The article describes the case of a 56-year-old never-smoker with metastatic lung adenocarcinoma and a specific mutation of EGFR exon 20 A767V769dup, with low expression of PD‑L1. The patient did not have access to the drug amivantamab at the time of diagnosis, so she received a high dose of osimertinib 160 mg once a day as a 1st line off-label. She achieved a sustained partial response on this treatment with mild grade 1 skin and nail adverse events without the need for dose reduction. After disease progression, after multidisciplinary discussion and with informed consent, she was switched to off-label furmonertinib 240 mg once daily, which led to further disease control. Sequential administration of high-dose osimertinib followed by furmonertinib resulted in an overall survival of approximately 37 months. The authors also performed a targeted narrative review and bibliometric analysis (CiteSpace, 2000–2023) from the Web of Science database, which showed growing global research on third-generation EGFR-TKIs and variant-specific strategies for EGFR exon 20 insertions. The article states that the described sequential strategy is not a standard treatment and generates a hypothesis that requires further prospective evaluation.