Chronic Lymphocytic Leukemia Samples Research Articles

NEAT1 Long Isoform Is Highly Expressed in Chronic Lymphocytic Leukemia Irrespectively of Cytogenetic Groups or Clinical Outcome.

The biological role and therapeutic potential of long non-coding RNAs (lncRNAs) in chronic lymphocytic leukemia (CLL) are still open questions. Herein, we investigated the significance of the lncRNA NEAT1 in CLL. We examined NEAT1 expression in 310 newly diagnosed Binet A patients, in normal CD19+ B-cells, and other types of B-cell malignancies. Although global NEAT1 expression level was not statistically different in CLL cells compared to normal B cells, the median ratio of NEAT1_2 long isoform and global NEAT1 expression in CLL samples was significantly higher than in other groups. NEAT1_2 was more expressed in patients carrying mutated IGHV genes. Concerning cytogenetic aberrations, NEAT1_2 expression in CLL with trisomy 12 was lower with respect to patients without alterations. Although global NEAT1 expression appeared not to be associated with clinical outcome, patients with the lowest NEAT1_2 expression displayed the shortest time to first treatment; however, a multivariate regression analysis showed that the NEAT1_2 risk model was not independent from other known prognostic factors, particularly the IGHV mutational status. Overall, our data prompt future studies to investigate whether the increased amount of the long NEAT1_2 isoform detected in CLL cells may have a specific role in the pathology of the disease.

Performance of anti-CD19 chimeric antigen receptor T cells in genetically defined classes of chronic lymphocytic leukemia

BackgroundWhile achieving prolonged remissions in other B cell-derived malignancies, chimeric antigen receptor (CAR) T cells still underperform when injected into patients with chronic lymphocytic leukemia (CLL). We studied the influence...

Expression of the muscle-associated gene MYF6 in hairy cell leukemia.

Hairy cell leukemia (HCL) is a purine analog-responsive B-cell malignancy containing the BRAF V600E mutation, expressing CD22, CD11c, CD103, tartrate resistant acid phosphatase (TRAP) CD25, CD123, and annexin 1A. BRAF V600E and the latter 4 markers are usually absent in the more aggressive and chemoresistant variant HCLv. To evaluate differences between HCL and HCLv, expression microarrays comparing HCL with HCLv were performed for 24694 genes using 47323 probes. Microarray data from 35 HCL and 27 HCLv purified samples showed the greatest HCL-HCLv difference in the muscle-associated gene MYF6, expressed by its 2 probes 18.5- and 10.8-fold higher in HCL than HCLv (p<0.0001). By real-time quantitative PCR (RQ-PCR), 100% of 152 classic HCL samples were MYF6-positive, vs 5 (6%) of 90 blood donors. MYF6-expression was also detected in 18 (35%) of 51 with HCLv, 11 (92%) of 12 with HCL expressing unmutated IGHV4-34, 35 (73%) of 48 with chronic lymphocytic leukemia (CLL), and 1 (8%) of 12 with mantle cell lymphoma. Hypomethylation status of MYF6 supported expression in HCL more than HCLv. Posttreatment blood samples becoming negative by flow cytometry remained MYF6+ by RQ-PCR in 42 (48%) of 87 HCL patients, and MYF6 RQ-PCR could detect 1 HCL in 105 normal cells. MYF6, universally expressed in HCL and in most CLL samples, may be a useful biomarker for these leukemias. Further studies are underway to determine the role of MYF6 in HCL.

CLEAR: coverage-based limiting-cell experiment analysis for RNA-seq

BackgroundDirect cDNA preamplification protocols developed for single-cell RNA-seq have enabled transcriptome profiling of precious clinical samples and rare cell populations without the need for sample pooling or RNA extraction. We term the use of single-cell chemistries for sequencing low numbers of cells limiting-cell RNA-seq (lcRNA-seq). Currently, there is no customized algorithm to select robust/low-noise transcripts from lcRNA-seq data for between-group comparisons.MethodsHerein, we present CLEAR, a workflow that identifies reliably quantifiable transcripts in lcRNA-seq data for differentially expressed genes (DEG) analysis. Total RNA obtained from primary chronic lymphocytic leukemia (CLL) CD5+ and CD5− cells were used to develop the CLEAR algorithm. Once established, the performance of CLEAR was evaluated with FACS-sorted cells enriched from mouse Dentate Gyrus (DG).ResultsWhen using CLEAR transcripts vs. using all transcripts in CLL samples, downstream analyses revealed a higher proportion of shared transcripts across three input amounts and improved principal component analysis (PCA) separation of the two cell types. In mouse DG samples, CLEAR identifies noisy transcripts and their removal improves PCA separation of the anticipated cell populations. In addition, CLEAR was applied to two publicly-available datasets to demonstrate its utility in lcRNA-seq data from other institutions. If imputation is applied to limit the effect of missing data points, CLEAR can also be used in large clinical trials and in single cell studies.ConclusionslcRNA-seq coupled with CLEAR is widely used in our institution for profiling immune cells (circulating or tissue-infiltrating) for its transcript preservation characteristics. CLEAR fills an important niche in pre-processing lcRNA-seq data to facilitate transcriptome profiling and DEG analysis. We demonstrate the utility of CLEAR in analyzing rare cell populations in clinical samples and in murine neural DG region without sample pooling.

EXPRESSION OF LIPOPROTEIN LIPASE AND c-MYC ONCOGENE IN PATIENTS WITH CHRONIC LYMPHOCYTIC LEUKEMIA AFFECTED BY THE CHORNOBYL ACCIDENT.

to determine the association between the expression of lipoprotein lipase (LPL) and c-MYC genes inperipheral blood cells of chronic lymphocytic leukemia (CLL) patients affected by the Chornobyl catastrophedepending on the mutational status of IGHV genes. Analysis was performed in the group of 69 CLL patients irradiated due to the Chornobyl NPP accident (58clean-up workers of 1986 year, 6 inhabitants of radionuclide contaminated areas, and 5 evacuees). The IGHV genemutational status was studied by polymerase chain reaction (PCR) followed by direct sequencing. LPL and c-MYCexpression was evaluated by Quantitative Real-time PCR. Data were analyzed with the SPSS software package, version 20.0. Relative LPL expression levels in CLL samples ranged from 0 to 1663.5 (mean 138.47 ± 30.69, median 26.1).A strong correlation between individual LPL expression levels and IGHV mutational status was found (r = 0.684;p < 0.0001). The average relative c-MYC expression level was 5.7 ± 0.87 (median 2.86; range 0-48.5). No association between c-MYC expression and IGHV mutational status was found. Among unmutated IGHV cases, a correlationbetween LPL and c-MYC gene expression levels was identified: r = 0.351; p = 0.013. Our data confirm the dominant concept that unmutated IGHV CLL cases are more sensitive to the actionof proliferative stimuli compared to mutated IGHV CLL cases. This is manifested by an increase in the expression ofa functionally significant LPL gene, is one for the strongest negative prognostic markers in CLL.

