427P - Pyrotinib plus trastuzumab versus pertuzumab plus trastuzumab in patients with HER2-positive metastatic breast cancer: A multicenter, retrospective study

Background

Pyrotinib has shown to be an effective antitumor agent in HER2-positive metastatic breast cancer (MBC). Pertuzumab, combined with trastuzumab and docetaxel, is the standard first-line dual anti-HER2 therapy for HER2-positive MBC. No direct comparison has been made between pyrotinib plus trastuzumab (PyroH) and pertuzumab plus trastuzumab (HP) in the treatment of HER2-positive MBC.

Methods

We retrospectively evaluated medical records for all patients with HER2-positive metastatic breast cancer who received PyroH plus chemotherapy or HP plus chemotherapy between 2017 and 2022 at five institutions in China. The primary endpoint was progression-free survival (PFS).

Results

This study included 333 patients, among which 161 received PyroH and 172 received HP. There was no significant difference between the two groups in either first-line or post second-line of systemic treatment (median PFS: 14.46 vs. 22.90 months, p=0.057; 8.67 vs. 7.92 months, p=0.286, respectively). Although HP group showed a significant longer PFS than PyroH group in the overall real-world setting (median PFS: 9.30 vs. 13.01 months, p=0.005), the treatment group is not an independent predictor of PFS in multivariate analysis (HR 1.134, 95% CI 0.710-1.811, p=0.598). PyroH demonstrated a longer PFS than HP when taxane was not utilized (median PFS: 10.12 vs. 8.15 months, p=0.017). In patients with brain metastases receiving first-line treatment, PyroH showed a potential advantage over the HP group, although this difference did not reach statistical significance (median PFS: 14.29 vs. 7.98 months, p=0.955). PyroH group had a higher incidence of grade 3/4 diarrhea (34.3% vs. 3.0%), but the overall incidence of adverse events did not differ between the two groups.

Conclusions

In real-world setting, although HP showed unshakable position when combined with taxane in first-line treatment, PyroH presented comparable effectiveness in post second-line treatment and patients with brain metastasis and even better efficacy in patients without combination of taxane. Toxicities in both groups were tolerable.

Clinical trial identification

NCT05572645.

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.