Single Myc Research Articles

Motive and opportunity: MYC rearrangements in high-grade B-cell lymphoma with MYC and BCL2 rearrangements (an LLMPP study)

AbstractRearrangements that place the oncogenes MYC, BCL2, or BCL6 adjacent to superenhancers are common in mature B-cell lymphomas. Lymphomas with diffuse large B-cell lymphoma (DLBCL) or high-grade morphology with both MYC and BCL2 rearrangements are classified as high-grade B-cell lymphoma with MYC and BCL2 rearrangements (“double hit”; HGBCL-DH-BCL2) and are associated with aggressive disease and poor outcomes. Although it is established that MYC rearrangements involving immunoglobulin (IG) loci are associated with inferior outcomes relative to those involving other non-IG superenhancers, the frequency of and mechanisms driving IG vs non-IG MYC rearrangements have not been elucidated. Here, we used custom targeted capture and/or whole-genome sequencing to characterize oncogene rearrangements across 883 mature B-cell lymphomas including Burkitt lymphoma, follicular lymphoma, DLBCL, and HGBCL-DH-BCL2 tumors. We demonstrate that, although BCL2 rearrangement topology is consistent across entities, HGBCL-DH-BCL2 have distinct MYC rearrangement architecture relative to tumors with single MYC rearrangements or with both MYC and BCL6 rearrangements (HGBCL-DH-BCL6), including both a higher frequency of non-IG rearrangements and different architecture of MYC::IGH rearrangements. The distinct MYC rearrangement patterns in HGBCL-DH-BCL2 occur on the background of high levels of somatic hypermutation across MYC partner loci in HGBCL-DH-BCL2, creating more opportunity to form these rearrangements. Furthermore, because 1 IGH allele is already disrupted by the existing BCL2 rearrangement, the MYC rearrangement architecture in HGBCL-DH-BCL2 likely reflects selective pressure to preserve both BCL2 and B-cell receptor expression. These data provide new mechanistic explanations for the distinct patterns of MYC rearrangements observed across different lymphoma entities.

Abstract 6418: Single-cell double expression of MYC and BCL2 proteins by fluorescent multiplex IHC is mainly in lymphoma cells with significant prognostic impact in large B-cell lymphoma while suggesting high cutoffs for routine IHC

Abstract Introduction: MYC+BCL2+ double expression (DE) is a biomarker for poor prognosis in diffuse large B-cell lymphoma (DLBCL), likely due to the cooperation between MYC and BCL2 oncoproteins in tumor cells. However, as generally MYC and BCL2 are separately assessed on two different slides by immunohistochemistry (IHC), MYC+ and BCL2+ results are from different cells. With the WHO-recommended cutoffs, ≥40% for MYC and ≥50% for BCL2 (sum < 100%), there is chance that the so-called DE comes from non-overlapping regions of the tumor (not single-cell DE). Moreover, tumor expression scores based on morphology assessment often vary among pathologists. In this study, we performed fluorescent multiplex IHC (fmIHC) using a MultiOmyxTM immunofluorescence platform (NeoGenomics Laboratories, Inc.) to determine single-cell MYC and BCL2 co-expression for prognostic analysis in DLBCL. Patients and Methods: Co-expression of MYC, BCL2, and 11 immunophenotypic markers by fmIHC was digitally quantified for 547 patients with DLBCL. Percentage of cells with MYC/BCL2 double or single expression was calculated for various cell types. Prognostic analysis was performed for de novo DLBCL cases, including 108 patients treated CHOP chemotherapy, and 356 patients treated with rituximab (R)-CHOP. Results: First, although MYC and BCL2 were expressed in multiple cell types, the vast majority (>90%) of MYC+BCL2+ DE cells were lymphoma cells. Frequencies of MYC and BCL2 co-expression were consistent with random distribution of independent MYC/BCL2 expression in positive cases. The activated B-cell-like subtype compared with the germinal center B-cell-like subtype had a significantly higher mean percentage of MYC+BCL2+ DE, but not single BCL2 or MYC expression, in PAX5+ cells. Second, in both the R-CHOP and CHOP cohorts, high percentages of DE in PAX5+ cells and in all DAPI+ cells were associated with significantly poorer survival of DLBCL patients. Very high percentage of single BCL2 expression in PAX5+ cells was also associated with poorer survival, however, only in a small number of patients in both cohorts. Only in the R-CHOP cohort, high single MYC expression in PAX5+ cells (in a significant proportion of the cohort) was associated with significantly poorer overall survival. In the R-CHOP cohort, eight cases had MYC/BCL2 double hit by FISH, including 3 cases with MYC/IGH fusions (DE) and 5 cases with MYC/non-IGH rearrangements (only one DE). The exclusion of these double hit cases did not impact the significance of DE and single MYC+ expression. Summary: True MYC+BCL2+ double protein expression at the single cell level is predominantly in lymphoma cells, and associated with significantly poor survival of DLBCL patients. Our results suggest high cutoffs for common MYC/BCL2 IHC to identify true double expressor lymphoma. Citation Format: Zijun Yidan Xu-Monette, Yong Li, Qingyan Au, Harry Nunns, Wenyu Shi, Alexandar Tzankov, Carlo Visco, Govind Bhagat, Eric Hsi, Xiaoxian X. Zhao, Karen Dybkaer, April Chiu, Wayne Tam, Youli Zu, Fredrick B. Hagemeister, Andrew Song, Michele Pellegrino, Heounjeong Go, Maurilio Ponzoni, Andrés Ferreri, Michael B. Møller, Benjamin Parsons, J. Han van Krieken, Miguel A. Piris, Jane N. Winter, Mingzhi Zhang, Bing Xu, Ken H. Young. Single-cell double expression of MYC and BCL2 proteins by fluorescent multiplex IHC is mainly in lymphoma cells with significant prognostic impact in large B-cell lymphoma while suggesting high cutoffs for routine IHC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6418.

