Abstract 5737
Background
HER2 breast cancer status determines patients’ eligibility for targeted therapy. HER2 level of amplification is associated with a better response to anti-HER2 therapy. Benefit of anti-HER2 therapy for equivocal cases remains debated.
Methods
We aimed to better characterize HER2-equivocal breast cancers by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) according to 2018 ASCO/CAP guidelines using PAM50 gene expression-based molecular subtyping and to investigate genome-wide copy number alterations of these cases. PAM50 (nCounter assay; Nanostring) was performed on RNA from FFPE samples of 60 HER2-equivocal cases. These cases were subsequently analyzed by Agilent 60-mer oligonucleotide microarrays for array-based comparative genomic hybridization (aCGH).
Results
The 60 HER2-equivocal cases were classified as Luminal B in 31 cases (52%), HER2-Enriched in 14 cases (23%), Luminal A in 13 cases (22%) and Basal-like in 2 cases (3%) using PAM50. By IHC, 52 cases (87%) were ER+, 43 (72%) were also PgR+, 40 (67%) were grade III and 45 (75%) showed a high Ki67 > 20%. With aCGH, 23 cases (38%) presented chr 17q large copy number gain, 14 (23%) showed segmental copy number gain including HER2, 10 (17%) showed HER2 amplification, one (2%) showed a large copy number loss and 12 cases (20%) didn’t show any copy number alteration of the chr 17. Out of the 14 PAM50 HER2-Enriched cases, only 5 showed HER2 genomic amplification (Table). In total, 14 cases (23%) were discordant between molecular classification and genomic alteration status of the chr 17.Table:
260P
Genomic alterations of chromosome 17 | Basal- like | HER2- Enriched | Luminal A | Luminal B | Total |
---|---|---|---|---|---|
HER2 amplified | 0 | 5 | 2 | 3 | 10 |
Large copy number gain | 0 | 1 | 5 | 17 | 23 |
Segmental copy number gain | 2 | 5 | 4 | 3 | 14 |
No alteration | 0 | 3 | 2 | 7 | 12 |
Large copy number loss | 0 | 0 | 0 | 1 | 1 |
Total | 2 | 14 | 13 | 31 | 60 |
Conclusions
Using PAM50, the majority of HER2-equivocal cases were classified as Luminal tumors (Luminal B 52% and A 22%) and harbored mostly at the genomic level chr 17 segmental or large copy number gains. As there is no evidence of benefit of anti-HER2 therapy in these cases, it emphasizes the need of genomic status determination of HER2-equivocal cases.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Anne Vincent-Salomon.
Funding
Has not received any funding.
Disclosure
P. Morel: Full / Part-time employment: Nanostring. H.A. Brauer: Full / Part-time employment: Nanosting. A. Vincent-Salomon: Advisory / Consultancy, Consulting fees: Roche; Advisory / Consultancy, Consulting fees: AstraZeneca; Non-remunerated activity/ies, Contracted Research: Nanostring. All other authors have declared no conflicts of interest.
Resources from the same session
3191 - The efficacy and safety of lenvatinib in patients who did not meet the inclusion criteria of the phase 3 trial (REFLECT trial) and those with BCLC Stage B hepatocellular carcinoma - A nationwide multicenter study in Japan-
Presenter: Azusa Sakamoto
Session: Poster Display session 2
Resources:
Abstract
1529 - Prognostic and predictive value of baseline alpha-fetoprotein (AFP) in patients with advanced hepatocellular carcinoma (HCC) treated with ramucirumab from two phase 3 studies (REACH, REACH-2)
Presenter: Andrew Zhu
Session: Poster Display session 2
Resources:
Abstract
2767 - Effect of second-line cabozantinib on health states for patients with advanced hepatocellular carcinoma (aHCC) after sorafenib: QTWiST analysis from the CELESTIAL study
Presenter: Nicholas Freemantle
Session: Poster Display session 2
Resources:
Abstract
2150 - Alpha-fetoprotein (AFP) response in patients with unresectable hepatocellular carcinoma (HCC) in the phase 3 RESORCE trial
Presenter: Jordi Bruix
Session: Poster Display session 2
Resources:
Abstract
3437 - Phase I/II trial of NBTXR3 activated by SBRT in patients with hepatocellular carcinoma or liver metastasis
Presenter: Marc Pracht
Session: Poster Display session 2
Resources:
Abstract
1758 - Efficacy and safety of ramucirumab (RAM) for advanced hepatocellular carcinoma (HCC) with elevated alpha-fetoprotein (AFP) following first-line sorafenib across age subgroups in two global phase 3 trials (REACH and REACH-2)
Presenter: Masatoshi Kudo
Session: Poster Display session 2
Resources:
Abstract
1192 - Ramucirumab in patients with advanced hepatocellular carcinoma (HCC) and elevated alpha fetoprotein (AFP): An exposure–response analysis
Presenter: Josep Llovet
Session: Poster Display session 2
Resources:
Abstract
1600 - Outcomes of Hepatocellular Carcinoma (HCC) Patients Treated with Nivolumab: The Mount Sinai Hospital Experience.
Presenter: Sirish Dharmapuri
Session: Poster Display session 2
Resources:
Abstract
2364 - Pembrolizumab vs Chemotherapy in Patients With Advanced/Metastatic Adenocarcinoma (AC) or Squamous Cell Carcinoma (SCC) of the Esophagus as Second-Line Therapy: Analysis of the Chinese Subgroup in KEYNOTE-181
Presenter: Jia Chen
Session: Poster Display session 2
Resources:
Abstract
1933 - A national comparative effectiveness study to assess definitive chemoradiation regimens in proximal oesophageal squamous cell cancer
Presenter: Judith de Vos-Geelen
Session: Poster Display session 2
Resources:
Abstract