurred in 11 pts (28%). Seven (18%) pts had both myeloid and lymphoid neoplasms either concurrently or sequentially. Sixteen (41%) pts presented with de-novo blastic phase at time of initial diagnosis. Among 23 pts who presented with chronic phase disease at diagnosis, nine patients did not receive TKI upfront. Five out of the nine patients (55%) developed blastic phase disease with a median follow up of 73 months. The median time to blastic phase was 45 months. No patients in the upfront TKI arm (n=14) had blastic transformation during follow up (Figure 1a, p<0.001). Among 21 pts who had blastic phase disease (16 pts with de-novo diagnosis and 5 pts with blastic transformations), 95% of them (20/21 pts) had treatment information and follow-up data available. At a median follow up of 37 months, 11 pts (55%) were deceased, and median OS was 44 months. Seven pts (35%) underwent allogeneic stem cell transplant (alloHSCT). Four patients received upfront TKI, and all of them achieved complete remission and were alive at the time of the study (Figure 1b). Among those pts, 2 had FLT3-ETV6 rearrangement, 1 with PDGFRA rearrangement and 1 with FGFR1 rearrangement. Two pts received single agent TKI only and two pts received TKIs followed by alloHSCT. In the univariate analysis, upfront TKI use was significantly associated with improved OS (HR 0.067, 95% CI [0.009-0.512], p=0.009). Complex cytogenetics at the time of initial diagnosis was associated with inferior OS, though statistical significance was not reached (table II). Conclusion Our data suggests that upfront TKI therapy is associated improved survival outcomes in pts with MLN-eo and is effective in preventing blastic transformation from chronic phase disease. As proposed, the driver oncogene most likely occurs in hematopoietic stem cells/progenitor cells in this entity. Upfront TKI can potentially suppress, even in some cases eradicate the malignant clone. The study is limited due to small sample size and retrospective nature, and larger study is needed to validate our observation. Figure 1 Figure 1. Disclosures Sokol: Kyowa-Kirin: Membership on an entity's Board of Directors or advisory committees; Dren Bio: Membership on an entity's Board of Directors or advisory committees. Shah: Novartis: Consultancy, Other: Expenses; Pfizer: Consultancy, Other: Expenses; Amgen: Consultancy; Precision Biosciences: Consultancy; Kite, a Gilead Company: Consultancy, Honoraria, Other: Expenses, Research Funding; Pharmacyclics/Janssen: Honoraria, Other: Expenses; Acrotech/Spectrum: Honoraria; BeiGene: Consultancy, Honoraria; Incyte: Research Funding; Jazz Pharmaceuticals: Research Funding; Servier Genetics: Other; Bristol-Myers Squibb/Celgene: Consultancy, Other: Expenses; Adaptive Biotechnologies: Consultancy. Lancet: Agios: Consultancy; AbbVie: Consultancy; Celgene/BMS: Consultancy; Daiichi Sankyo: Consultancy; Astellas: Consultancy; BerGenBio: Consultancy; Millenium Pharma/Takeda: Consultancy; ElevateBio Management: Consultancy; Jazz: Consultancy. Kuykendall: Protagonist: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; BluePrint Medicines: Honoraria, Speakers Bureau; Prelude: Research Funding; Abbvie: Honoraria; Incyte: Consultancy; Novartis: Honoraria, Speakers Bureau; PharmaEssentia: Honoraria; Celgene/BMS: Honoraria, Speakers Bureau; CTI Biopharma: Honoraria. Padron: Stemline: Honoraria; BMS: Research Funding; Kura: Research Funding; Blueprint: Honoraria; Incyte: Research Funding; Taiho: Honoraria.