Displaying One Session

Valencia Auditorium (Hall 5) Proffered Paper session
Date
28.09.2019
Time
16:30 - 18:00
Location
Valencia Auditorium (Hall 5)
Chairs
  • Iain M. Hagan (Manchester, United Kingdom)
  • Thomas Helleday (Stockholm, Sweden)
Proffered Paper session - Basic Science Proffered Paper session

1O - Suppression of KRAS-G12D and BRAF-V600E oncogene transcription with PNA-conjugates (ID 861)

Presentation Number
1O
Lecture Time
16:30 - 16:42
Speakers
  • Jeffrey H. Rothman (New York, NY, United States of America)
Location
Valencia Auditorium (Hall 5), Fira Gran Via, Barcelona, Spain
Date
28.09.2019
Time
16:30 - 18:00

Abstract

Background

We have developed a strategy to block transcription of oncogenes such as BRAF V600E and KRAS G12D directly using modified complementary peptide nucleic acid (PNA) oligomers that target oncogenesis specifically causing inhibition of tumour growth. This proof of principle strategy against BRAF V600E and KRAS G12D in vitro and in vivo should provide a new means to develop PNA-delivery peptide conjugates as targeted drug therapeutics across a broad range of oncogenes that drive cancer cell growth.

Methods

Obstruction of KRAS G12D and BRAF V600E expression was evaluated through suppression of cell proliferation and specific mRNA transcription. Tumour reduction was assessed through Xenograft mouse models.

Results

Exposure of KRAS G12D-dependent cell line to modified PNA-peptide conjugate complementary to KRAS G12D mutation sequence also results in concentration-dependent and time-dependent inhibition of cell growth and specific and complete suppression in mRNA transcription. Cell lines expressing KRAS WT and KRAS G12C, both differing by a single nucleobase, show no suppression. Exposure of the melanoma cell lines to a modified PNA-peptide conjugate complementary to BRAF V600E mutation sequence results in a concentration-dependent and time-dependent inhibition of cell growth that is specific for the BRAF V600E mutant melanoma cell lines with inhibition of mRNA and protein expression. Xenograft mouse trials show tumour growth delay and necrosis compared to PNA controls. This 50mg/kg dose was well tolerated without associated weight loss. By H&E staining, tumor tissue from trials shows ablation and extensive scaring upon exposure to BRAF V600E-complementary PNA-peptide conjugate whereas saline and scramble PNA sequence controls do not. Similarly quantitative measurement shows a 2.5-fold decrease in Ki67 and a 3-fold increase in TUNEL expression.

Conclusions

Our results indicate that these PNA-peptide derivatives could represent a novel and promising new therapy for patients with genes specific for and causative of tumorigenesis. This strategy could be applied to a multitude of cancers either with specific translocations or mutations differing from wild-type cells even by only a single base pair.

Legal entity responsible for the study

The authors.

Funding

Celgene, Fortress Biotech.

Disclosure

All authors have declared no conflicts of interest.

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Proffered Paper session - Basic Science Proffered Paper session

2O - Strategic inhibition of CEP55 in aggressive breast cancer leads to mitotic catastrophe (ID 4714)

Presentation Number
2O
Lecture Time
16:42 - 16:54
Speakers
  • Debottam Sinha (Brisbane, Australia)
Location
Valencia Auditorium (Hall 5), Fira Gran Via, Barcelona, Spain
Date
28.09.2019
Time
16:30 - 18:00

Abstract

Background

Triple negative breast cancers (TNBCs), with negligible ER, PR expression and HER2 amplification are the most aggressive form of breast cancer (BC). Due to the high level of genomic instability, treatment of TNBC patients is one of the prevalent challenges faced in the clinics. CEP55, a key regulator of cytokinesis and its malfunction leads to multi-nucleation. The functional role of CEP55 is critically regulated via phosphorylation of CEP55 by ERK2/PLK1 at specific stages of mitosis, sanctioning it to localise to the midbody for accurate cytokinesis. Studies have demonstrated the association of CEP55 with multiple malignancies especially BC as over-expression of CEP55 mRNA is linked with worse BC prognosis and poor survival. We postulate that CEP55 dictates the fate of aneuploid cell population, which are heavily reliant on mitotic genes for tumour progression among aggressive BC, thus can be targeted for therapy development.

