BH3 Profiling Predicts 5-Azacytidine Response in Malignant Myeloid Cells

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1432-1432
Author(s):  
James M Bogenberger ◽  
William E. Pierceall ◽  
Ryan Lena ◽  
Reinhold Munker ◽  
Kaoru Tohyama ◽  
...  
Keyword(s):  
Cell Line ◽  
Cell Lines ◽  
Cell Population ◽  
Research Funding ◽  
Family Members ◽  
Myeloid Cells ◽  
Functional Assay ◽  
Employment Equity ◽  
Mitochondrial Outer Membrane Permeabilization ◽  
Equity Ownership

Abstract Abstract 1432 Previously we demonstrated that inhibition of anti-apoptotic BCL-2 family members sensitize leukemic cells to 5-Azacytidine (5-Aza), using siRNA and pharmacological inhibition with the BH3-mimetic ABT-737, both in vitro and ex vivo (Bogenberger, JM., et. al. ASH Annual Abstracts 2011;118:Abstract 3513). Crucially, several anti-apoptotic BCL-2 members (e.g. BCL-2 and BCL-XL) required concurrent inhibition for potent and universal sensitization to 5-Aza. Anti-apoptotic BCL-2 proteins block the execution of programmed cell death (apoptosis) by binding to and counteracting two types of pro-apoptotic BCL-2 family proteins: the “BH3-only” proteins, including both activators (BIM and BID) and sensitizers (e.g. NOXA, PUMA, HRK), and the multi-domain effector proteins (BAX and BAK). Cells dependent on anti-apoptotic BCL-2 family members for survival have been defined as “primed for death” (Certo, M., et. al. Cancer Cell 2006 May;9(5):351-65). Importantly, the priming status reflects a dependence on anti-apoptotic BCL-2 family proteins and can be characterized with the BH3 profiling functional assay. This assay measures induction of mitochondrial outer membrane permeabilization (MOMP) in response to treatment with peptides derived from BH3-only proteins (Ni Chonghaile, T., et. al. Science 2011 Nov 25;334(6059);1129-33). Thus, the unique BH3 profile associated with a specific malignant cell population, is a function of the anti-apoptotic BCL-2 family member/s contextual expression in that cell population. Based on our observations of potent 5-Aza sensitization in combination with anti-apoptotic BCL-2 protein family inhibition, we hypothesized that BH3-profiling would predict response to 5-Aza. To address the potential utility of BH3 profiling in predicting response to 5-Aza in myeloid malignancies, we assayed a broad panel of AML-derived cell lines (N=13) by BH3 profiling and correlated BH3 metrics with 5-Aza response. Identical cell line passages were assayed by BH3 profiling and in 5-Aza drug dose response assays. The cell panel comprised lines derived from AML FAB subtypes M7, M6, M5, M4, M2 and M0, as well as diverse cytogenetics such as t(11;21), t(9;11), t(4;11), t(6;11), del 5q, del 7, and a broad spectrum of mutations such as FLT3, N-RAS, CDKN2A, NPM1 and DNMT3A. The panel included a normal karyotype AML cell line (CG-SH) (Munker, R., et. al. Leuk Res 2009 Oct:33(10):1405-8) and a blastic cell line derived from a patient with MDS (MDS-L) (Tohyama, K., et. al. Br J Haematol 1994 Jun;87(2):235-42). Partition modeling using several BH3 metrics discriminates 5-Aza response with statistical significance (N=13, Mann-Whitney p<0.01) between more sensitive (EC50<2uM) and less sensitive (EC50>2uM) AML lines. For instance, the Puma BH3 peptide alone distinguishes more sensitive from less sensitive cell lines (N=13, Mann-Whitney p=0.0046). Several more complex parameters, such as “Puma+Hrk”, “Puma+Noxa,” and “Bim+Puma+Noxa+Hrk,” also significantly discriminate 5-Aza response (Mann-Whitney p=0.0011). Using continuous variable analysis, a Puma+Hrk metric exhibited the strongest correlation with 5-Aza response (R2=0.85, p<0.0001), while an individual Puma metric yielded the second strongest correlation (R2=0.70, p=0.0004). In conclusion, BH3 profiling discriminates 5-Aza response and confirms a central role for anti-apoptotic BCL-2 members in 5-Aza response. Furthermore, HRK priming indicates that BCL-XL is an important, although not the sole, anti-apoptotic component determining 5-Aza response in myeloid cells. These BH3 profiling results are in agreement with our functional 5-Aza RNAi and BCL-XL/BCL-2 inhibitor data in combination with 5-Aza. Based on these results, we are currently evaluating BH3 profiles from 5-Aza responding and non-responding AML and MDS patients to validate BH3 profiling-derived metrics in predicting clinical outcomes to 5-Aza. Disclosures: Pierceall: Eutropics Pharmaceuticals: Employment, Equity Ownership. Lena:Eutropics Pharmaceuticals: Employment. Mesa:Sanofi: Research Funding; Incyte: Research Funding; Lilly: Research Funding; NS Pharma: Research Funding; YM Bioscience: Research Funding. Cardone:Eutropics Pharmaceuticals: Employment, Equity Ownership.

scholarly journals Genetic or CD40L-Mediated Loss of Iκbα Is Associated with Resistance to the Dual SYK/JAK Inhibitor Cerdulatinib in DLBCL Cell Lines

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2768-2768
Author(s):  
Greg P Coffey ◽  
Jiajia Feng ◽  
Sabah Kadri ◽  
Y. Lynn Wang ◽  
Pin Lu ◽  
...  
Keyword(s):  
B Cell ◽  
Cell Line ◽  
Cell Lines ◽  
Research Funding ◽  
Stop Codon ◽  
Family Members ◽  
B Cell Malignancies ◽  
Employment Equity ◽  
Equity Ownership ◽  
External Stimuli