PRIMA-1MET cytotoxic effect correlates with p53 protein reduction in TP53-mutated chronic lymphocytic leukemia cells

TP53 gene defects represent the most unfavorable prognostic factor in chronic lymphocytic leukemia (CLL). Although recently introduced small-molecule B-cell receptor signalling inhibitors have revolutionized CLL treatment, data for ibrutinib still point to impaired prognosis for TP53-affected patients. Among cancer-associated TP53 mutations, missense substitutions predominate and typically result in a high mutated-p53 protein level. Therefore, rescuing the p53 tumor suppressor function through specific small molecules restoring p53 wild-type (wt) conformation represents an attractive therapeutic strategy for cancer patients with TP53 missense mutations. We tested the effect of mutated-p53 reactivating molecule PRIMA-1MET in 62 clinical CLL samples characterized for TP53 mutations and p53 protein level. At the subtle PRIMA-1MET concentrations (1–4 μM), most samples manifested concentration-dependent viability decrease and, conversely, apoptosis induction, with the response being similar in both the TP53-mutated and TP53-wt groups, as well as in the TP53-mutated samples with p53 protein stabilization and without it. PRIMA-1MET was able to reduce mutated p53 protein in a proportion of TP53-mutated CLL samples, and this reduction correlated with a significantly stronger viability decrease and apoptosis induction than samples with stable p53 levels. CLL cells are mostly sensitive to PRIMA-1MET apart from those with stable mutated p53.

Decreased NOTCH1 Activation Correlates with Response to Ibrutinib in Chronic Lymphocytic Leukemia.

Ibrutinib, a Bruton tyrosine kinase inhibitor (BTKi), has improved the outcomes of chronic lymphocytic leukemia (CLL), but primary resistance or relapse are issues of increasing significance. While the predominant mechanism of action of BTKi is the B-cell receptor (BCR) blockade, many off-target effects are unknown. We investigated potential interactions between BCR pathway and NOTCH1 activity in ibrutinib-treated CLL to identify new mechanisms of therapy resistance and markers to monitor disease response. NOTCH activations was evaluated either in vitro and ex vivo in CLL samples after ibrutinib treatment by Western blotting. Confocal proximity ligation assay (PLA) experiments and analyses of down-targets of NOTCH1 by qRT-PCR were used to investigate the cross-talk between BTK and NOTCH1. In vitro ibrutinib treatment of CLL significantly reduced activated NOTCH1/2 and induced dephosphorylation of eIF4E, a NOTCH target in CLL. BCR stimulation increased the expression of activated NOTCH1 that accumulated in the nucleus leading to HES1, DTX1, and c-MYC transcription. Results of in situ PLA experiments revealed the presence of NOTCH1-ICD/BTK complexes, whose number was reduced after ibrutinib treatment. In ibrutinib-treated CLL patients, leukemic cells showed NOTCH1 activity downregulation that deepened over time. The NOTCH1 signaling was restored at relapse and remained activated in ibrutinib-resistant CLL cells. We demonstrated a strong clinical activity of ibrutinib in a real-life context. The ibrutinib clinical efficacy was associated with NOTCH1 activity downregulation that deepened over time. Our data point to NOTCH1 as a new molecular partner in BCR signaling with potential to further improve CLL-targeted treatments.

High Frequency Mutations of MYD88 and KMT2D in Chinese Chronic Lymphocytic Leukemia

