Preliminary results of immune modulating antibody MDV9300 (pidilizumab) treatment in children with diffuse intrinsic pontine glioma.

Diffuse intrinsic pontine glioma (DIPG) is an incurable disease with a median overall survival of 10 months. Immune modulating antibodies have recently emerged as a highly promising treatment modality in multiple cancer types. We present results from the first study to evaluate the immune modulating antibody MDV9300 (pidilizumab) in pediatric patients with DIPG. All patients aged 3 years and older, diagnosed with DIPG between February 2014 and June 2015 in Israel, were offered to participate in the study. Enrolled patients were started on biweekly 6 mg/kg MDV9300 after radiation completion. Treatment was continued until disease progression on imaging. Patients were followed biweekly for the occurrence of neurological deficit toxicities and side effects. Secondary endpoints were event free survival and overall survival. Of 13 children diagnosed with DIPG during the study period, nine were enrolled in the study. The patients underwent radiotherapy and none had chemotherapy. A total of 83 cycles of MDV9300 (range 2-16) were applied. The main side effects were neutropenia (CTCAE grade 1-3), mild to moderate fatigue, and acute elevation of blood pressure. Four patients died within 1 year of the diagnosis, another three died within 2 years and two children are still alive nearly 30 months from diagnosis, with stable disease. The median event free survival is 9.3 months (range 6.8-24) and the median overall survival is 15.6 months (range 6.9-28). Preliminary results demonstrate that MDV9300 treatment is safe and may be effective in the treatment of children with DIPG.