biostudies-literatureMaio MGSKe011475https://www.ebi.ac.uk/biostudies/studies/S-EPMC12352173biostudies-literatureUnknown13(8)<h4>Background</h4>Inducible costimulator (ICOS) receptor belongs to the CD28/CTLA immunoglobulin super family, whose expression is restricted to T cells and is weakly expressed on resting TH17, follicular helper T cells, and regulatory T cells, but is highly induced on CD4+ and CD8+ T cells on activation by T-cell receptors. ICOS stimulation downstream effects include activation of conventional CD4+cells and cytotoxic CD8+cells, resulting in a durable antitumor response in preclinical models.<h4>Methods</h4>As part of a larger first-in-human study (GSK Study 204691), this study focused on 2 cohorts of 25 and 67 participants enrolled in a dose escalation and pharmacokinetic/pharmacodynamic (PK/PD) analysis of the ICOS agonist feladilimab (GSK3359609) as monotherapy. For these cohorts, the Journal for immunotherapy of cancerFirst-in-human phase 1 study of the ICOS agonist feladilimab on patients with advanced solid tumors.PMC12352173NCT02723955GSK Study 204691EudraCT 2016-000148-32Hansen ABauer TMRischin DMaio MBallas MOpdam FItaliano AEllis CTurner DYadavilli SHirschfeld SLe Tourneau CMoreno VDiaz-Padilla IMartin-Liberal JAngevin EZhou HfalseFirst-in-human phase 1 study of the ICOS agonist feladilimab on patients with advanced solid tumors.<h4>Background</h4>Inducible costimulator (ICOS) receptor belongs to the CD28/CTLA immunoglobulin super family, whose expression is restricted to T cells and is weakly expressed on resting TH17, follicular helper T cells, and regulatory T cells, but is highly induced on CD4+ and CD8+ T cells on activation by T-cell receptors. ICOS stimulation downstream effects include activation of conventional CD4+cells and cytotoxic CD8+cells, resulting in a durable antitumor response in preclinical models.<h4>Methods</h4>As part of a larger first-in-human study (GSK Study 204691), this study focused on 2 cohorts of 25 and 67 participants enrolled in a dose escalation and pharmacokinetic/pharmacodynamic (PK/PD) analysis of the ICOS agonist feladilimab (GSK3359609) as monotherapy. For these cohorts, the 2025-01-01T00:00:00Z2025 Aug2026-07-15T10:49:51.362Z2026-07-04T03:12:05.598ZS-EPMC123521734078974210.1136/jitc-2025-011475