Efficacy and safety of inetetamab in combination with chemotherapy as first-line treatment of HER2-positive metastatic breast cancer: a subgroup analysis in the HOPES study

Background: Our aim was to evaluate the efficacy and safety of inetetamab plus chemotherapy in the firstline treatment of HER2-positive metastatic breast cancer. Methods: A HOPES study was conducted on patients with HER2-positive metastatic breast cancer. Eligible patients were randomly divided into test group and control group at a 2:1 ratio. Among them, patients in test group received inetetamab plus vinorelbine. Concurrently, patients in the control group received vinorelbine. During the trial, safety evaluation was conducted every 4 weeks and efficacy evaluation was conducted every 8 weeks. As assessed by the Response Criteria Evaluation in Solid Tumors (RECIST) 1.0 criteria, the primary endpoint was progression-free survival (PFS) and the secondary endpoints included objective response rate (ORR) and disease control rate (DCR). Safety was estimated according to the National Cancer Institute Common Toxicity Criteria (NCI-CTC) version 2.0. Efficacy and safety of the postoperative recurrent-metastases first-line subgroup in the HOPES registry study of inetetamab was analyzed and compared with previous clinical studies of trastuzumab in the first-line treatment of HER2-positive metastatic breast cancer. Results: In total, we included 315 patients. Among them, 114 patients in the postoperative recurrent-metastases first-line subgroup were assigned to the full analysis set (FAS) (test group, 72; and control group, 42). The test group significantly prolonged median PFS (mPFS) (11.1 vs. 3.3 months of the control group; P<0.0001). ORR and DCR were remarkably higher than the control group (ORR, 61.5% vs. 29.7% with an increase of 31.8%, P=0.0224; DCR, 93.8% vs. 59.4% with an increase of 34.4%, P=0.0003). Efficacy and safety of postoperative recurrent-metastases first-line subgroup in the HOPES study was comparable to previous clinical studies of trastuzumab as first-line treatment of HER2-positive metastatic breast cancer. Conclusions: Inetetamab has shown efficacy and safety equivalent to trastuzumab for patients in the first-line treatment of postoperative recurrence-metastases HER2-positive breast cancer, which confirms its important status and potential as first-line treatment. Inetetamab provides more first-line targeted therapy options for patients with HER2-positive metastatic breast cancer.