Furmonertinib Activity in NSCLC Harboring EGFR L858R and ERBB2 S310F Co-Mutations: A Case Report With Literature Review

While targeted therapies have remarkably transformed the landscape of lung adenocarcinoma (LUAD) management, the clinical implications of concurrent mutations in EGFR and ERBB2 remain inadequately understood due to their exceptional rarity in patients. This lack of understanding leads to significant uncertainty regarding therapeutic strategies for individuals with such co-mutations, as neither single-agent EGFR tyrosine kinase inhibitors (TKIs) nor HER2-targeted therapies have demonstrated established efficacy in this specific molecular context. Here, we present a compelling case involving a 61-year-old female patient diagnosed with advanced LUAD, with both EGFR L858R (exon 21) and ERBB2 S310F mutations identified through comprehensive next-generation sequencing. The patient received a treatment regimen consisting of the third-generation EGFR TKI furmonertinib, combined with localized radiotherapy, which resulted in a marked and significant clinical response. Our findings indicate that furmonertinib may effectively address the therapeutic uncertainties associated with EGFR/ERBB2 co-mutations, presenting a promising clinically actionable strategy while we continue to await the advent of more personalized and tailored treatment solutions.