Treatment of advanced lung adenocarcinoma with EGFR L833V/H835L compound mutations using furmonertinib: two case reports and literature review.

Background: Lung cancer remains the leading cause of cancer-related mortality worldwide. With advancements in molecularly targeted therapies, Epidermal growth factor receptor (EGFR) mutations have emerged as critical therapeutic targets in advanced lung adenocarcinoma. However, the EGFR p.L833V/p.H835L compound mutations are relatively uncommon, and their clinical characteristics and therapeutic response to EGFR tyrosine kinase inhibitors (TKIs) remain poorly defined. Case presentation: This study reports two cases of advanced lung adenocarcinoma harboring the EGFR p.L833V/p.H835L compound mutation, both treated with furmonertinib. Case 1 was a 62-year-old male, and Case 2 was a 61-year-old female, both diagnosed through tissue biopsy and next-generation sequencing (NGS). Following treatment, both patients achieved partial response (PR), with progression-free survival (PFS) of 29 months and not available (NA, >12 months), respectively, demonstrating good tolerability. Results: Furmonertinib appears to be an effective treatment for advanced lung adenocarcinoma with EGFR p.L833V/p.H835L compound mutations. Conclusion: This study further supports the therapeutic potential of furmonertinib in EGFR-mutant lung cancer.