Abstract Abnormal upregulation of NFκB activity is observed in a variety of B cell malignancies, resulting in proliferative and survival signals that contribute to tumor progression. Under normal resting conditions, NFκB is negatively regulated principally via its physical association with IκB (inhibitor of NFκB) family members, thereby inhibiting nuclear transport or access to DNA. In B cells, NFκB is typically activated via various external stimuli (e.g., ligation of the B cell antigen receptor (BCR), toll-like receptors, cytokine receptors, CD40), leading to IκB kinase complex-dependent phosphorylation of IκB members and targeting them for ubiquitination and degradation. In some cases, the need for external stimuli is diminished or completely circumvented by mutations to critical regulators of NFκB, as has been described in the context of activating mutations to CD79A/B, MYD88, and CARD11, as well as inactivation of negative regulators such as A20 and IκB family members (reviewed by Staudt, 2010). Each of these mutations has been observed clinically in patients with B cell malignancies (Wilson et al, 2012; Norenberg et al, 2015; Mansouri et al, 2015), and can impact the anti-tumor activity of selective BCR pathway inhibition (Davis et al, 2010; Wilson et al, 2012) in part via induction of autocrine cytokine stimulation leading to JAK/STAT-dependent up-regulation of MCL1 (Lam et al, 2008). We previously reported that cerdulatinib, a small molecule kinase inhibitor that dually targets SYK and the JAK family members JAK1, JAK3, and TYK2, maintained anti-tumor activity in DLBCL cell lines bearing mutations to CARD11, MYD88, and A20 (Ma et al, 2015). The majority of DLBCL cell lines exhibit various degrees of reliance on SYK and JAK signaling for survival, however in a screen of 15 DLBCL cell lines we found 3 that were completely resistant to cerdulatinib and are described here. In one of the cerdulatinib-resistant cell lines, RCK8, next generation sequencing revealed bi-allelic inactivation of the IκBα gene. One allele carries a frameshift mutation in exon 1 resulting in the generation of a premature stop codon, and the second allele is a nonsense mutation in exon 3 at Gln154, also leading to a stop codon. In accord with a previous report (Kalaitzidis et al, 2002), the cell line lacks IκBα protein expression. We therefore proceeded to explore the possibility that loss of IκBα was responsible for resistance to cerdulatinib. Consistent with the loss of IκBα, the RCK8 cell line exhibited enhanced basal NFκB activity. Genetic re-introduction of wild type IκBα led to rapid suppression of NFκB, and ultimately cell cycle arrest and cell death, indicating that the cell line was dependent upon loss of this gene for survival. Associated with suppression of NFκB was decreased phosphorylation of cellular pAKT S473 and pERK Y202, but not of pSTAT3 Y705. We then attempted to knock down IκBα in cerdulatinib-sensitive cell lines using siRNA to determine if resistance to SYK/JAK inhibition could be generated. None of the DLBCL cell lines tested (n=4) could tolerate IκBα gene knock down, suggesting an additional mutation in RCK8 enables survival under conditions of homozygous loss of IκBα. Ligation of CD40 leads to a transient down-regulation of IκBα at the protein level (Oeckinghaus and Ghosh, 2009). We therefore examined the effect of CD40L on multiple DLBCL cell lines and found that IκBα was maximally suppressed within 30-60 minutes post CD40 stimulation, returning to pre-treatment levels by 2-4 hours. In contrast, the impact on NFκB activation was much longer, and 5 of 7 cerdulatinib-sensitive cell lines tested were made resistant by incubation with CD40L. Associated with this resistance was not only induction of NFκB, but also pERK Y204, pAKT S473, and pSTAT3 Y705. Interestingly, whereas the CD40L-induced NFκB activation was not inhibited by cerdulatinib, the other signaling events were, despite the generation of resistance. Loss of IkB family members has been described in the context of Hodgkin's lymphoma, non-Hodgkin's lymphoma, and chronic lymphocytic leukemia (Cabannes et al, 1999; Norenberg et al, 2015; Mansouri et al, 2015). Here we demonstrate that loss of IκBα in multiple DLBCL cell lines generates resistance to cerdulatinib. We will be exploring the clinical relevance of these in vitro observations in cell lines as part of an ongoing phase II trial of cerdulatinib in patients with relapsed/refractory B cell malignancies. Disclosures Coffey: Portola Pharmaceuticals: Employment, Equity Ownership, Patents & Royalties, Research Funding. Feng:Portola Pharmaceuticals: Employment, Equity Ownership, Research Funding. Wang:Portola Pharmaceuticals: Honoraria, Research Funding. Michelson:Portola Pharmaceuticals: Employment, Equity Ownership, Patents & Royalties, Research Funding. Pandey:Portola Pharmaceuticals: Employment, Equity Ownership, Patents & Royalties, Research Funding. Curnutte:3-V Biosciences: Equity Ownership; Portola Pharmaceuticals: Employment, Equity Ownership, Patents & Royalties, Research Funding; Sea Lane Biotechnologies: Consultancy. Conley:Portola Pharmaceuticals: Employment, Equity Ownership, Patents & Royalties, Research Funding.

Antileukemic Effects of the Novel Agent Elesclomol.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2736-2736 ◽  
Author(s):  
Sue Chow ◽  
Masazumi Nagai ◽  
Suqin He ◽  
Ronald K Blackman ◽  
James Barsoum ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Membrane Potential ◽  
Cell Line ◽  
Mitochondrial Membrane Potential ◽  
Cell Lines ◽  
Research Funding ◽  
Mitochondrial Membrane ◽  
Membrane Integrity ◽  
Employment Equity ◽  
Equity Ownership

Abstract Abstract 2736 Poster Board II-712 Elesclomol (N-malonyl-bis (N′-methyl-N′-thiobenzoyl hydrazide)) is an investigational first-in-class oxidative stress inducer that triggers apoptosis in cancer cells (Kirshner et al., Mol Cancer Ther 2008;7:2319–27). In the clinic, elesclomol is well tolerated in humans and showed activity in combination with paclitaxel in patients with refractory solid tumors (Berkenblit et al., Clin Cancer Res 2007;13:584–90). The aims of the current study are to examine the activity of elesclomol against a range of AML cell lines, including primary patient blast cultures, to investigate the mechanisms of drug action and the potential to combine elesclomol with other agents, and to identify candidate biomarkers for monitoring effects during treatment of leukemia patients with elesclomol. Here we describe the effects of elesclomol treatment in 4 AML cell lines selected based on their varying molecular attributes. Effects on cellular redox state and mitochondrial function were monitored using a flow cytometry incorporating the glutathione (GSH) probe monobromobimane, the reactive oxygen species (ROS) probe carboxy-dichlorofluorescin and the mitochondrial membrane potential stain DiIC(1)5. In addition, outer cell membrane integrity was determined by propidium iodide exclusion. Dual staining of fixed, permeabilized cells with phospho-specific antibodies to p38 and SAPK/JNK was used to determine if elesclomol treatment results in activation of the stress-activated MAP kinase pathways. Elesclomol showed potent anti-leukemic effects in vitro at concentrations as low as 10nM, which is well below the concentrations achieved in cancer patients, and greater toxicity was achieved with prolonged drug exposure. In OCI-AML2, a factor-independent, poorly differentiated AML cell line, toxicity was associated with loss of reduced GSH that coincided with a large increase in ROS generation and depolarization of the mitochondrial inner membrane, and later with loss of surface membrane integrity. A similar pattern was seen in OCI-M2, a p53-deficient erythroblastic leukemia cell line, except that during the early stages of drug effect these cells showed a large increase in reduced GSH, suggesting that initially they are able to compensate for drug-induced oxidative stress through enhanced cellular antioxidant production. In contrast, the factor-dependent line OCI-AML5, which appeared most sensitive to elesclomol, showed loss of outer membrane integrity without obvious prior oxidative stress while the Flt-3 ITD mutant line MV4-11 showed an initial loss of mitochondrial membrane potential without accompanying oxidative stress. Strikingly, we did not observe activation of the stress-responsive p38 or SAPK/JNK pathways in any of these 4 cell lines tested, suggesting that this is not a prominent response to elesclomol activity in AML and that additional mechanisms may be at work for the activity of elesclomol in these cells. Further investigations are ongoing and additional studies, including evaluation of elesclomol activity in primary leukemic cells from AML patients, will be presented. In summary, elesclomol is a potent novel compound that exerts anti-leukemic effects in tissue culture at drug concentrations that are well below those achieved in patients, suggesting that it might be active in leukemia patients. Disclosures: Chow: Synta Pharmaceuticals Inc.: Research Funding. Nagai:Synta Pharmaceuticals Inc.: Employment. He:Synta Pharmaceuticals Inc.: Employment. Blackman:Synta Pharmaceuticals Inc.: Employment, Equity Ownership. Barsoum:Synta Pharmaceuticals Inc.: Employment, Equity Ownership. Vukovic:Synta Pharmaceuticals Inc.: Employment, Equity Ownership. Hedley:Synta Pharmaceuticals Inc.: Research Funding.

