ALBERT

Beschreibung: Lysine-specific demethylase (LSD1, also known as KDM1A) is an epigenetic regulator that has recently emerged as a potential therapeutic target in acute myeloid leukemia (AML). It is a flavin dependent monoamine oxidase which can demethylate monomethyl or dimethyl lysine 4 of histone H3. Pharmacological inhibition of LSD1 induces differentiation of blast cells in MLL-translocated AML and has shown significant promise in pre-clinical studies. With LSD1 inhibitors advancing through early-phase clinical trials, there is a strong pre-clinical rationale for the identification of genes whose protein products collaborate with LSD1 to retard differentiation in cancer and which could potentially be targeted in combination therapies for enhanced therapeutic benefit. To identify potential drug-gene synthetic lethal interactions, we performed a genome wide loss-of-function CRISPR-Cas9 screen in human THP1 AML cells treated with a potent and selective tranylcypromine-derivative LSD1 inhibitor trans-N-((2-methoxypyridin-3-yl)methyl)-2-phenylcyclopropan-1-amine (OG86). THP1 cells exhibit a t(9;11) MLL gene rearrangement and display similar phenotypic and functional responses to those observed in primary MLL-translocated AML cells following LSD1 inhibition. The cells were transduced with lentiviral human CRISPR knockout (hGeCKOv2) library containing 122,411 sgRNAs targeting 19,050 protein coding genes and 1864 miRNA precursors in the human genome. The transduced cells were divided into two groups, treated with either DMSO or 250nM OG86 and maintained in culture for ~10 population doublings. To investigate sgRNA representation in the cell population harvested at different stages of the screen, sgRNA cassettes were PCR amplified from genomic DNA and deep sequenced; negatively selected genes were identified with the MAGeCK computational algorithm. After successful initial quality assessment of the screen, we next searched for genes selectively depleted in OG86-treated versus DMSO-treated THP1 cells in samples collected on Day 15 and Day 18. At a false discovery rate of 7.5% there were 10 expressed genes whose sgRNA representation was depleted at both time points. In particular, these included two genes coding for components of the MTOR signaling pathway: MTOR associated protein, LST8 homolog (MLST8) and Ras-related GTP-binding protein A (RRAGA). In the Day 18 comparison, an additional MTOR pathway gene LAMTOR2 scored among the ten most depleted. MLST8 is a core component of TORC1/TORC2 complex and RRAGA is involved in the activation of TORC1 by amino acids. Recruitment of both RAG proteins and TORC1 to lysosomal membranes in response to amino acids, and the consequent activation of TORC1 signalling, requires the trimeric Ragulator complex, of which LAMTOR2 is a member.Based on our screen, we hypothesized that THP1 AML cells exposed to pharmacologic inhibition of LSD1 exhibit increased sensitivity to concomitant inhibition of the amino acid sensing component of the TORC1 pathway. Using genetic knockdown and pharmacological inhibition strategies, we then validated our screen hits in combination with LSD1 inhibition in targeting human AML cells. RNAi based knockdown of RRAGA, LAMTOR2 and MLST8 in combination with LSD1 inhibition were found to promote myeloid differentiation and reduce cell proliferation in THP1 cells. Interestingly the mTORC1 pathway inhibitor everolimus (RAD001) showed at least additive effect in combination with OG86 to decrease THP1 cell proliferation and promote immunophenotypic differentiation. Comparison of transcription changes in combined versus single treatment conditions by RNA-seq analysis further confirmed a more extensive and wide-ranging upregulation of a myeloid differentiation program upon concomitant inhibition of LSD1 and mTORC1 pathway. In vitro studies performed in primary patient AML cells gave similar results. Finally, in vivo studies using AML patient-derived xenograft mouse model confirmed that combination treatment promotes a strong myeloid differentiation program. In conclusion, we report here that inhibition of mTORC1 sensitizes human MLL-translocated AML cells to LSD1 inhibitor-mediated differentiation therefore highlighting a novel combination approach for evaluation in clinical trials. Disclosures No relevant conflicts of interest to declare.

