PDCD1 and non-small cell lung carcinoma: Herein, we show that ficoll density gradient centrifugation, ISET, and Parsortix result in comparable outcomes in spiking experiments; however, in patient samples, they demonstrate variable efficacy, enrich for distinct CTC subpopulations, and provide complementary prognostic information in NSCLC patients treated with anti-PD-1 ICIs.