255P - Prognostic stratification capacity of the CPS+EG scoring system in HER2-low and HER2-zero early breast cancer treated with neoadjuvant chemotherapy

Background

CPS+EG scoring system properly defined prognosis subgroups of early breast cancer (eBC) patients (pts) treated with neoadjuvant chemotherapy (NACT) with a higher CPS+EG associated with worse outcomes. It remains unknown if CPS+EG similarly stratify prognostic in HER2-low and HER2-zero eBC patients after NACT.

Methods

This pluricenter french retrospective study included eBC pts treated with NACT from 2 cohorts, a monocenter local database at CGFL, Dijon and a pluricenter clinical trial PRIMUNEO (NCT01513408). Molecular features were determined on core biopsies. Threshold for HR positivity was ≥10%. HER2-low/zero status was defined by immunohistochemistry (IHC) HER2 staining. CPS+EG score was calculated for all pts with available data.

Results

608 patients with HER2-negative eBC that have received NACT were included. Median age at diagnosis was 51.0 y-o. Nearly all pts (98.2%) received >3 NACT cycles. In the overall population, 288 pts (47.4%) were HER2-low. More pts were HR+ than TNBC with 367 (60.3%) and 241 pts (39.7%), respectively. The majority of pts harboring HR+ disease were HER2-low (61.0%) contrary to TNBC eBC pts (26.5%). In the HER2-low and HER2-zero population, CPS+EG was able to well categorized pts within prognosis subgroups (log-rank p <0.0001). Table: 255P

In HR+/HER2-negative pts, CPS+EG still properly separated pts within prognosis subgroups between HER2-low and HER2-zero pts (log-rank p =0.0012 and p <0.0001, respectively). In TNBC population, CPS+EG appears to be less accurate. Within HR+ and TNBC molecular subtypes, there was no difference in 5-year DFS between HER2-low and HER2-zero pts harboring a similar CPS+EG score.

Conclusions

In this study, we show that the CPS+EG scoring system retains its interest for the prognostic stratification of pts treated with NACT for HER2-low and HER2-zero eBC. While it seems especially true for HR+ disease, CPS+EG appears to be less effective for TNBC in isolating different outcomes.

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.