433P - Effectiveness and safety of vinorelbine + inetetamab + pyrotinib in ≥second-line treatment of HER2-positive metastatic breast cancer

Background

In real-world settings, patients with HER2-positive metastatic breast cancer (MBC) who cannot receive antibody-drug conjugates (ADCs) as standard second-line regimen and who have no preferred regimen in ≥third line by NCCN guidelines, require new regimens to meet their clinical needs. This study aimed to explore the effectiveness and safety of vinorelbine + inetetamab + pyrotinib (VIP) for ≥second-line treatment of HER2-positive MBC.

Methods

Patients with HER2-positive MBC who received ≥second-line treatment at our hospital from June 2020 to December 2022 were enrolled. Progression-free survival (PFS), objective response rate (ORR), clinical benefit rate (CBR) and adverse reactions were assessed. Patients received VIP regimen until disease progression or unacceptable toxicity and were evaluated every two cycles according to the RECIST 1.1 criteria.

Results

Eight-nine patients were included based on the inclusion and exclusion criteria. Among them, 45 patients received second-line treatment who couldn’t use T-DM1 or T-DXd, and 44 patients received ≥third-line treatment. The median PFS of the second-line treatment subgroup was 17months, the ORR and CBR were 60.0% and 86.7%, respectively, which were significantly higher than those in the ≥third-line treatment subgroup and numerically superior to T-DM1 as a second-line treatment option. Additionally, the median PFS of patients with baseline brain metastasis who did not receive radiotherapy was 7 months, and ORR and CBR were 27.3% and 72.7%, respectively. The most common adverse events observed were leukopenia (37.1%), neutropenia (42.7%), anemia (34.8%) and diarrhea (67.4%). The incidence of grade 3-4 leukopenia, neutropenia, anemia and diarrhea were 11.2%, 15.7%, 5.6% and 27.0%, respectively. A total of 8 patients (8.9%) discontinued medication due to adverse reactions.

Conclusions

The VIP regimen demonstrated good efficacy and controllable toxicity as a second-line treatment for HER2-positive MBC. This therapeutic regimen provides a viable alternative option for patients who are unable to receive ADCs as the second-line treatment.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The author.

Funding

Has not received any funding.

Disclosure

The author has declared no conflicts of interest.