Role of Companion Diagnostics in Advancing Patient-Centered Anticancer Drug Treatment

Cancer is an age-related disease that affects one in two Japanese individuals, placing a significant burden on both patients and caregivers due to its clinical characteristics, high treatment costs, and associated adverse events (AEs). Consequently, cancer treatment remains a major public concern. In recent years, patient-centered medical care has gained increasing attention and is strongly desired in cancer treatment. Companion diagnostics (CDx) are expected to facilitate personalized treatment; however, their current status remains unclear. In this study, we evaluated the role of CDx in anticancer drug treatment based on data available at the time of drug approval. Our analysis revealed that the benefit-risk ratio, defined as the objective response rate of an anticancer drug divided by the incidence of severe AEs, was significantly higher for anticancer drugs requiring CDx (wCDx) in Japanese patients (1.54-fold, p < 0.0135) than for anticancer drugs not requiring CDx. Although the objective response rate did not differ between the 2 groups, the incidence of severe AEs was lower in the wCDx group. These findings suggest that CDx helps identify patients who are better suited for specific anticancer treatments and/or that active pharmaceutical ingredients in wCDx therapies carry a lower risk of severe AEs. To further promote patient-centered medical care, the active development of CDx alongside new anticancer drugs should be encouraged, despite the higher development hurdles, through regulatory support, particularly since drug pricing does not differ between the 2 groups.