Advanced renal pelvis carcinoma patient with an ERBB2 insertion mutation: a case report.

The prognosis of renal pelvis cancer is poor and therapeutic options are limited, especially for patients with advanced disease. In this report, we present a case of advanced renal pelvis carcinoma in a male patient in his 60s, characterized by an activating mutation in ERBB2 . Clinical evaluation resulted in a pathological diagnosis of renal pelvis carcinoma with liver metastasis. Immunohistochemistry staining results suggested that CK, P63, and PAX8 were positively expressed, while Sy, CK7, CK20, S100, PAX8, and HEP1 were negatively expressed. Furthermore, next-generation sequencing results showed an activating mutation in the ERBB2 gene. The patient initially received a trastuzumab-based combination therapy, which led to a significant reduction in ERBB2 mutation frequency and a stable condition after three treatment cycles. However, following continuous treatment for 4 months, the patient developed drug resistance that resulted in disease relapse. Subsequently, the patient received apatinib treatment, but the therapeutic response was not satisfactory. The patient's condition underwent rapid deterioration and he ultimately succumbed to the disease. This case underscores the potential benefit of trastuzumab for treating ERBB2 -mutated advanced renal pelvis cancer, but further highlights that overcoming drug resistance remains a crucial challenge for long-term efficacy.