Beschreibung: Introduction: Acute Myeloid Leukemia (AML) is an elderly disease with a rising incidence in the past decades. Probability to achieve complete remission and survival rates decrease with age with standard chemotherapy options leading to very poor outcomes with less than 20% 5-year overall survival rates. It has been shown that Lysine-specific demethylase 1 (LSD1) is a partner in some gene transformation in AML and helps sustain the oncogenic process. Iadademstat is a potent and selective LSD1 inhibitor that has shown to be effective in preclinical models, both alone and in combination with other compounds, including azacitidine (Aza). A Phase I FiM study in acute leukemia showed that iadademstat exhibits a good safety profile and preliminary anti-leukemic activity as monotherapy. Iadademstat in combination with Aza may thus offer an alternative option for such a population with limited therapeutic options. Methods: ALICE is a Phase IIa clinical trial to assess the safety, tolerability and dose finding of iadademstat in combination with Aza and also to measure the clinical activity of the combination as overall response rate (ORR), time to response (TTR) and duration of response (DOR). Other assessments include hematological improvement and overall survival, along with PK/PD measures (including a set of 6 blood biomarkers). The dose finding stage (Part 1) planned to dose a maximum 18 patients with a starting dose of iadademstat of 90 μg/m2/d in combination with Aza. Iadademstat may be escalated or de-escalated depending on the observed dose limiting toxicities. Once the Recommended Dose (RD) is identified, an expansion cohort of 18 patients will be enrolled and treated with iadademstat combined with Aza (Part 2). ALICE includes subjects ≥ 60 years of age with AML according to World Health Organization (WHO) classification, who are considered by the investigator to be ineligible for intensive chemotherapy at that time or have refused standard chemotherapy and who have not received prior treatment for AML other than hydroxyurea. Results: According to the Safety Monitoring Committee of the study, the selected RD of iadademstat was 90μg/m2/d. This decision was made based on first dose finding cohort including 6 subjects with the observation of 1 DLT due to a differentiation syndrome (the sole SAE reported due to treatment) and based on the fact that the selected dose: i) was able to saturate LSD1 target engagement in PBMCs after 5 days of treatment; ii) was well tolerated (11 treatment cycles were completed at the moment of decision) and iii) demonstrated the first signs of efficacy. A short median time to first response was observed (around 1.5 months). Analysis of the first patients yielded an ORR in 4 of 5 evaluable patients (80%): in all of them the best observed response was CRi as per July 2019. A lower maintenance regime has been established for those patients that had attained CRi. The first patient that has followed this strategy has become transfusion independent. To date, no grade 3-4 non-hematological adverse events have been reported. The patient assessments of the still-ongoing subjects from Part 1 and all new enrolled study subjects in the expansion cohort will be presented following a November 2019 cut-off, with particular emphasis on available preliminary efficacy outcomes. Conclusions: To date, data from this Phase II study supports that iadademstat in combination with azacitidine in elderly previously untreated AML patients has a manageable toxicity and is a meaningful candidate for specific combinations in this and future leukemia studies. These encouraging results will be enriched with the inclusion of up to 18 additional patients in the expansion cohort and with longer clinical observation periods to better assess the frequency, deepness and duration of the responses. Disclosures Buesa: Oryzon Genomics: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Mendelion SL: Membership on an entity's Board of Directors or advisory committees. Somervaille:Novartis: Consultancy. Arevalo:Oryzon Genomics: Employment. Xaus:Oryzon Genomics: Employment. Gutierrez:Oryzon Genomics: Employment. Bullock:Oryzon Genomics: Consultancy.

Beschreibung: Background CCS1477 is a first in class potent, selective and orally bioavailable inhibitor of the bromodomains of p300 and CBP, two closely related histone acetyl transferases with oncogenic roles in haematological malignancies. In pre-clinical studies, CCS1477 was found to be a potent inhibitor of cell proliferation in acute myeloid leukaemia (AML) multiple myeloma (MM) and non-Hodgkin lymphoma (NHL) cell lines. In primary patient AML blast cells CCS1477 inhibited proliferation through a combination of cell cycle arrest at the G1/S transition and an induction of differentiation (up-regulation of CD11b and CD86). CCS1477 has significant anti-tumour activity, inducing tumour regressions in xenograft models of AML and MM. These effects were accompanied by significant reductions in tumour MYC and IRF4 expression. Additionally, there are molecular features of certain haematological malignancies that are likely to increase the sensitivity to p300/CBP inhibition with CCS1477. For example, in B-cell lymphomas there are frequent loss of function mutations in CBP that are associated with heightened sensitivity to pre-clinical inhibition of corresponding