The treatment of malignant gliomas is very tricky. Despite significant efforts over the last 30 years, patient prognosis remains poor, with the average survival for patients with glioblastoma (GBM) still less than 1 year and for patients with mesenchymal stromal cell tumor (AA) less than 2 years. Surgery combined with radiotherapy and chemotherapy remains the mainstay of treatment for malignant gliomas, however surgery does not completely remove residual tumor cells, which are the source of postoperative recurrence. Radiotherapy is also difficult to achieve cure due to dose limitation, and many chemotherapeutic drugs cannot cross the blood-brain barrier well, so the local drug concentration in the tumor is low, the maintenance time is short, and it is difficult to produce significant effect and heavy toxic reaction. Although malignant brain tumors grow infiltratively, most tumor recurrences are mostly within 2 cm of the primary site. Therefore, new effective local treatment modalities have attracted great academic interest and have shown great superiority. Under the current treatment paradigm, malignant gliomas almost invariably recur, and there is no uniform treatment plan after recurrence. Reoperation is the main option for many patients and has a definite role in prolonging their survival time. Since most patients have already received radiation therapy at the time of initial treatment, reoperation after recurrent malignant glioma is more often the only option for rechemotherapy. In recent years, with the development and application of medicinal polymer materials, local slow release of drugs has become possible and a new direction. Intra-stromal chemotherapy for intracranial tumors allows chemotherapeutic drugs to avoid the blood-brain barrier and act directly on the tumor, ensuring a long-lasting and more stable drug concentration in the local drug range, reducing the systemic drug concentration and alleviating toxic side effects, which brings hope to glioma chemotherapy. At present, there are many studies for local extended-release treatment of tumors, but few are approved for clinical application. Among them, the study of carmustine extended-release implant for the treatment of brain tumors is the most reported. Preclinical trials have demonstrated that this implant releases high concentrations of carmustine (BCNU) locally, which is significantly superior to conventional methods (Yang MB et al., 1989 Cancer Res 49: 5103-07 (Ref 1)). Intracranial placement of carmustine increases local drug concentrations by 4-1200-fold compared with intraperitoneal administration (Fung LK et al., 1998 Cancer Res 58:672-684 (Ref 2)). The treatment of brain tumors in patients with carmustine extended-release implants was first studied by Brem’s group at Hopkins University (Brem H et al., 1991 J Neurosurg 74: 441-446 (Ref 3)). Based on its safety and good therapeutic effect on tumors, phase III clinical studies of carmustine extended-release implants (trade name: Gliadel wafers) were approved in the United States and in many countries around the world. Between March 1989 and January 1992, Guilford Pharmaceuticals, Inc. conducted a randomized, double-blind, placebo-controlled phase III clinical trial at 27 centers in the United States and Canada to demonstrate the safety and efficacy of carmustine extended-release implants in the treatment of recurrent malignant gliomas (Brem H et al., 1995 Lancet 345: 1008-1012 (Another randomized, double-blind phase III clinical trial was conducted between December 1997 and June 2000, which included 240 patients with primary malignant glioma at 42 centers in 14 countries (Westphal M et al., 2003 Neuro-Oncol 5: 79-88 (Ref 5)). The above clinical studies became supportive studies for marketing approval in the US Food and Drug Administration (FDA), Canada and other developed countries. Polyphenylpropion implant tablets containing 3.85% carmustine, trade name Gliadel wafers, were first approved for the treatment of patients with recurrent malignant glioma and later added for the treatment of patients with newly diagnosed malignant glioma. McGirt et al. of the Department of Neurosurgery at Johns Hopkins School of Medicine studied the safety and efficacy of Gliadel in combination with temozolomide (TMZ) for the treatment of patients with glioblastoma multiforme after initial surgical resection (Ref 6). The results showed that the median survival in the radiotherapy + Gliadel + TMZ group (30 patients) compared with the radiotherapy + Gliadel group (78 patients) was 21.3 and 12.4 months, respectively (p = 0.005), with 2-year survival rates of 39% and 18%, respectively. Radiotherapy + Gliadel + TMZ treatment did not increase the incidence of adverse events before and after surgery compared with radiotherapy + Gliadel treatment. Shandong Lanjin Bioengineering Co., Ltd. developed China’s first anti-cancer slow-release implant with independent intellectual property rights, the treatment of carmustine slow-release implant. The active ingredient of the drug is the same as the foreign marketed implant (trade name: Gliadel wafers), which is carmustine, while the extended-release excipient is ethylene glycolate-propyleneglycolate copolymer. The ethylene glycolate-propyleneglycol copolymer is a biocompatible, biodegradable and absorbable polymer whose final metabolites are carbon dioxide and water, with no residues. The clinical study has been approved by the State Food and Drug Administration (CFDA), and a randomized, double-blind, placebo-controlled, multicenter clinical study of carmustine extended-release implant for the treatment of recurrent malignant glioma has been initiated in more than 20 hospitals nationwide.