Background & Aims: We investigated the efficacy and safety of immune checkpoint inhibitor (ICI) rechallenge in patients with hepatocellular carcinoma (HCC) who received ICI-based therapies in a previous systemic line., Methods: In this international, retrospective multicenter study, patients with HCC who received at least two lines of ICI-based therapies (ICI-1, ICI-2) at 14 institutions were eligible. The main outcomes included best overall response and treatment-related adverse events., Results: Of 994 ICI-treated patients screened, a total of 58 patients (male, n = 41; 71%) with a mean age of 65.0±9.0 years were included. Median systemic treatment lines of ICI-1 and ICI-2 were 1 (range, 1-4) and 3 (range, 2-9), respectively. ICI-based therapies used at ICI-1 and ICI-2 included ICI alone (ICI-1, n = 26, 45%; ICI-2, n = 4, 7%), dual ICI regimens (n = 1, 2%; n = 12, 21%), or ICI combined with targeted therapies/anti-VEGF (n = 31, 53%; n = 42, 72%). Most patients discontinued ICI-1 due to progression (n = 52, 90%). Objective response rate was 22% at ICI-1 and 26% at ICI-2. Responses at ICI-2 were also seen in patients who had progressive disease as best overall response at ICI-1 (n = 11/21; 52%). Median time-to-progression at ICI-1 and ICI-2 was 5.4 (95% CI 3.0-7.7) months and 5.2 (95% CI 3.3-7.0) months, respectively. Treatment-related adverse events of grade 3-4 at ICI-1 and ICI-2 were observed in 9 (16%) and 10 (17%) patients, respectively., Conclusions: ICI rechallenge was safe and resulted in a treatment benefit in a meaningful proportion of patients with HCC. These data provide a rationale for investigating ICI-based regimens in patients who progressed on first-line immunotherapy in prospective trials., Impact and Implications: Therapeutic sequencing after first-line immune checkpoint inhibitor (ICI)-based therapy for advanced hepatocellular carcinoma (HCC) remains a challenge as no available second-line treatment options have been studied in immunotherapy-pretreated patients. Particularly, the role of ICI rechallenge in patients with HCC is unclear, as data from prospective trials are lacking. We investigated the efficacy and safety of ICI-based regimens in patients with HCC pretreated with immunotherapy in a retrospective, international, multicenter study. Our data provide the rationale for prospective trials investigating the role of ICI-based regimens in patients who have progressed on first-line immunotherapy., Competing Interests: BS received travel support from AbbVie, Ipsen and Gilead. DR has received advisory fees from Bayer and speakers fees as well as travel grants from Ipsen. He is an investigator for Bayer, BMS, Lilly, AstraZeneca and Roche. SP has nothing to disclose. ML has nothing to disclose. KP has nothing to disclose. TP received consulting fees from IQVIA and Bayer; and institutional research funding from Lilly, Roche, Bayer. AC has nothing to disclose. TWF has nothing to disclose. JVF has received advisory board fees from Roche. KS served as consultant for Ipsen and Bayer, and conducts studies for Bayer, Roche, Lilly, MSD, and BMS. VH has nothing to disclose. FF received travel support from Abbvie and Novartis, and speaker fees from Abbvie and MSD. AD has nothing to disclose. ARS has served at advisory boards and received consulting honoraria from AMGEN, AAA, Bayer, BMS, IPSEN, Lilly, Merck, MSD, Pfizer, Roche, Sanofi, and Servier. KS has nothing to disclose. PR has nothing to disclose. BiS has nothing to disclose. MPE received consulting honoraria from BMS and MSD. AT received consulting honoraria and/or lecture fees from Bayer, IPSEN, Lilly, BMS, Eisai Novartis, Roche, Intercept, Falk, AbbVie, and Gilead. He received travel grants from IPSEN, AbbVie, and Gilead. He is an investigator for IPSEN and GILEAD. AngD received advisory board fees from Roche and BMS, and travel support from Roche and Ipsen. FH received travel support from Bayer, Abbvie, and Gilead. LB has nothing to disclose. ABP