non-mutated p300. CCS1477 represents a novel and differentiated approach to inhibiting cell proliferation and survival and offers a potential new therapeutic option for patients who have relapsed or are refractory to current standard of care therapies in AML, MM or NHL. Study Design and Methods This study is the first time that CCS1477 is being dosed in patients with haematological malignancies. The Phase I/IIa study aims to determine the maximum tolerated dose (MTD) and/or recommended Phase II dose (RP2D) and schedule(s) of CCS1477 and investigate clinical activity of CCS1477 monotherapy in patients with haematological malignancies. This study will also characterise the pharmacokinetics (PK) of CCS1477 and explore potential biological activity by assessing pharmacodynamic and exploratory biomarkers. The trial aims to enrol approximately 90 patients and is currently recruiting in the UK with plans to open additional sites in the USA. Key inclusion criteria include patients with confirmed (per standard disease specific diagnostic criteria), relapsed or refractory haematological malignancies (AML, MM and NHL). Patients must have received standard therapy which for the majority of therapeutic indications is at least 2 prior lines of therapy. Single dose and steady state pharmacokinetics will be determined in all patients. AML response will be measured in bone marrow samples. Myeloma response will be evaluated according to the 'International Myeloma Working Group Response Criteria' based on changes in M protein in blood and/or urine, changes in serum free light chains if measurable, and changes on imaging and/or bone marrow if applicable and according to the guidelines. In NHL patients, tumour assessments will be done for measurable disease, non-measurable disease, and new lesions on CT (or magnetic resonance imaging [MRI]) and/or combined with visual assessment of [18F]2-fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) for response assessment per recent International Working Group consensus criteria (RECIL 2017), until progression The study will begin with two parallel monotherapy dose-escalation arms; Arm 1: Relapsed or refractory NHL and MM; Arm2: Relapsed or refractory AML/high-risk MDS. Once a recommended phase 2 dose/schedule is reached, three monotherapy expansion arms will be opened in AML/high-risk MDS (15 patients), MM (15 patients) and NHL (30 patients). Blood samples along with bone marrow biopsies and aspirates will be collected for exploratory biomarker analysis to understand mechanisms of response to treatment or disease progression. This will include the analysis of tumour-specific and circulating biomarkers, such as tumour DNA, mRNA, proteins or metabolites. In NHL patients, analysis of CBP (and p300) mutations will be undertaken to allow retrospective correlation with tumour response and to determine if loss of function mutations in the genes for either proteins can be utilised as response predictive biomarkers in future studies. Disclosures Clegg: CellCentric Ltd: Employment, Equity Ownership. Brooks:CellCentric Ltd: Employment, Equity Ownership. Ashby:CellCentric Ltd: Employment, Equity Ownership. Pegg:CellCentric Ltd: Employment, Equity Ownership. West:CellCentric Ltd: Employment, Equity Ownership. Somervaille:Novartis: Consultancy. Knapper:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Daiichi Sankyo: Honoraria; Jazz: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Tolero: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees. Davies:ADCT Therapeutics: Honoraria, Research Funding; MorphoSys AG: Honoraria, Membership on an entity's Board of Directors or advisory committees; BioInvent: Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Kite Pharma: Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Research Funding; Karyopharma: Membership on an entity's Board of Directors or advisory committees, Research Funding; Acerta Pharma: Honoraria, Research Funding; GSK: Research Funding; Pfizer: Honoraria, Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria, Research Funding; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Beschreibung: Background: Myelofibrosis (MF) is associated with bone marrow fibrosis (BMF), splenomegaly, a high symptom burden, and poor prognosis; the JAK/STAT pathway is the central pathway implicated in its pathogenesis. Ruxolitinib, a JAK1/2 inhibitor and the only FDA-approved pharmacotherapy for treatment (Tx) of MF patients (pts), improves splenomegaly, but is unable to control all clinical manifestations of disease. Navitoclax is an orally bioavailable, novel small-molecule that targets and binds with high affinity to multiple antiapoptotic B-cell lymphoma 2 (BCL2) family proteins, including BCL-XL, BCL2, and BCL-W. Preclinical studies have demonstrated cytotoxic activity of navitoclax against myeloproliferative neoplasm-derived cell lines. Herein, the results of a phase 2 study (NCT03222609) evaluating the combination of navitoclax with ruxolitinib in pts with MF are reported. Methods: This phase 2 single-arm, multicenter, open-label study assessed the efficacy and safety of navitoclax combined with ruxolitinib in pts with MF. Eligible pts (≥18 yr, diagnosis of primary MF, post-essential thrombocythemia [PET]-MF, or post-polycythemia vera [PPV]-MF, ECOG 0-2, receiving at least 12 wk of continuous ruxolitinib therapy prior to study Tx