Updated data on real-world efficacy and safety of inetetamab-based therapy in HER2-positive metastatic breast cancer patients with prior exposure to trastuzumab

BackgroundUntil now there had been a lack of comprehensive data from extensive samples to assess the therapeutic potential of inetetamab (a novel recombinant humanized anti-HER2 monoclonal antibody) in metastatic breast cancer (MBC) patients who had previously received trastuzumab. This study aimed to provide a broad and in-depth analysis of the real-world efficacy and safety of inetetamab in the specific populations.MethodsA multicenter retrospective real-world study collected clinicopathological data from HER2-positive metastatic breast cancer patients (n = 500) between Jan 2022 and Oct 2023. Progression-free survival (PFS), objective response rate (ORR) and disease control rate (DCR) of patients who received inetetamab therapy were estimated. Adverse events (AEs) were classified based on the Common Terminology Criteria for Adverse Events.ResultsIn the overall cohort, the PFS was 7 months. The median number of treatment was three. The ORR was 28.6%, and the DCR was 89.2%. Meanwhile, patients who received a combination treatment regime of inetetamab + tyrosine kinase inhibitors (TKIs) + chemotherapy achieved the most prolonged PFS of 9.0 months and the higher ORR of 29.3%. Cox multivariate analysis revealed that PFS was associated with distant lymph nodes metastasis and previous TKIs treatment. The most common treatment-related AEs were neutropenia and leukopenia, which were generally well-tolerated.ConclusionsInetetamab demonstrated promising efficacy and safety in HER2-positive MBC patients who had prior exposure to trastuzumab, particularly in combination with TKIs and chemotherapy.Clinical trial identificationNCT06305702.Legal entity responsible for the studyThe authors.FundingHas not received any funding.DisclosureAll authors have declared no conflicts of interest.