Kidney damage as a rare side effect of durvalumab immunotherapy

What happened, in summary

An 84-year-old Japanese man was diagnosed with non-small cell lung cancer in August 2023. He received low-dose carboplatin with chest radiation, followed by consolidation durvalumab beginning in November. His lung-cancer burden decreased during treatment.

He had a short history of well-controlled type 2 diabetes and some protein in his urine before durvalumab. Four weeks after the immunotherapy began, the protein level increased sharply. By week 6, his blood albumin had fallen, durvalumab was stopped, and swelling developed in both legs. In January 2024, he was referred for further assessment. Testing confirmed nephrotic syndrome, with a urine protein-creatinine ratio of 13.57 g/gCr and a serum albumin level of 2.0 g/dL.

A kidney biopsy showed early membranous nephropathy. The findings did not look like advanced diabetic kidney disease, and the timing supported a probable immune-related effect of durvalumab. The cancer itself was shrinking, which also made a cancer-related kidney problem less likely.

Prednisolone 50 mg daily was started. The response was rapid: by day 13, 24-hour urine protein had fallen to 0.27 g/day, meeting criteria for complete kidney remission, while his blood albumin improved. The steroid was reduced to 30 mg without relapse and later tapered to 5 mg daily. Kidney remission remained stable during outpatient follow-up. Durvalumab was not restarted.

He had no diabetic eye disease, and the biopsy showed only mild diabetic-type changes. These details supported durvalumab, rather than diabetes, as the main cause of the sudden kidney injury.