Background: Chronic lymphocytic leukemia (CLL) is one of the most common forms of adult leukemia in the Western population but rare in Chinese descent. As Chinese CLL patients have distinct clinical features, higher frequency of mutated IGHV as well as unique BCR stereotype, we hypothesize that genetic alterations may contribute to the disease phenotype differences. We profiled the known recurrent mutated genes associated with Western CLLs in 338 Chinese CLL samples, with the goal to define the somatic mutation pattern in the Chinese CLL population. Methods: We first assessed 96 CLL mutated genes in a discovery cohort that includes 126 CLL samples using Illumina MiSeq platform. We then validated 20 recurrent mutated genes in a validation cohort that comprises of 212 CLL samples with Ion Torrent platform. The presence of mutation in DNA and mRNA were further validated by Sanger sequence. Results: A total of 303 untreated and 35 relapsed samples were investigated. The average sequencing depth was 1957X (range: 112 to 4254). In the discovery cohort, we identified recurrently mutated genes in TP53 (17.5%), SF3B1 (14.3%), ATM (13.7%), KMT2D (12.7%), MYD88 (10.3%), NOTCH1 (8.7%), FBXW7 (8.7%), BIRC3 (7.9%), POT1 (4.8%), KRAS (4.0%). This was further confirmed in the validation cohort. In comparison to the frequency of these mutations in the western studies, we observed an unexpected significantly higher frequency of mutations in MYD88 and KMT2D (Chi-squared test, p&lt;0.01). Mutations of KMT2D occurred with a similar frequency in treatment-naïve (8%) and relapsed samples (9%). 19/30 (63%) mutations were loss-of-function as they are predicted to generate truncated proteins due to lacking part or all of the C-terminal domains (Figure 1A). We observed a significant co-occurrence between KMT2D mutations and trisomy 12 (Chi-squared test, p&lt;0.01, Figure 1E), suggesting there could be intrinsic linkage between these lesions. Further integration with IGHV mutation status revealed that CLLs with KMT2D mutations were characterized by an overrepresentation of VH4-34 and VH4-39 (p&lt;0.01, p=0.03, respectively) and enriched in stereotyped subset #8 (4/12, 33.3%) (Figure 1B). Consistent with previous reports that VH4-34 and VH4-39 are commonly used in Asians CLLs, we confirmed the high frequency of subset #8 in Chinese patients [1], indicating KMT2D as a uniquely mutated gene in Chinese CLLs. MYD88 mutations were found in 38/303 (13%) untreated CLLs. 17/38 (45%) of the mutations were at the L265P site (Figure 1C). Additional hotspot mutations were also detected (V217F 29%; S219C 13%). These mutations are associated with a significant male predominance (Chi-squared test, p&lt;0.01), increased monoclonal gammopathy (15%, p=0.01), and a higher rate of Hepatitis B virus (HBV) infection (HBV core antibody positivity 56%, p=0.02). Most of these mutations (87%) were clonal and IGHV mutated (97%). It is worth to note that the usage of VH3-7 and VH4-34 were more dominant in patients with MYD88 V217F/S219C (6/16, 38%) and with L265P (6/17, 35%), respectively. Mutations of MYD88 are mutually exclusive with TP53 mutation and del(17p) (Chi-squared test, p&lt;0.01). Moreover, we found a superior time to first treatment in MYD88-mutated patients compared with wide-type patients (Log-rank test, p=0.03). To further understand the linkage between mutations and clinical outcome, we divided 303 treatment-naive patients into two groups: Non-progressor (NPRO, 39%) and Progressor (PRO, 61%). NPRO and PRO were classified as patients who developed symptoms that need treatment either more than or less than three years after sampling. Epigenetic modifiers pathway mutations (KMT2D, CREBBP, EP300, TET2, ARID1A and IKZF1) were more frequently in PRO group (17% vs. 8%, p=0.02). Inflammatory pathway mutations (MYD88, BIRC3, CARD11 and TRAF3) was more involved in NPRO group, compared to PRO or Relapsed samples (21%, 15% and 0%, p&lt;0.01). Conversely, DNA damage pathway mutations (TP53, ATM and POT1) was more frequently found in Relapsed and PRO groups compared to NPRO group (49%, 30% and 7%, p&lt;0.01). Conclusion: In summary, we observed high frequency mutations in KMT2D and MYD88 that correlated with specific IGHV repertoire in Chinese CLL population. This suggests that pathogenesis of CLL between the Chinese and Western population may be different and potentially have therapeutic value. [1] Marinelli M, et al. Oncotarget. 2016 Apr 12;7(15):20520-31. Figure 1 Disclosures No relevant conflicts of interest to declare.

Expression of the Tigit/CD226/CD155 Receptors/Ligand System in Chronic Lymphocytic Leukemia

Introduction: T cell immunoreceptor with Ig and ITIM domains (TIGIT) is a surface receptor mainly expressed by CD8+, regulatory T lymphocytes and natural killer (NK) cells, but not by normal B cells. It performs as an inhibitory immune checkpoint, activated through binding of CD155. TIGIT competes with CD226 for CD155 binding, resulting in opposite outcomes: while CD226 enhances cytotoxicity of T lymphocytes and NK cells, TIGIT exerts immunosuppressive effects. Whether TIGIT engagement triggers an alternative signaling cascade, or whether it simply prevents CD226 activation, remains an open point. Tumor-infiltrating T lymphocytes generally express high levels of the molecule, together with the other checkpoint inhibitor PD-1. On this basis, antagonist antibodies targeting TIGIT are under evaluation to restore immunity and treat cancer patients, alone or in various combinations. Chronic lymphocytic leukemia (CLL), the most common adult leukemia, is characterized by a highly heterogeneous clinical outcome. Several molecular markers can help in stratifying patients, including the presence or absence of somatic mutations in B cell receptor, cytogenetic aberrations and single gene mutations. Interestingly, CLL cells express several T cell specific antigens, including CD5. A previous report indicates that, in CLL, TIGIT is expressed by circulating CD4+T cells, increasing during disease progression, while nothing is known about its expression on CLL cells. Aim:This work was undertaken with the aim of studying expression of the TIGIT/CD226/CD155 axis in CLL. Methods:We assembled a cohort of 101 primary CLL samples (40% females, mean age of 61). All patients were either untreated or had not received treatment in the 6 months prior to analysis. PBMC samples were tested for expression of TIGIT, CD155 and CD226 in both T and B subsets. A multiparametric flow cytometry strategy was designed, combining anti-TIGIT, anti-CD155 and anti-CD226 antibodies with a panel of B- (anti-CD19, anti-CD5, anti-CD38, anti-CD49d and anti-CD73) and T-mono/NK specific (anti-CD3, anti-CD8, anti-CD4, anti-CD14 and anti-CD56) markers. The number of TIGIT molecules on leukemic cells was estimated by interpolating values of mean fluorescence intensity (MFI) of each sample with that of PE-Quantibrite beads. Results:CLL cells heterogeneously express surface TIGIT, ranging from 0.2 to 81% (mean value 20%, median 10%, SEM ±2.145). The estimated number of molecules per cell was in the range of 32.5-3571 (mean 1140, median 841.1, SEM ±83.6). Expression of TIGIT was independent of gender or age at diagnosis and there was no correlation between TIGIT levels and lymphocyte counts in peripheral blood. In contrast, in this cohort of untreated patients, we observed a significantly lower TIGIT expression in samples with advanced disease (RAI III-IV) compared to early stages (RAI 0-I). Accordingly, low TIGIT associated with unmutated (UM) IGHVgenes and with an unfavorable FISH profile (trisomy 12, deletion 17 and deletion 11 vs. deletion 13 or normal karyotype). Lower, although not significant, TIGIT levels were observed in NOTCH1-mutated CLL samples (n=11) compared to counterpart (n=89). Looking at the T cell population, we observed overall higher TIGIT levels in the CD8+vs CD4+subset (mean %TIGIT+cells in CD8+56.7±1.8 vs 27.2±1.3 in CD4+). In line with reported observations, we found a modest but significant increase of TIGIT+T cells in advanced stage CLLs, at variance with what observed on the leukemic B cell side. Accordingly, we observed higher percentages of TIGIT+/CD4+cells in CLL samples carrying UM IGHVgenes. CD226 and CD155 were more homogeneously expressed in all subsets without significant differences, both in CLL and T cell components. Conclusions: This work shows that CLL cells express the immunomodulatory molecule TIGIT, particularly in the early stages of the disease in untreated patients. While further studies are needed to characterize its functional implications as well as treatment effect on TIGIT expression, it is tempting to speculate that TIGIT expression by CLL cells may serve to trigger an immunosuppressive behavior in these cells, which is no longer needed when the disease becomes advanced. This observation represents a starting point for future studies investigating the role of TIGIT in CLL and hints to a possible use of anti-TIGIT antibodies to target different cellular components of the disease. Disclosures Hoofd: iTeos Therapeutics: Employment. Coscia:Abbvie: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm Therapeutics: Research Funding. Gaidano:Sunesys: Consultancy, Honoraria; AbbVie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astra-Zeneca: Consultancy, Honoraria; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Furman:Acerta Pharma: Consultancy; Beigene: Consultancy; Incyte: Consultancy; Janssen: Consultancy; Oncotracker: Consultancy; Pharmacyclics: Consultancy; Sunesis: Consultancy; TG Therapeutics: Consultancy; Verastem: Consultancy; Genentech: Consultancy; Abbvie: Consultancy; AstraZeneca: Consultancy. Deaglio:VelosBio Inc.: Research Funding; Verastem Inc: Research Funding; iTeos Therapeutics: Research Funding.

