Introduction: Immune checkpoint inhibitors (ICIs) plus chemotherapy is now a standard treatment for non-small cell lung cancer (NSCLC). Whether ICI plus chemotherapy (ICI-chemo) or ipilimumab plus nivolumab (I-N)-based therapy is superior for patients with NSCLC with a programmed death-ligand 1 (PD-L1) tumor proportion score (TPS) of 1-49 % has not been evaluated., Methods: This multicenter retrospective study included NSCLC patients with a TPS score of 1-49 %, who began first-line chemotherapy. Propensity score matching analysis was used to adjust for various confounders and evaluate treatment efficacy., Results: A total of 401 patients were enrolled, of whom 308 received ICI-chemo and 93 received I-N-based therapy. The median OS was 21.0 months in the ICI-chemo group and 20.0 months in the I-N-based therapy group. After propensity score matching, there was no difference in OS or PFS between the ICI-chemo group and the I-N-based therapy group (OS: hazard ratios (HR), 0.83; 95 % confidence interval [CI], 0.54-1.26, PFS: HR, 0.72; 95 % CI, 0.52-1.00). Among PD-L1 TPS 25-49 %, there was a tendency for OS to be favorable for the ICI-chemo group (OS: HR, 0.30; 95 % CI, 0.09-0.85). Treatment discontinuation occurred for 26.2 % of the patients in the ICI-chemo group and 41.9 % in the I-N-based therapy group., Conclusions: Among PD-L1 TPS 1-49 %, there was no significant difference in survival outcomes between the ICI-chemo group and the I-N-based therapy group. Based on the results of a subgroup analysis, ICI-chemo may be superior for treating NSCLC with a TPS of 25-49 %., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Dr. Tanaka reported receiving lecture fees from AstraZeneca K.K, Chugai Pharmaceutical Co., Boehringer-Ingelheim Japan Inc., Ono Pharmaceutical Co., Pfizer Japan Inc., and Bristol-Meyers Squibb. Dr. Makiguchi reported receiving honoraria from Asahi KASEI, Boehringer-Ingelheim Japan, Inc., AstraZeneca K.K, Eli Lilly, GlaxoSmithKline, Ono Pharmaceutical Co., Teijin Pharma, Taiho Pharmaceutical, Chugai Pharmaceutical Co., and LTD. Dr. Tozuka reported receiving honoraria from AstraZeneca and Chugai Pharmaceutical Co. Dr. Kawashima reported receiving honoraria from AstraZeneca K.K, Chugai Pharmaceutical Co, Taiho Pharmaceutical, Eli Lilly, Kyowa Hakko-Kirin, and Life Technologies Japan Ltd. Dr. Koyama reported receiving honoraria from AstraZeneca K.K. and Chugai Pharmaceutical Co. Dr. Tambo reported receiving honoraria from Chugai Pharmaceutical Co, Taiho Pharmaceutical, MSD K.K, and the Daiichi Sankyo Company. Dr. Ogusu reported receiving speakers’ bureau from MSD K.K, Bristol-Meyers Squibb, and Chugai Pharmaceutical Co. Dr. Hasegawa reported receiving honoraria from AstraZeneca K.K, Chugai Pharmaceutical Co., Eli Lilly, and Merck. Dr. Miyauchi reported receiving honoraria from AstraZeneca, Eli Lilly, Chugai Pharmaceutical Co, Boehringer-Ingelheim Japan, Inc., Taiho Pharmaceutical, Kyowa Hakko-Kirin, Daiichi-Sankyo, MSD, Bristol Myers Squibb, Merck, Amgen, Ono Pharmaceutical Co., Thermo Fisher Scientific, Nippon Kayaku, Takeda Pharmaceutical Co., and Sysmex. He received advisory roles from Boehringer-Ingelheim Japan Inc., Ono Pharmaceutical Co, Daiichi-Sankyo, and Merck outside of the submitted work. Dr. Sakatani reported receiving speakers’ bureau from AstraZeneca, Eli Lilly, MSD K.K, Boehringer-Ingelheim Japan, Inc., Takeda Pharmaceutical Co., Taiho Pharmaceutical, and Bristol Myers Squibb. Dr. Tsuchiya-Kawano reported receiving speakers’ bureau from Bristol Myers Squibb, AstraZeneca, Taiho Pharmaceutical, Chugai Pharmaceutical Co., MSD K.K, Ono Pharmaceutical Co., and Kyowa Hakko-Kirin. Dr. Nishio reported receiving honoraria from Pfizer Japan Inc, Bristol Myers Squibb, Ono Pharmaceutical Co., Chugai Pharmaceutical Co., Taiho Pharmaceutical, AstraZeneca, Boehringer-Ingelheim Japan, Inc., MSD K.K, Novartis, Eli Lilly, Nippon Kayaku, Takeda Pharmaceutical Co., Merck, Janssen, Amgen, Eisai, and Daiichi-Sankyo. He received research funding from Pfizer Japan Inc, Bristol Myers Squibb, Taiho Pharmaceutical, AstraZeneca, MSD K.K, Takeda Pharmaceutical Co, Merck, Janssen, and Amgen, outside of the submitted work. All remaining authors have declared no conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)