Combined Use of Gefitinib and Bevacizumab in Advanced Non-Small-Cell Lung Cancer with EGFR G719S/S768I Mutations and Acquired C797S Without T790M After Osimertinib: A Case Report and Literature Review.

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are effective in non-small-cell lung cancer (NSCLC) with sensitizing mutations. However, patients with uncommon EGFR mutations show variable responses, and resistance often develops. The C797S mutation is a common resistance mechanism after third-generation EGFR-TKI osimertinib therapy, with no standard treatment established. A 37-year-old Chinese woman with advanced NSCLC harboring EGFR G719S/S768I mutations developed an acquired C797S mutation without T790M after second- and third-generation EGFR-TKI therapy. She was treated with a combination of gefitinib and bevacizumab, achieving a partial response, particularly in liver metastases. Her overall survival exceeded 60 months. Gefitinib combined with bevacizumab demonstrates efficacy in managing NSCLC with uncommon EGFR mutations and overcoming acquired C797S resistance. This combination therapy offers a promising treatment strategy for patients with limited options after resistance to second- and third-generation EGFR-TKIs.