DA-EPOCH-R for High Grade B-Cell Lymphoma Patients with MYC and BCL2 and/or BCL6 Rearrangements: Clinical Results of the Induction Phase of the HOVON-152 Trial

Introduction Patients (pts) with high grade B-cell lymphoma (HGBL) with MYC and BCL2 and/or BCL6 gene rearrangements (double hit and triple hit (DH/TH)) have poor outcomes to standard R-CHOP. Retrospective studies reported improved disease-free survival (DFS) through intensification with dose-adjusted etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, and rituximab (DA-EPOCH-R). This regimen was studied in a small prospective trial including 24 DH/TH and 19 single MYC rearranged (SH) lymphomas (Dunleavy, Lancet Haematol 2019). No prospective studies evaluating DA-EPOCH-R exclusively for pts with DH/TH HGBL have been reported. The HOVON-152 trial aimed to improve outcomes in untreated DH/TH HGBL pts by investigating the efficacy of the immune checkpoint inhibitor nivolumab as consolidation treatment in pts achieving complete metabolic response (CMR) after DA-EPOCH-R induction. Here, we present the efficacy and safety profile of the induction phase with DA-EPOCH-R. Methods HOVON-152 is a prospective, multi-center, single arm phase II trial. Inclusion criteria were pts with newly diagnosed HGBL-DH/TH (according to the WHO 2016 classification), age ≥ 18 years, WHO performance status (PS) 0-3 and Ann Arbor stage II-IV. During the screening period for rearrangement status, pts could receive 1 cycle of R-CHOP or DA-EPOCH-R, followed by 5 cycles of DA-EPOCH-R. All pts received intrathecal CNS prophylaxis. All diagnostic lymphoma samples were centrally reviewed. PET-CT scans were performed at diagnosis, after 3 cycles and at end-of-induction (local review, central review will be reported at the conference). Pts in CMR after induction treatment (Deauville 1-3 or a negative lymphoma biopsy in case of Deauville 4) proceeded to nivolumab consolidation (480 mg every 4 weeks for one year). The HOVON-152 aimed to improve 12 months DFS of pts in CMR after induction from an expected 70% to 85% with nivolumab consolidation. Secondary objectives included evaluation of response rates, overall survival (OS) and safety. With a power of 0.90 a sample size of 97 pts was calculated. Here, we report efficacy (CMR rate) and safety of DA-EPOCH-R induction treatment. Logistic univariate analysis is used to analyze baseline characteristics associated with response. Adverse events (AEs) were defined according to the common terminology criteria for adverse events (CTC AE 5.0), counted by the highest grade per system organ class per patient. Results From August 2018 - March 2022, 97 pts have been enrolled (study inclusion completed). One patient was excluded due to CNS localization. The median age was 62 years (range 35-79); 90 (83%) pts had stage III-IV disease and 52 (54%) had (intermediate-)high international prognostic index (IPI) (Table 1). Central pathology review confirmed DH/TH in all pts. 65 pts (67%) had a BCL2 DH, 11 (12%) a BCL6 DH and 16 (17%) a TH. Dose adjustments were performed conform protocol. The maximum dose-level (DL) achieved was DL1 in 41 (43%), DL2 in 22 (23%), DL3 in 25 (25%), DL4 in 7 (7%) and DL5 in 1 (1%) of the pts. Vincristine dose was reduced in 28/81 (35%) pts. After DA-EPOCH-R induction, 63/96 (66%, 95% CI 55-75%) pts achieved CMR. WHO PS 2-3 (odds ratio (OR) 0.15, 95% CI 0.03-0.85, p=0.03), elevated LDH (OR 0.24, 95%CI 0.10-0.59, p=0.002) and bulky disease defined as ≥10 cm mass (OR 0.23, 95%CI 0.09-0.56, p=0.001), were significantly associated with a lower chance of achieving CMR. During treatment, 7 (7%) pts experienced a grade 5 AE (ileus, intestinal perforation, multi-organ failure/sepsis). Thereof, 4 patients died during DA-EPOCH-R and 3 patients died after DA-EPOCH-R. 31 (32%) experienced a grade 4 AE (e.g. sepsis, perforation, hemorrhage, thrombocytopenia and neutropenia), 21 (22%) a grade 3 AE (e.g. anemia, mucositis, infections and electrolyte disturbances) and 16 (17%) pts a grade 2 AE. Conclusion We report the largest prospective series of DH/TH HGBL patients treated with DA-EPOCH-R. DA-EPOCH-R induction was feasible, with toxicity and dose adjustments as previously described. The observed CMR rate of 66% was lower than previously reported in a prospective cohort of mixed DH/TH and SH patients (74%). For patients achieving CMR, the nivolumab consolidation phase is ongoing. Translational side studies investigating predictive factors to identify patients not achieving CMR are ongoing. For these patients, novel strategies to improve first-line treatment are warranted.

