New use for old drugs: The protective effect of atypical antipsychotics on hepatocellular carcinoma

<jats:sec><jats:label/><jats:p>It has been encouraged to use large existing data like insurance claims data to investigate the new indications of old drugs. New strategies of research are warranted to identify feasible drugs. We conducted a dual research model with a population‐based case–control study using Taiwan's National Health Insurance Research Database and an <jats:italic>in vitro</jats:italic> study to investigate the association between atypical antipsychotic and Hepatocellular carcinoma (HCC) risk. The study herein consists of two components. The first is a population‐based case–control study using existing data from the Taiwan National Health Insurance Research Database. The second component was an <jats:italic>in vitro</jats:italic> study in which HCC cell lines (Huh7 and Hep G2) were treated with risperidone, quetiapine and clozapine. after treatment of the foregoing antipsychotics, the HCC cell lines were assessed for cell proliferation, invasion and apoptosis. Multivariate conditional logistic regression analysis revealed that antipsychotic use was independently and inversely associated with HCC risk (adjusted odds‐ratio [aOR]:0.85, 95% CI: 0.81–0.89). The protective effect was dose‐dependent: compared to the low cumulative defined daily dose (cDDD) group (0–29 cDDD), the 30–89 cDDD and ≥90 cDDD groups were associated with significantly reduced risk for HCC (aOR: 0.56, 95% CI: 0.41–0.76; aOR: 0.37, 95% CI: 0.27–0.50, respectively). <jats:italic>In vitro</jats:italic> study results indicated that risperidone, quetiapine and clozapine significantly inhibited cell proliferation, invasion and induced apoptosis in human HCC cell lines. Our results herein suggested that antipsychotic use might reduce the risk of HCC and may provide evidence for new uses of old drugs.</jats:p></jats:sec>