ID #761 Feasibility study of hypofractionated radiotherapy in the setting of recurrent diffuse intrinsic pontine glioma
Natasha Pillay Smiley, Christopher Freese, Andrew Frankart, John Breneman, Ralph Vatner, Vinita Takiar, Luke PaterAbstract
Background
Diffuse intrinsic pontine glioma (DIPG) is a typically fatal brainstem tumor, with progression commonly occurring within several months after standard radiotherapy. Palliative re-irradiation (reRT) has shown symptomatic benefit in retrospective series; however, prospective data using hypofractionated regimens are limited. This study prospectively evaluated the tolerability of hypofractionated reRT in patients with progressive DIPG.
Methods
This study was performed at University of Cincinnati/Cincinnati Children’s Hospital Medical Center and enrolled progressive DIPG patients who previously received definitive radiotherapy (≥54 Gy) at least 6 months prior to enrollment. 15 Gy in 3 fractions of hypofractionated reRT was given twice weekly using intensity-modulated radiation therapy. The primary endpoint was tolerability, defined as completion of therapy without serious adverse events (SAEs) attributable to reRT.
Results
Five patients were enrolled (median age:4.8 years; range 3.2-10 years) and completed reRT without dose reductions or treatment discontinuation. ReRT was given at a mean of 12.3 months (median 12.9 mo., range 9.4-14.7 mo.) from diagnosis and a mean of 9.5 months from the end of initial radiation (median 10.1 mo., 7.6-10.3 mo.). Treatment was generally well tolerated with grade 1-2 adverse events most commonly neurologic, gastrointestinal, and ophthalmologic in nature (Table 1). Four grade ≥3 toxicities occurred, including gait disturbance/ ataxia, aphonia, and agitation. No grade 4–5 treatment-related toxicities were observed. All deaths (n = 5)were attributable to disease progression. No unexpected radiation-related AEs were seen. Mean overall survival from diagnosis was 17.4 months (median 16.1 mo., range 14.2-22.5 mo.) with mean survival from reRT of 4.9 months (median 5 mo., range 1.7-7.8 mo.)
Conclusions
Hypofractionated re-irradiation of 15 Gy in three fractions was feasible and reasonably well tolerated in this small cohort of patients with progressive DIPG. Further analysis of imaging characteristics and longer-term symptom control is pending.