DDEL-08. A multicenter phase II trial of convection-enhanced delivery of ACNU in children with DIPG: Comparison with Japanese historical control and examination of patient selection bias

Abstract Diffuse intrinsic pontine glioma (DIPG) is a very challenging-to-treat pediatric malignant tumor, with a median survival time less than 12 months. Convection-enhanced delivery (CED) allows for direct drug administration into the tumor site, showing potential as a novel therapeutic approach. Recently, we reported the result of our study that evaluated the efficacy of CED of nimustine hydrochloride (ACNU) in children with DIPG (Saito R, et al. Cancer Sci 2025; jRCT2021190003). This phase 2, single-arm, multicenter study enrolled patients aged 3–21 years and diagnosed with DIPG. As a result, the 1-year survival rate from the start of radiotherapy was 60%, and the median survival time was 15 months. The response rate analyzed in 20 patients resulted in a response rate of 35% (CR+PR). In this study, we compared the results with Japanese historical controls as well as international registries. Reported median overall survival in Japanese historical control was 11 months, and in two international registries were 11.2 months and 11 months. In addition, in this study, we examined the previously reported prognostic factors for brainstem gliomas including symptomatic period before diagnosis, presence of cranial nerve palsy, infiltration outside the pons, and enhancement on MRI. There was no obvious bias in this study group in terms of prognostic factors, confirming that although this is a single-arm study, the groups are sufficiently comparable to the historical control data. Therefore, we concluded that the CED of ACNU in the brainstem of children with DIPG after radiotherapy appears to be an effective therapeutic strategy.