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SMARCA4 is a subunit of the switch/sucrose non‐fermentable (SWI/SNF) chromatin‐remodeling complex. An effective treatment for SMARCA4‐deficient non‐small cell lung carcinoma (NSCLC) has not yet been established. Correlations between a response to immune checkpoint inhibitors and the SWI/SNF complex have been suggested, but little is known about the efficacy of immune checkpoint inhibitors against SMARCA4‐deficient NSCLC. A 43‐year‐old man underwent left upper lobe lung resection and was diagnosed with SMARCA4‐deficient lung adenocarcinoma. Two months after surgery, multiple lung metastases appeared. Immunohistochemical analysis showed no PD‐L1 expression. Whole‐exon sequencing revealed a relatively high tumor mutation burden at 396. After the failure of three standard chemotherapy regimens, the patient was treated with nivolumab as fourth‐line treatment. An obvious reduction in the lung metastases was obtained for more than 14 months. We report the first case of SMARCA4‐deficient NSCLC with a high tumor mutation burden successfully treated with nivolumab. Anti‐PD‐1 antibodies might be a promising treatment strategy for patients with SMARCA4‐deficient NSCLC.

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Cryoprobe is a novel transbronchial biopsy (TBB) tool that yields larger tissue samples than forceps. Pathological diagnosis and biomarker analysis, such as genetic alterations and programmed death‐ligand 1 (PD‐L1) expression, are paramount for precision medicine against lung cancer. We evaluated the safety and usefulness of cryoprobe TBB for lung cancer diagnosis and biomarker analysis. In this single‐center, prospective single‐arm study, patients suspected of having or diagnosed with primary lung cancer underwent cryoprobe TBB using flexible bronchoscopy after conventional forceps TBB from the same lesion. Cryoprobe TBB was performed in 121 patients. The incidence rate of severe bleeding and serious adverse events (4% [90% confidence interval: 2%‐9%]) was significantly lower than the expected rate (20% with 30% threshold, P < 0.01). Combining both central and peripheral lesions, the diagnostic yield rate of cryoprobe samples was 76% and that of forceps samples was 84%. Compared with forceps TBB samples, cryoprobe TBB samples were larger (cryoprobe 15 mm 2 vs forceps 2 mm 2 ) and resulted in a larger proportion of definite histomorphological diagnosis (cryoprobe 86% vs forceps 74%, P < 0.01), larger amounts of DNA extracted from samples (median: cryoprobe, 1.60 µg vs forceps, 0.58 µg, P = 0.02) and RNA (median: cryoprobe, 0.62 µg vs forceps, 0.17 µg, P < 0.01) extracted from samples, and tended to yield greater rates of PD‐L1 expression >1% (51% vs 42%). In conclusion, cryoprobe is a safe and useful tool for obtaining lung cancer tissue samples of adequate size and quality, which allow morphological diagnosis and biomarker analysis for precision medicine against lung cancer.

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