High-Level ROR1 and BCL2, Cancer-Stemness, and BCL2 Mutations Associate with Venetoclax Resistance in Chronic Lymphocytic Leukemia

High-Level ROR1 and BCL2, Cancer-Stemness, and BCL2 Mutations Associate with Venetoclax Resistance in Chronic Lymphocytic Leukemia

Expansion of T Helper Cell Subsets in Chronic Lymphocytic Leukemia Cell Co-Cultures with Nurselike Cells

Background: In secondary lymphatic organs (SLO), chronic lymphocytic leukemia (CLL) cells form characteristic pseudo-follicles, also called proliferation centers, in which proliferating CLL cells are in intimate contact with CD4+ T helper cells. Despite evidence for a co-evolution of CLL cells and counterpart T helper cells, the prevalence and dynamics of T cell subsets, such as T follicular helper cells (TFH), T regulatory helper cells (TRegs) and IL-17-producing T helper cells (Th17) has not been characterized in detail. The CLL nurselike cell (NLC) model recapitulates key cellular and molecular interactions between CLL cells and the microenvironment in SLO, based on functional and gene expression studies, and represents a valid in vitro model for the SLO microenvironment in CLL. To gain insight into the potential role of T cells in CLL SLO, we utilized the NLC model to characterize T helper cell subsets and their dynamics in NLC co-cultures. Methods and Results: First, we quantified CD4+ and CD8+ T cell subsets in fresh peripheral blood mononuclear cell (PBMC) samples from 14 patients and then placed 1x107 PBMCs/ml in culture to establish NLC. We rechecked the relative proportion of CD4+ and CD8+ T cells, as well as absolute T cell counts, and their viability after 3, 6, 9, 12 and 14 days in NLC co-culture conditions. Interestingly, throughout the 14 days of culture, the number of T helper cells remained stable when compared to baseline samples. Next, we characterized T helper cell subsets in 25 different CLL samples, comparing CD4+ T cell subsets in freshly isolated CLL PBMC with matched samples harvested after 14 days of NLC culture. Samples were stained with subset-specific fluorescence-labeled antibody combinations, and analyzed by flow cytometry. NLC co-culture resulted in a significant expansion of TFH and TReg cells. TFH absolute cell counts assessed by flow cytometry using counting beads, increased from 9.4±2.2/μl at baseline to 29.0±5.9/μl in NLC co-cultures (n=14, p=0.001) and TReg from 17.0±3.3/μl to 51.0±15.0/μl (n=14, p=0.027). In contrast, Th17 absolute cell counts declined after 14 days of culture from 113.0±21.0/μl to 68.0±13.0/μl (n=14, p=0.001). Moreover, TH2 cells declined from 42.0±7.4/μl to 30.0±8.2/μl (n=14, p=0.005). Next, we analyzed for changes in TFH subsets (TFH1, TFH2 and TFH17). When compared to TFH cells from CLL PBMC, NLC culture resulted in a relative increase in TFH2 from 17.0±2.4% to 26.0±1.7% (n=25, p=0.013), and in TFH17 from 12.0±1.6% to 21.0±2.7% (n=25, p=0.006) In contrast, TFH1 frequency decreased after 14 days of culture (54.0±3.5% versus 34.0±2.9%, n=25, p=0.001). T follicular regulatory (TFr) cells also increase under co-culture conditions from undetectable to 4.8±1.9% (n=25, p=0.025)(Figure1). Looking at the maturity of CD4+ cells we noted a relative increase of central memory cells from 42.0±3.2% to 50.0±3.2% (n=25, p=0.023), whereas effector memory cells decreased from 34.0±3.4% to 26.0±2.7% (n=25, p=0.009), the fraction of naïve CD4+ cells remained unchanged. Next, we assessed the activation status of co-inhibitory receptors on CD3+CD4+ cells. We found a significant relative increase in CD4+ T cells expressing PD1 and CTLA-4 after 14 days of culture. Additionally, the TFH and TReg subsets demonstrated a significantly higher CTLA-4 expression after culture while TReg cells also addressed an increase in PD1 frequency. Furthermore, we observed a significantly higher CD28 expression on TFH and TReg subsets after 14 days of co-culture. Following, to address the residence and migration capacity of T cells in NLC co-cultures, we analyzed the CD69 and CD62L expression. Our results revealed significantly higher expression of CD69 in NLC co-cultures, whereas CD62L levels remained unchanged. Conclusion: The expansion of TFH and TReg cells in NLC co-cultures suggests the selection and clonal expansion of T cells that may support and engage in crosstalk with CLL cells. Additionally, the expansion of TFr and TFH17 cells could reflect a milieu of immune tolerance establishing in NLC co-cultures. Ongoing TCR sequencing of serial CD4+ T cell samples (baseline versus 14 days under NLC conditions) will characterize changes of clonal architecture in the T helper cell compartment, and will further improve our understanding of co-evolution of CLL and T helper cells. Disclosures Wierda: Gilead Sciences: Research Funding; Juno Therapeutics: Research Funding; KITE pharma: Research Funding; Sunesis: Research Funding; Miragen: Research Funding; Janssen: Research Funding; Xencor: Research Funding; Acerta Pharma Inc: Research Funding; Pharmacyclics LLC: Research Funding; Genentech: Research Funding; AbbVie: Research Funding; GSK/Novartis: Research Funding; Oncternal Therapeutics Inc.: Research Funding; Cyclcel: Research Funding; Loxo Oncology Inc.: Research Funding. Burger:Aptose Biosciences, Inc: Research Funding; BeiGene: Research Funding; Gilead Sciences: Research Funding; AstraZeneca: Honoraria; Janssen Pharmaceuticals: Consultancy, Honoraria; Pharmacyclics, an AbbVie company: Research Funding.

