Abstract 1674
Background
Triple negative breast cancer (TNBC) is an incurable disease, therefore novel therapies are needed. Bromo and extraterminal domain inhibitors (BETi) are currently in clinical development with promising activity in TNBC. However, resistance to these agents will limit their efficacy. Proteolysis targeting chimeric (PROTAC) are novel compounds that by binding to a ubiquitin ligase promotes protein degradation.
Methods
In our study we explore the antitumoral activity of two BET-PROTACs, MZ1 and ARV-825 in TNBC and ovarian cancer. We used MDAMB-231, BT549 and MDAMB-231 JQ1 resistant TNBC cells lines; and OVCAR3 and SKOV3 ovarian cancer cells lines. We evaluated the antiproliferation effect using MTT assay, colony-forming assay and three-dimensional cultures in Matrigel. To explore the molecular mechanism of drugs we used flow cytometry (cell cycle and cell death). The analysis of protein expression was determined by western blot. In vivo studies included BALB/c nu/nu mice that were injected with MDAMB-231 JQ1 resistant cells and later treated with BETi JQ1 and BET-PROTAC MZ1.
Results
Both PROTACs efficiently and maintained deleted the levels of BRD4 in MDA-MB-231 and in the resistant JQ1 cell line MDA-MB-231R. MZ1 and ARV-825 showed a profound antiproliferative effect in MDA-MD-231 sensitive and resistant cells using 2D and 3D cultures, and had a similar activity in other triple negative (BT549) and ovarian cancer (SKOV3, OVCAR) cell lines. MZ1 slightly arrested cells at G2/M in sensitive and resistant JQ1 MDA-MB-231 cells. In addition, a profound effect on apoptosis was observed, that was more evident in the sensitive cell line, effect that was caspase dependent. Given the potent antiproliferative activity of MZ1 no synergistic activity was observed when combined with docetaxel, cisplation or olaparib. Finally, administration of MZ1 was able to recue tumor growth in nude mice of MDA-MB-231 JQ1 resistant cells, by reducing the expression of BRD4.
Conclusions
We describe the profound activity of BET-PROTACs in TNBC cell lines and in an in vivo BETi resistant model. This data provides options for further clinical development of these agents in TNBC.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Instituto de Salud Carlos III (PI16/01121), ACEPAIN; Diputación de Albacete, CIBERONC, CRIS Cancer Foundation, implementation research program of the UCLM System of Science, Technology and Innovation-Secti (co-funded by the European Commission/FSE funds) and scientific foundation of the AECC.
Disclosure
All authors have declared no conflicts of interest.
Resources from the same session
2860 - Prognostic value of metabolic response assessed by 18FDG-PET after induction chemotherapy and after chemoradiotherapy (CRT) in localized esophageal squamous cell carcinoma (ESCC) patients (pts) receiving definite CRT (dCRT)
Presenter: Yeonghak Bang
Session: Poster Display session 2
Resources:
Abstract
3881 - Comprehensive genomic profiling of early-stage esophageal squamous cell carcinoma
Presenter: Jing Zuo
Session: Poster Display session 2
Resources:
Abstract
3944 - A novel nomogram and risk classification system predicting radiation pneumonitis in patients with esophageal cancer receiving radiotherapy
Presenter: Lu Wang
Session: Poster Display session 2
Resources:
Abstract
1956 - Drinking alcohol, smoking, multiple dysplastic lesions and the risk of field cancerization of squamous cell carcinoma in the esophagus and head and neck region
Presenter: Chikatoshi Katada
Session: Poster Display session 2
Resources:
Abstract
2144 - Neoadjuvant chemotherapy can eliminate the negative impact of postoperative infectious complications on recurrence in patients with esophageal cancer
Presenter: Kazuki Kano
Session: Poster Display session 2
Resources:
Abstract
2403 - Comparison of chemoradiotherapy (CRT) followed by consolidation with cisplatin and 5-fluorouracil (CF) versus definitive CRT with carboplatin and paclitaxel (CP) in esophageal cancer
Presenter: Marcelle Cesca
Session: Poster Display session 2
Resources:
Abstract
3247 - Paclitaxel in Combination with Cisplatin and 5-fluorouracil(TPF) Induction Chemotherapy for Locally Advanced Borderline-resectable Esophageal Squamous cell Carcinoma: A Phase II Clinical Trial
Presenter: Yuhong Li
Session: Poster Display session 2
Resources:
Abstract
4293 - Prognosis of esophageal squamous cell carcinoma based on local immunity evaluation
Presenter: Elena Zlatnik
Session: Poster Display session 2
Resources:
Abstract
5419 - Impact of Sarcopenia and adiposity in survival of metastatic esophageal cancer (MEC)
Presenter: Aline Fares
Session: Poster Display session 2
Resources:
Abstract
2083 - PALAESTRA - A phase II trial with short-course radiotherapy followed by chemotherapy as palliative treatment in esophageal adenocarcinoma
Presenter: David Borg
Session: Poster Display session 2
Resources:
Abstract