Abstract: T cell receptor (TCR) diversity of a subject, including TCR diversity in CD8+ T cell subsets, is used as a predictive indicator of responsiveness of the subject to cancer immunotherapy prior to initiation of the immunotherapy. Exemplified immunotherapy comprises administering an immune checkpoint inhibitor to a subject, wherein a TCR diversity value in CD8+ T cell subsets from the subject, such as CD8+ T cell subpopulations defined by differential cell surface marker expression, is higher than a reference value.

Abstract: The present disclosure provides a technique whereby the influence of an endogenous TCR is eliminated in TCR gene transfer. A TCR gene is edited using a genome editing enzyme, said genome editing enzyme having one characteristic that amino acids at two specific positions in DNA-binding modules contained in a DNA-binding domain thereof show repeating patterns which differ from one module to another among the four DNA-binding modules. Thus, a lowering in the expression efficiency of the transferred TCR caused by mispairing with an endogenous TCR and the occurrence of a self-reactive TCR are avoided.

Abstract: The repertoire of the variable region of T cell receptors (TCR) or B cell receptors (BCR) is quantitatively analyzed using non-biased gene sequence analysis. The present invention provides the following: a method for quantitatively analyzing the repertoire of the variable region of the T cell receptors (TCR) or B cell receptors (BCR) of a subject by using a database, wherein the method includes (1) a step for providing a nucleic acid sample containing the nucleic acid sequence of T cell receptors (TCR) or B cell receptors (BCR) amplified in a non-biased manner from the subject; (2) a step for determining the nucleic acid sequence contained in the nucleic acid sample; and (3) a step for calculating the frequency of appearance of each gene or combination thereof on the basis of the determined nucleic acid sequence and deriving the TCR or BCR repertoire of the subject.