Everolimus in acute kidney injury in a patient with breast cancer: a case report.

Introduction: Everolimus, a mammalian target of Rapamycin inhibitor, has recently been approved for the treatment of metastatic estrogen receptor-positive breast cancer, in combination with exemestane at a daily dose of 10mg. In the literature, few cases of acute kidney injury have been reported related to everolimus use, but none of them in a patient with breast cancer as we report here. Our case report of acute kidney injury demonstrates the potential nephrotoxic effects of everolimus therapy, necessitating close monitoring of renal function prior to, during and after discontinuation of the drug.

Case Presentation: We report the first published case of acute kidney injury shortly after initiation of exemestane and everolimus for metastatic breast cancer resistant to letrozole in a 69-year-old Caucasian woman, initially treated for a stage IIB estrogen receptor-positive breast cancer in 1997. Within 2 weeks of therapy, she developed grade 1 to 2 diarrhea, lower extremity edema, lethargy, and anorexia. After 4 weeks of therapy, her blood pressure was 85/59 mmHg and she lost 4 kg bodyweight. Her serum creatinine was 3.34 mg/dL. Everolimus was stopped, and she was hospitalized for rehydration. Her serum creatinine levels peaked at 8.85 mg/dL 8 days after treatment discontinuation, with a calculated creatinine clearance of 7 mL/minute. Dialysis was not required. A month later, her serum creatinine levels slowly dropped to 2.26 mg/dL but did not return to baseline. No re-challenge of everolimus was attempted.

Conclusions: Extreme vigilance should be used when prescribing everolimus for metastatic breast cancer. Although the exact cause of acute kidney injury in our case is unknown, dehydration must be avoided and renal function closely monitored after initiating therapy. Spontaneous recovery after drug discontinuation is possible.