Therefore, the cardiotoxicity of the Herceptin-loaded hydrogel was analyzed by echocardiography for the first time, and to simulate clinical application, a relapse model of HER2+ breast tumors was also constructed by imitative breast-conserving surgery on nude mice and the anti-relapse efficacy was evaluated after administration of the abovementioned hydrogel formulation, as illustrated in Figure 1B. The gene discussed is ERBB2; the disease is breast neoplasm.