Yu Inutsuka

BACKGROUND: Despite an initial favorable response of EGFR-mutant non-small cell lung cancer (NSCLC) to osimertinib, an EGFR tyrosine kinase inhibitor (TKI), resistance to this drug inevitably develops. Whereas genetic mechanisms for such acquired resistance have been identified, the molecular mediators of resistance induction have remained unclear. METHODS: To identify factors that mediate induction of osimertinib resistance, we studied clinical samples from individuals with EGFR-mutant NSCLC as well as cell lines including PC-9 and H1975. Methods adopted included transcriptomics analysis and immunohistochemistry of pretreatment NSCLC specimens, spatial transcriptomics analysis, a cell viability assay, immunofluorescence and quantitative PCR analysis, RNA sequencing, immunoblot analysis, comprehensive proteomics analysis by mass spectrometry, co-immunoprecipitation and proximity ligation assays, and a mouse xenograft tumor model. RESULTS: Transcriptomics analysis of pretreatment clinical specimens identified IFITM3 (interferon-induced transmembrane protein 3) as a gene specifically upregulated in patients with a poor response to osimertinib treatment. Immunohistochemistry confirmed that patients with IFITM3-positive tumors experienced a shorter progression-free survival on osimertinib treatment. Spatial transcriptomics and other analyses further revealed that IFITM3 expression in tumor cells was increased in response to cytokines derived from the tumor microenvironment (TME) during osimertinib treatment. IFITM3 was found to promote the development of osimertinib resistance in NSCLC cell lines through interaction with MET and activation of the AKT signaling pathway. Furthermore, combined treatment with a MET inhibitor suppressed the development of osimertinib resistance in a mouse xenograft tumor model. CONCLUSIONS: Our findings reveal that upregulation of IFITM3 driven by TME cytokines represents a previously unrecognized mechanism of osimertinib resistance, and they suggest that targeting of the IFITM3-MET axis may improve EGFR-TKI treatment outcome for EGFR-mutant NSCLC.

We describe the case of a 60-year-old Japanese man with relapsing polychondritis (RP). The patient was referred to Hamanomachi Hospital due to mild elevation of C-reactive protein and mild anemia on medical checkup without any symptoms. Body CT imaging showed thickened tracheal and bronchial walls with no active lesions in the lung. Precise physical examination revealed swelling in both ears. Bronchoscopy revealed redness and swelling of the tracheal and bronchial mucosa in the membranous lesion. Histologic examination of the bronchial biopsy showed inflammatory cell infiltration in the sub-mucosa with no vasculitis. Serum anti-type 2 collagen antibodies were found to be positive (33.9 EU/mL). Corticosteroid treatment improved his tracheochondritis. It is challenging to diagnose RP in the early stage due to its rarity and nonspecific symptoms. Airway involvement in RP is irreversible and the major cause of morbidity and mortality; hence, early recognition of airway involvement and treatment is warranted.

We present a case of a 54-year-old Japanese woman with established human T-lymphotropic virus type 1 (HTLV-1)-associated myelopathy who developed a refractory infected lung bulla and lung abscess caused by Pseudomonas aeruginosa, Methicillin-resistant Staphylococcus aureus, and Aspergillus species. Since antibiotic treatment alone failed to resolve the infection, percutaneous drainage of the infected bulla was performed. Although a prolonged treatment period was necessary, the infected lung bulla and the lung abscess were eventually resolved. During her illness, the patient also developed arthritis, possibly related to the HTLV-1 infection. Thus, persons infected with HTLV-1 can develop refractory infections, myelopathy, and arthritis. Percutaneous drainage is an option to treat refractory infected lung bullae.

We describe a Case of a 74-year-old Japanese man with poorly differentiated carcinoma of the anterior mediastinum. The patient underwent anterior mediastinal tumor resection through median sternotomy. The tumor, 7.0 × 5.0 cm, had invaded surrounding tissues (pericardium, right lung, right and left brachiocephalic veins, and superior vena cava). Complete resection of the tumor was not performed. One month after the operation, the patient developed multiple pulmonary metastases, right pleural dissemination, and carcinomatous pleurisy. He was treated with lenvatinib, a novel multi-kinase inhibitor, to which the metastasis responded favorably. This case reports for the first time the clinical usefulness of lenvatinib for poorly differentiated carcinoma of the anterior mediastinum. Management of side effects by several methods, including suspending use of medication on weekends (called a weekends-off strategy), is another strong argument to continue lenvatinib administration.