Impact of Double Expression of MYC and BCL-2 on Outcomes in Primary CNS Lymphoma: A UK Multicentre Analysis

Introduction Primary central nervous system lymphoma (PCNSL) is a rare B cell lymphoma with an aggressive course. Relapses remain common even with intensive immuno-chemotherapy treatment options such as MATRix and consolidation with autologous stem cell transplant (ASCT), and prognostic tools are limited. Although, double expressor status (co-expression of both MYC and BCL-2) is well established in systemic de novo DLBCL, its prognostic impact in PCNSL has been understudied. Here we evaluated the prognostic value of BCL-2, BCL-6, and MYC expression in a retrospective cohort of treated PCNSL patients diagnosed at 7 academic centres in the UK. Methods We performed this retrospective analysis on histologically-confirmed PCNSL patients diagnosed consecutively between 1st May 2015 and 31st May 2020. Treatment with a high-dose methotrexate-based chemotherapy regimen was a mandatory inclusion criterion. BCL-2 and MYC immunohistochemistry (IHC) protein expression data were collated from local diagnostic histology reports and double expressor (DE) status was defined as per WHO criteria (MYC: surface expression > 40% of cells and BCL-2: >50% of cells). Outcomes included response rates, progression-free survival (PFS) and overall survival (OS). Where available, diagnostic fluorescence in situ hybridisation (FISH) data was collected for BCL-2, BCL-6 and MYC loci translocations. Cox-regression for PFS and OS were used to determine baseline predictors of response and survival and to construct multivariable models for factors associated with outcome. Results In total, 242 patients were analysed. Key baseline patient characteristics and IHC data are summarised in Table 1. Median age was 65 years (IQR 56-71), 60% were male and 64% of patients had an ECOG performance status (PS) of 0-1. One hundred and seventy-four (72%) patients received treatment with MATRix chemotherapy; these patients were younger (median age 62 vs. 73 years, p< 0.01), had better baseline PS (PS ≤ 1: 75% vs. 37%, p< 0.01) and higher rates of consolidation with BCNU-thiotepa ASCT (58% vs. 7%, p< 0.01). Double expressor (DE) status was assessable in 169/242 (69%) patients. Reasons for absent DE status were missing IHC expression data (BCL-2: n=28; MYC: n=44) or IHC expression data not reported in line with WHO recommended criteria (BCL-2: n=45; MYC: n=7). In the DE-assessable cohort (n = 169 patients), 40% of patients had DE PCNSL, higher than estimates of DE prevalence in systemic DLBCL (reported rates between 20 and 30%). As only 40 cases (17%) underwent FISH assessment for concurrent MYC and BCL-2 loci translocation (double hit status), correlation between double hit and DE status was not possible. DE status was not associated with patient age at diagnosis, baseline PS or treatment received. With a median follow up of 1.7 years, 34% of patients relapsed and 45% died. Although single MYC or BCL-2 expression alone had no significant association with OS or PFS in the entire cohort, DE status was associated with significantly poorer PFS, and earlier relapse (median 0.86 years vs. 2.77 years; HR 1.61 (1.07 - 2.41); p=0.021) (Fig. 1). In a subgroup analysis restricted to patients treated with MATRix chemotherapy (n = 116 patients), there was a trend towards inferior PFS and OS, although this did not reach significance in a univariable analysis. However, the adverse prognostic impact of DE status on PFS was maintained in a multivariable analysis modelling age, baseline PS, treatment received, ASCT consolidation status and DE status both for the entire cohort (HR 1.75 (1.15 - 2.66); p<0.01) and the MATRix treated subgroup (HR 1.91 (1.08 - 3.36); p=0.03). A trend towards an association between DE status and OS was noted but did not reach significance in either a univariable or multivariable analysis. We observed no significant difference in PFS or OS between DE-PCNSL and non-DE-PCNSL patients who received MATRix and consolidation with ASCT, perhaps indicating that the adverse impact of DE status is modified by this treatment strategy, although the sample size was small (n=66). Conclusions In a large, retrospective cohort of PCNSL patients treated at 7 UK academic treatment centres, double expression of MYC and BCL-2 by IHC was associated with inferior PFS even in patients treated with MATRix chemotherapy. Validation of this finding in independent cohorts is warranted. ___ JO, CPF and KC share senior authorship Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Development of an endogenously myc-tagged TARDBP (TDP-43) zebrafish model using the CRISPR/Cas9 system and homology directed repair

