The application of radiation therapy to the Pediatric Preclinical Testing Program (PPTP): results of a pilot study in rhabdomyosarcoma.
BACKGROUND
The Pediatric Preclinical Testing Program (PPTP) has been successfully used to determine the efficacy of novel agents against solid tumors by testing them within a mouse-flank in vivo model. To date, radiation therapy has not been applied to this system. We report on the feasibility and biologic outcomes of a pilot study using alveolar and embryonal rhabdomyosarcoma xenograft lines.


METHODS
We developed a high-throughput mouse-flank irradiation device that allows the safe delivery of radiotherapy in clinically relevant doses. For our pilot study, two rhabdomyosarcoma xenograft lines from the PPTP, Rh30 (alveolar) and Rh18 (embryonal) were selected. Using established methods, xenografts were implanted, grown to appropriate volumes, and were subjected to fractionated radiotherapy. Tumor response-rates, growth kinetics, and event-free survival time were measured.


RESULTS
Once optimized, the rate of acute toxicity requiring early removal from study in 93 mice was only 3%. During the optimization phase, it was observed that the alveolar Rh30 xenograft line demonstrated a significantly greater radiation resistance than embryonal Rh18 in vivo. This finding was validated within the standardized 30 Gy treatment phase, resulting in overall treatment failure rates of 10% versus 60% for the embryonal versus alveolar subtype, respectively.


CONCLUSIONS
Our pilot study demonstrated the feasibility of our device which enables safe, clinically relevant focal radiation delivery to immunocompromised mice. It further recapitulated the expected clinical radiobiology.
Wexner Medical Center at The Ohio State University, Arthur G. James Comprehensive Cancer Center and Richard L. Solove Research Institute, Columbus, Ohio.
Rita
R
Kaplon
Wexner Medical Center at The Ohio State University, Arthur G. James Comprehensive Cancer Center and Richard L. Solove Research Institute, Columbus, Ohio.
Mersiha
M
Hadziahmetovic
Wexner Medical Center at The Ohio State University, Arthur G. James Comprehensive Cancer Center and Richard L. Solove Research Institute, Columbus, Ohio.
Jim
J
Sommerfeld
Wexner Medical Center at The Ohio State University, Arthur G. James Comprehensive Cancer Center and Richard L. Solove Research Institute, Columbus, Ohio.
Kathryn
K
Bondra
Wexner Medical Center at The Ohio State University, Arthur G. James Comprehensive Cancer Center and Richard L. Solove Research Institute, Columbus, Ohio.
Lanchun
L
Lu
Wexner Medical Center at The Ohio State University, Arthur G. James Comprehensive Cancer Center and Richard L. Solove Research Institute, Columbus, Ohio.
Justin
J
Leasure
Wexner Medical Center at The Ohio State University, Arthur G. James Comprehensive Cancer Center and Richard L. Solove Research Institute, Columbus, Ohio.
Phuong
P
Nguyen
Wexner Medical Center at The Ohio State University, Arthur G. James Comprehensive Cancer Center and Richard L. Solove Research Institute, Columbus, Ohio.
Kelsey
K
McHugh
Wexner Medical Center at The Ohio State University, Arthur G. James Comprehensive Cancer Center and Richard L. Solove Research Institute, Columbus, Ohio.
Ning
N
Li
Wexner Medical Center at The Ohio State University, Arthur G. James Comprehensive Cancer Center and Richard L. Solove Research Institute, Columbus, Ohio.
Christopher
C
Chronowski
Wexner Medical Center at The Ohio State University, Arthur G. James Comprehensive Cancer Center and Richard L. Solove Research Institute, Columbus, Ohio.
Nikhil
N
Sebastian
Wexner Medical Center at The Ohio State University, Arthur G. James Comprehensive Cancer Center and Richard L. Solove Research Institute, Columbus, Ohio.
Mamta
M
Singh
Nationwide Children's Hospital, Columbus, Ohio.
Raushan
R
Kurmasheva
Nationwide Children's Hospital, Columbus, Ohio.
Peter
P
Houghton
Wexner Medical Center at The Ohio State University, Arthur G. James Comprehensive Cancer Center and Richard L. Solove Research Institute, Columbus, Ohio.|Nationwide Children's Hospital, Columbus, Ohio.
Christopher E
CE
Pelloski
D000818:Animals; D019583:Dose Fractionation, Radiation; D057166:High-Throughput Screening Assays / Q000295:instrumentation*; D006801:Humans; D051379:Mice; D010865:Pilot Projects; D011878:Radiotherapy / Q000295:instrumentation* / Q000379:methods*; D012208:Rhabdomyosarcoma / Q000532:radiotherapy*; D023041:Xenograft Model Antitumor Assays