Long-term benefit of afatinib combined with bevacizumab in a lung adenocarcinoma patient with a novel rare EGFR Q787L mutation

Background: The epidermal growth factor receptor (EGFR) is among the most frequently mutated genes in lung adenocarcinomas (LUAC). The combination of afatinib and bevacizumab has primarily been reported in LUAC cases exhibiting resistance to EGFR tyrosine kinase inhibitors (EGFR-TKI), particularly in classical variants such as EGFR exon 19 deletions and the L858R mutation in exon 21. However, the clinical efficacy of afatinib combined with bevacizumab in treating rare EGFR mutations remains underexplored. Case presentation: We present a case of T4N0M0 stage IIIA LUAC in which disease progression occurred following tumor resection and subsequent chemotherapy combined with bevacizumab. Next-generation sequencing of peripheral blood identified a novel and rare EGFR exon 20 Q787L mutation. Maintenance therapy with icotinib, a first-generation EGFR-TKI, combined with bevacizumab was initiated, but the patient developed resistance to icotinib after 8 months. No drug availability variants or acquired resistance-related mutations were detected. Subsequently, maintenance therapy with oral afatinib plus bevacizumab was initiated, resulting in partial remission after 3 months. As of the most recent CT scan in November 2023, the patient has achieved a progression-free survival (PFS) of 56 months on afatinib plus bevacizumab maintenance therapy, representing the longest reported duration to date, with no severe side effects observed. Conclusion: Our findings suggest that the combination of afatinib and bevacizumab may offer long-term clinical benefits for LUAC patients harboring the novel and rare EGFR Q787L mutation. This case highlights a potential therapeutic strategy warranting further investigation in clinical studies.