Dysregulation of different classes of tRNA fragments in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is the most common human leukemia, and dysregulation of tRNA-derived short noncoding RNA (tsRNA) (tRF-1) expression is an accompanying event in the development of this disease. tsRNAs are fragments originating from the 3' end of tRNA precursors and do not contain mature tRNA sequences. In contrast to tsRNAs, mature tRFs (tRF-3s, tRF-5s, and internal tRFs) are produced from mature tRNA sequences and are redundant fragments. We investigated tsRNA expression in CLL and determined tsRNA signatures in indolent CLL and aggressive CLL vs. normal B cells. We noticed that both ts-43 and ts-44 are derived from distinct genes of pre-tRNAHis, and are down-regulated in CLL 3- to 5-fold vs. normal B cells. Thus, we investigated expression levels of tRF-5 fragments from tRNAHis in CLL samples and healthy controls, and determined that such fragments are down-regulated by 5-fold in CLLs vs. normal controls. Given these results, we investigated the expression of all mature tRFs in CLLs vs. normal controls. We found a drastic dysregulation of the expression of mature tRFs in CLL. In aggressive CLL, for the top 15 up-regulated fragments, linear fold change varied from 2,053- to 622-fold. For the top 15 down-regulated fragments in CLL, linear fold change varied from 314- to 52-fold. In addition, 964 mature tRFs were up-regulated at least 2-fold in CLL, while 701 fragments were down-regulated at least 2-fold. Similar results were obtained for indolent CLL. Our results suggest that mature tRFs may have oncogenic and/or tumor suppressor function in CLL.

A Core Proliferative Program Induced By B-Cell Receptor Stimulation in Chronic Lymphocytic Leukemia Cells

B-cell receptor (BCR) engagement is widely acknowledged to sustain aberrant cell behavior and uncontrolled monoclonal proliferation in chronic lymphocytic leukemia (CLL), as well as in most leukemias and lymphomas arising from mature B lymphocytes. The precise mechanisms by which BCR signaling controls neoplastic B-cell proliferation are ill characterized. In this work, primary leukemic cells of untreated patients at initial stage of CLL (Binet stage A / Rai 0) presenting biological characteristics of aggressive form of the disease (unmutated IGHV genes and ZAP70 protein expression) were studied. Proliferation of CLL cells was induced ex vivo in six CLL samples using anti-IgM, together with mandatory co-stimulating factors (CD40L, IL-4 and IL-21) (Schleiss, Sci Rep, 2019). Using this model, we generated a unique set of 108 transcriptional and proteomic profiles during four days after activation (9 points from T0 to 96 hours after stimulation). A total of 23,348 transcripts and 50,503 unique peptides, the latter corresponding to 4,664 unique proteins, were identified and quantified. Statistical analysis of genes and proteins expression patterns identified a structured proliferative signature. In unsupervised analysis, principal component analysis (PCA) representation of the whole transcriptional profile showed the temporality of the response. Moreover, unsupervised temporal gene expression analysis using iterative optimization revealed clusters of temporal patterns exhibiting structured expression modulations during the time course after cell stimulation. Although the overall proteomic response appeared less structured than the transcriptional one at early time points after stimulation, samples showed a tendency for segregation with respect of their proliferative response at the two later time points. Hierarchical clustering, aimed to search for correlations between the transcriptional profiles, confirmed the temporal organization of the samples, while proliferative and non-proliferative cells were still distinguishable. Also, we identified a CLL cell activation signature corresponding to 3,097 differentially expressed genes (DE) and 1,209 differentially-abundant (DA) proteins. This unique dataset provided a unique opportunity to model the proliferative program of CLL cells after BCR engagement. We used the reverse engineering approach based on regression and system of equations previous published (Vallat et al., PNAS 2013). Thus, a temporal label was assigned to each gene and protein, restricting its potential link to actors with later temporal labels. The temporal model inferred with the genes and proteins datasets of proliferating CLL cells resulted in a regulatory network composed of 2,167 genes and 1,074 proteins representing 2,848 unique symbols, among which 395 gene-protein pairs, connected by 53,131 oriented links. Different temporal layers of actors were identified. At the earliest time-point after cell activation a first group was identified, involving transcriptional repression, negative regulation of BCR signaling, apoptotic process actors and a second group involving G1/S transition, DNA-replication genes. Later, expression of G0/G1 switch genes and regulators of cell proliferation and differentiation were identified. In conclusion, using a large dataset of temporal transcriptional and proteomic measurements coupled with mathematical modelling, we were able to unravel the molecular program downstream the signaling cascade activated by the engagement of the BCR and triggering primary CLL cell proliferation. This program was proven to organize around a limited number of hub genes and proteins whose sequential commitment drives the cellular response leading to proliferation days after cell activation. These hubs represent potential candidates for the development of novel therapeutic strategies for the treatment of aggressive CLL. Disclosures No relevant conflicts of interest to declare.

