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William J. Gradishar, MD, FACP, FASCO


Antibody-Drug Conjugate ARX788 Under Study in HER2-Positive Breast Cancer

By: Chris Schimpf, BS
Posted: Wednesday, July 3, 2024

The site-specific antibody-drug conjugate ARX788 significantly prolonged progression-free survival compared with lapatinib plus capecitabine in patients with HER2-positive advanced breast cancer who were previously treated with trastuzumab and a taxane, according to research presented at the 2024 American Society for Clinical Oncology (ASCO) Annual Meeting (Abstract 1020). Xichun Hu, MD, PhD, of Fudan University Shanghai Cancer Center, and colleagues reported interim results of the phase II/III ACE-Breast-02 trial, noting ocular toxicity and interstitial lung disease were common and manageable among participants and gastrointestinal toxicities compared favorably with already available antibody-drug conjugates.

A total of 441 patients with unresectable or metastatic breast cancer previously treated with trastuzumab and a taxane were included in the multicenter study. Participants were randomly assigned to receive ARX788 (n = 221) or lapatinib plus capecitabine (n = 220), stratified by previous chemotherapy lines and visceral metastasis. The investigators noted that ARX788 was not premedicated with any prophylactic measures.

The researchers reported a median progression-free survival of 11.33 months with ARX788 vs 8.25 months with lapatinib plus capecitabine (hazard ratio [HR] = 0.64; P = .0006). They observed treatment-related adverse events of any grade in 98.6% and 99.1% of participants, respectively, and noted rates of grades 3 to 5 were similar in both groups (41.4% and 40.0%, respectively). Most common among patients who received ARX788 were blurred vision (12.3%), dry eye (9.1%), keratopathy (5.9%), and interstitial lung disease (5.9%), with hand-foot syndrome (18.1%), hypokalemia (5.1%), and diarrhea (4.2%) most common among those who received lapatinib plus capecitabine. Interstitial lung disease was reported in 32.3% of participants who received ARX788, with 1.4% possibly having drug-related deaths. Finally, ocular events were reported in 74.5% of those who received ARX788—primarily grade 1 or 2 (55.5%) with no grade 4 or 5.

Disclosure: The study authors reported no conflicts of interest.

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