What happened, in summary

This 56-year-old woman, a never-smoker with hypertension, came to the hospital in May 2022 after 1 month of cough and phlegm. Chest CT showed a right lower-lobe lung mass with cavitation, disseminated nodules in both lungs, and enlarged mediastinal and bilateral hilar lymph nodes. Neck ultrasound also found enlarged right supraclavicular and level 4 cervical lymph nodes. Brain MRI, bone scan, and abdominal/adrenal imaging did not show distant spread at diagnosis. Lung biopsy and cervical lymph-node biopsy supported lung adenocarcinoma, and the disease was staged as Stage IVA, T4N3M1a. Tumor sequencing found an EGFR exon 20 insertion, p.P772_H773insPHP, with high mutation abundance, along with TP53 p.Q192. PD-L1 testing was negative, with TPS and CPS both 0%. She began furmonertinib 160 mg daily in May 2022. At the first follow-up in July 2022, the lung mass and mediastinal nodes had decreased, meeting criteria for partial response. Further CT scans in September and November 2022, and again in 2023, showed ongoing response or stable disease, with only minor rash and mouth ulcers. In December 2023, the lung lesion grew slightly but remained stable enough for continued furmonertinib. In October 2024, headache led to discovery of a right cerebellar brain metastasis. She received stereotactic radiation, 30 Gy in 5 fractions, beginning October 25, 2024, while continuing furmonertinib. By December 2024, the brain lesion had decreased. As of April 2025, she continued to benefit from treatment, with 27 months of progression-free survival reported. No serious furmonertinib-related complications were described during long-term treatment and follow-up.