New research being presented during the European Society for Medical Oncology (ESMO) Congress 2025 showed that thymic health is linked to response to immune checkpoint inhibition in patients with cancer (Abstract 108O). “Immunotherapy relies on unleashing T cells, and the thymus is where T cells are matured. Our study shows that thymic health is associated with improved immunotherapy outcomes across diverse cancer types,” stated lead study author Simon Bernatz, MD, Research Fellow in the AI in Medicine Program at Mass General Brigham.
Study Methods
Researchers analyzed routine chest CT scans from 3,476 patients with cancer who were treated with immune checkpoint inhibitors. They developed and used a deep learning framework to quantify patients' thymic health and functionality by assigning scores based on size, shape, and structure.
Biological validation was conducted in the TRACERx study of 464 patients with non–small cell lung cancer (NSCLC) by using T-cell receptor sequencing and plasma proteomics.
Key Study Findings
In patients with NSCLC specifically, higher thymic health was associated with a reduced risk of disease progression (hazard ratio [HR] = 0.65; 95% confidence interval [CI] = 0.54–0.77) and death (HR = 0.56; 95% CI = 0.46–0.68), which was also seen after multivariate adjustments (P < .001).
Even when taking into account clinically relevant subgroups of PD-L1 and tumor mutational burden levels, the associations between thymic health and overall survival and progression-free survival remained significant (P < .03).
In the TRACERx trial, thymic health was associated with more peripheral and intratumoral T-cell receptor diversity as well as with adaptive immune signaling, showing that thymic health represents immune competence.
When looking across cancer types, the positive associations between thymic health and immunotherapy responses were confirmed in melanoma, renal, and breast cancers (P < .02).
These findings suggest thymic health as a noninvasive, tumor-agnostic biomarker of adaptive immune competence, with potential to enhance patient stratification in precision oncology, the study authors concluded.
Disclosure: Financial support for the study was provided by the National Institutes of Health and the European Union - European Research Council. For full disclosures of the study authors, visit ctimeetingtech.com/esmo2025/.