Methods

Using a series of in vitro studies in BC cell lines, we demonstrated that CEP55 depletion leads to unscheduled CDK1/Cyclin B activation and favour CDK1-Caspase 3-dependent mitotic catastrophe after sensitising cells to anti-mitotic drugs like PLK1 inhibitor (BI2536). We have demonstrated that CEP55 mRNA is transcriptionally controlled by ERK1/2 and to overcome lack of a specific small molecule inhibitor against CEP55, inhibition of MEK1/2 using the small molecule inhibitor selumetinib, can mimic depletion of CEP55 in vivo. Thus, we rationalised the usage of a MEK1/2 inhibitor to inhibit CEP55 in combination with anti-mitotic agent.

Results

We observed that compared to normal like and receptor-positive BC cell lines with lower CEP55 level, the aggressive hormone receptor negative cell lines with higher expression of CEP55 demonstrated robust synthetic lethality. Using xenograft models, we validated synergism of MEK1/2 and PLK1 inhibition, results of which imitated the in vitro findings.

Conclusions

Collectively, we propose a novel treatment strategy of MEK1/2 -PLK1 dual combination for selectively targeting CEP55 over-expressing BC in the clinics.

Legal entity responsible for the study

The author.

Funding

NHMRC.

Disclosure

The author has declared no conflicts of interest.

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Proffered Paper session - Basic Science Proffered Paper session

1981O - The m(6)A methyltransferase METTL3 promotes gastric cancer progression through facilitating primary microRNA maturation (ID 4136)

Presentation Number
1981O
Lecture Time
16:54 - 17:06
Speakers
  • Yiting Sun (Jinan, China)
Location
Valencia Auditorium (Hall 5), Fira Gran Via, Barcelona, Spain
Date
28.09.2019
Time
16:30 - 18:00

Abstract

Background

Gastric cancer is an aggressive disease that has substantial impacts on global health. N6-Methyladenosine (m6A) is an epigenetic modification on RNA that plays an important role in cancer progression. However, the biological roles of m6A and its regulators, such as METTL3, in gastric cancer, are unknown. The regulation of primary miRNA maturation by METTL3 in cancers is also unclear.

Methods

Levels of m(6)A and METTL3 were measured in paired clinical tissues in gastric cancer. The functions of METTL3 were determined by in vitro and in vivo studies. The RNA targets of METTL3 were screened by correlation studies in TCGA and confirmed in our cohorts. The METTL3-mediated primary miRNA-17-92 processing was verified by PCR and RNA-immunoprecipitation. The mTOR pathway was further studied as the downstream targets of miR-17-92 cluster by immunoblot and rescue study. Influences of METTL3 on the efficacy of Everolimus were tested in cell and animal models.

Results

The m6A level was upregulated in gastric cancer and prominently regulated by METTL3. Clinically, overexpression of METTL3 indicated poor prognosis and adverse pathological features. In cell and animal models, METTL3 promoted tumor growth and metastasis. Among the top seven METTL3-correlated miRNAs, six were derived from the primary miRNA pri-miR-17-92. METTL3 promoted m6A modification of pri-miR-17-92 on the A879 site, recruitment of DGCR8, and the subsequent processing into mature miRNAs. Pri-miR-17-92-derived miRNAs inhibited activation of the mTOR pathway by targeting PTEN and TMEM127. Forced expression of these miRNAs counteracted the anti-tumor and anti-mTOR effects by METTL3 knockout. In addition, METTL3 increased the sensitivity of gastric cancer to Everolimus.

Conclusions

The METTL3-mediated m6A modification on pri-miR-17-92 promotes gastric cancer progression through mTOR activation. The mechanism and function of m6A methylation modification of long non-coding RNA by METTL3 in gastric cancer was reported for the first time, which offers a novel point of view on the onco-regulating role of METTL3 in cancers and may provide a new therapeutic target for GC treatment.

Legal entity responsible for the study

The authors.

Funding

National Natural Science Foundation of China (81172487 to Lian Liu and 81500092 to Song Li), Natural Science Foundation of Shandong Province, China (ZR201702180008 to Lian Liu).

Disclosure

All authors have declared no conflicts of interest.

