start-ver=1.4 cd-journal=joma no-vol=117 cd-vols= no-issue=5 article-no= start-page=1260 end-page=1272 dt-received= dt-revised= dt-accepted= dt-pub-year=2026 dt-pub=20260227 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=TGF-β Inhibitor Potentiates Osimertinib-Induced Anti-Tumor Immunity in Egfr-Mutant Lung Cancer en-subtitle= kn-subtitle= en-abstract= kn-abstract=Immunotherapy for epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (NSCLC) remains challenging. We previously found that EGFR-tyrosine kinase inhibitors induced antitumor immunity but also triggered immunosuppressive cytokines, including transforming growth factor-β (TGF-β), in Egfr-mutant lung cancer. Here, we investigate whether TGF-β inhibition potentiates osimertinib-induced antitumor immunity using a syngeneic mouse model of Egfr-mutated lung cancer, with cancer cells subcutaneously transplanted into wild-type C57BL/6J mice. We evaluated the antitumor effect of the combination therapy with osimertinib and either nintedanib (an indirect TGF-β inhibitor) or vactosertib (a specific TGF-β type I receptor kinase inhibitor). Changes in the tumor microenvironment during treatment were assessed using immunohistochemical staining, western blot analysis, and flow cytometry. We found that TGF-β expression was upregulated in the tumor treated with osimertinib. Nintedanib monotherapy showed no significant antitumor effect, whereas osimertinib combined with nintedanib significantly potentiates the antitumor effect compared with osimertinib monotherapy in vivo. Crucially, no additive effect of nintedanib on osimertinib monotherapy was observed in vitro. Combination therapy with osimertinib and nintedanib significantly increased effector T cells (CD8+CD44+CD62L−) and Granzyme B+ areas and decreased CD206+ cells, while significantly decreasing TGF-β and SMAD2/3 expression. Similar effects were observed with vactosertib but not with a vascular endothelial growth factor receptor 2 inhibitor. In conclusion, combination therapy with osimertinib and TGF-β inhibitors potentiates osimertinib-induced antitumor immunity. These findings highlight a novel therapeutic strategy for EGFR-mutated NSCLC and warrant further clinical investigation. en-copyright= kn-copyright= en-aut-name=KuribayashiTadahiro en-aut-sei=Kuribayashi en-aut-mei=Tadahiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=NishimuraJun en-aut-sei=Nishimura en-aut-mei=Jun kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=OkawaSachi en-aut-sei=Okawa en-aut-mei=Sachi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=TaokaMasataka en-aut-sei=Taoka en-aut-mei=Masataka kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=MoriShunta en-aut-sei=Mori en-aut-mei=Shunta kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=TanakaTakaaki en-aut-sei=Tanaka en-aut-mei=Takaaki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=NishimuraTomoka en-aut-sei=Nishimura en-aut-mei=Tomoka kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=MoritaAyako en-aut-sei=Morita en-aut-mei=Ayako kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= en-aut-name=HaraNaofumi en-aut-sei=Hara en-aut-mei=Naofumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=9 ORCID= en-aut-name=NinomiyaKiichiro en-aut-sei=Ninomiya en-aut-mei=Kiichiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=10 ORCID= en-aut-name=MakimotoGo en-aut-sei=Makimoto en-aut-mei=Go kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=11 ORCID= en-aut-name=RaiKammei en-aut-sei=Rai en-aut-mei=Kammei kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=12 ORCID= en-aut-name=IchiharaEiki en-aut-sei=Ichihara en-aut-mei=Eiki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=13 ORCID= en-aut-name=HottaKatsuyuki en-aut-sei=Hotta en-aut-mei=Katsuyuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=14 ORCID= en-aut-name=TogashiYosuke en-aut-sei=Togashi en-aut-mei=Yosuke kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=15 ORCID= en-aut-name=MaedaYoshinobu en-aut-sei=Maeda en-aut-mei=Yoshinobu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=16 ORCID= en-aut-name=KiuraKatsuyuki en-aut-sei=Kiura en-aut-mei=Katsuyuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=17 ORCID= en-aut-name=OhashiKadoaki en-aut-sei=Ohashi en-aut-mei=Kadoaki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=18 ORCID= affil-num=1 en-affil=Department of Hematology, Oncology and Respiratory Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=2 en-affil=Department of Hematology, Oncology and Respiratory Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=3 en-affil=Department of Hematology, Oncology and Respiratory Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=4 en-affil=Department of Hematology, Oncology and Respiratory Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=5 en-affil=Department of Hematology, Oncology and Respiratory Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=6 en-affil=Department of Hematology, Oncology and Respiratory Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=7 en-affil=Department of Hematology, Oncology and Respiratory Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=8 en-affil=Department of Hematology, Oncology and Respiratory Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=9 en-affil=Department of Respiratory Medicine, Okayama University Hospital kn-affil= affil-num=10 en-affil=Center for Comprehensive Genomic Medicine, Okayama University Hospital kn-affil= affil-num=11 en-affil=Department of Respiratory Medicine, Okayama University Hospital kn-affil= affil-num=12 en-affil=Center for Innovative Clinical Medicine, Okayama University Hospital kn-affil= affil-num=13 en-affil=Center for Clinical Oncology, Okayama University Hospital kn-affil= affil-num=14 en-affil=Center for Innovative Clinical Medicine, Okayama University Hospital kn-affil= affil-num=15 en-affil=Department of Respiratory Medicine, Okayama University Hospital kn-affil= affil-num=16 en-affil=Department of Hematology, Oncology and Respiratory Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences kn-affil= affil-num=17 en-affil=Department of Respiratory Medicine, Okayama University Hospital kn-affil= affil-num=18 en-affil=Department of Respiratory Medicine, Okayama University Hospital kn-affil= en-keyword=EGFR kn-keyword=EGFR en-keyword=lung cancer kn-keyword=lung cancer en-keyword=nintedanib kn-keyword=nintedanib en-keyword=osimertinib kn-keyword=osimertinib en-keyword=TGF-β kn-keyword=TGF-β END