Many of the modern advances in cellular biology have been made by the expression of engineered constructs with epitope tags for subsequent biochemical investigations. While the utility of epitope tags has permitted insights in cellular and animal models, these are often expressed using traditional transgenic approaches. Using the CRISPR/Cas9 system and homology directed repair we recombine a single myc epitope sequence following the start codon of the zebrafish ortholog of TARDBP (TDP-43). TDP-43 is an RNA binding protein that is involved in the neurodegenerative disease amyotrophic lateral sclerosis and frontotemporal dementia. We report that zebrafish expressing the myc-tardbp engendered allele produced a stable protein that was detected by both western blot and immunofluorescence. Furthermore, both heterozygous and homozygous carriers of the myc-tardbp allele developed to sexual maturity. We propose that the methodology used here will be useful for zebrafish researchers and other comparative animal biologists interested in developing animal models expressing endogenously tagged proteins.

High-grade B-cell lymphoma

Introduction. Aggressive B-cell lymphomas are a heterogeneous group of diseases with various clinical, patohistological, genetic characteristics and a variety of treatment outcomes. Diffuse large B-cell lymphoma is the most common lymphoma in European countries, some lymphomas are recognized as specifically aggressive, providing non-adequate response to the standard treatment (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone). High-grade B-lymphomas. One group consists of those which are carriers of the c-myc, bcl-2 or bcl-6 rearrangement established by Fluorescence in situ hybridization, and are called high grade B lymphomas, which can be double hit or triple hit. The other group consists of those with blastoid morphology, which are not carriers of the c-myc, bcl-2 and bcl- 6 rearrangement and are called Not Otherwise Specified. This heterogeneous group is a carrier of a single myc mutation in 45% of cases, in 15% of patients, an additional analysis of gene expression profiling indicates the presence of high grade B lymphomas double hit sig+. Extranodal localization with Central Nervous System involvement is frequently reported. Clinical staging and disease progression along with risk assessment by means of IPI scores and aaIPI scores in patients with high-grade B-lymphomas. Diagnostic procedures during the clinical interview, physical examination, laboratory analyses and various additional diagnostic procedures. High-grade Blymphomas treatment. Studies indicate more intensive induction chemotherapy including central nervous system prophylaxis for these patients. Conclusion. The question of how to choose the most effective therapeutic strategy in high grade B lymphomas is still open at this moment, and examinations are focused on the research of molecular mechanisms of lymphomagenesis.