The Protein Kinase C Inhibitor MS-553 for the Treatment of Chronic Lymphocytic Leukemia

The Protein Kinase C Inhibitor MS-553 for the Treatment of Chronic Lymphocytic Leukemia

Role of Mutant p53 in the Progression of Chronic Lymphocytic Leukemia

Patients with Chronic Lymphocytic Leukemia (CLL) have a variety of chromosomal abnormalities and mutations. At diagnosis, about 10% of CLL patients have deletions of chromosome 17 (Del17p) leading to the loss of one allele of tumor suppressor protein TP53, which increases to over 30% in relapsed/refractory disease. Additionally, 83% of patients with a Del17p acquire a mutation on their second TP53 allele at one of several sites within the DNA binding domain. While the consequence of some of these "hotspot" mutations (R175H, R179H, G245D, G248Q/W, Y220, R213X, R273H and R282H) has been described in solid tumors and AML, very little is known of their role in CLL. Clinically, patients with Del17p/Mutp53 have worse overall survival, increased disease progression and are more likely to relapse on the current targeted therapies such as ibrutinib. Although relapse to these treatments is largely due to acquired mutations in Bruton's Tyrosine Kinase (BTK) or its downstream target PLCg2, we hypothesize that the biology of mutant 53 bearing CLL is a key driver of resistance and progression. Specifically, we aim to determine the molecular signature and downstream effectors that allow mutant p53 to drive the adverse biology associated with this subtype. Conversely, we hypothesize that targeting the mutant p53 pathway will lead to better outcomes and overall survival for patients bearing this adverse prognosis marker. We performed high-throughput Sequencing of DNA from 270 CLL patients with high coverage in the exonic regions of TP53 prior to ibrutinib therapy as well as during progression. At baseline, 40% of patients had mutations found in the DNA binding region with the most frequent occurring in R248Q, R175H and R273H. We then characterized each p53 mutant (n=106) functionally in terms of their ability to ability to activate p21, PUMA, and Bax which serve as cell cycle checkpoint and apoptotic effectors of wild type p53 in response to DNA damage. Most mutants were incompetent in upregulating p21, PUMA or Bax at the transcript level. A few mutants upregulated p21 protein in a p53 independent fashion. We then evaluated the consequence of mutant p53 in CLL. We performed chromatin immunoprecipitation (ChIP-Seq), open chromatin signatures (ATAC-Seq) and expression analysis (RNA-Seq) on CLL samples with R248Q or R175H as well as in wild-type (WT) p53 samples. Integration of ChIP, ATAC and RNA Seq profiles indicated that mutant p53 activated a unique transcriptomic profile not shared by wt p53 bearing CLL. Several genes that facilitated survival or progression were downstream targets of mutant p53. Of these, we identified PRKCB (PKC-beta), BCL2L1 (Bcl-xL), EZH2, MLL and MALAT as a potential key downstream effectors of mutant p53. To determine whether mutations at R248Q and R175H in p53 were causal in the observed increases in PKC-beta, Bcl-xL, EZH2, MLL, and MALAT we used CRISPR/Cas9 editing to introduce mutations at R175H and R248Q in the p53 wildtype CLL cell lines HG-3 and PGA-1. These were accomplished by electroporating sgRNA-Cas9 ribonucleoprotein complexes (RNPs). Western blotting of mutants revealed an increase in the mRNA and protein expression of PKC-beta, and BCL-xL in mutant p53 compared to WT. Levels of EZH2 and MLL were not increased in these cells indicating that PKC-beta and Bcl-xL may be direct transcriptional targets upregulated by mutations at R248Q and R175H in p53. Ongoing efforts will characterize the transcriptional profile of all p53 mutants in our cohort to determine whether they all have a unifying transcriptomic profile that confers a gain of function phenotype to this subtype of CLL. Disclosures Byrd: Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; BeiGene: Research Funding; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Ohio State University: Patents &amp; Royalties: OSU-2S; Novartis: Other: Travel Expenses, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Genentech: Research Funding; BeiGene: Research Funding; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Ohio State University: Patents &amp; Royalties: OSU-2S; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Genentech: Research Funding; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Acerta: Research Funding; Ohio State University: Patents &amp; Royalties: OSU-2S; Novartis: Other: Travel Expenses, Speakers Bureau; Acerta: Research Funding; BeiGene: Research Funding; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Acerta: Research Funding; Genentech: Research Funding; Novartis: Other: Travel Expenses, Speakers Bureau. Woyach:Janssen: Consultancy, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; AbbVie: Research Funding; Karyopharm: Research Funding; Loxo: Research Funding; Morphosys: Research Funding; Verastem: Research Funding.

Systematic Investigation of Microenvironmental Drug Resistance Mechanisms in Chronic Lymphocytic Leukemia

Introduction and Methods To investigate the mechanisms by which microenvironmental signals induce treatment resistance in chronic lymphocytic leukemia (CLL) we conducted a high-throughput perturbation assay combining pairwise 15 clinically relevant drugs with 18 stimulations mimicking the tumor microenvironment. We combined this with multi-layer omics data using whole exome sequencing, genome-wide DNA-methylation profiles and RNA sequencing to investigate molecular determinants of microenvironmental drug resistance. In parallel we assessed the in-vivo relevance of investigated pathways in 100 CLL infiltrated- and 100 healthy lymph node (LN) biopsies by staining for stimulus specific downstream pathway components using immunohistochemistry (IHC). Results We initially clustered drugs and microenvironmental stimuli separately based on the similarity of their response profiles across all CLL samples. We found drug response profiles to be correlated closely for drugs targeting the same signaling-pathway, e.g. the B-cell receptor inhibitors Ibrutinib (BTK) and PRT062607 (Syk) (Pearson correlation coefficient: r=0.78, 95% CI: 0.72 - 0.83). In contrast, responses to microenvironmental stimuli were less correlated, indicating diverse effects are caused by the tumor microenvironment (e.g. Interleukin 4 (IL-4) vs. Interleukin 2, Pearson correlation coefficient: r=0.17, 95% CI: 0.03 - 0.31). Twelve of the 18 tested stimulations enhanced survival of CLL cells, whereas two reduced the viability of CLL cells in-vitro (comparisons yielded BH adjusted t-test p-values &lt;0.0001). The strongest pro-survival effects were mediated by IL-4 and Toll-like receptor (TLR) 7/8/9 stimulation, whereas transforming growth factor β1 (TGF-β1) and Interleukin-6 reduced the viability of CLL cells in-vitro. Ten of the 18 stimulation effects were modulated by genetic alterations in CLL cells, for 6 stimuli two or more response modulating genetic alterations were identified (FDR 10%). IGHV mutation status for instance modulated the effects of TLR 7/8/9 agonists as well as Interleukine-1β, CD40 ligand and TGF-β1. We will present a detailed analysis of how microenvironmental stimuli depend on specific genetic alterations in CLL. To understand how soluble stimuli interfere with drug response we searched for specific interactions between stimulations and drugs with the following linear model: Viability ~ drug-effect + stimulation-effect + drug-effect:stimulation-effect and tested for significance of the interaction term. This approach allowed us to dissect interactions independently of the individual effects. We discovered different types of drug-effect:stimulation-effect interactions: 1) The microenvironmental stimulus had a strong pro-survival effect on the baseline viability and interfered with the response to drugs (e.g. IL-4:Ibrutinib, p-value&lt; 0.0001). 2) The microenvironmental stimulus had no major effect on baseline viability but significantly interfered with response to drugs (e.g. Interferon-γ:Ibrutinib, p-value: 0.014). 3) The microenvironmental stimulus and the drug exhibited no major individual effect on CLL cell survival, but together significantly increased CLL cell viability (e.g. Interferon-γ:Ralimetinib, p-value: &lt; 0.0001). We will present a detailed analysis of microenvironmental stimuli and their influence on drug response. In the final step we investigated the biological relevance of selected microenvironmental stimuli in patient LN- and bone marrow biopsies by IHC. CLL infiltrated LN exhibited a higher signaling activity of the IL-4 and TLR pathway than non-neoplastic LN (t-test, p-values &lt;0.0001). A high signaling activity of IL-4 was associated with shorter time to treatment, indicating that CLL progresses faster with strong microenvironmental support. Conclusion We present a systematic investigation on the tumor microenvironment in CLL, the underlying molecular determinants as well its interference with drug response which will serve as a scientific resource and starting point for further mechanistical investigations. Figure Disclosures Kriegsmann: Celgene: Research Funding; Bristol-Myers Squibb: Research Funding; Sanofi: Research Funding; Morphosys: Research Funding. Müller-Tidow:MSD: Membership on an entity's Board of Directors or advisory committees.

