We radiolabelled a previously characterised selective peptide modulator (EgK5) of Kv1.3 channels [16] to quantify Kv1.3 channel expression on tumour infiltrating TEM cells and evaluated whether this novel Kv1.3-targeting peptide-radiopharmaceutical, [18F]AlF-NOTA-KCNA3P (Figure 1), was able to successfully stratify response to ICIs in a CT26 syngeneic colon cancer model in vivo, correlating tumour retention to tumour infiltrating immune cells using flow cytometry. The gene discussed is KCNA3; the disease is colonic neoplasm.