Background: NIS793 is a human IgG2 monoclonal antibody that binds to transforming growth factor beta (TGF-β). This first-in-human study investigated NIS793 plus spartalizumab treatment in patients with advanced solid tumors., Methods: Patients received NIS793 (0.3-1 mg/kg every 3 weeks (Q3W)) monotherapy; following evaluation of two dose levels, dose escalation continued with NIS793 plus spartalizumab (NIS793 0.3-30 mg/kg Q3W and spartalizumab 300 mg Q3W or NIS793 20-30 mg/kg every 2 weeks [Q2W] and spartalizumab 400 mg every 4 weeks (Q4W)). In dose expansion, patients with non-small cell lung cancer (NSCLC) resistant to prior anti-programmed death ligand 1 or patients with microsatellite stable colorectal cancer (MSS-CRC) were treated at the recommended dose for expansion (RDE)., Results: Sixty patients were treated in dose escalation, 11 with NIS793 monotherapy and 49 with NIS793 plus spartalizumab, and 60 patients were treated in dose expansion (MSS-CRC: n=40; NSCLC: n=20). No dose-limiting toxicities were observed. The RDE was established as NIS793 30 mg/kg (2100 mg) and spartalizumab 300 mg Q3W. Overall 54 (49.5%) patients experienced ≥1 treatment-related adverse event, most commonly rash (n=16; 13.3%), pruritus (n=10; 8.3%), and fatigue (n=9; 7.5%). Three partial responses were reported: one in renal cell carcinoma (NIS793 30 mg/kg Q2W plus spartalizumab 400 mg Q4W), and two in the MSS-CRC expansion cohort. Biomarker data showed evidence of target engagement through increased TGF-β/NIS793 complexes and depleted active TGF-β in peripheral blood. Gene expression analyses in tumor biopsies demonstrated decreased TGF-β target genes and signatures and increased immune signatures., Conclusions: In patients with advanced solid tumors, proof of mechanism of NIS793 is supported by evidence of target engagement and TGF-β pathway inhibition., Trial Registration Number: NCT02947165., Competing Interests: Competing interests: TMB has received support for the present manuscript from Novartis (to institution); consulting fees from AstraZeneca, Bayer, Blueprint, Lilly, and Pfizer; and has received honoraria from Bayer, Lilly and Pfizer. ASa has received consulting fees from Incyte and Sanofi; has received honoraria from AbbVie, Amgen, AstraZeneca, Bayer, Bristol Myers Squibb, Celgene, Eisai, Gilead, Lilly, Merck Sharp & Dohme, Novartis, Pfizer, Roche, Sandoz, Servier, and Takeda; and has participated in advisory boards for Bayer, Bristol Myers Squibb, Eisai, Gilead, Merck Sharp & Dohme, Pfizer, and Servier. C-CL has received consulting fees from Bayer, Blueprint Medicines, Boehringer Ingelheim, Bristol Myers Squibb, Daiichi Sankyo, Merck KGaA, Novartis, and PharmaEngine; has received honoraria from Boehringer Ingelheim, Novartis, and Roche; has received attendance/travel support from BeiGene, Daiichi Sankyo, and Eli Lilly; and has participated in an advisory board for Novartis. IG-L has received consulting fees from Jazz, Kanaph, OncXer and SOTIO; has received research support funding from Bayer, BridgeBio Pharma, Bristol Myers Squibb, GlaxoSmithKline, Incyte, Jacobio, Lilly, MedImmune, Novartis, Pfizer, Repare Therapeutics, Sumitomo Dainippon Pharma Oncology (to institution), and Tolero Pharmaceuticals. MJ has received research support from Basilea Pharmaceutica, Bristol Myers Squibb, Immunophotonics, Innomedica, Merck Sharp & Dohme, and Novartis (to institution); has received attendance/travel support from Bristol Myers Squibb and Roche; and has participated on an advisory board for Sanofi. RG has received consulting fees from AbbVie, AstraZeneca, Bristol Myers Squibb, Celgene, Daiichi Sankyo, Gilead, Janssen, Merck, Merck Sharp & Dohme, Novartis, Roche, Sanofi, and Takeda; has received honoraria from AbbVie, Amgen, AstraZeneca, Bristol Myers Squibb, Celgene, Daiichi Sankyo, Gilead, Merck, Merck Sharp & Dohme, Novartis, Roche, Sandoz, Sanofi, and Takeda; has received attendance/travel support from AbbVie, Amgen, AstraZeneca, Bristol Myers Squibb, Celgene, Daiichi Sankyo, Gilead, Janssen, Merck Sharp & Dohme, Novartis, and Roche; has participated in advisory boards for AbbVie, AstraZeneca, Bristol Myers Squibb, Celgene, Daiichi Sankyo, Gilead, Janssen, Merck, Merck Sharp & Dohme, Novartis, Roche, Sanofi, and Takeda. ASp received research support from Alkermes, Amgen, Array Biopharma/Pfizer, AstraZeneca/Medimmune, Bayer, Bristol Myers Squibb, GlaxoSmithKline, Janssen Oncology/Johnson & Johnson, Merck, Novartis, Northern Biologics, NuBiyota, Oncorus, Surface Oncology, Symphogen, Regeneron, Roche, and Treadwell; has participated in advisory boards for Bristol Myers Squibb, Janssen, Medison & Immunocore Merck, and Oncorus. TY has received support for the present manuscript from Novartis (institution); has received consulting fees from AstraZeneca, Bristol Myers Squibb, Eisai, Ipsen, and Merck Sharp & Dohme; has received support for attending meetings and/or travel from Roche and Bayer; holds stock with Moderna; has received receipt of medical writing from Ipsen and Taiho; has received payments (institution) for clinical trial investigatorship from AstraZeneca, Bristol Myers Squibb, Eli Lilly, Exelixis, Merck Sharp & Dohme, Roche, and Taiho. M-EG has received honoraria from AstraZeneca, Bristol Myers Squibb, Janssen, and Novartis; has participated in advisory boards for Bristol Myers Squibb and Janssen-Cilag. MLH-K has received support for attending meetings and/or travel from Jazz pharmaceuticals; has participated in advisory boards for Grifols. P-EJ and CF are former employees of Novartis. DL, MP, LB, and VC are employees of Novartis and hold stock with Novartis. HE is an employee of Novartis and holds Novartis shares. TD has received research support funding from AbbVie, Bristol Myers Squibb, Boehringer Ingelheim, Chugai Pharma, Daiichi Sankyo, Eisai, IQVIA, Janssen, Lilly Merck, Merck Sharp & Dohme, Novartis, Pfizer, SHIONOGI, Sumitomo Dainippon Pharma Oncology (to institution), and Taiho; consulting fees from A2 Health Care, AbbVie, Bayer, Chugai Pharma, KAKEN Pharma, KYOWA KIRIN, Noil Immune, Otsuka Pharma, PRA Health Science Rakuten Medical, SHIONOGI, Sumitomo Dainippon, Taiho, and Takeda; has received honoraria from AstraZeneca, Bristol Myers Squibbs, Daiichi Sankyo, Ono Pharma, and Rakuten Medical; has participated in advisory boards for AbbVie, Amgen, Astellas Pharma, Bayer Boehringer Ingelheim, Daiichi Sankyo, Janssen Pharma, Merck Sharp & Dohme, and Novartis. AP has no conflicts of interests to declare., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)