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e-Posters

69P - HER2 status in RAS and BRAF wild-type metastatic colorectal cancer - Portuguese study

Date

06 Oct 2021

Session

e-Posters

Presenters

Maria Joao de Sousa

Citation

Annals of Oncology (2021) 32 (suppl_6): S1345-S1371. 10.1016/annonc/annonc740

Authors

M.J.P. de Sousa1, T. Fraga2, J. Correia Magalhães2, R. Basto2, J. Paulo2, P. Jacinto2, N. Bonito2, J.P. Magalhães2, P. Figueiredo2, G. Sousa2

Author affiliations

  • 1 Instituto Portugues Oncologia de Coimbra Francisco Gentil E. P. E. (IPO Coimbra), Coimbra/PT
  • 2 Instituto Portugues Oncologia de Coimbra Francisco Gentil E. P. E. (IPO Coimbra), 3000-075 - Coimbra/PT
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Abstract 69P

Background

Colorectal cancer (CRC) is the second most deadly cancer worldwide but currently there are few precision treatments available. Amplification/overexpression of HER2 (HER2+) is a well-established therapeutic target in breast and gastric cancer. HER2+ is present in approximately 5% of CRC and has been implicated in resistance to therapy with anti-epidermal growth factor receptor antibodies. The aim of our study was to evaluate HER2 status in RAS and BRAF wild-type metastatic CRC (mCRC) and its correlation with survival outcomes.

Methods

We performed a single-centre retrospective analysis of RAS and BRAF wild-type mCRC patients undergoing systemic treatment from July 2014 to September 2020. Tissue HER2 status was determined by performing immunohistochemistry (IHC) and/or fluorescence in situ hybridization (FISH) and/or chromogenic in situ hybridization (CISH). HER2+ was defined as either IHC3 (+) or IHC2 (+) through FISH or CISH (+).

Results

Fifty-nine patients were included. Four patients had HER2+ tumors (7%). The median age was 68 years (range 54-72). The majority of HER2+ mCRC occurred in males (n=3) and left-sided CRC (n=3). All patients received FOLFIRI plus Cetuximab as first-line treatment. At a median follow-up of 24.0 months, patients with HER2 negative mCRC presented with a median overall survival (OS) of 45.1 months (95% confidence interval [CI] 32.7-46.0). The four patients with HER2+ mCRC presented with an OS of 18.4 months, 20.4 months, 29.6 months, and 30.2 months.

Conclusions

To our knowledge, this is the first study reporting HER2+ in mCRC patients in a Portuguese population and the HER2+ rate was consistent with previous studies. Our study suggests that HER2+ may potentially be a marker that is able to predict poor prognosis in RAS and BRAF wild-type mCRC. There is potential that with the continued evolution of data in this area, HER2 may become a validated therapeutic target.

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.

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