What happened, in summary

A woman in her early 70s had metastatic lung adenocarcinoma and had previously undergone left-lung surgery. She then received her first cycle of paclitaxel, carboplatin, and pembrolizumab. One week later, she was brought to the emergency department with altered mental status and concern for a stroke.

Her condition was immediately critical. She had severe low blood pressure, low blood sugar, acute kidney and liver failure, profound metabolic abnormalities, and imaging findings involving several organs. Her oncology team was concerned that pembrolizumab had triggered severe immune-related toxicity, although infection and stroke were also considered. High-dose intravenous steroids were started along with fluids, antibiotics, vasopressors, and intensive-care support.

Despite treatment, she remained in refractory shock with multiorgan failure. Because of her rapidly worsening condition and previously expressed preferences, her family chose end-of-life care. She died less than 12 hours after arriving at the hospital.

The clinical team considered a severe immune-related reaction to pembrolizumab the leading explanation for the abrupt multiorgan injury, but her rapid decline prevented a complete diagnostic workup. The case highlights how quickly life-threatening treatment toxicity can emerge after immunotherapy.