Background: Thymic carcinoma (TC) is a rare thymic epithelial tumor, and advanced or recurrent TC has limited prognosis. Treatment for chemotherapy-naïve, advanced, or recurrent TC remains unchanged with the combination of carboplatin and paclitaxel; therefore, a new treatment strategy is warranted. Immune checkpoint blockades inhibiting the programmed cell death-1 (PD-1) pathway (PD-1 and its ligand, PD-L1) have shown potential as a monotherapy for TC, although the efficacy of monotherapy was moderate for previously treated TC. We hypothesized that the combination of an anti-PD-L1 antibody, atezolizumab, with carboplatin and paclitaxel, would be effective in inducing immunogenic cell death in patients with advanced or recurrent TC., Methods: We initiated a multicenter, single-arm, open-label phase II study of atezolizumab combined with carboplatin and paclitaxel for metastatic or recurrent TC. Eligible patients will receive atezolizumab plus carboplatin and paclitaxel every 3 weeks for up to 6 cycles, followed by atezolizumab every 3 weeks for up to 2 years until progression or unacceptable toxicity. A total of 47 patients will be enrolled in this study, with a 24-month enrollment period and 12-month follow-up. The primary endpoint is the objective response rate (ORR), based on an independent central review. The secondary endpoints are the investigator-assessed ORR, disease control rate, progression-free survival, duration of response, overall survival, and safety., Results: This study aims to establish the safety and efficacy of atezolizumab combined with carboplatin and paclitaxel in patients with advanced or recurrent TC., Trial Registration: Japan Registry of Clinical Trials (jRCT), jRCT2031220144. Registered on June 18, 2022, https://jrct.niph.go.jp/en-latest-detail/jRCT2031220144., Competing Interests: Disclosure TA reports honoraria from AstraZeneca, Boehringer Ingelheim, Bristol Myers Squibb, Chugai Pharmaceutical, Daiichi Sankyo, Eli Lilly Japan, Merck Biopharma, MSD, Nippon Kayaku, Ono, Pfizer, Taiho, and Takeda. T Shukuya reports grant support for the current study from Chugai Pharmaceutical; grant support from AstraZeneca, Boehringer Ingelheim, Chugai Pharmaceutical, MSD, Novartis; honoraria from AstraZeneca, Boehringer Ingelheim, Bristol-Myers Squibb, Chugai Pharmaceutical, Daiichi Sankyo, Eli Lilly, MSD, Nippon Kayaku, Novartis, Ono, Pfizer, Taiho, and Takeda. YG reports grant support for the clinical trial group from AstraZeneca, Pfizer, institutional grant support from AbbVie, Bristol Myers Squibb, Daiichi Sankyo, Eli Lilly, Kyorin, Novartis, Ono, Pfizer, and Preferred Networks; honoraria from Boehringer Ingelheim, Bristol Myers Squibb, Chugai, Eli Lilly, Merck, MSD, Novartis, Ono, Pfizer, Taiho, and Thermo Fischer; participation on an advisory board for AstraZeneca, Bristol Myers Squibb, Boehringer Ingelheim, Chugai Pharmaceutical, Daiichi Sankyo, Eli Lilly, Guardant Health, Illumina, MSD, Novartis, Ono, Pfizer, and Taiho; and leadership or fiduciary role at Cancer Net Japan and Japanese Association of Medical Technologists. HT reports institutional grant support from AbbVie, Amgen, AstraZeneca, Boehringer Ingelheim, Bristol Myers Squibb, Chugai Pharmaceutical, Daiichi Sankyo, Eli Lilly, Merck