What happened, in summary

A 72-year-old man was diagnosed with Stage III lung adenocarcinoma in 2018 after a persistent cough. He had surgery to remove the right upper lobe of his lung, followed by 4 cycles of chemotherapy and radiation. Testing showed high PD-L1 expression at 80%, while several common driver alterations were negative.

In May 2020, scans showed that the cancer had spread to the brain and liver, making it Stage IV. The brain lesion was treated with focused radiation, and pembrolizumab immunotherapy started several months later. Within about 10 weeks, both the brain and liver disease showed a sustained partial response.

After 10 cycles of pembrolizumab, he developed severe high blood sugar and was diagnosed with immunotherapy-related diabetes. He required insulin and remained permanently insulin-dependent. Because of his age and the risk of further metabolic complications, pembrolizumab was stopped.

The cancer remained controlled for several years without further systemic treatment. In December 2025, a new brain lesion appeared and was treated with focused radiation. He remained clinically stable under oncology and endocrinology follow-up.