Abstract B057: Decoding tumor microenvironment and resistance following immune checkpoint inhibition therapy in anaplastic thyroid carcinoma

Abstract Purpose: The vast majority of patients with anaplastic thyroid carcinoma (ATC) without BRAF V600E mutations have limited therapeutic options. We sought to investigate why only a third of ATC patients have tumor responses to immune checkpoint inhibition (ICI) with dual anti-programmed death-1 (PD-1) and anti cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) blockade (PMID: 39446365) in hopes of identifying novel therapeutic targets in this population. Methods: To dissect the tumor immune-microenvironment and understand mechanisms of response future experiments will analyze samples with and without clinical response to ICI therapy. Citation Format: Kartik Sehgal, Kevin Bi, Theodora Pappa, Justine A. Barletta, Laura A. Goguen, Rosh K. Sethi, Eleni M. Rettig, Glenn J. Hanna, Erik K. Alexander, Gerard M. Doherty, Yashika Rustagi, Anwesha Nag, Aaron R. Thorner, Michael J. Dennis, Jonathan D. Schoenfeld, Ravindra Uppaluri, David A. Barbie, Kathleen B. Yates, Robert T. Manguso, Robert I. Haddad. Decoding tumor microenvironment and resistance following immune checkpoint inhibition therapy in anaplastic thyroid carcinoma abstract. In: Proceedings of the AACR Immuno-Oncology Conference (AACR IO): Discovery and Innovation in Cancer Immunology: Revolutionizing Treatment through Immunotherapy; 2026 Feb 18-21; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Immunol Res 2026;14(2 Suppl):Abstract nr B057.