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This study examined the reproducibility of MYC and BCL-2 immunohistochemical scoring as well as the impact of higher expression of both proteins (double expressor status, DE) on survival and progression in a large retrospective cohort of aggressive B-cell lymphoma patients treated with rituximab plus cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP) or R-CHOP-like regimens with a median follow up of 67 months (range 0–138). We also investigated possible MYC protein expression cut offs with the highest reproducibility among pathologists and predictability of gene translocation. We showed that immunohistochemistry (IHC) for MYC and BCL-2 is highly reproducible when cut-off values of >70% for MYC and >50% for BCL-2 are used. This threshold not only predicts the presence of rearrangements (with respect to MYC), but is also clinically valuable. In fact, it identifies a subset of patients who are poor responders and who may benefit from alternate therapeutic strategies

SummaryThe discovery of mutated Calreticulin (CALR) in myeloproliferative neoplasms (MPN) has provided proof of clonality, diagnostic importance, and influence on prognosis of this pathology. The identification of this MPN-associated driver mutation -currently based on molecular assays- is represented as a major diagnostic criterion for essential thrombocythaemia (ET), pre-fibrotic myelofibrosis and primary myelofibrosis (PMF) in the updated World Health Organization (WHO) 2008 classification. In the present study, we validated by immunohistochemistry the diagnostic usefulness of the monoclonal CAL2 antibody. Cases of acute myeloid leukaemia (AML) and myelodysplastic/ myeloproliferative neoplasms (MDS/MPN) have been also investigated to assess the specificity of CAL2 antibody. For this purpose, the result of the CAL2 immunostaining was compared with the result of molecular assays. Additionally, we investigated by double staining whether expression of mutated CALR can also be demonstrated on cells of the erythroid and myeloid lineage. We confirmed the usefulness of the CAL2 monoclonal antibody in successfully detecting mutant CALR in bone marrow biopsies. We showed that the immune-reactivity of CAL2 was absolutely restricted to the presence of CALR mutations, which were seen only in ET and MDS/MPN biopsies, but not in AML biopsies (14/14). There was 100% concordance in biopsy specimens with the concomitant molecular results. We applied double staining technique and confirmed that a subpopulation of granulopoietic and erythropoietic cells express mutated CALR as demonstrated with the CAL2 antibody in cases of MPNs. This supports the suggestion that the CALR mutations occur in a multipotent progenitor capable of generating both myeloid and erythroid progeny with preferential expansion of megakaryocytic cell lineage as a result of CALR mutation in an immature hematopoietic stem cell.

MYC is the most altered oncogene in human cancer, and belongs to a large family of genes, including MYCN and MYCL. Recently, while assessing the degree of correlation between MYC gene rearrangement and MYC protein expression in aggressive B-cell lymphomas, we observed few Burkitt lymphoma (BL) cases lacking MYC protein expression despite the translocation involving the MYC gene. Therefore, in the present study we aimed to better characterize such cases. Our results identified two sub-groups of MYC protein negative BL: one lacking detectable MYC protein expression but presenting MYCN mRNA and protein expression; the second characterized by the lack of both MYC and MYCN proteins but showing MYC mRNA. Interestingly, the two sub-groups presented a different pattern of SNVs affecting MYC gene family members that may induce the switch from MYC to MYCN. Particulary, MYCN-expressing cases show MYCN SNVs at interaction interface that stabilize the protein associated with loss-of-function of MYC. This finding highlights MYCN as a reliable diagnostic marker in such cases. Nevertheless, due to the overlapping clinic, morphology and immunohistochemistry (apart for MYC versus MYCN protein expression) of both sub-groups, the described cases represent bona fide BL according to the current criteria of the World Health Organization.

