Dacomitinib overcomes afatinib-refractory carcinomatous meningitis in a lung cancer patient harbouring EGFR Ex.19 deletion and G724S mutation; a case report.

It has been reported that the efficacy of EGFR-TKI is predicted, not by which exon of the EGFR gene is mutated, but by the structural change in the EGFR protein due to the mutation. Here, we present an EGFR-mutated lung cancer patient with a 13-year history of anticancer treatment, in which EGFR ex.19 deletion (E746_S752 > V) and G724S mutations were detected by liquid biopsy during 12th line afatinib treatment, and switching to dacomitinib showed improvement of cancerous meningitis. We choose dacomitinib as 14th line chemotherapy based on ex.19 deletion and G724S mutant EGFR structure and its penetration rate to cerebral fluid, which successfully prolonged her life by 6 months. The optimal EGFR-TKI may be selected by understanding the EGFR compound mutation profile by next generation sequencing and predicting the effect based on the structure. Dacomitinib may be effective choice in afatinib-refractory carcinomatous meningitis harboring G724S mutation. This is the first case report showing that a change to dacomitinib responded to afatinib refractory cancerous meningitis.