ESMO Congress 2023 | OncologyPRO

Abstract 255P

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

	CPS+EG HER2-low (n =288)	CPS+EG HER2-zero (n =320)
Score	5-year DFS rate (%) (95% CI)	5-year DFS rate (%) (95% CI)
0	100 (100-100)	100 (100-100)
1	92.9 (82.14-97.28)	86.11 (74.1-92.81)
2	71.95 (60.8-80.43)	86.8 (77.89-92.3)
3	69.78 (58.09-78.8)	72.5 (61.18-81.01)
4	48.03 (29.17-64.63)	55.48 (40.12-68.39)
5	38.1 (8.92-68.02)	30.77 (9.5-55.43)

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.