Maria Pamela Dobay

Activating mutations in genes related to TCR signaling in angioimmunoblastic and other follicular helper T-cell-derived lymphomas

Angioimmunoblastic T-cell lymphoma (AITL) and other lymphomas derived from follicular T-helper cells (TFH) represent a large proportion of peripheral T-cell lymphomas (PTCLs) with poorly understood pathogenesis and unfavorable treatment results. We investigated a series of 85 patients with AITL (n = 72) or other TFH-derived PTCL (n = 13) by targeted deep sequencing of a gene panel enriched in T-cell receptor (TCR) signaling elements. RHOA mutations were identified in 51 of 85 cases (60%) consisting of the highly recurrent dominant negative G17V variant in most cases and a novel K18N in 3 cases, the latter showing activating properties in in vitro assays. Moreover, half of the patients carried virtually mutually exclusive mutations in other TCR-related genes, most frequently in PLCG1 (14.1%), CD28 (9.4%, exclusively in AITL), PI3K elements (7%), CTNNB1 (6%), and GTF2I (6%). Using in vitro assays in transfected cells, we demonstrated that 9 of 10 PLCG1 and 3 of 3 CARD11 variants induced MALT1 protease activity and increased transcription from NFAT or NF-κB response element reporters, respectively. Collectively, the vast majority of variants in TCR-related genes could be classified as gain-of-function. Accordingly, the samples with mutations in TCR-related genes other than RHOA had transcriptomic profiles enriched in signatures reflecting higher T-cell activation. Although no correlation with presenting clinical features nor significant impact on survival was observed, the presence of TCR-related mutations correlated with early disease progression. Thus, targeting of TCR-related events may hold promise for the treatment of TFH-derived lymphomas.

Genomics and drug profiling of fatal TCF3-HLF-positive acute lymphoblastic leukemia identifies recurrent mutation patterns and therapeutic options

TCF3-HLF−positive acute lymphoblastic leukemia (ALL) is currently incurable. Using an integrated approach, we uncovered distinct mutation, gene expression and drug response profiles in TCF3-HLF−positive and treatment-responsive TCF3-PBX1−positive ALL. We identified recurrent intragenic deletions of PAX5 or VPREB1 in constellation with the fusion of TCF3 and HLF. Moreover somatic mutations in the non-translocated allele of TCF3 and a reduction of PAX5 gene dosage in TCF3-HLF ALL suggest cooperation within a restricted genetic context. The enrichment for stem cell and myeloid features in the TCF3-HLF signature may reflect reprogramming by TCF3-HLF of a lymphoid-committed cell of origin toward a hybrid, drug-resistant hematopoietic state. Drug response profiling of matched patient-derived xenografts revealed a distinct profile for TCF3-HLF ALL with resistance to conventional chemotherapeutics but sensitivity to glucocorticoids, anthracyclines and agents in clinical development. Striking on-target sensitivity was achieved with the BCL2-specific inhibitor venetoclax (ABT-199). This integrated approach thus provides alternative treatment options for this deadly disease.

Immunohistochemistry as a valuable tool to assess CD30 expression in peripheral T-cell lymphomas: high correlation with mRNA levels

The extended use of brentuximab-vedotin was reported for CD30(+) nonanaplastic peripheral T-cell lymphomas (PTCLs) with promising efficacy. CD30 status assessment is thus a critical factor for therapeutic decision, but the reliability of immunohistochemistry (IHC) in evaluating its expression remains to be defined. This prompted us to investigate the correlation between semiquantitative CD30 protein assessment by IHC and messenger RNA (mRNA) assessment by microarrays in a cohort of 376 noncutaneous PTCLs representative of the main entities. By IHC, CD30 expression was heterogeneous across and within entities and significantly associated with large tumor cell size. In addition to 100% anaplastic large-cell lymphomas, 57% of other PTCL entities were CD30-positive at a 5% threshold. CD30 protein expression was highly correlated to mRNA levels. mRNA levels were bimodal, separating high from low CD30-expressing PTCL cases. We conclude that IHC is a valuable tool in clinical practice to assess CD30 expression in PTCLs.