scholarly journals Anti-Apoptotic BCL-2 Family Members Confer Resistance to Calicheamicin-Based Antibody-Drug Conjugate Therapy of Acute Leukemia

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 2561-2561
Author(s):  
Colin D. Godwin ◽  
Olivia M. Bates ◽  
Sae Rin Jean ◽  
George S. Laszlo ◽  
Eliotte E. Garling ◽  
...  
Keyword(s):  
Acute Leukemia ◽  
Cell Line ◽  
Cell Lines ◽  
Small Molecule ◽  
Research Funding ◽  
Small Molecule Inhibitors ◽  
Family Members ◽  
Equity Ownership ◽  
Reh Cells ◽  
Antibody Drug

BACKGROUND: With gemtuzumab ozogamicin (GO; targeting CD33) and inotuzumab ozogamicin (IO; targeting CD22), 2 antibody-drug conjugates delivering a toxic calicheamicin (CLM) derivative have recently been approved for the treatment of people with acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL), respectively. While effective in some, many patients do not benefit from these ADCs. It is unclear to what degree anti-apoptotic BCL-2 family members are involved in modulating efficacy of CLM-based ADCs, with limited studies coming to differing conclusions. Given the clinical availability of small molecule inhibitors for BCL-2 family proteins (BCLi), here we clarify the impact of BCL-2 family proteins on the anti-leukemic activity of CLM-ADCs. MATERIALS AND METHODS: Human AML and ALL cell lines were engineered to overexpress BCL-2, BCL-XL, and MCL-1 via lentiviral gene transfer. AML and ALL cell lines as well as AML patient samples were exposed to increasing concentrations of GO or IO with or without the BCL-2 inhibitor ABT-199 (venetoclax), the BCL-2/BCL-XL inhibitor ABT-263 (navitoclax), and the MCL-1 inhibitor AZD5991. Dead cells were enumerated by flow cytometry via 4',6-diamidino-2-phenylindole staining after 72 hours. For BH3 profiling of AML patient specimens, thawed AML patient specimen aliquots were exposed to JC-1 mitochondrial dye and BH3 peptides, and peptide-induced depolarization was then calculated as a percent relative to a CCCP positive control, yielding a priming score for each BH3 peptide. RESULTS: At a dose of 1000 pg/ml, GO killing of ML-1 (AML) cells decreased from 56±5% (mean±SEM) in parental cells to 32±7% (p<0.01) and 26±6% (p<0.01) in cells overexpressing BCL-2 and BCL-XL, respectively (all n=3). Similar results were seen in another AML cell line (HL-60). In REH (ALL) cells treated with IO, overexpression of BCL family members also reduced killing - at 500 pg/ml, 59±8% of cells were killed in contrast to 12±1% (p<0.01) of BCL-2-expressing and 11±1% (p<0.01) of BCL-XL-expressing cells, with similar results seen in another ALL cell line (RS4;11). Addition of ABT-199 or ABT-263 at 1 µM modestly increased GO-mediated killing of AML cell lines - for example, ML-1 cells treated with GO at 100 pg/ml, cytotoxicity increased from 41±6% to 57±7% (ABT-199, p<0.01) and 61±8% (ABT-263, p<0.01). The effect of BCLi was more pronounced on IO-mediated killing of ALL cell lines than on GO-mediated killing of AML lines. For example, killing of REH cells treated with IO at 25 pg/ml increased from 39±7% (without BCLi) to 72±8% (ABT-199 1 µM, p<0.01) and 87±9% (ABT-263 1 µM, p<0.01), with similar results seen in RS4;11 cells. BH3 peptide profiling of AML patient specimens treated with GO implicated MCL-1 as a potential additional modulator of AML response to GO. Consistent with this finding, overexpression of MCL-1 reduced leukemia cell death in HL-60 cells treated with GO (GO at 1000 pg/ml, 41±2 % vs. 26±1 %, p=0.01) and RS4;11 cells treated with IO (IO at 100 pg/ml, 76±2% vs. 27±6%, p<0.01). The MCL-1 inhibitor AZD5991 modestly increased the anti-leukemic efficacy of GO in ML-1 cells and AML patient specimens, but more dramatically enhanced IO killing of REH cells (IO at 10 pg/ml, 18±2% without AZD5991 vs. 70±2% with 0.1 µM AZD5991, p<0.01). The triplet combination of GO, ABT-199 and AZD5991 did not improve markedly on the ABT-199/AZD5991 combination in the absence of GO in cell lines or AML patient specimens, though the triplet combination of IO, ABT-199 and AZD5991 showed promising activity: in REH cells treated with 10 pg/ml IO, cytotoxicity was 18±2% without BCLi, 32±8% with ABT-199 0.1 µM, 19±2% with AZD5991 0.01 µM, and 56±14% with the triplet combination (p<0.01 for comparison of triplet combination with IO/BCLi doublet). CONCLUSIONS: Our studies establish an important role of anti-apoptotic BCL-2 family members as resistance factor for CLM-based ADC therapy of acute leukemia. These findings provide the rationale to explore the combination of small-molecule inhibitors of BCL-2 family members with CLM-ADCs as a combination strategy in the clinic to improve the efficacy of GO and, particularly, IO. These therapeutic strategies may incorporate the assessment of the relative contribution of specific BCL-2 family members to an individual cancer patient's disease. Disclosures Jean: Eutropics Pharmaceuticals: Employment. Cardone:Eutropics Pharmaceuticals: Employment, Equity Ownership. Walter:Seattle Genetics: Research Funding; Kite Pharma: Consultancy; Daiichi Sankyo: Consultancy; Jazz Pharmaceuticals: Consultancy; Agios: Consultancy; Amgen: Consultancy; Amphivena Therapeutics: Consultancy, Equity Ownership; Aptevo Therapeutics: Consultancy, Research Funding; Argenx BVBA: Consultancy; Astellas: Consultancy; BioLineRx: Consultancy; BiVictriX: Consultancy; Boehringer Ingelheim: Consultancy; Boston Biomedical: Consultancy; Covagen: Consultancy; New Link Genetics: Consultancy; Pfizer: Consultancy, Research Funding; Race Oncology: Consultancy.