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Proffered Paper session - Basic Science Proffered Paper session

Invited Discussant 1O, 2O and 1981O (ID 6641)

Lecture Time
17:06 - 17:24
Speakers
  • Iain M. Hagan (Manchester, United Kingdom)
Location
Valencia Auditorium (Hall 5), Fira Gran Via, Barcelona, Spain
Date
28.09.2019
Time
16:30 - 18:00
Proffered Paper session - Basic Science Proffered Paper session

3O - Systemic gut microbial metabolites limit the anti-tumour effect of CTLA-4 blockade in hosts with cancer (ID 1203)

Presentation Number
3O
Lecture Time
17:24 - 17:36
Speakers
  • Clelia Coutzac (Paris, France)
Location
Valencia Auditorium (Hall 5), Fira Gran Via, Barcelona, Spain
Date
28.09.2019
Time
16:30 - 18:00

Abstract

Background

Gut microbiota composition might influence the clinical benefit of immune checkpoints in patients with advanced cancer but mechanisms underlying this relationship remained unclear. Molecular mechanism whereby the gut microbiota influences immune responses is mainly assigned to gut microbial metabolites. The main metabolites of the gut microbiota are short-chain fatty acids (SCFAs), which are produced in large amounts in the colon through bacterial fermentation of dietary fiber. We evaluated in mice and in patients treated with anti-CTLA-4 if SCFAs levels could be related to the clinical outcome.

Methods

Thirty-nine patients with metastatic melanoma were treated with ipilimumab were prospectively enrolled. Fecal microbiota composition was assessed using 16S metagenomic analysis and quantitative PCR (Q-PCR) analyses for Faecalibacterium prausnitzii (F. prausnitzii) at baseline. Stool and serum concentrations of acetate, propionate and butyrate were also evaluated in two independent cohorts in accordance with clinical outcomes. Peripheral blood lymphocytes immunophenotypes were studied in parallel. The anti-CTLA-4 anti-tumor effect was also evaluated in mice models in with or without butyrate supplementation.

Results

Systemic butyrate was linked to Faecalibacterium prausnitzii enrichment in the stool of patients. High blood SCFAs levels (mainly propionate or butyrate) were associated with resistance to CTLA-4 blockade and were associated with a rise of Treg cells. During the course of anti-CTLA-4 treatment, butyrate limited the up-regulation of CD80/CD86 expression on dendritic cells, the induction of tumor-specific T cells and the accumulation of memory T cells in mice with cancer. In patients, restricted accumulation of memory T cells and IL-2 impregnation after ipilimumab treatment was observed.

Conclusions

Altogether, these results suggested that gut microbial metabolites might favor an immune tolerance profile that limits anti-CTLA-4 activity.

Legal entity responsible for the study

Institut Gustave Roussy.

Funding

This study was funded by Gustave Roussy Cancer Campus, Fondation Gustave Roussy, the Institut national de la santé et de la recherche médicale (INSERM), the Centre national de la recherche scientifique (CNRS), SIRIC SOCRATE (INCa DGOS INSERM 6043), SIRIC SOCRATE 2.0 (INCa-DGOS-INSERM_12551), MMO program: ANR-10IBHU-0001); Direction General de l’Offre de Soins (DGOS; TRANSLA 12-174); Institut National du Cancer (INCa; 2012-062 N_ Canceropole: 2012-1-RT-14-IGR-01). Dr. Clélia Coutzac was supported by fellowships from Fondation pour la Recherche Medicale (FRM) from 2015 to 2016.

