A case report of interstitial lung disease caused by HER2-positive breast cancer patient receiving two antibody-drug conjugate drugs successively.

Background: Comprehensive treatment of breast cancer includes surgery, radiotherapy, chemotherapy, endocrine therapy, targeted therapy and immunotherapy, and the means are extremely rich. In recent years, the antibody-drug conjugates (ADCs) have become one of the significant treatment drugs for patients with human epidermal growth factor receptor 2 (HER2)-positive. ADCs provides new treatment options, and it improves outcomes and quality of life for patients with HER2-positive advanced breast cancer. However, we need to pay special attention to the adverse events (AEs) caused by ADCs, such as gastrointestinal reactions, bone marrow suppression, and interstitial lung disease (ILD), etc. At present, clinicians are in the initial stage of understanding the AEs caused by ADCs, and there is no expert consensus for the treatment on the AEs caused by ADC. For example, ILD caused by ADCs.

Case Description: Here, we reported one case with HER2-positive advanced breast cancer. The patient was treated with ADCs of ARX-788 for third-line treatment, she had ILD. After treatment of ILD, the patient was treated with ADCs of trastuzumab-DM1 (T-DM1) for fourth-line treatment and she had ILD again. After suspension of such drugs, the patient's condition was stable without significant progress over 1 year.

Conclusions: For such patients, how to diagnose and treat them appropriately has become a new challenge for oncologists. Whether other anti-HER2 ADCs can be tried in the later lines is still being cautious. Whether there is a certain relationship between the side effects and efficacy of ADCs, there is no evidence-based data.