Background: There is no established standard 3 rd line treatment for patients with advanced non-small cell lung cancer (NSCLC). Although cytotoxic chemotherapeutic agents that are not used as 1 st or 2 nd line treatment are administrated as 3 rd line treatment, their anti-tumor efficacy is insufficient. Anti-programmed death ligand-1 (PD-L1)/programmed death-1 (PD1) treatment is more effective and less toxic than chemotherapy in anti-PD-L1/PD-1 treatment-naïve patients with NSCLC. Therefore, anti-PD-L1/PD-1 therapy is considered an appropriate 3 rd line treatment. However, the anti-tumor efficacy is limited in patients previously treated with anti-PD-L1/PD-1 antibody. Today, new drugs are needed to increase the efficacy of anti-PD-L1/PD-1 antibodies., Methods: This open-label, single-arm, investigator-initiated phase II study is designed to evaluate combination treatment of nivolumab and TM5614, a plasminogen activator inhibitor (PAI-1) inhibitor as 3 rd or more line treatment in NSCLC patients who underwent standard treatment. The primary endpoint is the objective response rate and the secondary endpoints are progression-free survival (PFS), overall survival (OS), duration of response (DOR) and safety. Recruitment began in September 2023 and is expected to continue for approximately three years., Discussion: Currently, there is no standard 3 rd line treatment for advanced NSCLC, and we hope that the findings of this study will facilitate more effective treatments in this setting. Ethics and dissemination: the study protocol conformed to the ethical principles outlined in the Declaration of Helsinki. All patients will provide written informed consent prior to enrollment. Results will be published in a peer-reviewed publication., Trial Registration: This study is registered to Japan Registry of Clinical Trials with number: jRCT2061230039 (19/July/2023)., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-23-1858/coif). T.M. reports honoraria from Chugai Pharmaceutical Co. Ltd., AstraZeneca K.K., Eli Lilly Japan K.K., MSD K.K., Taiho Pharmaceutical Co., Ltd., Ono Pharmaceutical Co., Ltd., Bristol-Myers Squibb Co. Ltd. and Kyowa Kirin Co., Ltd. outside the submitted work. T.S. reports honoraria from Chugai Pharmaceutical Co. Ltd., AstraZeneca K.K., Eli Lilly Japan K.K., MSD K.K., Taiho Pharmaceutical Co., Ltd., Ono Pharmaceutical Co., Ltd., Kyowa Kirin Co., Ltd., Novartis Pharma K.K., Merck Biopharma Co., Ltd., Janssen Pharmaceutical K.K., Amgen Inc., Daiichi-Sankyo Co., Ltd., Takeda Pharmaceutical Co., Ltd., Hisamitsu Pharmaceutical Co., Inc. and Illumina, Inc. outside the submitted work. Y.T. reports honoraria from Daiichi Sankyo Co. Ltd., AstraZeneca K.K., Chugai Pharmaceutical Co. Ltd., Kyowa Kirin Co., Ltd., TAIHO PHARMACEUTICAL Co., Ltd. and Bristol-Myers Squibb K.K. outside the submitted work, in addition to grants from Pfizer Health Research Foundation outside the submitted work. E.I. reports grants from Janssen Pharmaceutical K.K., Pfizer Japan Inc., Bristol-Myers Squibb Co. Ltd., Ono Pharmaceutical Co., Ltd. and Takeda Pharmaceutical Co., Ltd., outside the submitted work and honoraria from Chugai Pharmaceutical Co. Ltd., AstraZeneca K.K., Eli Lilly Japan K.K., Ono Pharmaceutical Co. Ltd., Takeda Pharmaceutical Co., Ltd., Bristol-Myers Squibb Co. Ltd., Pfizer Japan Inc., Janssen Pharmaceutical K.K., Novartis Pharma K.K. and Boehringer-Ingelheim Japan Inc., outside the submitted work and research material from AstraZeneca K.K. and Janssen Pharmaceutical K.K. outside the submitted work. T.K. reports honoraria from Chugai Pharmaceutical Co. Ltd., AstraZeneca K.K., Eli Lilly Japan K.K., Ono Pharmaceutical Co. Ltd., Takeda Pharmaceutical Co., Ltd., Bristol-Myers Squibb Co. Ltd., Pfizer Japan Inc., Novartis Pharma K.K., Taiho Pharmaceutical Co., Ltd., MSD K.K., Kyowa Kirin Co., Ltd., Boehringer-Ingelheim Japan Inc., Nippon Kayaku Co., Ltd., Daiichi-Sankyo Co., Ltd., Amgen Inc., Eisai Co. Ltd., Merck Biopharma Co., Ltd., Bayer Holding Ltd., Sawai Pharmaceutical Co., Ltd. outside the submitted work and grants from Chugai Pharmaceutical Co. Ltd., AstraZeneca K.K., Eli Lilly Japan K.K., Ono Pharmaceutical Co. Ltd., Bristol-Myers Squibb Co. Ltd., Pfizer Japan Inc., Taiho Pharmaceutical Co., Ltd., MSD K.K., Kyowa Kirin Co., Ltd., Daiichi-Sankyo Co., Ltd., Amgen Inc., Eisai Co. Ltd., Merck Biopharma Co., Ltd., Bayer Holding Ltd., Pfizer Japan Inc., AbbVie GK., LabCorp Japan, G.K., IQVIA Inc., Gilead Sciences, Inc. outside the submitted work, and consulting fee from Chugai Pharmaceutical Co. Ltd., AstraZeneca K.K., Ono Pharmaceutical Co. Ltd., Pfizer Japan Inc., Daiichi-Sankyo Co., Ltd., Bayer Holding Ltd., AbbVie GK. outside the submitted work. S.H. reports honoraria from Bristol-Myers Squibb Co. Ltd. outside submitted work. Y.O. reports consulting fee from Kitasato University Hospital and Association of Medical Education and Ethics outside submitted work, and honoraria for lectures of biostatistics from Tokai University, Graduate School of Medicine outside submitted work and is Data Monitoring Committee member of EVA-001-02 study sponsored by Evastem Co., Ltd., and Certified Committee member for Regenerative Medicine, Tokai University outside the submitted work. T.M. declares research grants from Astellas Pharma Inc., Daiichi Sankyo Co., Ltd., and KOWA DENTAL HEALTH K.K. and Renascience Inc. outside the submitted work, and honoraria from Renascience Inc. outside the submitted work, and stocks of Renascience Inc. N.H. reports honoraria from Chugai Pharmaceutical Co. Ltd., AstraZeneca K.K., MSD K.K., Ono Pharmaceutical Co., Ltd. and Bristol-Myers Squibb Co. Ltd. outside the submitted work. N.H. reports that this study is supported by Renascience Inc. (to Hiroshima University Hospital). The other authors have no conflicts of interest to declare., (2024 Journal of Thoracic Disease. All rights reserved.)