Afaf Abed, MBBS, FRACP, Fiona Stanley Hospital, Murdoch, Australia, provides an overview of the prognostic and predictive value of the pre-treatment T-Cell receptor (TCR) repertoire in patients with non-small-cell lung cancer (NSCLC) receiving single agent immunotherapy. Increased clonality and a reduction in Shannon diversity is linked to an increased response to single agent immunotherapy. Whilst the potential the pre-treatment TCR repertoire as a predicative biomarker is promising, further research is required and may need to be combined with existing biomarkers. This interview took place during the 36th Society for Immunotherapy of Cancer (SITC) Annual Meeting in Washington, D.C.