Innovent Biologics has announced that the first patient has been dosed in the phase III HeriCare-Breast01 trial evaluating IBI354, a HER2-targeted Antibody–Drug Conjugate (ADC), as a first-line treatment for patients with unresectable locally advanced or metastatic HER2-positive breast cancer.

HeriCare-Breast01 is a multicentre, randomised, open-label, active-controlled study assessing the safety and efficacy of IBI354, administered with or without pertuzumab, compared with the current standard-of-care regimen of paclitaxel plus trastuzumab and pertuzumab (THP). The primary endpoint of the study is Progression-Free Survival (PFS).

IBI354 is developed using Innovent’s proprietary SoloTx ADC platform and represents a next-generation HER2-targeted therapy designed to deliver high antitumour potency with a favourable safety profile. The company is also advancing a second pivotal phase III study, HeriCare-Ovarian01, evaluating IBI354 in ovarian cancer.

The phase III programme follows encouraging results from a multicentre phase I/II study involving 88 patients with HER2-positive breast cancer who had received a median of four prior treatment lines. As of March 24, 2025, the confirmed Objective Response Rate (cORR) was 59.1 percent, while the Disease Control Rate (DCR) reached 90.9 percent.

In the 9 mg/kg every three weeks (Q3W) cohort, objective response rate increased to 72.4 percent, with a disease control rate of 89.7 percent. With a median follow-up of 13.6 months, median progression-free survival in this dose group was 14.1 months. These findings were presented at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting.

The safety data from 368 patients in the phase I/II programme showed no dose-limiting toxicities up to 18 mg/kg. In the 9 mg/kg Q3W cohort, grade 3 or higher treatment-related adverse events (TRAEs) occurred in 21.0 percent of patients. TRAEs leading to dose interruption were reported in 9.9 percent of patients, while dose reduction and discontinuation were each observed in 1.2 percent of cases. No treatment-related deaths were reported. The most common TRAEs included decreased white blood cell count, nausea and anaemia. Interstitial lung disease was reported in 1.2 percent of patients, all grade 1.

Professor Binghe Xu, Principal Investigator of the HeriCare-Breast01 study at the Cancer Hospital, Chinese Academy of Medical Sciences, said that while the THP regimen has improved outcomes in first-line HER2-positive advanced breast cancer, challenges such as toxicity and tolerability remain. He noted that early clinical data suggest IBI354 may offer strong antitumour activity with reduced incidence of key adverse events, including interstitial lung disease, peripheral neuropathy and neutropenia, potentially expanding treatment access to a broader patient population.

Dr. Zhou Hui, Chief R&D Officer (Oncology) at Innovent, described the initiation of the pivotal trial as a significant milestone for the company’s ADC pipeline. He said early-stage results have validated the company’s SoloTx platform and highlighted the potential of IBI354 to become a new first-line option that balances durable efficacy with long-term tolerability.

Breast cancer remains one of the most common cancers among women globally, with approximately 1.3 million new diagnoses each year. Around 20 percent of cases are HER2-positive, a subtype associated with higher recurrence risk and poorer prognosis. While HER2-targeted therapies have transformed treatment outcomes, no HER2-directed ADC has yet received full approval for first-line treatment of advanced breast cancer in China.