What happened, in summary

An 82-year-old Japanese woman who had never smoked was diagnosed with Stage IVB lung adenocarcinoma, cT4N2M1c, with an EGFR exon 19 deletion. She started first-line osimertinib 80 mg daily, but after only 7 days she developed grade 3 osimertinib-induced interstitial lung disease. CT showed a diffuse alveolar damage pattern, and she needed oxygen up to 4 L by nasal cannula. Osimertinib was stopped. Her lung injury was treated with methylprednisolone 1000 mg for 3 days, followed by prednisolone 50 mg daily. While prednisolone was being tapered, the cancer worsened as cancerous lymphangiopathy progressed. Once the prednisolone dose reached 15 mg daily, her team started gefitinib 250 mg daily as second-line EGFR-targeted treatment because osimertinib could not be continued. Specific distant metastatic organs were not named for this patient. As of August 2024, she was continuing gefitinib without recurrence of interstitial lung disease. Prednisolone had been tapered to 5 mg daily and was also ongoing. The case highlights careful rechallenge with a different EGFR inhibitor after severe osimertinib lung toxicity, but it does not report a clear tumor response duration for this individual patient. The broader article included 6 patients treated with gefitinib after osimertinib-related lung injury; this story focuses on Case 2 only. Steroid tapering was part of the toxicity management, not a cancer-directed treatment line.