scholarly journals Single Cell Analysis of Acquired Pomalidomide-Resistance in Multiple Myeloma Cell Lines Reveals Distinct Subclonal Cereblon Mutations and Gene Expression Heterogeneity

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 2648-2648 ◽  
Author(s):  
Sarah Gooding ◽  
Chad C. Bjorklund ◽  
Michael Amatangelo ◽  
Yan Ren ◽  
Mathieu Marella ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Single Cell ◽  
Cell Line ◽  
Cell Lines ◽  
Research Funding ◽  
Target Gene ◽  
Protein Quantification ◽  
Cell Protein ◽  
Employment Equity ◽  
Equity Ownership

Abstract Background: Multiple myeloma (MM) is a clonally heterogeneous cancer that recurrently relapses during its clinical course, demonstrating how interplay among subclones can lead to differentially drug-tolerant populations. The determination of onset and mechanisms of drug resistance is of clinical interest, and the improved understanding of this will drive innovative therapeutic approaches. The IMiD® agents lenalidomide (Len) and pomalidomide (Pom) bind to the E3-ubiquitin ligase receptor, Cereblon (CRBN), leading to ubiquitination and subsequent proteosomal degradation of key transcription factors Ikaros (IKZF1) and Aiolos (IKZF3). As a consequence of this degradation, direct antitumor and immunostimulatory effects are observed. Previous studies have revealed potential mechanisms of resistance to Len and Pom in both MM cell lines and clinical cohorts, including mutations, transcriptional downregulation or alternative splicing of CRBN, or mutations elsewhere in the E3 ligase pathway (CUL4A, DDB1), IKZF1/3 or IRF4. In resistant cell lines and patients, activation of proliferation, cell cycle, IGF-1, MAPK and FOXM1 pathways are reported, in addition to non-activation of interferon signature genes (ISGs). We hypothesize that rare MM cells/subclones with genetic, epigenetic or proteomic architecture permitting survival against Len or Pom in vitro may exist prior to acquired resistance, but may not be detectable by bulk genomic, transcriptional or proteomic analyses. Our goal is to define such populations using a combination of single cell technologies, initially focusing on acquired Pom-resistance mechanisms and quantifying genetic and transcriptional changes in Cereblon and its mechanistic targets, and to identify features of pre-existing resistant cell populations. Methods: To investigate the mechanism and timing of onset of acquired resistance, we utilized H929 and MM1S MM cell lines made resistant to Pom by serial dose increments over time, to a final Pom concentration of 10 μM (H929/PR and MM1S/PR respectively). Samples were collected at various timepoints for analysis by genomic, bulk and single cell (10X genomics) RNASeq techniques, and single cell protein quantification of Cereblon, Ikaros and Aiolos by IHC. Results: Bulk genomic sequencing revealed the H929/PR cell line had gained two CRBN mutations, a frameshift deletion of the glutarimide-binding region present in 10.9% alleles, and a point mutation in the non-glutarimide binding region present in 71% alleles. Concurrent single-cell protein quantification showed a near complete loss of Cereblon expression in the majority of cells, with little change in Ikaros or Aiolos staining. Bulk RNASeq of the H929/PR cell line showed a significant enrichment of cell cycle, E2F and MYC target gene sets. Using single cell transcriptomics, we found high expression of the signature genes of the Pom-resistant population to co-localise with an independently derived FOXM1 target gene set to a cluster of sensitive single cells defined by a gene expression profile identifying cells at the G2M checkpoint. Sanger sequencing of CRBN in the MM1S/PR cell line showed a de novo 12 bp deletion in intron 5 which is required for spliceosome assembly, resulting in deletion of exon 6 of the mature mRNA transcript. Interestingly, CRBN exon 6 is required for interaction with DDB1, suggesting loss of a functional E3-ligase. Analysis by single cell IHC showed substrate levels similar to sensitive parental cell lines. As in the H929/PR cell line, bulk RNASeq again showed enrichment of E2F and MYC targets, and independently derived Pom-resistant and FOXM1 target gene sets co-localised to the same cluster of MM1S drug-naïve single cells, identified by a G2M checkpoint signature. Conclusions: A range of CRBN mutations, Cereblon protein loss and enrichment of cell cycle, FOXM1 target and G2M checkpoint-related signatures was found at the onset of Pom resistance. This association with altered cell cycle progression dynamics may lead to, correlate with or result from drug survival. Tracking mutation- and non mutation-associated transcription factor signatures through sequential time points from first drug exposure to full resistance may reveal mechanisms by which functional CRBN loss causes drug resistance. Disclosures Gooding: Celgene: Research Funding. Bjorklund:Celgene Corporation: Employment, Equity Ownership. Amatangelo:Celgene Corporation: Employment, Equity Ownership. Ren:Celgene Corporation: Employment, Equity Ownership. Marella:Celgene: Employment. Couto:Celgene: Employment. Towfic:Celgene Corporation: Employment, Equity Ownership. Oppermann:Bayer Pharma: Research Funding. Ramasamy:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Pierceall:Celgene Corporation: Employment, Equity Ownership. Thakurta:Celgene Corporation: Employment, Equity Ownership.

