Immunophenotyping of peripheral CD8+ T cells from classical Hodgkin Lymphoma patients treated with PD-1 blockade

Although PD-1 inhibitors (PD-1i) are effective in some relapsed cHL patients, the mechanisms of resistance remain unclear. We investigated T cell dynamics in cHL using whole-exome sequencing (WES) of plasma circulating tumor DNA and longitudinal single-cell RNA and T-cell receptor sequencing of peripheral blood lymphocytes from a relapsed patient before and after PD-1i therapy.

Findings were validated at the protein level by flow cytometry in 11 relapsed HL patients (pre- and post-PD1i) and 6 healthy age-matched controls, and by PhenoCycler imaging of 24 tissue biopsies (13 diagnostic, 11 post-PD1i). WES identified two somatic mutations at relapse—MEX3B-Lys201* and TNFRSF10A-Tyr409His—potentially contributing to immune escape. Immune profiling revealed clonal expansion of CD8⁺ T cells at relapse and a shift from precursor-like (TCF1⁺) to intermediately exhausted (CX3CR1⁺) phenotypes.