3011 - The potential of neratinib plus dasatinib in overcoming and preventing neratinib resistance in HER2-positive breast cancer models

Background

Neratinib (NER) is an irreversible pan-HER kinase inhibitor with demonstrated clinical activity for HER2-positive and HER2-mutated breast cancers (BC). Mechanisms of resistance to NER are poorly understood. The Src/Abl inhibitor dasatinib (DAS) has shown ability to overcome resistance to HER2-targeted agents such as lapatinib (LAP) and TRAS in vitro. This pre-clinical study investigated the efficacy of DAS in combination with NER to overcome or prevent NER resistance in BC models.

Methods

Anti-proliferative effects of NER, LAP, TRAS, DAS, and NER plus DAS were assessed in five NER-resistant HER2+ BC cell lines (HCC1954-N, HCC1569-N, EFM192A-N, BT474-N, and SKBR3-N) by acid phosphatase assay. IC₅₀values and Combination index (CI) values were calculated to determine synergy (CI < 0.8) using Calcusyn. Neratinib resistance was defined as an IC₅₀value > 150 nM NER. Apoptosis induction was assessed by Caspase 3/7-Glo assay. Reverse phase protein array was used to determine changes in key signalling pathways in HCC1954-N cells. BC cells were treated twice weekly with NER and/or DAS and crystal violet stained when confluent to examine resistance development.

Results

All NER resistant cell lines examined had significantly reduced response to NER (11-83 fold increase in IC₅₀values versus parental cells), as well as LAP and TRAS, compared to their parental cells.The combination of NER and DAS displayed synergy in all five NER resistant cell lines (CI = 0.1-0.6). NER plus DAS caused a strong induction of apoptosis in the HCC1954-N cells (p = 0.015). NER/DAS treatment caused changes in 23 phospho- or total protein levels, including suppression of Akt, MAPK, Src, p38 and AMPK signalling. NER alone (9 phospho- and 1 total proteins) and DAS alone (3 phospho- and 3 total proteins) altered fewer targets. The addition of DAS to NER prevented the emergence of NER resistance in parental HCC1954 and HCC1569 cells.

Conclusions

This study provides pre-clinical rationale for the combination of NER and DAS in NER-resistant HER2+ BC and shows that this combination warrants further investigation.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Puma Biotechnology.

Disclosure

N. Conlon: Research grant/Funding (institution): Puma Biotechnology. J. Crown: Full/Part-time employment: OncoMark; Honoraria (self), Advisory/Consultancy, Speaker Bureau/Expert testimony, Research grant/Funding (institution): Eisai; Honoraria (self): Amgen; Honoraria (self), Advisory/Consultancy, Research grant/Funding (institution): Puma Biotechnology; Honoraria (self): Seattle Genetics; Honoraria (self), Advisory/Consultancy, Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: Pfizer; Honoraria (self), Advisory/Consultancy: Vertex; Honoraria (self), Advisory/Consultancy, Research grant/Funding (institution), Travel/Accommodation/Expenses: Roche; Honoraria (self), Travel/Accommodation/Expenses: MSD Oncology; Travel/Accommodation/Expenses: AstraZeneca; Travel/Accommodation/Expenses: Abbvie; Honoraria (self), Advisory/Consultancy, Research grant/Funding (institution): Boehringer Ingelheim; Honoraria (self), Speaker Bureau/Expert testimony: Genomic Health. D.M. Collins: Research grant/Funding (institution): Puma Biotechnology; Research grant/Funding (institution): Roche. All other authors have declared no conflicts of interest.