Predictors of Relapse and Survival Following Autologous Stem Cell Transplant in Patients with Diffuse Large B-Cell Lymphoma

Background: Although the majority of patients with diffuse large B-cell lymphoma (DLBCL) can be cured with intensive chemotherapy and rituximab, 30-40% of patients will be refractory to or relapse after first line treatment. For these patients, the current standard of care is salvage chemotherapy followed by high-dose chemotherapy and autologous stem cell transplantation (ASCT). Prior studies have largely examined clinical risk factors associated with higher risk of relapse after ASCT; however, there is limited data integrating both pathologic and molecular features. Thus, we aimed to identify high-risk features associated with relapse and survival after ASCT using a combination of clinical, molecular, pathologic, and transplant characteristics.Methods: We retrospectively analyzed the medical records of all adult patients with DLBCL who underwent ASCT at our two institutions from 2010 to 2020. Patients with primary CNS lymphoma, primary mediastinal B-cell lymphoma, or Burkitt lymphoma were excluded. We analyzed demographics, clinical characteristics, cell of origin (COO) by immunohistochemistry (IHC), fluorescence in-situ hybridization (FISH) testing, and treatment/transplant characteristics. The primary endpoints were 3-year progression-free survival (PFS) and overall survival (OS) from ASCT. The Kaplan-Meier method was used to estimate survival with univariate and multivariate Cox proportional hazards regression performed to identify factors associating with PFS and OS, summarized using hazard ratios (HR) with 95% confidence intervals (CI).Results: A total of 235 DLBCL patients underwent ASCT from 2010 to 2020. Median age at ASCT was 61 years (range: 25-75) and 63% were male. At DLBCL diagnosis, 80% had advanced stage disease, 74% had extranodal involvement, 13% had poor performance status, and 65% had elevated lactate dehydrogenase (LDH). 71 patients (30%) had a prior or concurrent indolent lymphoma diagnosis indicating transformed disease. Of the patients with available COO and molecular data, 115 (60%) had germinal center B-cell (GCB) phenotype by IHC, 10 (6%) had a single MYC rearrangement by FISH, and 35 (22%) had MYC plus BCL2 and/or BCL6 rearrangements (DHL/THL). After first-line treatment, 12% remained refractory and 62% later relapsed at a median of 13 months (range: 1-240). Patients received a median of 2 (range: 1-5) lines of treatment pre-ASCT. At time of ASCT, 66% were in complete response (CR) and 32% were in partial response (PR) by standard of care imaging and response criteria.With median follow-up of 5.2 years from time of ASCT, 98 patients (42%) relapsed and 78 (33%) died. 3-year PFS and OS were 58% (95% CI 51-64%) and 74% (95% CI 67-79%), respectively. In univariate analysis, factors associated with worse PFS and worse OS included 3 or more lines of treatment pre-ASCT (p<0.01 for both) and non-CR at ASCT (p<0.01 for both) (Figure 1A and B). Transformed disease was also associated with worse PFS (p=0.03). In multivariate analysis, non-CR at ASCT remained significant (HR 2.22, 95% 1.26-3.90, p<0.01) for worse OS, along with non-GCB COO (HR 1.81, 95% CI 1.03-3.18, p=0.04) and age >60 at ASCT (HR 1.92, 95% CI 1.06-3.47, p=0.03) (Figure 1C). Stratifying by COO and disease status at transplant, 3-year OS was best in the GCB/CR group (84%, 95% CI 73-90%), while worse but similar in the GCB/non-CR and non-GCB/CR groups (68%, 95% CI 51-80% and 71%, 95% CI 56-83%, respectively) (Figure 1D). The non-GCB/non-CR group had the worst 3-year OS (48%, 95% CI 27-67%). No individual factors beyond CR/non-CR at ASCT were associated with worse 3-year PFS. Notably, DHL/THL patients (77% of whom were in CR at time of ASCT) had similar PFS (p=0.08) and OS (p=0.30) to non-DHL/THL patients, suggesting that response to therapy may be more prognostic than high-risk molecular features alone.Conclusions: This analysis indicated that factors associated with OS after ASCT were disease status at time of transplant and COO, with non-GCB patients not in CR having the poorest outcomes. GCB patients not in CR were still able to be cured by ASCT at a high rate. Molecular rearrangements including DHL/THL were not prognostic, although interpretation may be limited by the modest number of DHL/THL patients. These findings may inform which patients should undergo ASCT, while the highest risk group may be better treated with alternatives including novel targeted agents or chimeric antigen receptor cell therapy. [Display omitted] DisclosuresBachanova: FATE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Research Funding; KaryoPharma: Membership on an entity's Board of Directors or advisory committees; Gamida Cell: Membership on an entity's Board of Directors or advisory committees, Research Funding. Fehniger: Compass Therapeutics: Research Funding; Affimed: Research Funding; ImmunityBio: Research Funding; Wugen: Consultancy, Current equity holder in publicly-traded company, Patents & Royalties: related to memory like NK cells, Research Funding; OrcaBio: Other; Kiadis: Other; HCW Biologics: Research Funding; Indapta: Other. Weisdorf: Fate Therapeutics: Research Funding; Incyte: Research Funding.