Background: The advent of B-cell-receptor associated kinase inhibition (BCR-KI) inaugurated a novel therapeutic principle in chronic lymphocytic leukemia (CLL). First-in-class Ibrutinib (Ib) and Idelalisib (Id) received marketing authorization from the EMA for the treatment of relapsed/refractory (r/r) CLL in 2012 and 2014, respectively. In spite of ample evidence from trials, real life data are scarce. Methods: Our clinical registry has been previously described in detail [https://doi.org/10.1182/blood-2018-99-110618]. It comprises of 168 unselected CLL patients (pts.), who were observed between 10/2014 and 08/2020. 65 of them required treatment during this period: 39 x 1st line only and 26 x > 2nd line. 18 of these 26 r/r CLL pts were treated either with Ib (11 x) or Id (7 x). Treatment was started according to iwCLL guidelines. The type of BCR-KI was chosen based on an individual's performance status, previous treatment and co-morbidity. Median 1st line-treatment (as a rule immunochemotherapy) started 27.5 months (m) after diagnosis (range: 0.5 m to 87.5 m). Time from 1st line therapy to BCR-KI treatment ('Ctx effected time') was 13.0 to 128.1 m (median 50.5 m), in total (18 pts.) 1052.5 m, i.e. 87.7 years (y). 17 of 18 pts. had received Rituximab (R) as part of a pre-BCR-treatment protocol. Estimated charges per month are 9.000 € in Id + R, 7.000 € in R + chemotherapy (ctx, i.e. Fludara or Bendamustin mostly) and 4.500 € in Ib or Id mono or R + Chlorambucil (Clb) respectively. Results: Patients described herein differed according to age at start of BCR-KI (44.4 to 86.8 y, median 76.0 y), sex (10 m, 8 f), types and lines (1 to 6, median 2) of prior treatment. Indications for BCR-KI were increasing tumor burden (17 x, 1 x combined with pleural effusion) and persistent hemolysis (1 x). Genetic high risk features comprised of at least one of the following: IGHV unmutated status, mutation and/or deletion of TP53 gene, deletion of 11q, and complexe karyotype. These features were present in 17 of 18 pts. (median 3 features). In particular, unmutated IGHV was found in 13/18 r/r pts who received BCR-KI (total cohort of r/r pts, 21/26). Overall response rate was 78% (Ib 8/11; Id 6/7). Time to next therapy or death (`KI effected time`) varies from 1.1 m to 69.1 m - in total 286.9 m until now. 4 pts. continued BCR-KI from 30 to 67 months. This was always the longest period of unchanged therapy in these 4 pts. Shorter `KI effected time` in the other 14 pts. was associated with higher treatment line and treatment interruptions. 2 responding pts. (without side effects) stopped BCR-KI and stayed in ongoing hematological remission for 11 and 25 months after cessation of treatment. Adverse drug reactions occurred in 6 pts. (Ib 4 x, Id 2 x). 5 pts. died on BCR-KI, but there was no therapy related death. Approximate costs per month in Germany are 1700 € in `Ctx effected time` (1.800.000 € per 1052,9 m) and 4.700 € in `KI effected time` (1.350.000 € per 286,9 m). Of note, one pt. on Id showed clinical progression associated with genetic evolution after 67 months of BCR-KI. He promptly responded to venetoclax. Discussion: In real live many r/r CLL pts. are elderly and present a broad spectrum of different clinical features. A clinical registry can reflect this and may add to our knowledge from multicenter studies. Remarkably almost all of our unselected r/r CLL pts. revealed genetic high risk features, in particular unmutated IGHV status, making them ideal candidates for targeted treatment strategies. These strategies take advantage of the fact that BCR-KI has been demonstrated to be well tolerated and effective in elderly and pre-treated pts. Undoubtedly BCR-KI increases the total costs of therapy, but affords a prolongation of overall survival. Remaining open questions include optimal treatment sequences, combination partners for BCR-KI as well as thorough analysis in the quality of molecular remissions. Disclosures Böttcher: Janssen: Honoraria, Research Funding; Celgene: Research Funding; AbbVie: Honoraria, Research Funding; Roche: Consultancy, Honoraria, Research Funding; Novartis: Honoraria.

Recent advances in the diagnostic of myeloproliferative neoplasms (MPNs) discovered CALRETICULIN (CALR) mutations as a major driver in these disorders. In contrast to JAK2 mutations being mainly associated with polycythaemia vera, CALR mutations are only associated with primary myelofibrosis (PMF) and essential thrombocythaemia (ET). CALR mutations are present in the majority of PMF and ET patients lacking JAK2 and MPL mutations. As these CALR mutations are absent from reactive bone marrow (BM) lesions their presence indicates ET or PMF. So far these mutations are detectable only by molecular assays. Their molecular detection is cumbersome because of the great CALR mutation heterogeneity. Therefore, the availability of a simple assay would be of great help. All CALR mutations reported lead to a frameshift generating a new 36 amino-acid C-terminus. We generated a monoclonal antibody (CAL2) to this C-neoterminus by immunizing mice with a representative peptide and compared its performance with Sanger sequencing data in 173 MPNs and other BM diseases. There was a 100% correlation between the molecular and the CAL2 immunohistochemical (IHC) assays. Thus, the detection of CALR mutations by the CAL2 IHC is a specific, sensitive, rapid, simple and low-cost method.

