Abstract
The histological transformation from lung squamous cell carcinoma (LUSC) to lung adenocarcinoma (LUAD) and p. N771delinsGF mutations in EGFR exon 20 (ex20) are exceedingly rare in non–small cell lung carcinoma (NSCLC). EGFR ex20 mutations are insensitive to EGFR tyrosine kinase inhibitors in NSCLC. Here, we present a 76-year-old male smoker harboring LUAD with a novel p. N771delinsGF deletion/insertion mutation in EGFR ex20 transdifferentiating from advanced LUSC after chemoradiotherapy. The patient presented reduced hydrothorax and relieved tightness with the treatment of nivolumab plus docetaxel and carboplatin after the failure of second-line chemotherapy. The case highlights the importance of rebiopsy and molecular retesting after the progression of lung cancer and supports the idea that the combination of immune checkpoint blockade and chemotherapy may be an attractive option for patients with EGFR ex20 mutations associated with LUSC–LUAD transformation.
Highlights
Lung cancer has the highest lethality rate among all cancers
We report a patient who was initially diagnosed with lung squamous cell carcinoma (LUSC) and was found to have lung adenocarcinoma (LUAD) cells in the pleural effusion after chemotherapy resistance
One explanation for this is that the LUAD cells may have arisen from an original LUAD component of adenosquamous carcinomas (ASCs) in our case
Summary
Lung cancer has the highest lethality rate among all cancers. Non–small cell lung carcinoma (NSCLC) is a major subtype of lung cancer, accounting for 85% of lung cancer cases, including lung adenocarcinoma (LUAD), lung squamous cell carcinoma (LUSC), and large cell carcinoma histologic subtypes. The immunohistochemistry of pulmonary biopsy samples was positive for PCK, P40, CK7, CK5/ 6, and PD-L1 (40%) and was negative for TTF1 Genetic abnormalities such as amplification of CCDN1, CCDN2, FGF19, FGF3, FGF4, FGFR1, KRAS, and PIK3CA; ex missense mutation of CDKN2A; and ex code-shift mutation of TP53 were observed in the primary lung cancer lesion by using next-generation sequencing (NGS; 520-gene panel, Oncoscreen plus, Burning Rock Biotech, Guangzhou, China). From July to December 2019, the patient was treated with six cycles of paclitaxel plus cisplatin chemotherapy and subsequent radiotherapy (60 Gy/30 fractions at 2 Gy per day) He experienced an initial partial response with a decrease in tumor size (from 8.5 × 9.6 × 10.4 cm to unmeasurable). During the whole process of treatment with immunochemotherapy, the patient experienced no severe side effects
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