A 10-Color Flow Cytometry Panel for Both Diagnosis and Minimal Residual Disease Measurement in Chronic Lymphocytic Leukemia

A 10-Color Flow Cytometry Panel for Both Diagnosis and Minimal Residual Disease Measurement in Chronic Lymphocytic Leukemia

Clinical Impact of Clonal and Subclonal TP53 Mutations and Deletions in Chronic Lymphocytic Leukemia: An Italian Multicenter Experience

Background. TP53 mutations (TP53mut) along with 17p13 deletion (del17p) are strong predictors of poor survival and refractoriness to chemo-immunotherapies (CIT) in chronic lymphocytic leukemia (CLL), and their analyses should be always performed before treatment. Studies based upon ultra-deep-NGS have shown that TP53mut can be present at very low level in CLL cell populations, although their detrimental clinical impact in this setting is still matter of debate (Rossi, Blood 2014), and ERIC recomendations discourage to report TP53 mutations if subclonal Malcikova, Leukemia 2018). Aim. To investigated the presence and clinical relevance of clonal/subclonal TP53 aberrations in a large CLL cohort. Methods. The study includes 1,058 out of 1,613 CLL patients (509 treated with standard CIT) diagnosed between 1991 and 2018, and consecutively referred to a single institution for del17p analyses by FISH (167-kb 17p13 orange probe, MetaSystems), and TP53mut by ultra-deep NGS (MiSeq Illumina; median coverage &amp;gt;2,000X with an amplicon-based strategy covering exons 2-11 using 40ng DNA/test) in CD19-purified (&amp;gt;85% pure) CLL samples, collected before treatment (as per ERIC recommendations). For TP53mut analyses, FASTQ files were aligned to the Hg19 reference with Burrows-Wheeler Aligner-MEM algorithm, and allele variants called by FreeBayes (Garrison &amp; Marth, arXiv 2102) with non-stringent parameters. To calculate random/systematic errors we generated a specific database with all the variant allele frequencies (VAF) observed in a subset of TP53 wild type (wt) subjects (n=362). TP53mut were accepted if: i) validated by Fisher exact test after Bonferroni correction (p&amp;lt;0.01); ii) with a VAF at least 2.75 standard deviations from the mean of the transformed distributions. The minimal allelic fraction for TP53mut calling was 0.4%. TP53mut cases with less than 2% VAF were tested twice. Outcome was overall survival (OS) from the date of exam. Results. A total of 248 TP53mut (Fig.A) were found in 154 patients (13.5%, Fig.B) with a median mutations/patient of 1.65 (range 1-11). According to the 12.5% VAF cutoff for TP53mut (Nadeu, Blood 2016), 87 cases were clonal (at least one clone &amp;gt; 12.5%) and 67 subclonal (all clones &amp;lt;12.5%; Fig.AB). Clonal and subclonal TP53mut have similar molecular characteristics (Fig.C), supporting the idea of comparable pathogenic effects. In fact, cases bearing clonal and subclonal TP53mut experienced comparably OS, shorter than TP53-wt cases (Fig.D). Accordingly, ROC analysis identified a cutoff of VAF &amp;gt;0.4% for the clinical impact of TP53mut (Fig.D), and the c-index of combined clonal/subclonal TP53mut (0.645) was significantly higher than the c-index of clonal TP53mut alone (0.602; P&amp;lt;0.001). Del17p was found in 178 patients (16.8%; Fig.E). In keeping with a ROC analysis (Fig.F, inset), the 64 cases with del17p in &amp;gt;10% of nuclei had significantly shorter OS than cases with del17p in &amp;lt;10% or without del17p (Fig.F). By combining del17p and TP53mut according to ROC cutoffs, 891 cases (84.2%) presented no TP53 aberrations, 13 cases (1.2%) were del17p only, 103 cases (9.7%) were TP53mut only, and 51 cases (4.8%) were del17p/TP53mut. Compared to TP53-wt cases, similar shorter OS were observed for TP53mut and del17p/TP53mut cases (Fig.G). Same results were obtained in the context of treated patients when OS was computed from the date of treatment (Fig.H). The "yes/no effect" of TP53 mutations on CLL outcome was verified dividing our cohort in a training cohort of 630 CLL cases, and in a validation cohort of 428 CLL patients. These two cohorts presented similar OS, and the same proportion of TP53 mutated cases and 17p deletion. ROC analysis on training cohort based on TP53 mutation variables, identified &amp;gt;0.5% as the best cutoff. In keeping with this cutoff, TP53 mutated patients experienced a significantly shorter OS than wt patients. Again cases with clonal and subclonal mutation experienced the same OS (Fig.I). Importantly, the cutoff found in the training cohort was able to reproduce the very same results also in the validation cohort both in term of mutation per se and in terms of clonal and subclonal TP53 mutations (Fig.J). Conclusion. i) By applying ERIC recommendations and a rigorous pipeline of analysis, TP53mut impacted on OS also with VAF &amp;lt;1%; ii) del17p associated with short OS only when detectable in &amp;gt;10% of nuclei. These cutoffs may be employed for the clinical management of CLL patients. Figure Disclosures Di Raimondo: Takeda: Consultancy; Amgen: Consultancy, Honoraria, Research Funding. Rossi:Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Honoraria, Other: Scientific advisory board; Janseen: Honoraria, Other: Scientific advisory board; Roche: Honoraria, Other: Scientific advisory board; Astra Zeneca: Honoraria, Other: Scientific advisory board.