Absence Of Mutation In Cereblon (CRBN) and DNA Damage Binding Protein 1 (DDB1) Genes In Myeloma Cells and Patients and Its Clinical Significance

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3139-3139
Author(s):  
Anjan Thakurta ◽  
Anita K Gandhi ◽  
Michelle Waldman ◽  
Chad C. Bjorklund ◽  
Suzanne Lentzsch ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Cell Lines ◽  
Research Funding ◽  
Heterozygous Mutation ◽  
Employment Equity ◽  
Advisory Committees ◽  
Single Nucleotide ◽  
Truncating Mutation ◽  
Equity Ownership

Abstract Background CRBN, a target of thalidomide and IMiDs® immunomodulatory agents lenalidomide (LEN) and pomalidomide (POM), is a component of the E3 ubiquitin cullin 4 ring ligase (CRL4) complex that also includes DDB1, Roc1, and Cul4. Two CRBN mutations have been reported in multiple myeloma (MM) patients: truncating mutation (Q99) and point mutation (R283K). One copy of the CRBN gene was shown to be deleted in the MM1S and MM1S.R cell lines. No DDB1 mutation has been described previously. Results We investigated the incidence of CRBN and DDB1 mutations by next-generation sequencing in 20 MM cell lines and MM subjects. Of 90 MM patients, 24 were newly diagnosed and 66 were relapsed and refractory of which 36 patients were LEN resistant. Out of the cell lines tested, 1 heterozygous CRBN mutation (D249Y) was found in the LEN-resistant ANBL6R cells, which is located in the putative DDB1 binding domain, and 2 single silent mutations were identified in the KMS-12-BM (rs17027638) and OPM-2 cells. One DDB1 heterozygous mutation (E303D) was identified in ANBL6 cells. In the cohort of patients assessed, no CRBN mutation was detected; however, 5 single nucleotide variations (SNV) were identified. Three of the 5 SNVs were at position 735 (Y245Y) and 1 each at position 219 (H73H) and 939 (C313C), respectively. The first 2 SNVs (rs17027638 and rs1045309) are described but not the last. We found a single SNV (P51P; rs2230356) in DDB1 gene the patient samples. Conclusion Mutations within the coding sequences of CRBN and DDB1 are rare in MM patients and cell lines. Most intrinsically LEN-resistant cells and cell lines made resistant to LEN or POM do not have CRBN or DDB1 mutations, suggesting the potential role of other sources, such as genetic or epigenetic pathways in developing resistance to IMiD drug–based therapy. Disclosures: Thakurta: Celgene: Employment, Equity Ownership. Gandhi:Celgene: Employment, Equity Ownership. Waldman:Celgene: Employment, Equity Ownership. Bjorklund:Celgene: Employment, Equity Ownership. Lentzsch:Celgene: Research Funding. Schey:Celgene: Consultancy, Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau; NAPP: Consultancy, Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau; BMS: Consultancy, Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau. Orlowski:Bristol-Myers Squibb: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Millennium: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Onyx: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Resverlogix: Research Funding; Array: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Merck: Membership on an entity’s Board of Directors or advisory committees. Madan:Covance Genomics Lab: Employment. Ning:Celgene: Employment, Equity Ownership. Mendy:Celgene: Employment, Equity Ownership. Lopez-Girona:Celgene: Employment, Equity Ownership. Schafer:Celgene: Employment, Equity Ownership. Avet-Loiseau:Celgene: Research Funding. Chopra:Celgene: Employment, Equity Ownership.

BH3 Profiling As Predictor Of 5-Azacytidine and Decitabine Clinical Responses

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 603-603 ◽  
Author(s):  
Raoul Tibes ◽  
Steven M. Kornblau ◽  
William E. Pierceall ◽  
Ryan Lena ◽  
Yi Hua Qiu ◽  
...  
Keyword(s):  
Cell Lines ◽  
Statistical Significance ◽  
Family Members ◽  
Specific Inhibitor ◽  
Hypomethylating Agents ◽  
Employment Equity ◽  
Number Of Patients ◽  
Clinical Responses ◽  
Equity Ownership

Abstract Hypomethylating agents have changed treatment and outcomes in MDS and are active in AML patients. However a significant number of patients do not respond to 5-Azacytidine or Decitabine and there is no clinically validated assay that predicts response to 5-Azacytidine (5-Aza) or Decitabine (DAC). Clinical parameters and recently TET2 mutations have been identified as genetic predictors of response to 5-Aza. Several recent papers report on the possible predictive value of anti-apoptotic proteins, for example BCL2L10. In previous genome-scale RNA-interference (RNAi) screens anti-apoptotic BCL-2 family members, most potently BCL-XL, were identified as top targets whose down-regulation sensitize to 5-Aza. Results were confirmed with the BCL-XL and BCL-2 inhibitor ABT-737, as well as the BCL-2-specific inhibitor ABT-199, both of which sensitized myeloid cells to 5-Aza. Although it is expected that interfering with anti-apoptotic genes would sensitize to hypomethylating similar to cytotoxics, few of the other >900 genes from our RNAi sensitizer screens, including few of the 571 kinases, sensitized to 5-Aza as potently as inhibition of BCL-XL. Thus BCL-2 family members constitute an especially potent context to modulate the activity of 5-Aza. To assess if protein expression of the top targets BCL-XL, BCL-2 or MCL-1 correlate with and may explain a preferential sensitization, 577 primary AML samples were examined by Reverse Phase Protein Array (RPPA). There was substantial overlap of expression across and within FAB subgroups and cytogenetics, and expression of neither of these genes/proteins could explain the observed effects. This may be expected due to functional redundancies amongst the different anti-apoptotic BCL-2 family members, as well as distinct, yet overlapping binding affinities between anti- and pro-apoptotic BCL-2 proteins and BH3 peptides. Thus, we next aimed to functionally interrogate the overall balance of pro- and anti-apoptotic BCL-2 family members, also described as “primedness” by BH3 profiling. This assay uses peptides derived from pro-apoptotic BH3-only proteins to determine the capacity of cells to initiate apoptosis in response to pro-apoptotic BH3 molecules [anti-apoptotic BCL-2 molecules like BCL-XL and BCL-2 bind and inhibit BH3-only molecules]. This assay is a broad functional readout that incorporates many parameters including the consequences of varying BCL2L10 expression. To establish a proof-of-concept that the functional interrogation of specific apoptotic thresholds may be an optimal readout for 5-Aza response, we first assessed a broad panel of 13 AML-derived cell lines by BH3 profiling and in parallel 5-Aza drug dose response experiments. Several BH3 profiling metrics, including NOXA plus BIM, significantly correlated with 5-Aza sensitivity in vitro (Figure 1). Next, to correlate actual clinical responses to 5-Aza with BH3 profiling, specimens from 28 AML, MDS and MDS/MPN overlap patients treated with 5-Aza or DAC-based regimens and for whom clinical outcome was available, were assayed in BH3 assays. In the clinic, the best BH3 metrics were combined values from NOXA and BIM peptides similar to cell lines. NOXA plus BIM discriminated clinical responses defined as achieving any response (sensitive) versus a patient being resistance/refractory to 5-Aza/DAC based regimens with statistical significance (Mann-Whitney two-tailed p = 0.001). This was true for the entire group of patients (5-Aza- and DAC- regimens) with a Receiver Operating Characteristic (ROC) of an AUC=0.875, with a further increase for patients treated only with 5-Aza based regimens with an AUC=0.95.Figure 1BH3 metrics distinguish cell lines with higher EC 50 (> 2uM) from those with lower EC50 (generally < 1uM).Figure 1. BH3 metrics distinguish cell lines with higher EC 50 (> 2uM) from those with lower EC50 (generally < 1uM). In conclusion, due to significant expression overlap and functional redundancies of the BCL-2 family proteins, expression does not correlate with 5-Aza clinical or in vitro responses. However, BH3 profiling as a general functional readout of apoptotic primedness, significantly discriminated responses in patients as well as in vitro. Thus, BH3 profiling incorporates the entirety of pro- and anti-apoptotic molecules (including BCL2L10) and is promising to predict responses to hypomethylating agents. We propose to prospectively validate BH3 profiling as a predictive biomarker assay for 5-Aza or DAC based regimens. Disclosures: Pierceall: Eutropics: Employment, Equity Ownership. Lena:Eutropics: Employment, Equity Ownership. Cardone:Eutropics: Employment, Equity Ownership. Elashoff:Eutropics: Employment. Blake:Noel Blake: Employment, Equity Ownership.