Hintergrund Die Detektion charakteristischer genomischer Aberrationen mittels nicht radioaktiver In-situ-Hybridisierung (ISH) hat nach den Vorschlagen der World Health Organization (WHO) eine wichtige Rolle in der Lymphomdiagnostik. Um die Reproduzierbarkeit entsprechender Analysen zu untersuchen, wurde ein Ringversuch mit acht Instituten fur Hamatopathologie durchgefuhrt.

Background: Therapy studies yield important insights into clinical features and therapeutic options of CLL. However studies in Germany represent less then 20% of all CLL patients (pts); pts >75 years (yrs) are included in 3% only. Furthermore initial phases are not reflected in multicenter studies and data representing real life situation are scarce. Methods: Out of 1.443 patients consulting our center because of leucocytosis (>10 Gpt/l) between 2003/07/01 and 2018/06/30 we diagnosed CLL consecutively in 234 pts (16,2%): 143 male (m), 91 female (f). Median age at diagnosis is 71,4 yrs. Median leucocyte count is 18,0 Gpt/l. BINET - Stages are: A in 82%, B in 11% and C in 7% of pts. Diagnoses are strictly based on WHO definition: Pts with small lymphocytic lymphomas (sLL, n=11) are included but those with monoclonal lymphocytosis of unknown significance (MLUS) or monoclonal B - lymphocytoses with uncertainly flow cytometry (FC) results are excluded. Histopathology, FC and genetics have been performed by external hematological reference laboratories. All investigations followed the rules of best clinical and laboratory practice. Dates of death are given by the record sections of the involved communities (deadline 2018/06/30). To address different questions we defined 3 groups of pts: A: "collective group", (n=234), i.e. all pts.diagnosed from 2003/07/01 to 2018/06/30. B: "epidemiological group" (n=129), i.e. pts from 3 communities (113.000 inhabitants - inc - in 2009/12/31) in close proximity referred to our center. C: "genetic features group" (n=99), i.e. pts diagnosed continuously between 2012/07/01 and 2018/06/30 with systematically performed genetics, (i.e. at least 80% of pts in this group. Genetics are: Cytogenetic (banding) n=88; FISH (del 6q21/6q, del 11q22.3, +12/+12q, del 13q14/ 13q34, del 17p13.1, 14q32) n=85. PCR (IgVH status - mutated vs. unmutated; TP53, NOTCH1, SF3B1 mutation) n=82. Results: "Collective group" (A): 7,5 years OS is 72% and 15 years OS is 33% respectively (KAPLAN-MEIER). Age of pts acts as a predominant factor for long term OS: 77% in pts < 60 yrs vs. 40% in pts ≥60 to "Epidemiological group" (B): Raw incidence is 7,56/105 inh. (m: 9,13, f: 6,06), age adjusted incidence is 10,3/105 inh (m: 12,5, f: 8,3), with highest rate of age between 75 to < 80 yrs. Standard incidence is calculated as 6,27/105 (BRD 1987), 4,78/105 (Europe) and 5,06/105 (USA 2000). Prevalence could be measured directly (2017-12-31): 79,1/105 inh. "Genetic features group" (C): IgVH mutation status is hypermutated in 48 pts. vs. unmutated in 39 pts. Results of FISH analyses (n = 85) are: del 6: 5,5%, del 11: 17,6%, +12: 3%, del 13q: 70,3%, del 17p: 8,8%; normal status: 13,2%. PCR revealed mutations of NOTCH1 in 7%, of SF3B1 in 10,5% and of TP53 in 8,6% of 82 pts, respectively. Combined del17p by FISH and molecular TP53 mutations at diagnosis are found in 3 of 81 pts (3,7%). Cytogenetic findings different to results of FISH and/or PCR were found in 36 of 82 pts (43,9%). Calculated 5 yrs freedom of therapy is 75% in IgVH hypermutated pts vs. 45% in unmutated pts (p = 0,0005; log rank test); calculated 5 yrs OS is 92% vs. 59% (p=0,023). Special situations in CLL: 13 of 234 pts (5,5%) have one parent or sibling with low grade NHL, mostly CLL. In contrast there is non spouse suffering of CLL / low grade NHL. Deficiency in Immunoglobuline G (Ig G < 4,0 g/l) was found in 17 of 199 pts at diagnose (8,5%), 29 pts (12,4%) were substituted with Ig G's in the Course of CLL. In 14 (6,0%) pts. we diagnosed a 2nd hematologic malignancy (3x cMPN, 1x CML, 3x MDS, 3x AML, 1x FL, 1x MCL, 1x MZL, 1x DLCBL-independent of CLL; monoclonal gammopathies are not considered). RICHTER syndrome was found in 1 case, but progression to plasmocytic/plasmoblastic disease was seen in 3 cases. Li FRAUMENI Syndrome was revealed in 1 male patient, he has been in stable disease for 13 yrs. Conclusion: CLL seems to be more frequent than yet considered. IgVH mutation status seems to be very important as a single prognostic factor concerning time of 1st therapy as well as OS. Clinical features of CLL are very different and impressing. Disclosures Böttcher: Genentech: Research Funding; Janssen: Honoraria; AbbVie: Honoraria, Research Funding; Celgene: Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Aims In the era of potentially disease-modifying agents such as Janus kinase inhibitors, accurate grading and differentiation of bone marrow (BM) fibrosis has become more relevant to assess staging of disease and therapeutic effects. However, different fibrosis grading models have been used in the past without uniformity, including the proposal by the World Health Organization. Current scoring systems are based only on reticulin fibrosis. Therefore, additional assessment of collagen and the grade of osteosclerosis appear to be essential to discriminate all components of the complex BM fibrous matrix. Methods and results We evaluated problems and pitfalls regarding staining techniques and the interpretation of reticulin fibrosis on a total of 352 samples. Furthermore, we propose a minor modification of the current grading and separate scoring for collagen deposition and osteosclerosis. Reproducibility of gradings was tested among 11 haematopathologists in a blinded assessment. Overall, the inter-rater reliability of all three grading systems ranged between 0.898 and 0.926. Conclusions A standardized assessment of BM fibrosis with differentiation between reticulin, collagen and osteosclerosis is recommended to evaluate the various components of the fibrous matrix which may be delinked after therapy. In this regard, quality of staining and application of laboratory standards enable a highly reproducible scoring.

