Disclosed are applications of spermidine and its derivative. Based on existing protein structure data and small molecular data, the inventor performs screening by means of software-based computational analysis to obtain compounds that can effectively interfere with PAICS activity. After the compounds are used, the synthesis of SAICAR can be reduced, so that the purpose of treating or mitigating tumors. By using drugs in combination, it is likely to achieve a better effect of treating or mitigating tumors.
