Dacomitinib in Combination with chemotherapy is effective in lung adenocarcinoma with rare EGFR L747P mutation and bone metastases: a case report

BackgroundRare epidermal growth factor receptor (EGFR) mutations have a low incidence, and their response to EGFR tyrosine kinase inhibitors (TKI) has not been sufficiently studied. L747P is a rare EGFR mutation located in exon 19. Previous case reports have demonstrated the efficacy of dacomitinib for EGFR L747P mutation. This case report specifically investigates the therapeutic effects of dacomitinib in combination with chemotherapy for L747P mutation and bone metastases, with longer efficacy observation and deeper exploration of molecular mechanisms.Case DescriptionWe present the case of a 56-year-old female with lung adenocarcinoma and bone metastases. Next-generation sequencing (NGS) detected an EGFR L747P mutation. The patient initially received pemetrexed plus carboplatin chemotherapy. However, after three cycles, tumor markers continued to rise, pulmonary lesions showed insignificant regression, and bone metastases progressed. Dacomitinib was subsequently added to the treatment regimen. Tumor markers decreased one month after initiating combined therapy, and follow-up imaging at 2 and 6 months revealed regression of both pulmonary lesions and bone metastases. The patient achieved a progression-free survival (PFS) of 16 months. The treatment efficacy was evaluated as a partial response (PR), with manageable adverse events including skin rash and paronychia.ConclusionDacomitinib may provide sustained clinical benefit and an acceptable safety profile in lung adenocarcinoma patients with L747P mutation and bone metastases.