Biopharma, MSD, Ono, Taiho, and Takeda; honoraria from AstraZeneca, Boehringer Ingelheim, Bristol Myers Squibb, Chugai Pharmaceutical, Daiichi Sankyo, Eisai, Eli Lilly, Merck Biopharma, MSD, Novartis, Ono, Sun Pharmaceutical, Taiho, and Takeda. K Takayama reports grant support for Chugai Pharmaceutical; honoraria from Chugai Pharmaceutical. YT reports institutional grant support for Ono and Pfizer Health Research Foundation; honoraria from AstraZeneca, Chugai Pharmaceutical, and Daiichi Sankyo. MT reports honoraria from AstraZeneca, Bristol Myers Squibb, Chugai Pharmaceutical, Eli Lilly, MSD, Novartis, Ono, and Takeda. T Suzuki reports honoraria from AstraZeneca and Boehringer Ingelheim. KK reports honoraria from AstraZeneca, Boehringer Ingelheim, Chugai Pharmaceutical, Eli Lilly, Ono, and Taiho. RK reports grant support from AstraZeneca and MSD; honoraria from AstraZeneca, Boehringer Ingelheim, Chugai Pharmaceutical, Daiichi-Sankyo, Eli Lilly, MSD, Ono, Pfizer, Taiho, and Takeda. YZ reports grant support from Amgen, AstraZeneca, Daiichi Sankyo, Merck Biopharma, and MSD; honoraria from Amgen, AstraZeneca, Boehringer Ingelheim, Bristol Myers Squibb, Chugai, Eli Lilly, Kyowa Kirin, MSD, Nihon Kayaku, Novartis, Pfizer, Taiho, and Takeda. HA reports grant support from Amgen, Chugai Pharmaceutica, and MSD; honoraria from Amgen, AstraZeneca, Boehringer Ingelheim, Bristol Myers Squibb, Chugai Pharmaceutical, Eli Lilly, MSD, Nippon Kayaku, Novartis, Ono, Pfizer, Taiho and Takeda; data safety monitoring or advisory board participation with Amgen, Janssen, and Sandoz; and a leadership or fiduciary role with World Conference on Lung Cancer Patient Advocate Committee. JT reports honoraria from AstraZeneca, Bristol Myers Squibb, Chugai Pharmaceutical, Daiichi Sankyo, Eli Lilly, Janssen Pharmaceutical, MSD, Nihon Medi-Physics, Ono, Nippon Boehringer-Ingelheim, Nippon Kayaku, Taiho, and Pfizer. SI reports institutional grant support for AstraZeneca and Chugai; honoraria from AstraZeneca, Boehringer Ingelheim, Bristol Myers Squibb, Chugai Pharmaceutical, Eli Lilly, Ono, Pfizer, and Takeda. SS reports honoraria from AbbVie, Amgen, AstraZeneca, Boehringer Ingelheim, Bristol Myers Squibb, Chugai Pharmaceutical, Eli Lilly, Kyowa Kirin, Merck Biopharma, MSD, Nippon Kayaku, Novartis, Ono, Otsuka, Pfizer, Taiho, Takeda, Thermo Fisher Scientific, Towa Pharmaceutical, and Yakult Honsha. KM reports honoraria from Chugai Pharmaceutical, Eli Lilly, and Ono. K Takahashi reports grant support from Asahi Kasei Pharma, Bayer, Boehringer Ingelheim, Chugai Pharmaceutical, Daiichi Sankyo, Eli Lilly, Kyorin, Nippon Kayaku, Kyowa Kirin, Nippon Pharma, Nippon Shinyaku, Novartis, Ono, Sanofi, Shionogi, Taiho, Takeda, Teijin, Tsumura, and Pfizer; honoraria from Abbott, AstraZeneca, Boehringer Ingelheim, Bristol Myers Squibb, Chugai Pharmaceutical, Eli Lilly, Janssen, Kyorin, Meiji Seika Pharma, Merck Biopharma, MSD, Nippon Kayaku, Novartis, Ono, Pfizer, Sumitomo Dainippon Pharma, Taiho, Takeda, Thermo Fisher Scientific and Viatris; patent with Oncolys BioPharma; and leadership or fiduciary role with The Japan Lung Cancer Society and The Japan Respiratory Society. All other authors (HM, TM) declare no competing interests., (Copyright © 2023 Elsevier Inc. All rights reserved.)