Pediatric Cancer

SS 14 - Pediatrics 2

100 - A Phase I/II Trial of Reirradiation for Diffuse Intrinsic Pontine Glioma

Monday, October 22
10:55 AM - 11:05 AM
Location: Room 008

A Phase I/II Trial of Reirradiation for Diffuse Intrinsic Pontine Glioma
M. J. Amsbaugh1, A. Mahajan2, P. Thall1, M. F. McAleer3, D. R. Grosshans1, A. C. Paulino3, L. Ketonen3, S. Khatua3, and S. L. McGovern3; 1University of Texas MD Anderson Cancer Center, Houston, TX, 2Department of Radiation Oncology, Mayo Clinic, Rochester, MN, 3The University of Texas MD Anderson Cancer Center, Houston, TX

Purpose/Objective(s): Reirradiation (reRT) is increasingly considered for treatment of progressive diffuse intrinsic pontine glioma (DIPG). This phase I/II trial was performed to identify an optimal radiation dose for reRT of DIPG.

Materials/Methods: Patients with progressive DIPG at least 10 months after initial radiation were eligible. ReRT dose levels were selected sequentially using an adaptive utility based dose-finding method. The co-primary endpoints were toxicity (mild, moderate, high or severe) and efficacy one month following ReRT. Efficacy was based on improvement in three domains: imaging, physician assessment of clinical status, and patient and family reported quality of life (QOL). Secondary endpoints were progression free and overall survival. Utility of each dose level was calculated based on a combined toxicity/efficacy score: 0 (maximal toxicity, no efficacy) to 100 (no toxicity, maximal efficacy).

Results: Between 2012 and 2015, 12 patients were enrolled and underwent reRT at three dose levels: 24Gy in 12 fractions of 2Gy (6 patients), 26.4 Gy in 12 fractions of 2.2Gy (4 patients) and 30.8 Gy in 14 fractions of 2.2 Gy (2 patients). Median age of all patients was 6 years (range 4 - 26 years) and median interval from initial radiation was 12.8 months (range 10.6 – 74.6 months). Patients had previously received treatment to a median dose of 54 Gy (range 50.4 – 56 Gy). All patients completed the planned reirradiation. Only one patient treated at dose level 3 developed a grade 3 acute toxicity. All other patients experienced grade 1 or 2 toxicities at most. Five of the six patients receiving 24 Gy demonstrated improvement in two of three efficacy domains, and the sixth demonstrated improvement in all three efficacy domains. Of four patients receiving 26.4 Gy, one demonstrated no improvement and one patient each demonstrated improvement in one, two and three efficacy domains. Of two patients receiving 30.8 Gy, one did not complete the QOL and could not be assessed; the other demonstrated improvement in all three efficacy domains. Mean utilities were 88 for dose level 1, 76 for dose level 2, and 25 for dose level 3. For all patients, the median overall survival was 19.5 months from initial diagnosis (95% CI 15.6 – 21.1 months) and the median progression free survival was 4.5 months from start of reRT (95% CI 2.7 – 6.2 months).

Conclusion: ReRT can safely be delivered for progressive DIPG. In this first prospective assessment of reRT in DIPG, all but one demonstrated objective clinical improvement. Utility analysis suggests that the best balance of toxicity and efficacy after reRT was obtained with 24 Gy in 12 fractions.

Author Disclosure: M.J. Amsbaugh: Employee; Mischer Neuroscience Associates. A. Mahajan: Secretary; PTCOG-NA. Membership; PROS. P. Thall: None. M. McAleer: Honoraria; PREX S. p. A, AOSpine, Osler Institute. Speaker's Bureau; Osler Institute. Travel Expenses; Osler Institute. D.R. Grosshans: Employee; MD Anderson. A.C. Paulino: Royalties for text book; Elsevier Inc. Committee Member; ABR. L. Ketonen: None. S. Khatua: None. S.L. McGovern: Independent Contractor; MD Anderson Physicians Network. Honoraria; American College of Radiology. Travel Expenses; American College of Radiology.

Mark Amsbaugh, MD

Disclosure:
Employment
MD Anderson: Fellow: Employee; Mischer Neuroscience Associates: Physician: Employee

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