M. Fernández Abad (Madrid, Spain)
Hospital Universitario Ramon y CajalAuthor Of 1 Presentation
121P - Impact of HER2 Low (H2L) expression on prognosis in luminal locally advanced or metastatic breast cancer (BC): A retrospective study.
Abstract
Background
HER2 expression assessment is mandatory for the management of BC due to its predictive and prognosis value. So far, antiHER2 therapies only showed benefit in HER2 positive BC, rather, when immunohistochemistry (IHC) score 3+ and/or ERBB2 gene is amplified by ISH techniques. However, H2L expression (IHC score 1+ or 2+ without ERBB2 amplification) has gained value since the promising results of HER2-directed antibody-drug conjugates in that context. Our aim is to assess the potential prognostic value of H2L expression.
Methods
We performed a retrospective observational study in selected patients treated in our centre in 2012 - 2018. Inclusion criteria: irresectable locally advanced or metastatic BC, hormonal receptors expression, H2L or negative (score 0+). Exclusion criteria: incomplete information, antiHER2 therapy. Data about diagnosis and treatment were collected. Stata 14.0 was employed for statistical analyses.
Results
94 women were included, mean age 61 years. 75% BC were ductal, 100% with oestrogen receptor expression and 66% with progesterone positivity. HER2 expression scored 0+ in 27% of patients versus (vs) 73% H2L, of which 55% were 2+ and 45%, 1+. 67% were treated with hormonal-based therapies (HT) in the first line (1L) setting. Median of follow up and overall survival (OS) were 71.7 and 52 months, respectively. No statistically significant differences are observed between the HER2-low and HER2 0+ in OS (hazard ratio (HR) 1.09, confidence interval (CI) 0.61-1.93, p 0.78), neither are between score 1+ or 2+ (HR 1.16, CI 0.61-2.21, p 0.66). H2L BC does not show differences in progression-free survival (PFS) to 1L therapy (HR 1.43, CI 0.84-2.44, p 0.19), but PFS is worse in BC with HER2 score 2+ vs 1+ (HR 2.28, CI 1.22-4.24, p 0.010). This only remains significant in patients receiving HT (HR 2.04, CI 1.01-4.13, p 0.046).
Conclusions
H2L expression does not show a prognosis value but deeper research in the impact on 1L therapy efficacy will be promising. However, due to the retrospective design of the study, conclusions should be drawn with caution. Molecular profiles will provide more information about this subgroup of tumours, in the line of new investigations already opened.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
C. Saavedra Serrano: Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: Pfizer; Speaker Bureau/Expert testimony: Roche; Travel/Accommodation/Expenses: Ipsen; Travel/Accommodation/Expenses: Pierre Fabre. M. Gion Cortes: Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: Roche. M. Fernández Abad: Advisory/Consultancy: Daiichi. N. Martinez-Jañez: Advisory/Consultancy, Travel/Accommodation/Expenses: AstraZeneca; Advisory/Consultancy: Daiichi; Advisory/Consultancy, Travel/Accommodation/Expenses: Pfizer; Advisory/Consultancy, Travel/Accommodation/Expenses: Novartis; Advisory/Consultancy: Lilly; Advisory/Consultancy: Pierre Fabre; Advisory/Consultancy, Travel/Accommodation/Expenses: Roche; Advisory/Consultancy: GSK; Advisory/Consultancy: Seagen. M. Soriano: Travel/Accommodation/Expenses: MSD. E.M. Guerra: Advisory/Consultancy, Speaker Bureau/Expert testimony: AstraZeneca; Advisory/Consultancy, Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: GSK-Tesaro; Advisory/Consultancy, Speaker Bureau/Expert testimony: PharmaMar; Advisory/Consultancy, Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: Roche; Advisory/Consultancy: Clovis Oncology. E. Lopez Miranda: Advisory/Consultancy, Speaker Bureau/Expert testimony: AstraZeneca; Advisory/Consultancy, Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: Roche; Advisory/Consultancy, Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: Novartis; Advisory/Consultancy: Pfizer; Speaker Bureau/Expert testimony: Eisai. All other authors have declared no conflicts of interest.