Abstract: Objective: To explore the effects and mechanism of slow intra-tumor release of drugs on B16 melonoma in mice. Methods: Bearing-tumor mice were randomly divided into four groups: the normal saline group, the Ara-C group, the Ara-C plus releasing drugs group and the the Ara-C plus releasing drugs and DNP group. Four days later, mice were treated again and the gross tumor volume was determined. Then 1 week later, the contents of three fibers were detected in the interstitial substances of the tumor and the infiltrations of T cells were determined in the splenic organs. Results: HE staining results showed that there was a large part of stenosis in the tumor, the fibers in the matrix of tumor were significantly increased and the CD4⁺T cells were also significantly increased in the two slow-release groups. Conclusion: Slow-release of drugs into the tumor is one of effective managements for directly inhibiting tumor growth and preventing micro-metastasis.

Key words: Melanoma, Slow-release drug therapy, Intratumoral chemotherapy, Dinitrophenyl, Modified antigen