Effect of the BET Inhibitor, Cpi-0610, Alone and in Combination with Lenalidomide in Multiple Myeloma

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 4255-4255 ◽  
Author(s):  
Ka Tat Siu ◽  
Homare Eda ◽  
Loredana Santo ◽  
Janani Ramachandran ◽  
Miroslav Koulnis ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Protein Expression ◽  
Cell Lines ◽  
Positive Feedback ◽  
Research Funding ◽  
Cytotoxic Effect ◽  
Feedback Mechanism ◽  
Employment Equity ◽  
Equity Ownership ◽  
Rpmi 8226

Abstract The bromodomain and extraterminal (BET) proteins recognize acetylated lysine residues on histone tails and recruit transcriptional machinery to promote gene expression. The BET proteins are attractive drug targets because they regulate the expression of MYC, BCL2 and NF- κB target genes. We investigated the therapeutic potential of CPI-0610, an inhibitor of BET proteins, currently in Phase I testing in multiple myeloma (MM). Our preliminary data show that human MM cell lines are sensitive to BET inhibition, with IC50 values of 800-1000 nM being observed in MM.1S, MM.1R, RPMI-8226, LR5, H929 and U266 cell lines in 72h culture. We further show that CPI-0610 inhibits MM cell growth in the presence of cytokines and when co-cultured with bone marrow stromal cells. CPI-0610 induces apoptosis and G1 cell cycle arrest associated with MYC downregulation. However, protein levels of BCL2, NF- κ B and MCL1 remain unchanged in MM cells upon BET inhibition. The zinc finger transcriptional factor Ikaros (IKZF1) is highly expressed in MM (GEO dataset GSE36133). It is actively transcribed in the MM.1S cell line with an active transcription start site occupied by BRD4 and MED1 (Loven J et al. Cell 2013). Interestingly, we found that CPI-0610 suppresses Ikaros and IRF4 expression at the levels of both transcription and protein in MM cells. With the use of doxycycline-inducible shRNAs targeting IKZF1, IRF4 and MYC, we identified a positive feedback mechanism that is critical for MM cell survival. Individual knockdown of IRF4, IKZF1 or MYC all lead to induction of apoptosis in MM cells. Suppression of IRF4 decreases both Ikaros and MYC protein expression, suggesting that IRF4 is upstream of both Ikaros and MYC. Downregulation of MYC protein expression is observed following IKZF1 knockdown, suggesting that MYC is downstream of Ikaros. Finally, we observed a decrease in IRF4 protein level upon MYC downregulation, implicating a feedback mechanism from MYC to IRF4. Together, these data illustrate a molecular sequence of events going from IRF4 to IKZF1 to MYC and then back to IRF4, forming a positive feedback loop in MM cells. Based on the observation that shRNA-mediated knockdown of MYC and IKZF1 are toxic to MM, we combined CPI-0610 with lenalidomide, an immunomodulatory drug which stabilizes cereblon and facilitates Ikaros degradation in MM cells (Kronke J et al., and Lu G et al., Science 2014). We observed a synergistic cytotoxic effect in the cell lines tested (MM.1S and RPMI-8226). The enhanced cytotoxic effect of the combined treatment in MM cell lines is due in part to suppression of MYC, IKZF1 and IRF4. Ongoing studies will focus on understanding the molecular mechanism underlying this synergistic combination and validating its efficacy in vivo in order to provide a rationale for clinical protocols of BET inhibitors in MM. Disclosures Mertz: Constellation Pharmaceuticals: Employment, Equity Ownership. Sims:Constellation Pharmaceuticals: Employment, Equity Ownership. Cooper:Constellation Pharmaceuticals: Employment, Equity Ownership. Raje:Celgene Corporation: Consultancy; Eli Lilly: Research Funding; Takeda: Consultancy; Amgen: Consultancy; Onyx: Consultancy; AstraZeneca: Research Funding; Novartis: Consultancy; BMS: Consultancy; Acetylon: Research Funding; Millenium: Consultancy.

Filanesib Primarily Initiates the Apoptotic Program By Activating Bax through a Calpain-Dependent Mechanism

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 5353-5353 ◽  
Author(s):  
Susana Hernández-García ◽  
Lorena González-Méndez ◽  
Irena Misiewicz-Krzeminska ◽  
Esperanza Macarena Algarín ◽  
Ana Alicia López-Iglesias ◽  
...  
Keyword(s):  
Cell Line ◽  
Cell Lines ◽  
Research Funding ◽  
Family Members ◽  
Calpain Inhibitor ◽  
Caspase Inhibitor ◽  
Proliferating Cells ◽  
Bax Protein ◽  
Pre Treatment ◽  
Interfering Rna

