Furmonertinib in the treatment of de novo extensive-stage small cell lung cancer harboring an EGFR sensitive mutation:phenotypic analysis of a case
Objective:We investigated the efficacy of furmonertinib in the treatment of de novo small cell lung cancer (SCLC) carrying epi-dermal growth factor receptor (EGFR) sensitive mutations,and elucidated characteristics of the tumor genome,transcriptome,and immune microenvironment. Methods:We analyzed the case of a female patient initially diagnosed with extensive-stage SCLC who had an exon 19 deletion in her EGFR gene. The patient's disease progressed under first-line standard chemotherapy. She thus received the third-generation EGFR-TKI furmonertinib as her second-line treatment,achieving a partial response (PR) and 5-month progression-free survival. After furmon-ertinib treatment failed,a lung tumor biopsy was performed. Genomic,transcriptomic,and tumor immune microenvironment analyses were performed. Results:The histopathological diagnosis of SCLC was confirmed after progression on furmonertinib. Genetic testing of the treated tumor tissues showed that the patient carried an EGFR exon 19 deletion mutation. Transcriptome analysis revealed that the patient's transcriptional molecular subtype was SCLC-A. The tumor mutational burden,PD-L1 TPS,and density of tumor-infiltrating CD4+and CD8+T cells remained at a low level throughout the course of the disease,suggesting that the immune microenvironment was suppressive. Conclu-sions:Extensive-stage SCLC with EGFR-sensitive mutations exhibits a unique phenotype and tumor immune microenvironment. Furmon-ertinib could be an alternative second-line treatment for this type of tumor entity.