MYC single-hit large B-cell lymphoma: clinicopathologic difference from MYC-negative large B-cell lymphoma and MYC double-hit/triple-hit lymphoma

MYC-rearranged large B-cell lymphoma with BCL2 and/or BCL6 rearrangement, double-hit (DH) or triple-hit (TH) lymphoma, is associated with poor survival after standard treatment. To investigate the clinical impact of single-hit (SH) MYC rearrangement, we analyzed 241 cases of diffuse largeB-cell lymphoma (DLBCL) for MYC, BCL2, and BCL6 rearrangement by fluorescence in situ hybridization. Fifty-five of 241 (22.8%) cases showed MYC rearrangements. Twenty-three cases were diagnosed as DLBCL; 18 as high-grade B-cell lymphoma (HGBCL)-DH; 3 as HGBCL-TH; and 11 as HGBCL, not otherwise specified. Both DH and TH lymphomas showed high-grade morphology (P=0.002), higher stage (P=0.022), and more frequent germinal center B-cell-likephenotype (P=0.008). SH lymphomas displayed high-grade morphology (P=0.002) but were not different from MYC-negative lymphomas in cell of origin, clinical stage, international prognostic index (IPI), or extranodal involvement. Patients with DH/TH lymphomas had worse overall survival (OS) (P=0.016) and progression-free survival (PFS) (P<0.001), while OS and PFS of SH lymphomas were not different from those of MYC-negative lymphomas. There was no survival difference between cases of BCL2 and BCL6 rearrangements. Poorer prognostic factors included higher ECOG class, higher IPI, and DH or TH translocation for OS, and higher IPI and DH or TH translocation for PFS. Higher IPI was an independent prognostic factor for OS and PFS. In conclusion, large B-cell lymphomas with single MYC rearrangement showed high-grade morphology but were otherwise not different from MYC-negative lymphomas.

PF518 SOMATIC COPY NUMBER GAINS IN MYC, BCL2, OR BCL6, IN ADDITION TO TRANSLOCATIONS, IDENTIFIES A SUBSET OF AGGRESSIVE ALTERNATIVE‐DH/TH DLBCL PATIENTS