Abstract Introduction: Filanesib (ARRY-520) is a highly selective inhibitor of kinesin spindle protein (KSP), a microtubule motor protein active in proliferating cells, which plays an essential role in assembly and maintaining of the bipolar spindle. In cells arrested by KSP inhibition, Mcl-1 is rapidly depleted resulting in cell death, and consequently cells that are dependent on this pro-survival protein, such as myeloma cells, are particularly sensitive to filanesib. We investigated the mechanisms underlying the antimyeloma effect of this agent, focusing on other Bcl-2 family members. Methods: In vitro action of filanesib, alone and in combination with calpain inhibitor PD150606, was evaluated in multiple myeloma (MM) cell lines by MTT assay, Annexin V staining and cell cycle profile analysis by flow cytometry. MM cells were transiently transfected with non- targeting control short interfering RNA (NT-siRNA), Bax siRNA ON TARGET plus SMART pool siRNA using the cell line Nucleofector Kit V. Expression levels of different proteins were analyzed by Western-Blot. Results: We previously showed that all 11 MM cell lines tested were sensitive to filanesib and that sensitivity to this agent correlated with Bax levels. For these experiments, we focused on 3 cell lines with different Bax expression and sensitivity to filanesib: OPM-2 and MM1S (sensitive and high Bax levels) and U266 (less sensitive and low Bax levels). Treatment of MM1S with this agent triggered the translocation to the mitochondria of several proapoptotic Bcl-2 family members such as Noxa, Bim and Bax with several downstream effects. The mitochondrial translocation and activation of Noxa is key in the degradation of Mcl-1 by mediating the translocation of this protein from the cytosol to the mitochondria promoting its degradation. Regarding Bim, filanesib also induced the early (12-24 hours) expression of several proapoptotic isoforms of Bim that also translocated to the mytochondria. As previously reported, Bax is the top determinant of sensitivity to filanesib. In the present study, remarkably, once translocated into the mitochondria, Bax was also cleaved into the very potent proapoptotic 18 kDa fragment. All these events triggered the mitochondrial release of cytochrome C (caspase dependent apoptosis) and AIF (caspase independent apoptosis). In order to confirm the role of Bax in filanesib-induced apoptosis, we knocked-down Bax in MM1S by using small interfering RNA. This approach clearly decreased the sensitivity of these cells to filanesib, as treatment with 10 nM for 24 hours induced only 26% apoptosis in the siRNA-Bax cells as compared with 50% in the non-targeted cells (as compared with 58% vs 61% for bortezomib). Furthermore, treatment with filanesib also induced cleavage of effector caspases (3 and 7) in all cell lines studied (OPM2, MM1S, U266). PARP was also cleaved in these cells, but it was previous to caspase activation in the most sensitive cell lines (OPM2, MM1S) suggesting a caspase-independent mechanism of apoptosis. This was confirmed by pre-treatment with the pan caspase-inhibitor Z-VAD-FMK, which did not rescue OPM2 and MM1S cells from apoptosis. Interestingly, one potential mechanism that could link both effects is the activity of calpain, a cysteine protease involved in caspase-independent apoptosis. This protein is a well-known caspase-independent way of processing PARP into the 60 kDa fragment, and has also been described as being responsible for Bax cleavage into the 18-kDa fragment. Consistent with this hypothesis, pre-treatment with the calpain inhibitor PD150606 clearly reduced the activity of filanesib in these cells (35 % to 70 % of survival) as assessed by MTT. Finally, consistent with the previous hypothesis, the less sensitive U266 cell line contained undetectable Bax protein suggesting that filanesib was not able to trigger caspase-independent apoptosis. However, a secondary caspase dependent apoptosis mechanism was confirmed as the pan-caspase inhibitor ZVAD-FMK was able to almost completely abrogate the activity of filanesib. Conclusions: Our results show that filanesib primarily initiates apoptosis by activating Bax in a caspase-independent manner, probably via calpain, a powerful accelerator of the apoptotic process. In addition, Noxa and BIM appear to be crucial for modulating Mcl-1 proteasomal degradation and Bax activation. This work was funded in part by the company Array BioPharma. Disclosures Tunquist: Array BioPharma: Employment. Mateos:Takeda: Consultancy; Onyx: Consultancy; Janssen-Cilag: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Ocio:Mundipharma: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy; Novartis: Consultancy, Research Funding; MSD: Research Funding; Amgen/Onyx: Consultancy, Honoraria, Research Funding; Array BioPharma: Consultancy, Research Funding; Celgene: Consultancy, Honoraria; Pharmamar: Consultancy, Research Funding; Janssen: Honoraria.

scholarly journals Hematologic Malignancies Exhibit Selective Vulnerability to Inhibition of De Novo Pyrimidine Biosynthesis By AG-636, a Novel Inhibitor of Dihydroorotate Dehydrogenase in Phase 1 Clinical Trials

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1570-1570
Author(s):  
Danielle Ulanet ◽  
Victor Chubukov ◽  
John Coco ◽  
Gabrielle McDonald ◽  
Mya Steadman ◽  
...  
Keyword(s):  
Cell Lines ◽  
Cancer Cell ◽  
Solid Tumor ◽  
Research Funding ◽  
De Novo ◽  
Phase 1 ◽  
Cancer Cell Lines ◽  
Pyrimidine Biosynthesis ◽  
Employment Equity ◽  
Equity Ownership

Rapidly proliferating cells reprogram metabolism to support increased biosynthetic demands, a feature that can expose targetable vulnerabilities for therapeutic intervention. A chemical biology screen was performed in an effort to identify metabolic vulnerabilities in particular tumor subtypes, and revealed potent and selective activity of a novel dihydroorotate dehydrogenase (DHODH) inhibitor, AG-636, in cancer cell lines of hematologic origin. In contrast, cancer cell lines of solid tumor origin exhibited comparatively poor sensitivity. Evaluation of a lymphoma cell line panel demonstrated broad responsiveness to DHODH inhibition, independent of clinical subtype (e.g. ABC, GCB, double-hit). The on-target cellular activity of AG-636 was evaluated by examining the metabolic effects of AG-636 on cells and by evaluating the ability of extracellular uridine to rescue the effects of AG-636 on proliferation and viability. The metabolic changes incurred upon treatment of cells with AG-636 were consistent with a mechanism of action driven by inhibition of DHODH and de novo pyrimidine biosynthesis. Supraphysiologic concentrations of extracellular uridine rescued the effects of AG-636 on growth and viability as well as the effects on metabolism, further confirming on-target activity. The mechanistic basis for differential sensitivity to AG-636 was assessed by comparing the activity of the de novo pyrimidine biosynthesis and uridine salvage pathways in cancer cell lines of hematologic or solid tumor origin with similar proliferative rates. Differential response to AG-636 could not be attributed to varying abilities to utilize the de novo pyrimidine biosynthesis pathway or to salvage extracellular uridine. Real-time imaging of cells treated with AG-636, along with monitoring of extracellular uridine concentrations, demonstrated immediate effects on the viability of lymphoma cell lines in the setting of depleted extracellular uridine. In contrast, solid tumor cell lines were able to maintain growth for an additional period of time, suggestive of adaptive mechanisms to supply pyrimidine pools and/or to cope with nucleotide stress. The high in vitro activity of AG-636 in cancer cells of hematologic origin translated to xenograft models, including an aggressive, patient-derived xenograft model of triple-hit lymphoma and an ibrutinib-resistant model of mantle cell lymphoma in which complete tumor regression occurred. These studies support the development of AG-636 for the treatment of hematologic malignancies. A phase 1 study has been initiated in patients with relapsed/refractory lymphoma (NCT03834584). Disclosures Ulanet: Agios: Employment, Equity Ownership. Chubukov:Agios: Employment, Equity Ownership. Coco:Agios: Employment, Equity Ownership. McDonald:Agios: Employment, Equity Ownership. Steadman:Agios: Employment, Equity Ownership. Narayanaswamy:Agios: Employment, Equity Ownership. Ronseaux:Agios: Employment, Equity Ownership. Choe:Agios: Employment, Equity Ownership. Truskowski:Agios: Employment, Equity Ownership. Nellore:Aurigene Discovery Technologies: Employment. Rao:Firmus Laboratories: Employment, Equity Ownership. Lenz:Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Agios: Research Funding; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; Gilead: Consultancy, Honoraria, Research Funding, Speakers Bureau; BMS: Consultancy; AstraZeneca: Consultancy, Honoraria, Research Funding; Bayer: Consultancy, Honoraria, Research Funding, Speakers Bureau; Roche: Employment, Honoraria, Research Funding, Speakers Bureau. Cooper:Agios: Employment, Equity Ownership. Murtie:Agios: Employment. Marks:Agios: Employment, Equity Ownership.