initiation) received a starting dose of 50 mg navitoclax once-daily combined with the current stable dose of ruxolitinib (≥10 mg BID). Weekly intra-patient dose-escalation of navitoclax was allowed to a maximum daily dose of 300 mg based on tolerability and platelet count. Tx continued until the end of clinical benefit, unacceptable toxicity, or discontinuation. The primary efficacy endpoint was percentage reduction in splenic volume from baseline. Secondary endpoints included effect on total symptom score (TSS), overall response rate, rate of anemia response, improvement in BMF, and safety profile. Results: As of May 1, 2019, 34 pts (primary MF, n=16; PET-MF, n=5; PPV-MF, n=13) had received ≥1 dose of navitoclax in combination with ruxolitinib. Median age was 68 yr (range 42-86), 68% were male, and 9 pts (26%) had ≥3 prior lines of MF therapy. The median duration of prior ruxolitinib exposure was 745 days (range 134-4549). Of the 34 pts enrolled, 27 (79%) had JAK2 and 7 pts (21%) had CALR mutations. There were no pts enrolled with triple-negative MF. Of 33 pts with available baseline testing, 17 (52%) had high molecular risk, defined by mutations within ASXL1, EZH2, IDH1/2, SRSF2, or U2AF1. The mean baseline platelet count was 231 x 109/L (range 99-706); mean baseline Hgb was 10.8 g/dL; 19 (56%) pts had elevated WBC at baseline (〉1.5× ULN). Maximal navitoclax dose of 300 mg was achieved in 23 pts (68%). Of the 25 (74%) pts that enrolled on ruxolitinib doses 〉10 mg BID, 22 (88%) subsequently had the dose of ruxolitinib reduced to 10 mg BID. At the time of this analysis, 24 pts were evaluable for efficacy, with 20 pts completing ≥24 wk on study and 4 pts with Tx discontinuations prior to 24 wk. At wk 24, 7 of 24 pts (29%) achieved a spleen volume reduction of ≥35% (SVR35) from baseline by MRI as determined by prespecified central review; the median TSS was 7.4 (range 0-23), a 20% improvement from baseline. A SVR35 at any time on study was achieved in 10 pts (42%). Reductions in driver mutation allelic burden of 〉5% were observed in 10 (42%) pts; 6 pts (25%) had BMF improvement of ≥1 grade. One pt (4%) had an anemia response; the mean Hgb at wk 24 was slightly improved over baseline at 11.3 g/dL. Of the 19 pts with elevated baseline WBC, 16 (84%) reduced to within normal limits during Tx, with a median WBC reduction of 17.7 × 109/L. All pts experienced a Tx-emergent adverse event (TEAE); most common (≥20%) were thrombocytopenia (82%), diarrhea (62%), fatigue (53%), anemia (27%), nausea (27%), contusion (24%), and vomiting (21%). Grade ≥3 TEAEs occurred in 26 pts (77%); most common were thrombocytopenia (n=15, 44%; Grade 4 n=1, 3%) and anemia (n=8, 24%; no Grade 4). Five pts (15%) experienced serious AEs that resolved including anemia, upper abdominal pain, vomiting, chest pain, increased C-reactive protein, and abnormal liver function test (3% each). There were no significant episodes of bleeding and no TEAE-related deaths. Conclusions: Navitoclax in combination with ruxolitinib was well tolerated with clinically meaningful spleen responses, allelic burden reductions, TSS improvements, and encouraging improvements in BMF in pts with MF who have received prior Tx with ruxolitinib. Disclosures Harrison: CTI: Speakers Bureau; Promedior: Honoraria; Roche: Honoraria; Celgene: Honoraria, Speakers Bureau; Gilead: Speakers Bureau; Shire: Speakers Bureau; Incyte: Speakers Bureau; Sierra Oncology: Honoraria; Janssen: Speakers Bureau. Garcia:Genentech: Research Funding; Abbvie: Research Funding. Mesa:CTI: Research Funding; Galena Biopharma: Consultancy; Samus: Research Funding; Genotech: Research Funding; AbbVie: Research Funding; NS Pharma: Research Funding; Baxalta: Consultancy; LaJolla: Consultancy; Shire: Honoraria; PharmaEssentia: Research Funding; Genentech: Consultancy; Celgene Corporation: Research Funding; AOP Orphan Pharmaceuticals: Honoraria, Other: travel, accommodations, expenses; Promedior: Research Funding; Novartis: Consultancy, Honoraria, Other: travel, accommodations, expenses; Incyte: Other: travel, accommodations, expenses, Research Funding; Gilead Sciences: Research Funding; Pfizer: Research Funding; Sierra Oncology: Consultancy. Somervaille:Novartis: Consultancy. Komrokji:pfizer: Consultancy; celgene: Consultancy; DSI: Consultancy; Incyte: Consultancy; Agios: Consultancy; JAZZ: Consultancy; Novartis: Speakers Bureau; JAZZ: Speakers Bureau. Pemmaraju:sagerstrong: Research Funding; celgene: Consultancy, Honoraria; Stemline Therapeutics: Consultancy, Honoraria, Research Funding; Daiichi-Sankyo: Research Funding; samus: Research Funding; novartis: Consultancy, Research Funding; plexxikon: Research Funding; incyte: Consultancy, Research Funding; abbvie: Consultancy, Honoraria, Research Funding; mustangbio: Consultancy, Research Funding; cellectis: Research Funding; affymetrix: Research Funding. Papadantonakis:Agios: Consultancy, Honoraria. Foran:Agios: Honoraria, Research Funding. O'Connell:Astex: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech: Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Shionogi: Membership on an entity's Board of Directors or advisory committees. Holes:AbbVie Inc: Employment, Other: Stock/stock options. Jia:AbbVie: Employment, Other: Stock/stock options. Harb:AbbVie Inc: Employment, Other: Stock/stock options. Hutti:AbbVie: Employment, Other: Stock/stock options.