Type II enteropathy-associated T-cell lymphoma features a unique genomic profile with highly recurrent SETD2 alterations.

Enteropathy-associated T-cell lymphoma (EATL), a rare and aggressive intestinal malignancy of intraepithelial T lymphocytes, comprises two disease variants (EATL-I and EATL-II) differing in clinical characteristics and pathological features. Here we report findings derived from whole-exome sequencing of 15 EATL-II tumour-normal tissue pairs. The tumour suppressor gene SETD2 encoding a non-redundant H3K36-specific trimethyltransferase is altered in 14/15 cases (93%), mainly by loss-of-function mutations and/or loss of the corresponding locus (3p21.31). These alterations consistently correlate with defective H3K36 trimethylation. The JAK/STAT pathway comprises recurrent STAT5B (60%), JAK3 (46%) and SH2B3 (20%) mutations, including a STAT5B V712E activating variant. In addition, frequent mutations in TP53, BRAF and KRAS are observed. Conversely, in EATL-I, no SETD2, STAT5B or JAK3 mutations are found, and H3K36 trimethylation is preserved. This study describes SETD2 inactivation as EATL-II molecular hallmark, supports EATL-I and -II being two distinct entities, and defines potential new targets for therapeutic intervention.

Ex vivo drug response profiling detects recurrent sensitivity patterns in drug-resistant acute lymphoblastic leukemia

Drug sensitivity and resistance testing on diagnostic leukemia samples should provide important functional information to guide actionable target and biomarker discovery. We provide proof of concept data by profiling 60 drugs on 68 acute lymphoblastic leukemia (ALL) samples mostly from resistant disease in cocultures of bone marrow stromal cells. Patient-derived xenografts retained the original pattern of mutations found in the matched patient material. Stromal coculture did not prevent leukemia cell cycle activity, but a specific sensitivity profile to cell cycle-related drugs identified samples with higher cell proliferation both in vitro and in vivo as leukemia xenografts. In patients with refractory relapses, individual patterns of marked drug resistance and exceptional responses to new agents of immediate clinical relevance were detected. The BCL2-inhibitor venetoclax was highly active below 10 nM in B-cell precursor ALL (BCP-ALL) subsets, including MLL-AF4 and TCF3-HLF ALL, and in some T-cell ALLs (T-ALLs), predicting in vivo activity as a single agent and in combination with dexamethasone and vincristine. Unexpected sensitivity to dasatinib with half maximal inhibitory concentration values below 20 nM was detected in 2 independent T-ALL cohorts, which correlated with similar cytotoxic activity of the SRC inhibitor KX2-391 and inhibition of SRC phosphorylation. A patient with refractory T-ALL was treated with dasatinib on the basis of drug profiling information and achieved a 5-month remission. Thus, drug profiling captures disease-relevant features and unexpected sensitivity to relevant drugs, which warrants further exploration of this functional assay in the context of clinical trials to develop drug repurposing strategies for patients with urgent medical needs.

Integrative clinicopathological and molecular analyses of angioimmunoblastic T-cell lymphoma and other nodal lymphomas of follicular helper T-cell origin.