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is a rare lymphoma entity. We performed a matched-pair analysis to evaluate the prognostic impact of several histopathological features in this distinct Hodgkin lymphoma subtype. Lymph node samples of NLPHL patients were tested for CD15, IgD, phosphorylated STAT6, ICOS and Epstein-Barr virus status of the malignant lymphocyte-predominant cells as well as epithelioid cell clusters and activated T cells in the microenvironment. None of these features was associated with a particular clinical outcome. However, patients presenting with epithelioid cell clusters showed a non-significant trend towards a lower relapse rate, justifying further evaluation of this marker.

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) accounts for approximately 5% of all Hodgkin lymphoma cases. The aim of this study was to evaluate the prognostic implication of histopathologic NLPHL variants. Biopsies of 423 NLPHL patients treated within 9 prospective clinical trials performed by the German Hodgkin Study Group were classified as tumor cell-rich cases (n = 10), typical NLPHL (n = 308), or histopathologic variants (n = 105). Histopathologic variants were characterized by the presence of lymphoma cells outside the B-cell nodules or B-cell depletion of the microenvironment. Compared with typical NLPHL, histopathologic variants were associated with advanced disease (29.5% vs 14.6%, P = .0012) and a higher relapse rate (18.1% vs 6.5% at 5 years, P = .0009). Variant histology represented an independent prognostic factor (odds ratio = 2.955) in a multivariate model of progression/relapse. A prognostic score, including the risk factors variant histopathologic growth pattern, low serum albumin, and male gender, was derived from this model and allowed the definition of 3 distinct risk groups. NLPHL patients presenting with histopathologic variants have a poorer outcome compared with those showing typical histology. The newly developed prognostic score combining histologic and clinical features allows allocating NLPHL patients to defined risk groups.

