MDM2 Inhibition in Combination with Endocrine Therapy and CDK4/6 Inhibition for the Treatment of ER-Positive Breast Cancer

Abstract Background Resistance to endocrine therapy is a major clinical challenge in the management of estrogen receptor (ER)-positive breast cancer. In this setting p53 is frequently wildtype and its activity may be suppressed via upregulation of its key regulator MDM2. This underlies our rationale to evaluate MDM2 inhibition as a therapeutic strategy in treatment resistant ER-positive breast cancer.Methods We used the MDM2 inhibitor NVP-CGM097 to treatin vitroandin vivomodels alone and in combination with fulvestrant or palbociclib. We perform cell viability, cell cycle, apoptosis and senescence assays to evaluate antitumor effects in p53 wildtype and p53 mutant ER positive cell lines (MCF-7, ZR75-1, T-47D) and MCF-7 lines resistant to endocrine therapy and to CDK4/6 inhibition. We further assess the drug effects in patient-derived xenograft (PDX) models of endocrine-sensitive and -resistant ER positive breast cancer.Results We demonstrate that MDM2 inhibition results in cell cycle arrest and increased apoptosis in p53-wildtypein vitroandin vivobreast cancer models, leading to potent anti-tumour activity. We find that endocrine therapy or CDK4/6 inhibition synergises with MDM2 inhibition but does not further enhance apoptosis. Instead, combination treatments result in profound regulation of cell cycle-related transcriptional programmes, with synergy achieved through increased antagonism of cell cycle progression. Combination therapy pushes cell lines resistant to fulvestrant or palbociclib to become senescent and significantly reduces tumour growth in a fulvestrant resistant patient derived xenograft model.Conclusions We conclude that MDM2 inhibitors in combination with ER degraders or CDK4/6 inhibitors represent a rational strategy for treating advanced, endocrine resistant ER-positive breast cancer, operating through synergistic activation of cell cycle co-regulatory programs..

Medienart:

Preprint

Erscheinungsjahr:

2021

Erschienen:

2021

Enthalten in:

bioRxiv.org - (2021) vom: 20. März Zur Gesamtaufnahme - year:2021

Sprache:

Englisch

Beteiligte Personen:

Portman, Neil [VerfasserIn]
Milioli, Heloisa H. [VerfasserIn]
Alexandrou, Sarah [VerfasserIn]
Coulson, Rhiannon [VerfasserIn]
Yong, Aliza [VerfasserIn]
Fernandez, Kristine J. [VerfasserIn]
Chia, Kee Ming [VerfasserIn]
Segara, Davendra [VerfasserIn]
Parker, Andrew [VerfasserIn]
Haupt, Sue [VerfasserIn]
Haupt, Ygal [VerfasserIn]
Tilley, Wayne D. [VerfasserIn]
Swarbrick, Alex [VerfasserIn]
Caldon, C. Elizabeth [VerfasserIn]
Lim, Elgene [VerfasserIn]

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doi:

10.1101/2020.06.09.140921

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

XBI018123554