Early T cell immunodynamics in blood

Prof Dr Lieve Brochez from the University Hospital Gent, Belgium, presented research from the Skin Cancer Research Institute Gent at the EADO 2025 meeting in Athens. The focus was on identifying early blood-based biomarkers that could help predict response to anti-PD-1 immunotherapy in patients with stage IV melanoma.

The study included 20 melanoma patients from a phase 2 trial, which compared immunotherapy with or without radiotherapy. Although radiotherapy showed no added benefit, the researchers analysed blood samples (PBMCs) taken at baseline and after two cycles of anti-PD-1 therapy.

They found that at baseline, there were no significant differences between responders and non-responders. However, after two cycles of treatment, patients who did not respond had higher expression of PD-L1 and LAG-3 on their CD4 and CD8 T cells. These markers were often co-expressed on the same cells. High expression levels were associated with poorer PFS and a lower chance of durable response. Responders had lower increases in PD-L1 and LAG-3 expression.

These findings suggest that changes in immune checkpoint expression in the blood could be used to identify patients who may benefit from a switch to combination therapy early in the treatment course. Although the study was small, the results were statistically significant. The team plans to validate the findings in larger cohorts and other cancer types.

Prof Dr Brochez concluded that such markers could support more personalised and adaptive immunotherapy approaches in the future.