Aims: Marginal zone B cells (MZCs) and monocytoid B cells (MBCs) appear to be related lymphoid cells that take part in reactive and neoplastic marginal zone proliferations. These lesions are not yet well characterized, and the aim of this study was to find better diagnostic criteria for them. Methods and results: We analysed 60 nodal lesions with MBC and/or MZC proliferation for their morphological, immunophenotypic, molecular genetic and IG gene rearrangement features. On the basis of the results of the rearrangement assay and immunoglobulin light chain restriction, the lesions were divided into reactive and neoplastic groups. Among the neoplastic lesions, polymorphic and monomorphic subgroups emerged. All reactive lesions had morphological features of the polymorphic subgroup. By immunohistochemistry, IRTA1 and/or T-bet expression was found in all reactive lesions and in 90% of neoplastic lesions. Conclusions: IRTA1 and T-bet are positive markers for the identification of MZC/MBC proliferations, and thus for the diagnosis of nodal marginal zone lymphoma (NMZL). Polymorphic and monomorphic subgroups of NMZL could be distinguished. Most morphological and immunophenotypic patterns in reactive and neoplastic nodal expansions of MZCs and MBCs overlapped. Therefore, PCR clonality assay of the immunoglobulin heavy and light chain gene loci is the most reliable method for their differentiation. © 2013 John Wiley & Sons Ltd.

Hodgkin disease was the first defined lymphoid neoplasm. For many decades it was regarded as a disease separate from non-Hodgkin lymphoma. However, recent studies have shown that the dysplastic cells of Hodgkin lymphoma (HL) are monoclonal B cells. This finding raised again the question “Is HL just another B-cell lymphoma?” This article reviews the different aspects of HL and B-cell non-Hodgkin lymphoma (B-NHL), concluding that—despite the same cell of origin—fundamental differences exist in morphology, cellular composition, immunophenotype, activation or inhibition of transcription factors, epigenetics, and clinical behavior. These findings lead us to conclude that HL and B-NHLs should stay as two separate categories.

Abstract 1941 Poster Board I-964 Multiple studies have repeatedly shown that loss of MHC II expression correlates with poor patient prognosis in diffuse large B-cell lymphoma (DLBCL). Major histocompatibility complex class II (MHCII) molecules present peptides for antigen recognition and are important for the adaptive immune response. Loss of MHCII expression is also one of the changes seen during normal B-cell differentiation into plasma cells. Plasmablastic lymphoma (PBL) is another B-cell lymphoma characterized by a proliferation of large B-cells with a plasma cell immunophenotype and very poor prognosis. In this study, we questioned whether DLBCL cases that have low MHCII expression have a similar gene expression pattern to PBL. Unstained cuts from formalin-fixed, paraffin-embedded tissue blocks of 101 DLBCL and 76 PBL cases were analyzed for gene expression using a quantitative nuclease protection assay (qNPA, ArrayPlateR). The 42 genes on the array were previously identified as B-cell lineage-related or prognostically important in DLBCL. DLBCL cases were divided into low [MHCII(-)] and high [MHCII(+)] MHC II expression using a 20% cutoff for expression of HLA-DRB by qNPA, as previously described (L Rimsza et al, Blood 2008). Genes that differed significantly between lymphoma types were determined using the Partek Genomics SuiteR software, using ANOVA tests with a false discovery rate of 0.05. Thirty of the 42 genes on the array (71%) were differentially expressed between DLBCL as a whole and PBL. As expected from the literature, the PBL cases had less expression of B-cell antigen, MHCII, and germinal center-related genes as compared to DLBCL. Of these 30 genes, 29 were also different between MHCII(+) and PBL. In contrast, only 21 genes of the 42 on the array (50%) were differentially expressed between MHCII(-) and PBL, indicating a less dissimilar expression pattern between these two sets of cases. Of the 21 genes, two were uniquely different between MHCII(-) and PBL. Both of these, FN1 and CTGF, are found in the extracellular matrix and were low in the MHCII(-) cases. This finding, that the MHCII(-) cases are similar, but not identical to PBL, agrees with our previous immunohistochemistry studies suggesting MHCII(-) cases may be invoking selected mechanisms of differentiation (S Wilkinson et al, AACR Annual Meeting 2009, #2712). Our findings confirm the hypothesis that MHCII(-) DLBCL have a more plasma cell-like expression pattern than MHCII(+) DLBCL. These findings may have implications for pathogenesis and treatment. Disclosures: Schwartz: High Throughput Genomics: Employment. Gascoyne:Roche Canada: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Rimsza:High Throughput Genomics: Memorandum of understanding with HTG to run qNPA assay at no cost..