280P - Personalized treatment approaches with HER2DX in early HER2-positive breast cancer: A precision tool for treatment decision-making

Background

HER2DX test is a genomic assay that evaluates the expression of 27 genes across four signatures (proliferation, luminal, immune and HER2 amplicon). The test provides prognostic (HER2DX risk score), predictive (HER2DX pathological complete response (pCR) score) information and levels of ERBB2 expression (ERBB2-score) in HER2+ early breast cancer (BC). We outline the preliminary results from the ongoing decision impact study of HER2DX at Valencia.

Methods

We conducted an observational, prospective, pilot, multicentric study involving 10 hospitals since Feb-23 (ongoing) to evaluate the clinical utility of HER2DX in early-stage HER2+ BC patients (pts). The main objective was to assess the % of change in the therapeutic plan after obtaining the HER2DX report.

Results

We analyzed the first consecutive 66 HER2DX tests performed. Median age was 54 years (range 28-79). The majority of pts were classified as stage II (66.7%), follow by stage I (19.7%), and stage III (13.6%). Luminal-HER2+ represented 66.7% of cases, and median ki67 was 30% (range 10-95%). Notably, 15.2% of test were conducted post-surgery. Among stage II, 50% of pts presented a high relapse risk, while, only 23.1% of stage I and 88.9% of stage III were considered high risk. A change in the treatment plan before and after the HER2DX result was observed in 27 of 66 (40.9%) cases, with 67.9% of the cases involving pts diagnosed at stage II. De-escalation of therapy was observed in 92.3% of pts (less poly-chemotherapy).

Conclusions

Our findings demonstrate the significant impact of HER2DX on clinical management decisions in early HER2+ BC, prompting oncologist to modify treatment strategies based on its results.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.