Preliminary Results of the Canadian Paediatric Brain Tumour Consortium Phase II Study of Re-Irradiation as Treatment of Progressive or Recurrent Diffuse Intrinsic Pontine Glioma (Rerad)

Abstract

Background and Aims: The median survival from diffuse intrinsic pontine glioma (DIPG) remains under one year from initial therapy. At progression, re-irradiation (rRT) has been used at various doses and schedules, indicating extended survival around six months. Safety and effectiveness data are limited. Methods: In this international prospective study, patients with progressive DIPG were treated with rRT using consistent dosing and without additional anti-tumour intervention. rRT dose was 30.6 Gy if initial RT was given 6-18 months prior, and 36 Gy is given more than 18 months prior. The primary goal was to assess if rRT prolonged survival by >6 months in > 35% of patients. Results: Twenty-six eligible patients diagnosed at a median age of 6 years (4-12) initially treated with 54 Gy focal RT (54-55.8) were included. Median time from initial RT to rRT was 8 months (6-25). Dose of 30.6 Gy and 36 Gy rRT were delivered to 23 and 2 patients, respectively. One patient who withdrew early from study only received 25.2 Gy. Overall patient status and disease response, measured at 2 weeks (n = 26) and 6-8 weeks (n = 23) post rRT was stable or improved in 57% and 21%, respectively. The median survival time post rRT was 6.7 months (2.8-24.6). Nine patients (35%) subsequently enrolled on other clinical trials or pursued anti-tumor interventions at a median time of 4 months post rRT, either because of progression or personal choice. Of the remaining 17 patients, seven (41%) survived > 6 months.Grade II intratumoral necrosis was described on MRI in two patients. No patients discontinued rRT due to toxicity. Themedian duration of dexamethasone treatment was 12.5 days (1-37) used at a median maximum dose of 4 mg (2-16). Conclusions: rRT for progressive DIPG is safe and prolonged survival >6 months with improved or stable overall status within the first 6-8 weeks post treatment.