In addition to angioimmunoblastic T-cell lymphoma (AITL), the 2016 revised WHO classification of haematological malignancies recognizes two provisional lymphoma entities of follicular helper T-cell (TFH) derivation, namely follicular peripheral T-cell lymphoma (F-PTCL) and nodal PTCL with a TFH phenotype. Here, we performed a comprehensive, integrative clinicopathological and molecular analysis of these three entities. We found that F-PTCL and other nodal PTCL with TFH phenotype share not only immunophenotypical features, but also similar clinical, genetic and molecular features with AITL. Our results support the view that these lymphomas belong to the spectrum of a common disease. AITL and PTCL, not otherwise specified (PTCL-NOS), account for the majority of nodal PTCLs. While PTCLNOS is by definition heterogeneous and an exclusion diagnosis, AITL is characterized by a constellation of clinical, morphological, and immunophenotypical features, and defined by its cellular derivation from TFH cells. The typical pathological features, i.e., clear cells, increased vascularization, follicular dendritic cell (FDC) proliferation, and the presence of eosinophils, inflammatory cells, and EBV-positive B-blasts, are variably developed. An overlap between AITL and PTCL-NOS was substantiated by the observation that a subset of cases diagnosed as PTCL-NOS, upon routine pathological evaluation, actually harbor imprints of the TFH signature and/or express TFH-associated markers. Furthermore, the rare “follicular” T-cell lymphoma (F-PTCL), initially classified as a PTCL-NOS variant, is characterized by a TFH immunophenotype and clinicopathological features overlapping with AITL. Recently, recurrent AITL-associated TET2, DNMT3A and RHOA mutations were also found in a subset of PTCL-NOS, and tended to correlate with TFH features. Based on these recent findings, the 2016 update of the WHO classification groups AITL and other nodal lymphomas of TFH origin under the same umbrella. However, a thorough, systematic and multiparametric comparison of these entities is lacking. Here, we performed a comprehensive integrative clinicopathological and molecular analysis comparing AITL and other nodal PTCLs of TFH origin. Twenty-one such cases, including five F-PTCL, were identified in the TENOMIC biobank of the LYSA, and compared to 94 AITL and 36 PTCL-NOS. All cases were reviewed by three hematopathologists according to the 2016 WHO classification criteria ( and Online Supplementary Information). The five F-PTCL by definition comprised FDCs associated to the follicles without extrafollicular FDC expansion, and were positive for all TFH markers tested (4 or 5) (Figure 1A-B). The 16 other nodal PTCL with TFH phenotype (referred to as “TFH-like PTCL”) (Figure 1A, 1C, 1D) lacked typical morphological AITL

Targeting BET proteins improves the therapeutic efficacy of BCL-2 inhibition in T-cell acute lymphoblastic leukemia.

Inhibition of anti-apoptotic BCL-2 (B-cell lymphoma 2) has recently emerged as a promising new therapeutic strategy for the treatment of a variety of human cancers, including leukemia. Here, we used T-cell acute lymphoblastic leukemia (T-ALL) as a model system to identify novel synergistic drug combinations with the BH3 mimetic venetoclax (ABT-199). In vitro drug screening in primary leukemia specimens that were derived from patients with high risk of relapse or relapse and cell lines revealed synergistic activity between venetoclax and the BET (bromodomain and extraterminal) bromodomain inhibitor JQ1. Notably, this drug synergism was confirmed in vivo using T-ALL cell line and patient-derived xenograft models. Moreover, the therapeutic benefit of this drug combination might, at least in part, be mediated by an acute induction of the pro-apoptotic factor BCL2L11 and concomitant reduction of BCL-2 upon BET bromodomain inhibition, ultimately resulting in an enhanced binding of BIM (encoded by BCL2L11) to BCL-2. Altogether, our work provides a rationale to develop a new type of targeted combination therapy for selected subgroups of high-risk leukemia patients.

