Another CRISPR/Cas9 application in humans is the ex vivo‐programmed cell death protein 1 (PD1) gene deactivation in T‐lymphocytes of a lung cancer patient and subsequent introduction of the edited cells into the patient, which was based on previous encouraging in vitro results.113, 114PD‐1 gene modification is a promising approach that should be clinically trialed for other malignancies, but caution in trial designs with CRISPR/Cas9 needs to be taken when it comes to ethical requirements of scientific validity.115. The gene discussed is PDCD1; the disease is lung cancer.