Background:Diffuse Large B Cell Lymphoma (DLBCL) is characterized by both biologic and genetic heterogeneity. While significant therapeutic advances have been made, nearly 30% of cases fail frontline treatment. Recent data suggest that 5–10% of DLBCL can be categorized as double/triple hit lymphoma (DH/TH), defined as having concurrent MYC, BCL2 and/or BCL6 gene rearrangements, identified by fluorescence in‐situ hybridization (FISH) probes. According to the 2017 revision of the World Health Organization classification of lymphoid neoplasms, DH/TH DLBCL is now considered a high grade B‐cell lymphoma (HGBL). While gene rearrangements represent significant genetic events in cancer, copy number alterations (CNAs) also play an important role, often through genomic amplification of oncogenes or loss of tumor suppressors. Despite their similarities, the contributions of CNAs in MYC, BCL2, and BCL6, alone, or in combination with gene rearrangements, are largely unknown in DLBCL and could identify a group of previously uncharacterized patients that may have high expression of MYC, BCL2 and/or BCL6 driven by alternative mechanisms.Aims:The goal of the study is to define the landscape and prognostic significance of gene rearrangements and copy gains in MYC, BCL2, and BCL6 in a cohort of newly diagnosed DLBCL.Methods:A total of 176 cases of DLBCL with both FISH and CNA data were available for the study. FISH was performed on formalin‐fixed paraffin‐embedded sections using break‐apart probes to MYC, BCL2, and BCL6 in the Mayo Clinic Department of Lab Medicine and Pathology. Somatic copy number alterations were identified using whole exome sequencing and the Affymetrix OncoScan® FFPE assay on patient tumor FFPE tissue, and were interrogated using Nexus Copy Number 9.0 software. All patients were treated with immunochemotherapy and prospectively followed for event‐free and overall survival.Results:FISH identified 3 groups of previously described patients, DH/TH or HGBL (n = 11), translocation positive (single MYC, BCL2, BLC6, or double BCL2/BLC6, n = 86), and translocation negative (n = 79). Expanding upon the translocation positive subgroup, copy number analysis identified patients (19 of 86, 22%) with copy number gains in a second or third gene resulting in genomic hits at both MYC and BCL2/6; we classified these as alternative‐double/triple‐hit (A‐DH/TH). An example of this would be a MYC translocation plus a BCL2 and/or BCL6 gain (n = 5), or a BCL2 and/or BCL6 translocation plus a copy gain in MYC (n = 14). Similar interrogation of a publically available dataset (n = 250), revealed similar proportions of these patient groups in an independent cohort of DLBCL, validating our findings. Cell of origin classification of the A‐DH/TH cases revealed that they were 53% GCB. A‐DH/TH patients, in comparison to the translocation‐positive/copy‐gain‐negative cases, were at greater risk of an event (Cox HR = 1.5, 95% CI = 0.71–3.0) and the cases trended towards a worse overall survival (log‐rank P = 0.065; Cox HR = 2.0, 95% CI = 0.94–4.3). Patients with copy‐gains alone had similar outcomes as those with no copy‐gain or translocations, suggesting a central role for at least one translocation event in predicting outcome.Summary/Conclusion:Our data suggest that use of CNA data in combination with traditional FISH can identify a unique subset of DLBCL, A‐DH/TH, that are missed by standard clinical practice. More importantly, we find that these patients do poorly and may benefit from more aggressive treatment, although we do acknowledge that our population size was small and further validation is needed.image

Successful Treatment of MYC rearrangement Positive Large B Cell Lymphoma Patients with R-CHOP21 Plus Lenalidomide: Results of a Multicenter Phase II HOVON Trial

Successful Treatment of MYC rearrangement Positive Large B Cell Lymphoma Patients with R-CHOP21 Plus Lenalidomide: Results of a Multicenter Phase II HOVON Trial

MYC-mediated synthetic lethality for treatment of hematological malignancies.

Deregulated c-MYC expression is found in many human malignancies. MYC activation induces multiple lineages of hematological malignancies in single Myc transgenic mice. MYC inactivation causes tumor regression. MYC is therefore an attractive target for cancer treatment. However, little progress has been made in the development and application of targeted MYC inactivation in clinical practice. In double Myc transgenic mouse models, Myc-driven leukemogenesis and lymphomagenesis can be accelerated by transduction of non-MYC oncogenes, leading to dual addiction to MYC and the non-MYC oncogenes. Wang et al. (2004) first established the concept of MYC-mediated synthetic lethality (MYC-SL). MYC overexpression sensitized cells to TRAILand DR5-agonist-induced apoptosis. This suggests that MYC-dependent tumor cells may be killed by targeting partner oncogenes of MYC. Many small molecule inhibitors (SMIs) have been proven to induce MYC-SL by targeting AUK-B, Brd4, CDK1, CHK1, MCL-1, the mTOR/4E-BP1/eIF4E pathway, and PIM1/2. Compared with conventional treatment approaches, SMI-induced MYC-SL displays highly selective anticancer activity and much lower cytotoxicity to normal cells. SMI-induced MYC-SL can reverse eIF4F- and PIM2-induced multiple chemoresistance. The combination of an SMI with chemotherapeutic agents can elevate chemotherapy efficacy by enhancing chemosensitivity. This combination will be a promising novel approach to treating MYC-dependent tumors by inducing MYC-SL.

Myc Function in Drosophila

Drosophila contains a single MYC gene. Like its vertebrate homologs, it encodes a transcription factor that activates many targets, including prominently genes involved in ribosome biogenesis and translation. This activity makes Myc a central regulator of growth and/or proliferation of many cell types, such as imaginal disc cells, polyploid cells, stem cells, and blood cells. Importantly, not only does Myc act cell autonomously but it also affects the fate of adjacent cells and tissues. This potential of Myc is harnessed by many different signaling pathways, involving, among others, Wg, Dpp, Hpo, ecdysone, insulin, and mTOR.