Beschreibung: E1A binding protein (p300) and CREB binding protein (CBP) are two closely related histone acetyl transferases with oncogenic roles in acute myeloid leukaemia (AML) and multiple myeloma (MM). Here we describe the pre-clinical characterization of CCS1477, an orally bioavailable, potent and selective inhibitor of the bromodomain of p300/CBP and its therapeutic application in AML and MM. CCS1477 binds to p300 and CBP with high affinity (KD=1.3/1.7nM), and selectivity (e.g. KD=222nM; BRD4) in a surface plasmon resonance assay. It is a potent inhibitor of cell proliferation in a panel of 16 AML and 9 MM human cell lines. MM cells were particularly sensitive to CCS1477 with the majority of lines having a GI50 below 100nM. In stromal co-culture assays CCS1477 also inhibited proliferation of primary patient AML blast cells from a range of patients with a variety of molecular subtypes. These anti-proliferative effects were due to a combination of cell cycle arrest (with a decrease of cells in S-phase and an increase in cells in G1/G0) and induction of differentiation, as confirmed by up regulation of selected differentiation markers (e.g. CD11b & CD86) flow cytometric analyses. In xenograft models of AML (MOLM-16) and MM (OPM-2), daily oral dosing with CCS1477 as monotherapy, caused a dose-dependent reduction in tumour growth with regressions observed at the highest dose of 20mg/kg. After cessation of treatment with 20mg/kg CCS1477, there was sustained inhibition of tumour growth for approximately 11 days before re-growth began. The inhibition of tumour growth during drug treatment, was accompanied by significant reduction in tumour expression of MYC and IRF4 by qPCR in the OPM-2 model and in MYC expression in MOLM-16. The effects of CCS1477 were further evaluated in murine models by comparison with candidate standard of care regimens for AML & MM. In the MOLM-16 (AML) model, CCS1477 administered daily by oral gavage (10mg/kg) demonstrated superior tumour growth inhibition by comparison with azacitidine or cytarabine. There was also a significant combination benefit of CCS1477 when administered with these two agents in this model. In OPM-2 MM cells that are sensitive to lenalidomide, CCS1477 was a significantly more potent inhibitor of cell proliferation (GI50 = 5nM; CCS1477 vs. 100nM; lenalidomide). CCS1477 also retains exquisite anti-proliferative potency in MM cells that are either intrinsically resistant to lenalidomide (KMS-11 and RPMI 8226) or in OPM-2 cells that have developed resistance after long-term culture in lenalidomide. CCS1477 shows significant synergy when combined with lenalidomide in OPM-2 cells in vitro and also in an OPM-2 xenograft model in vivo. Significant combination benefit of CCS1477 with vorinostat or velcade is also observed in this xenograft model. These data support the clinical testing of CCS1477 in haematological malignancies, including MM and AML, with a strong pre-clinical rationale for use as monotherapy or in combination with standard of care agents, such as lenalidomide. CCS1477 is currently in Phase I/II clinical trials. Disclosures Brooks: CellCentric Ltd: Employment, Equity Ownership. Somervaille:Novartis: Consultancy. Pegg:CellCentric Ltd: Employment, Equity Ownership.