Phosphoproteomic-based kinase profiling early in influenza virus infection identifies GRK2 as antiviral drug target

Although annual influenza epidemics affect around 10% of the global population, current treatment options are limited and development of new antivirals is needed. Here, using quantitative phosphoproteomics, we reveal the unique phosphoproteome dynamics that occur in the host cell within minutes of influenza A virus (IAV) infection. We uncover cellular kinases required for the observed signaling pattern and find that inhibition of selected candidates, such as the G protein-coupled receptor kinase 2 (GRK2), leads to decreased IAV replication. As GRK2 has emerged as drug target in heart disease, we focus on its role in IAV infection and show that it is required for viral uncoating. Replication of seasonal and pandemic IAVs is severely decreased by specific GRK2 inhibitors in primary human airway cultures and in mice. Our study reveals the IAV-induced changes to the cellular phosphoproteome and identifies GRK2 as crucial node of the kinase network that enables IAV replication.Influenza A virus (IAV) causes annual epidemics and development of antivirals is needed. Here, the authors perform phosphoproteomics during IAV entry and identify GRK2 as drug target, inhibition of which decreases replication of seasonal and pandemic IAV in primary human cells and animal models.

Context-based retrieval of functional modules in protein–protein interaction networks

&NA; Various techniques have been developed for identifying the most probable interactants of a protein under a given biological context. In this article, we dissect the effects of the choice of the protein‐protein interaction network (PPI) and the manipulation of PPI settings on the network neighborhood of the influenza A virus (IAV) network, as well as hits in genome‐wide small interfering RNA screen results for IAV host factors. We investigate the potential of context filtering, which uses text mining evidence linked to PPI edges, as a complement to the edge confidence scores typically provided in PPIs for filtering, for obtaining more biologically relevant network neighborhoods. Here, we estimate the maximum performance of context filtering to isolate a Kyoto Encyclopedia of Genes and Genomes (KEGG) network Ki from a union of KEGG networks and its network neighborhood. The work gives insights on the use of human PPIs in network neighborhood approaches for functional inference.

Abstract 493: Drug response profiling to inform individualized treatment approaches in high risk leukemia

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA Novel treatment approaches are needed for patients with acute lymphoblastic leukemia (ALL) who respond poorly to current therapies. The genotypic diversity identified recently by next generation sequencing technologies within ALL calls for individualized novel strategies. However, functional correlations of oncogenic lesions with drug response profiles are ill defined for ALL. We have established an imaging-based cell viability analysis platform to generate drug response profiles for primary patient-derived ALL samples co-cultured with mesenchymal stroma cells, expecting to derive functional information directly from individual patient samples. Such response profiles may mirror perturbations in relevant cellular programs that could be exploited therapeutically. Our pipeline integrates high-content screening, newly developed bioinformatics tools and biochemical approaches. We screened a library of 65 compounds for activity in 37 precursor B-ALL and 23 T-ALL samples including refractory cases. Cross-sample comparisons revealed that cells from relapsed refractory patients showed a more resistant phenotype for most of the drugs. While only a few agents including genotoxic drugs showed activity across all samples, we detected selective activity of given drugs that distinguish patient sample groups. MLL-rearranged and TCF3-HLF-positive ALL samples as well as a subgroup of T-ALL cases were highly sensitive to the BCL-2 specific BH3-mimetic ABT-199 suggesting BCL-2 dependency for these cases. Multiparametric analyses of in vitro responses predicted in vivo activity of ABT-199 in xenografted mice. Moreover, we could identify synergistic activity of ABT-199 with clinical and preclinical compounds, such as topotecan or epigenetic modifiers. Our drug response profiling pipeline contributes to the identification of distinct vulnerabilities in leukemia and may facilitate the selection of candidate drugs for further development into clinical application. Citation Format: Viktoras Frismantas, Anna Rinaldi, Maria Pamela Dobay, Salome Higi, Sabrina Eugster, Blerim Marovca, Peter Horvath, Mauzro Delorenzi, Joachim Kunz, Obul R. Bandapalli, Gunnar Cario, Martin Stanulla, Andreas E. Kulozik, Martina Muckenthaler, Cornelia Eckert, Thomas Radimerski, Jean-Pierre Bourquin, Beat C. Bornhauser. Drug response profiling to inform individualized treatment approaches in high risk leukemia. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 493. doi:10.1158/1538-7445.AM2015-493