It has been found that BRG1 and BRM have a synthetic-lethal relationship, and that a treatment for inhibiting BRM is a promising approach for treating a BRG1-deficient cancer having no mutation in known therapeutic target genes. Moreover, it has also been revealed that, in this therapeutic strategy, a BRM inhibitor may be administered to a cancer patient after the selection based on BRG1 function suppression, thus enabling an efficient treatment based on the companion diagnosis.