Myc on my mind: a transcription factor family's essential role in brain development.

Myc on my mind: a transcription factor family's essential role in brain development.

A High Affinity Hepatocyte Growth Factor-binding Site in the Immunoglobulin-like Region of Met

Hepatocyte growth factor (HGF) and its high affinity receptor, the tyrosine kinase Met, play a key role in embryo development and tumor invasion. Both HGF and Met are established targets for cancer therapy. However, the mechanism of their interaction is complex and remains elusive. HGF is secreted as a monomeric precursor (pro-HGF) that binds to but does not activate Met. Mature HGF is a α/β heterodimer containing a high affinity Met-binding site in the α-chain (HGF-α) and a low affinity Met-binding site in the β-chain (HGF-β). The extracellular portion of Met contains a semaphorin (Sema) domain, a cysteine-rich hinge (plexin-semaphorin-integrin), and four immunoglobulin-like domains (immunoglobulin-like regions in plexins and transcription factors (IPT) 1-4). HGF-β binds to Sema through a low affinity contact. The domain of Met responsible for high affinity binding to HGF-α has not been identified yet. Here we show that this long sought after binding site lies in the immunoglobulin-like region of Met and more precisely in IPT 3 and 4. We also show that IPT 3 and 4 are sufficient to transmit the signal for kinase activation to the cytoplasm, although the lack of Sema makes the receptor equally sensitive to mature HGF and pro-HGF. Finally, we provide evidence that soluble Met-derived proteins containing either the low affinity or high affinity HGF-binding site antagonize HGF-induced invasive growth both in vitro and in xenografts. These data suggest that the immunoglobulin-like region of Met cooperates with the Sema domain in binding to HGF and in controlling Met kinase activity. Although the IPT-HGF-α interaction provides binding strength, the Sema-HGF-β contact confers selective sensitivity to the active form of the ligand.

Control of the Myc-Max mediated transactivation in yeast by natural promoter elements.

Transcriptional activation studies involving the human oncoprotein and transcription factor Myc and its helix-loop-helix partner protein Max in mammalian cells are critical due to the presence of endogenous Myc and Max proteins. Here we show that co-expression of the human c-myc and max genes from 2micro circle derived high copy number vectors in yeast cells stimulate the transcriptional activation of a LacZ reporter gene fused to the yeast cytochrome-c1 oxidase minimal promoter containing the adenovirus major late promoter element (AMLPE). The exchange of the single Myc binding site in the AMLPE by the two E-box DNA motifs (CACGTG) present in the Myc responsive element of a human Myc target gene (ornithine decarboxylase) in front of a promoter-reporter gene cassette results in a two-fold enhanced beta-galactosidase expression. Low expression of max and high level expression of c-myc at the same time led to a further enhancement of transcriptional activation from this promoter-reporter gene cassette.

Three cell lines from hamster buccal pouch tumors induced by topical 7,12-dimethylbenz(a)anthracene, alone or in conjunction with herpes simplex virus inoculation

Three squamous carcinoma cell lines HBPC-1, HBPC-2, and HBPC-3 were established from hamster buccal pouch tumors induced by topical 7,12-dimethylbenz(a)anthracene (DMBA) treatment alone, topical DMBA treatment in conjunction with type 1 herpes simplex virus (HSV-1) inoculation, and topical DMBA application in combination with type 2 HSV (HSV-2) inoculation, respectively. The cells were epithelial in morphology, had a doubling time of approximately 18 h, and required bovine serum for optimal growth. They demonstrated an in vitro anchorage-independent growth and produced squamous cell carcinomas when transplanted into normal hamster pouch submucosa. The carcinoma cell lines equally expressed cellular hst, src, abl, and raf proto-oncogenes that were not expressed in the normal hamster pouch epithelial cells. An equal amount of fos gene expression was noticed in the normal pouch epithelial cells, HBPC-1 and HBPC-3, but the HBPC-2 expressed less fos poly(A+)RNA than the other cell lines. The myc proto-oncogene was also expressed both in the normal pouch epithelial cells and in the cancer cell lines. However, the size and number of expressed myc poly(A+)RNA in the normal cells and cancer cell lines differed. Although the normal cells and HBPC-1 expressed a single myc transcript, 1.7-kilobase (kb) and 2.3-kb, respectively, both HBPC-2 and HBPC-3 expressed two myc poly(A+)RNAs, 1.7-kb and 2.3-kb.