Efficacy and safety of inetetamab-containing regimens in patients with HER2-positive metastatic breast cancer in first-line/second-line setting.

BACKGROUND

Inetetamab is a novel recombinant humanized anti-Human epidermal growth factor receptor 2 (HER2) monoclonal antibody. This real-world retrospective study assessed the efficacy and safety of inetetamab-containing regimens in first-line/second-line treatment of HER2-positive metastatic breast cancer (MBC).

METHODS

This study retrospectively recruited HER2-positive MBC patients who received inetetamab- containing regimens from June 2020 to May 2023. The outcomes included progression-free survival (PFS), objective response rate (ORR), and disease control rate (DCR).

RESULTS

A total of 329 patients were enrolled and included in the efficacy analysis. The most frequently used treatment strategy was contained inetetamab plus pyrotinib (205/329, 62.3%). Patients treated with first-line regimens benefited the most, with a median PFS of 15.0 versus (vs.) 10.0 months (first-line- vs. second-line inetetamab plus pyrotinib, 0.001), 19.0 vs. 17.0 months (first-line- vs. second-line inetetamab plus pertuzumab, =0.096), and 13.0 vs. not reached months (first-line- vs. second-line inetetamab plus chemotherapy, =0.229). The complete response (CR) was observed in 16 (4.9%) patients of all cohort, with the ORR was 51.1% (95% confidence interval [CI], 45.7%-56.4%), and the DCR was 96.4% (95% CI, 93.7%-97.9%). The grade 3 or higher adverse events (AEs) were observed in 29.5% of the whole study cohort. Diarrhea (39.2%), white blood cell count decreased (33.0%), and myelosuppression (18.6%) as the most frequent ones.

CONCLUSIONS

Following the first- and second-line of treatment, inetetamab- containing combinations demonstrated promising clinical activity and a manageable safety profile in patients with HER2-positive MBC, especially in the first-line treatment.