The U1 Spliceosomal RNA: A Novel Non-Coding Hotspot Driver Mutation Independently Associated with Clinical Outcome in Chronic Lymphocytic Leukemia

Introduction: Genomic studies of chronic lymphocytic leukemia (CLL) have uncovered &amp;gt;80 potential driver mutations. The vast majority of these mutations affect coding regions, and just two potential drivers have been identified in non-coding elements. Aim: To describe the biological and clinical impact of a recurrent A&amp;gt;C mutation at the third base of the small nuclear RNA U1, the non-coding component of the spliceosome involved in the recognition of the 5' splice site (5'SS). Methods: Whole-genome sequencing (WGS) and RNA-seq from 318 CLL patients were used to identify and characterize a highly recurrent A&amp;gt;C point mutation occurring at position 3 of the U1 snRNA gene (g.3A&amp;gt;C mutation). The U1 wild-type and mutant forms were introduced into three CLL cell lines (JVM3, HG3, MEC1) to validate in vitro the predicted effect of this alteration. We screened two independent cohorts including a total of 1,314 CLL patients for the presence of the mutation using the rhAmp SNP genotyping assay, and integrated the U1 mutational status with well-known driver alterations, IGHV and epigenetic subgroups, and clinical parameters. Results: The U1 mutation was found in 8/78 (10.3%) CLL cases analyzed by WGS. Given its role in 5'SS recognition by base-pairing, we reasoned that this mutation was likely to alter the splicing and expression patterns of CLL. We were able to confirm widespread specific alterations in the transcriptome by comparing RNA-seq data between wild-type and g.3A&amp;gt;C mutated samples. Applying this knowledge to an algorithm aimed to infer the U1 mutational status from expression data, we were able to identify 4 mutated cases among 240 additional cases that had RNA-seq but no WGS. In total, 12/318 (3.8%) CLL patients analyzed by WGS and/or RNA-seq harbored this mutation. This g.3A&amp;gt;C U1 mutation changes the preferential A-U base-pairing between U1 and 5'SS to C-G base-pairing, creating novel splice junctions and altering the splicing pattern of 3,193 introns in 1,519 genes. In addition to altered splicing, 869 genes were differentially expressed between mutated and wild-type cases. We identified specific cancer genes (e.g. MSI2, POLD1, or CD44) and pathways (B-cell receptor signaling, promotion of apoptosis, telomere maintenance, among others) altered by the U1 mutation. To confirm a causal link between this mutation and splicing changes, we introduced exogenous U1 genes with or without the mutation into three cell lines. Subsequent RNA-seq of these cell lines recapitulated the altered splicing and expression patterns observed in CLL patients. We next screened for the presence of the U1 mutation 1,057 patients (cohort 1) using the rhAmp assay and it was found in 30 (2.8%) cases. The distribution of the mutation was similar in Binet stages and CLL vs monoclonal B-cell lymphocytosis. However, the U1 mutation was almost always found in IGHV unmutated CLL (29/30, p=9.0e-11) and within the naïve-like CLL epigenetic subgroup (p=3.7e-7). None of the U1 mutated cases had mutations in the SF3B1 splicing factor. Considering only pre-treatment CLL samples, U1 mutation was associated with a shorter time to first treatment independently of the Binet stage, IGHV mutational status, epigenetic subgroups, and mutations in the well-known CLL drivers SF3B1, NOTCH1, ATMor TP53. In cohort 2 (n=257), this mutation was found in 13 (5.1%) patients, confirming its enrichment in IGHV unmutated cases, naïve-like epigenetic subgroup, and splicing modulation. Despite the relatively small number of pre-treatment samples carrying the U1 mutation (7/178) and short follow-up of the patients (median 2.6 years), the effect of this mutation on time to first treatment in cohort 2 was compatible with the one observed in cohort 1. Finally, we screened for the U1 mutation a cohort of diffuse large B-cell lymphoma (n=108), mantle cell lymphoma (n=101), follicular lymphoma (n=87), splenic marginal zone lymphoma (n=12), acute myeloid leukemia (n=52), and myelodysplastic syndrome (n=67). The mutation was not present in any of the samples analyzed. Conclusions: Here we have reported that the third base of the small nuclear RNA U1 is recurrently mutated in CLL, proved its effect in splicing and gene expression, and shown that this mutation is independently associated with faster disease progression. The g.3A&amp;gt;C U1 mutation represents a novel non-coding driver alteration in CLL with potential clinical and therapeutic implications. Disclosures Ramirez Payer: GILEAD SCIENCES: Research Funding. Terol:Astra Zeneca: Consultancy; Gilead: Research Funding; Abbvie: Consultancy; Janssen: Consultancy, Research Funding; Roche: Consultancy. Lopez-Guillermo:Celgene: Consultancy, Research Funding; Janssen: Research Funding; Roche: Consultancy, Research Funding; Gilead: Consultancy, Research Funding.

MCL-1 and PKA/AMPK Axis Fuel Venetoclax Resistance in Lymphoid Cancers

MCL-1 and PKA/AMPK Axis Fuel Venetoclax Resistance in Lymphoid Cancers