scholarly journals ASLAN003, a Novel and Potent Dihydroorotate Dehydrogenase (DHODH) Inhibitor, Induces Differentiation of Acute Myeloid Leukemia

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 4047-4047 ◽  
Author(s):  
Jianbiao Zhou ◽  
Jessie Yiying Quah ◽  
Jing Yuan Chooi ◽  
Sabrina Hui-Min Toh ◽  
Yvonne Ng ◽  
...  
Keyword(s):  
Cell Growth ◽  
Cell Lines ◽  
Research Funding ◽  
Tissue Bank ◽  
Dihydroorotate Dehydrogenase ◽  
Employment Equity ◽  
Healthy Control ◽  
Equity Ownership ◽  
Nbt Reduction

Abstract Background: Differentiation therapies achieve remarkable success in acute promyelocytic leukemia (APL), a subtype of acute myeloid leukemia (AML). However, clinical benefits of differentiation therapies are negligible in non-APL AML, which accounts for the majority of AML cases. Dihydroorotate dehydrogenase (DHODH) regulates the fourth step of the de novo pyrimidine synthesis pathway. DHODH is a key therapeutic target for auto-immune diseases and cancer, particularly differentiation of AML. ASLAN003 is a novel, potent small molecule DHODH inhibitor being developed in AML by ASLAN Pharmaceuticals. Methods: We investigated activity of ASLAN003 in AML cell lines and primary bone marrow (BM) cells (NUS Leukemia Tissue Bank) from patients with AML (N = 14) or myelodysplastic syndromes (MDS) (N = 6) and healthy control (N = 1). We performed CTG assay, FACS analysis of cell viability and myeloid markers, wright-giemsa staining, NBT reduction assay, and qRT-PCR analysis of key lineage transcription factors to evaluate the effects of ASLAN003 on cell growth, differentiation, apoptosis, and gene expression changes in vitro. Two AML cell lines and 1 leukemic patient derived xenograft (PDX) line (NUS Leukemia Tissue Bank) were studied in NSG xenograft mice. Mice were administrated with vehicle control or ASLAN003 50 mg/kg by oral gavage once daily. Results: ASLAN003 inhibited leukemic cell growth of THP-1, MOLM-14 and KG-1 with IC50 of 152, 582 and 382 nM, respectively, at 48 h. Treatment of these leukemia cells with ASLAN003 for 96 h consistently resulted in remarkable increase of CD11b (p < 0.001) and displayed morphologic changes of terminal differentiation and positivity for NBT reduction. ASLAN003 was active in differentiation with an EC50 of 28, 85, and 56 nM, in these 3 lines, respectively. ASLAN003 induced approximately 2-fold higher CD11b+ cells than Brequinar (BRQ), another DHODH inhibitor. Addition of uridine rescued differentiation and improved cell viability in ASLAN003 treated-cells, implying on-target specificity of ASLAN003. Mechanistically, ASLAN003 induced differentiation through induction of myeloid lineage transcription factor Runx1, Pu.1, Gif1 and repression of HoxA9, Gata1. The response of primary BM cells to ASLAN003 was classified into 3 categories: sensitive if any of myeloid markers CD11b, CD14, CD13 or CD33 increased ≥ 15%; moderate: ≥ 5%, but < 15%; resistant: < 5%. Among AML samples, we observed 6 (43%) sensitive cases, 6 (43%) moderate cases and 2 (14%) resistant cases. Three (50%) MDS samples displayed sensitive response and 3 cases (50%) showed moderate response. The healthy control sample was resistant to ASLAN003. Importantly, ASLAN003 promoted differentiation and cell death of myeloid cells in one relapsed AML case. Morphologic analysis and NBT assay demonstrated the features of neutrophil differentiation in selected ASLAN003-treated primary AML blasts. For in vivo experiments, significantly prolonged survival was seen in ASLAN003-treated groups when compared to vehicle control group in both MOLM-14 (p = 0.031) and THP-1 (p < 0.001) xenograft models. ASLAN003 substantially reduced disseminated tumors and leukemic infiltration into liver in xenografted mice. The human CD45+ cells were significantly reduced in BM, peripheral blood, spleen and liver, with significantly increased differentiation of AML cells (CD11b and CD14 positive cells) in BM of treated mice in both models (p < 0.01). We also evaluated the therapeutic efficacy of ASLAN003 in one PDX line, AML-14. At the end of experiments (day 77 post treatment), all PDX mice were alive in both control and ASLAN003 group. The leukemic burden was significantly lower in ASLAN003-treated PDXs than in vehicle-treated PDXs (p = 0.04). Overall, these data demonstrate potent in vivo efficacy of ASLAN003 in inducing myeloid differentiation of blast cells and the drug appears highly tolerable even after prolonged administration. Conclusion: ASLAN003 is a novel, highly potent DHODH inhibitor that induces terminal differentiation, inhibits cell growth and promotes cell death of AML blasts, including relapsed AML blasts. ASLAN003 prolongs survival and shows therapeutic effects in mice bearing different AML cell lines and reduces leukemic burden in an AML PDX model. Currently, ASLAN003 efficacy is being evaluated in a Phase IIa clinical trial in patients with AML (NCT03451084; Ting, ASH abstract 2018). Disclosures Seet: ASLAN Pharmaceuticals: Employment, Equity Ownership. Ooi:ASLAN Pharmaceuticals: Employment, Equity Ownership. Lindmark:ASLAN Pharmaceuticals: Employment, Equity Ownership. McHale:ASLAN Pharmaceuticals: Employment, Equity Ownership. Chng:Amgen: Consultancy, Honoraria, Other: Travel, accommodation, expenses; Aslan: Research Funding; Merck: Research Funding; Janssen: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding; Takeda: Consultancy, Honoraria, Other: Travel, accommodation, expenses; Celgene: Consultancy, Honoraria, Other: Travel, accommodation, expenses, Research Funding.

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