Disclosure

C. Coutzac: Honoraria (self): AMGEN; Honoraria (self): Servier. L. Lacroix: Advisory/Consultancy, Speaker Bureau/Expert testimony: Roche; Advisory/Consultancy, Speaker Bureau/Expert testimony: AstraZeneca; Advisory/Consultancy: BMS; Advisory/Consultancy: Genomic Health; Advisory/Consultancy: Illumina; Advisory/Consultancy: Qiagen; Advisory/Consultancy: Novartis Thermofisher; Speaker Bureau/Expert testimony: Amgen; Speaker Bureau/Expert testimony: Dyn; Speaker Bureau/Expert testimony: Vela diagnostics; Speaker Bureau/Expert testimony: Luye Pharma. F. Carbonnel: Advisory/Consultancy: enterome; Advisory/Consultancy: Amgen; Advisory/Consultancy: Astra; Advisory/Consultancy: MSD; Advisory/Consultancy: BMS; Advisory/Consultancy: Janssen; Advisory/Consultancy: Pfizer; Advisory/Consultancy: Abbvie; Advisory/Consultancy: Mayoly Spindler; Advisory/Consultancy: Takeda; Advisory/Consultancy: Pileje; Advisory/Consultancy: Roche. P.A. Ascierto: Advisory/Consultancy: Bristol Myers-Squibb; Advisory/Consultancy, Research grant/Funding (self): Roche-Genentech; Advisory/Consultancy: Merck Sharp & Dohme; Advisory/Consultancy, Research grant/Funding (self): Array; Advisory/Consultancy: Novartis; Advisory/Consultancy: Amgen; Advisory/Consultancy: Merck Serono; Advisory/Consultancy: Pierre Fabre; Advisory/Consultancy: Incyte; Advisory/Consultancy: NewLink Genetics; Advisory/Consultancy: Genmab; Advisory/Consultancy: Medimmune; Advisory/Consultancy: AstraZeneca; Advisory/Consultancy: Syndax; Advisory/Consultancy: SunPharma; Advisory/Consultancy: Sanofi; Advisory/Consultancy: Idera. C. Robert: Advisory/Consultancy: Roche; Advisory/Consultancy: GSK; Advisory/Consultancy: Merck Sharp & Dohme; Advisory/Consultancy: Novartis; Advisory/Consultancy: Amgen; Advisory/Consultancy: BMS. N. Chaput: Research grant/Funding (self): Cytune Pharma; Research grant/Funding (self): GSK; Speaker Bureau/Expert testimony, Research grant/Funding (self): Sanofi; Advisory/Consultancy, Speaker Bureau/Expert testimony: AstraZeneca. All other authors have declared no conflicts of interest.

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Proffered Paper session - Basic Science Proffered Paper session

4O - Novel dendritic cell based immunotherapy for advanced cancer (ID 5319)

Presentation Number
4O
Lecture Time
17:36 - 17:48
Speakers
  • Aanchal P. Kaur (Nottingham, United Kingdom)
Location
Valencia Auditorium (Hall 5), Fira Gran Via, Barcelona, Spain
Date
28.09.2019
Time
16:30 - 18:00

Abstract

Background

Immune-checkpoint inhibitors (ICI) such as Ipilumimab and Nivolumab have made long-term survival a real possibility for advanced cancer patients. Despite the success, only a proportion of patients receiving ICI show meaningful clinical benefit. Developing a more personalized treatment strategy using patient’s own immune cells may be a promising approach for treating non-responding patients. Natural circulating dendritic cells (nDC) such as CD1c+ DC (cDC2) subset and plasmacytoid DC (pDC) are essential for efficient activation of immune responses after ICI therapy. Thus understanding the condition of these cells in patients and devising new strategies to improve their functions may help improve response to ICI in advanced cancer patients.

Methods

To investigate this we measured the number and phenotype of nDC in 29 advanced cancer patients versus 21 age and gender-matched healthy controls using flow cytometry. We further identified that inhibition of the p38 MAPK pathway using small molecule inhibitors in cDC2 cells increases their immune-stimulatory capacity, measured by functional assays.

Results

The number of pDC were significantly reduced in cancer patients as compared to healthy controls (1221 vs 2843 pDC/mL) (p-value<0.01). Although the number of cDC2 were slightly reduced in cancer patients (4476 vs 5053 of cDC2/mL), a good proportion of patients had sufficient number of DC eligible for a DC-based immunotherapy. Patient cDC2 were immune-suppressed with low secretion of immune-stimulatory cytokines (IL-12) and impaired homing to lymph-nodes. We identified that the p38 MAPK signalling pathway was controlling immune-suppression in cDC2 cells. Inhibiting this pathway restored the secretion of IL-12 in all patients (n = 5), increased the homing of DC to lymph-node chemokines, and prevented them from secreting the immune-suppressive cytokine, IL-10.

Conclusions

The number and phenotype of nDC are suppressed in advanced cancer patients. Inhibition of p38 MAPK can restore the function of patient cDC2 subset. Co-culture of these p38-inhibited cDC2 with pDC further show promising results important for developing advanced DC vaccines. Our study has paved the way for a phase I clinical trial of adoptive transfer of p38-MAPK inhibited cDC2 in 24 advanced cancer patients.

Legal entity responsible for the study

University of Nottingham.

Funding

University of Nottingham.

Disclosure

All authors have declared no conflicts of interest.

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Proffered Paper session - Basic Science Proffered Paper session

Invited Discussant 3O and 4O (ID 6642)

Lecture Time
17:48 - 18:00
Speakers
  • Bertrand Routy (Montreal, Canada)
Location
Valencia Auditorium (Hall 5), Fira Gran Via, Barcelona, Spain
Date
28.09.2019
Time
16:30 - 18:00