has nothing to disclose. DH received research support from Pfizer. MV received speaker fees from Nordic Pharma, Ipsen, Merck Serono, Bayer Vital, Lilly, AstraZeneca, Merck Sharp & Dohme (MSD), Bristol-Myers Squibb (BMS), and Sirtex, advisory board fees from Roche, Ipsen, Lilly, Nordic Pharma, Bristol-Myers Squibb (BMS), Merck Sharp & Dohme (MSD), Eisai, AstraZeneca and Amgen, research grants from Sirtex. FS has nothing to disclose. MT received speaker fees from Bristol-Myers Squibb (BMS), Falk Foundation, Gilead, Intercept and Merck Sharp & Dohme (MSD); advisory board fees from Abbvie, Albireo, Boehringer Ingelheim, BiomX, Falk Pharma GmbH, GENFIT, Gilead, Intercept, Janssen, MSD, Novartis, Phenex, Regulus and Shire; travel grants from AbbVie, Falk, Gilead, and Intercept; and research grants from Albireo, CymaBay, Falk, Gilead, Intercept, MSD, and Takeda. He is also coinventor of patents on the medical use of norUDCA filed by the Medical University of Graz. ADA received travel support and consultancy fees from Roche. CAMF has nothing to disclose. DJP received lecture fees from ViiV Healthcare, Bayer Healthcare, BMS, Roche, Eisai, Falk Foundation, travel expenses from BMS and Bayer Healthcare; consulting fees for Mina Therapeutics, EISAI, Roche, DaVolterra, Mursla, Exact Sciences and Astra Zeneca; research funding (to institution) from MSD and BMS. MPR is advisor/consultant for Astra Zeneca, Bayer, BMS, Eisai, Ipsen, Lilly, MSD, and Roche; he served as a speaker for Bayer, Eisai, Ipsen, Lilly, and Roche; he is an investigator for Bayer, BMS, Eisai, Exelixis, Lilly, and Roche. JFD received compensations as a member of scientific advisory boards of Abbvie, Bayer, Bristol–Myers Squibb, Falk, Galapagos, Genfit, Genkyotex, Gilead Sciences, HepaRegenix, Intercept, Lilly, Merck, and Novartis. AW received compensations as a member of scientific advisory boards for BMS, Wako and Sanofi. He served as a speaker for Leo Pharma, Eisai, Ipsen and Roche and received travel support from Merck and Servier. AEK has received consulting fees from Abbvie, AstraZeneca, Bayer, CymaBay, Escient, FMC, Gilead, GSK, Guidepoint, Intercept, Mirum, Medscape, MSD, Myr, Viofor; lecture fees from Abbvie, AOP Orphan, Bayer, BMS, CMS, CymaBay, Eisai, Falk, Gilead, GSK, Intercept, Janssen, Newbridge, Novartis, Lilly, MSD, Zambon; and institutional research funding from Intercept. AGS served on advisory boards and as a consultant for Genentech, AstraZeneca, Eisai, Bayer, Exelixis, TARGET RWE, FujiFilm Medical Sciences, Glycotest, Exact Sciences, GRAIL, and Freenome. ENDT has served as a paid consultant for AstraZeneca, Bayer, BMS, EISAI, Eli Lilly & Co, MSD, Mallinckrodt, Omega, Pfizer, IPSEN, Terumo and Roche. He has received reimbursement of meeting attendance fees and travel expenses from Arqule, Astrazeneca, BMS, Bayer, Celsion and Roche, and lecture honoraria from BMS and Falk. He has received third-party funding for scientific research from Arqule, AstraZeneca, BMS, Bayer, Eli Lilly, and IPSEN and Roche. LR has received consulting fees from Amgen, ArQule, AstraZeneca, Basilea, Bayer, BMS, Celgene, Eisai, Exelixis, Genenta, Hengrui, Incyte, Ipsen, IQVIA, Lilly, MSD, Nerviano Medical Sciences, Roche, Sanofi, Servier, Taiho Oncology, Zymeworks; lectures fees from AbbVie, Amgen, Bayer, Eisai, Gilead, Incyte, Ipsen, Lilly, Merck Serono, Roche, Sanofi, Servier; travel expenses from AstraZeneca; and institutional research funding from Agios, ARMO BioSciences, AstraZeneca, BeiGene, Eisai, Exelixis, Fibrogen, Incyte, Ipsen, Lilly, MSD, Nerviano Medical Sciences, Roche, Zymeworks. MP is an investigator for Bayer, BMS, Eisai, Ipsen, Lilly, and Roche; he received speaker honoraria from Bayer, BMS, Eisai, Lilly, MSD, and Roche; he is a consultant for Bayer, BMS, Eisai, Ipsen, Lilly, MSD, and Roche; he received travel support from Bayer, BMS, and Roche. Please refer to the accompanying ICMJE disclosure forms for further details., (© 2022 The Author(s).)