[Efficacy and safety of sacituzumab govitecan in patients with metastatic HR+/HER2- pleomorphic lobular breast cancer complicated by renal impairment.]

Abstract

The case concerns a 68-year-old female patient with metastatic HR-positive/HER2-negative pleomorphic lobular breast carcinoma and severe chronic renal impairment since diagnosis, previously treated with multiple lines of therapy. At diagnosis in September 2021, the disease was already metastatic, with bone, nodal, and pleural involvement. The patient received endocrine therapy with CDK4/6 inhibitors, chemotherapy, and targeted agents, with subsequent multiorgan progression. The clinical course was further complicated by persistent severe renal impairment requiring urinary diversion procedures prior to sacituzumab govitecan initiation. In November 2025, the patient experienced multiorgan progression and clinical deterioration (ECOG PS 2), including ascites, peripheral edema, dyspnea, and anorexia. Following multidisciplinary evaluation, sacituzumab govitecan was initiated in December 2025 at full dose (10 mg/kg), with primary prophylaxis using filgrastim. During the first cycle, worsening renal function and grade 2 toxicity occurred, leading to omission of day 8 administration. Treatment was subsequently resumed at a reduced dose (7.5 mg/kg), achieving good tolerability, stabilization of renal function, and clinical benefit. At reassessment in March 2026, a partial response was documented. The patient is currently continuing treatment with overall good tolerability. This case highlights the feasibility of a personalized approach with sacituzumab govitecan in frail patients with severe renal impairment and lobular breast cancer, populations underrepresented in clinical trials.