Dynamics of the immune cell signature associated with the development of immune-related adverse event: Results from longitudinal immune profiling.

[BACKGROUND] The dynamics of peripheral immune cells during the development of immune-related adverse events (irAEs) remain incompletely characterized, underscoring the need to elucidate their temporal patterns to uncover immune disturbances and identify biomarkers.

[METHODS] In this prospective study, patients with lung cancer receiving immune checkpoint inhibitors (ICIs) were enrolled at Peking Union Medical College Hospital and were consecutively followed up for the development of irAEs. Comprehensive immune profiling by multicolor flow cytometry of peripheral blood samples collected at baseline (T0), early (T1, 1-3 weeks) and late (T2, 3-6 months) treatment, and at the onset of irAE (Tae) was performed. We utilized Mfuzz clustering analysis to characterize immune cell trajectories and calculated the change in cell frequencies (ΔT) from T0 to subsequent time points (ΔTae, ΔT1, and ΔT2) to identify time-dependent immune signatures predictive of irAE occurrence, severity, and specific organ involvement.

[RESULTS] Among the 60 lung cancer patients who received ICIs, 26 (43.3 %) developed irAEs. Mfuzz clustering highlighted the distinct dynamics of CD8 T cells and CD14CD16HLA-DR monocytes during ICIs therapy. During early treatment, the irAE group showed a greater increase in CD8CTLA-4 T cells and greater reductions in both total CD8 T cells and double-negative B (DNB) cells. At ΔT2, the irAE group exhibited significantly greater alterations in CD4CD25 T cells, CD4HLA-DR T cells, CD14CD16HLA-DR monocytes, and CD8 T cells. At ΔTae, patients with irAEs exhibited a significant expansion of non-switched memory (NSM) B cells and a reduction in CD3 T cells, whereas non-irAE patients showed opposite trends. Stratified analysis confirmed that the ΔT of NSM B cells, CD8CTLA-4 T cells, DNB cells, CD4CD25 T cells, and CD14CD16HLA-DR monocytes aligned with both clinical severity and specific organ involvement of irAEs.

[CONCLUSION] The distinct dynamics of cellular signatures during irAEs development provide potential biomarkers associated with the development of irAEs and shed novel insights into immune disturbance.