Clinical trials for diffuse intrinsic pontine glioma: the current state of affairs

Purpose: Diffuse intrinsic pontine glioma (DIPG) is a lethal high-grade pediatric brainstem tumor without a cure. Despite numerous clinical trials over the last decades, the prognosis has remained poor. The aim of this update was to report on the status and outcomes of all clinical trials for DIPG performed to better understand the landscape of research efforts for this diagnosis to date. Methods: The ClinicalTrials.gov database was reviewed in May 2019 for all possible interventional clinical trials that included DIPG as a diagnosis of primary investigation. These were then screened against selection criteria to identify pertinent clinical trials. Results: Ninety-five clinical trials satisfied all inclusion criteria, with 55 (58%) trials specific to the DIPG diagnosis only. In terms of the most prevalent design features, 42 (44%) were phase I trials, with median expected start and completion years in 2011 (range, 1994–2020) and 2018 (range, 2005–2047), respectively. Median target number of patients to enroll was 38 (range, 1–1500), and the most common primary outcome was safety and toxicity (56%). There were 69 (73%) trials originating from the USA, with 49 (52%) of them being single institutional. Only 10 (11%) trials have reported results to date. Conclusions: To date, 95 clinical trials investigating DIPG with specific emphasis have been registered on ClinicalTrials.gov. There were only a small number of trials that had study results available, and they uniformly reported non-significant improvement to prognosis. Given the rarity and lethality of DIPG, which limits the accumulation of large cohorts, our results mandate the need for more robust, systematic clinical trial design to minimize redundancies and maximize yield in the future.