Polyphyllins in cancer therapy: A systematic review and meta-analysis of animal studies

Background: Polyphyllins are secondary metabolites that inhibit the growth of various tumours; however, clinical trials on their use are lacking. Hypothesis/purpose: In this study, we aimed to evaluate the antitumour efficacy of polyphyllins in animal models. Study design: Systematic review and meta-analysis. Methods: Electronic bibliographic databases including PubMed, Web of Science, China Science and Technology Journal Database, Wanfang Data, and China National Knowledge Infrastructure were searched for relevant articles. The Systematic Review Centre for Laboratory Animal Experimentation's Risk of Bias tool was used to assess methodological quality. RevMan V.5.4 (Cochrane) and Stata MP 17 software were used to perform a meta-analysis. Results: Thirty articles were analysed including 33 independent experiments and 452 animals in this paper. Overall, tumour volume (standardised mean difference [SMD]: -3.35; 95 % confidence interval [CI]: -4.27 to -2.43; p < 0.00001) and tumour weight (SMD: -3.79; 95% CI: -4.75 to -2.82; p < 0.00001) were reduced by polyphyllins, which showed a good cancer therapeutic effect; mouse weight (SMD: -0.22; 95% CI: -0.61 to -0.18; p = 0.28) was insignificantly different, which indicated that polyphyllins did not affect the growth of the mice within the test range. Moreover, the molecular mechanisms of the antitumour activity of polyphyllins were explained, including the P53, NF-kB, AMPK, and ERK signalling pathways. Conclusion: Polyphyllins inhibit the growth of cancers within the experimental dose. However, due to heterogeneity of the results of the included studies, more studies are needed to support this conclusion.