Third-Generation TKI Resistance Due to SCLC Transformation: A Case Report and Brief Review

OBJECTIVE: We reported a case of pathologic type transformed from adenocarcinoma to small-cell lung cancer (SCLC) after being treated with third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI). MATERIALS AND METHODS: The lung cancer pathologic type was transformed from adenocarcinoma to SCLC after the treatment of third-generation EGFR-TKI for 4.3 months. Four times of lung biopsies were conducted at a different time and different lesions. And the patient was treated with a variety of regimens after SCLC transformation, including etoposide combined with carboplatin (EC), irinotecan combined with oxaliplatin (IO), Abraxane, and Apatinib. These treatments got a good response, but quick progression. We also monitored the dynamic change of serum neuron-specific enolase (NSE) and pro-gastrin releasing peptide (Pro-GRP). RESULTS: Adenocarcinoma could transform into SCLC after the treatment of TKI. Tumor cells were heterogeneity, so adenocarcinoma and SCLC could be co-existed. The fluctuation of the NSE was consistent with the response of treatment and the progression of the tumor. CONCLUSION: Regimens for the primary SCLC were also available for the transformed SCLC, but the duration of the response was short. NSE could be an effective biomarker for dynamic monitoring of the efficacy in SCLC transformation.