- Email: [email protected]
A Modern Animal Model of Radiation-induced Erectile Dysfunction
I. J. Radiation Oncology d Biology d Physics
S40
Volume 78, Number 3, Supplement, 2010
Such findings support the concept that bSOD protein might be a potential candidate for further, accelerated development as a therapeutic agent for use in deliberate or accidental radiation exposure. Acknowledgements: NIH-5U19AI-067798-04(ZNR)/RO1CA098452 (ZV). Author Disclosure: Z. Rabbani, None; I. Jackson, None; X. Zhang, None; P. Xu, None; Z. Vujaskovic, None.
84
Attenuation and Reversal of Radiation-induced Pulmonary Fibrosis in a Murine Model by an Anti-CTGF Monoclonal Antibody
S. Bickelhaupt1, P. Peschke1, C. Erbel2, A. Tietz1, C. Timke1, U. Wirkner1, J. Debus1, K. Lipson3, P. E. Huber1 1 3
Radiation Oncology dkfz/University Hospital, Heidelberg, Germany, 2Cardiology University Hospital, Heidelberg, Germany, FibroGen, San Francisco, CA
Purpose/Objective(s): Connective tissue growth factor (CTGF) is a matricellular protein that is a central mediator of tissue remodeling. CTGF expression is elevated in patients with idiopathic pulmonary fibrosis. Several studies in different organs have suggested that CTGF is essential for sustained fibrosis. Therefore, inhibition of CTGF may be therapeutically beneficial to fibrosis patients. Radiation induced lung fibrosis is a dose limiting side effect. Here we investigated this concept in a murine model of radiation induced lung fibrosis. Materials/Methods: Pulmonary fibrosis was initiated with a single, full thorax irradiation (20 Gy) to 6 groups of 25 mice. One group of mice remained untreated, while the other 5 groups received 8 weeks of control human IgG or an anti-CTGF monoclonal antibody (FG-3019). Administration of FG-3019 began 2 days before or after irradiation, or 20 days, or 16 weeks after irradiation. Two additional groups were not irradiated, but received 8 weeks of human IgG or FG-3019. Lung density of all surviving mice was monitored by computed tomography (CT). 30 weeks after irradiation, oxygen saturation was determined by blood gas analysis of surviving mice. Results: All groups receiving FG-3019 exhibited better survival than irradiated, untreated groups, with the 20-day group demonstrating the best survival. Histological examination demonstrated that significant lung remodeling occurred between 13 and 19 weeks after irradiation. FG-3019 attenuated this remodeling in a schedule-dependent manner, with the 20-day group exhibiting the least remodeling. Increased lung densities observed between 22 and 31 weeks after irradiation were attenuated by FG-3019 beginning 2 days before or after irradiation. Administration of FG-3019 beginning 20 days or 16 weeks after irradiation had also a beneficial effect on lung densities, with a sustained effect after cessation of the drug administration. Since the lung density in the 16-week group had already increased at the time that drug administration began, achieving normal lung density required reversal of the radiation-induced changes. Comparison of oxygen saturation with lung density at 30 weeks demonstrated a good correlation and suggested that reduction in lung density is a good surrogate for improvement in lung function. Conclusions: The anti-CTGF monoclonal antibody FG-3019 can attenuate radiation induced lung fibrosis and reverses established fibrosis, improves lung function, and increases the survival of mice. The data support further research on the role of CTGF in radiation response in general and may suggest a clinical evaluation of blocking CTGF signaling as a new concept for preventing radiation induced lung injury. Author Disclosure: S. Bickelhaupt, None; P. Peschke, None; C. Erbel, None; A. Tietz, None; C. Timke, None; U. Wirkner, None; J. Debus, None; K. Lipson, A, A. Employment; P.E. Huber, B, B. Research Grant.
85
A Modern Animal Model of Radiation-induced Erectile Dysfunction
M. Kimura1, B. F. Koontz1, H. Yan1, Z. Rabbani1, T. Satoh2, S. Baba2, F. Yin1, C. F. Donatucci1, T. J. Polascik1, Z. Vujaskovic1 1
Duke University Medical Center, Durham, NC, 2Kitasato University School of Medicine, Sagamihara, Japan
Purpose/Objective(s): To develop an animal model of radiation-induced erectile dysfunction (ED) mimicking highly conformal modern prostate therapies. Materials/Methods: Sixty young adult male rats aged 70-80 days old were divided into two groups: control (C) and treatment (T). For T animals, a single 20 Gy fraction to the prostate was delivered by 3D dynamic conformal arc using NovalisTX. Bioassay and intracavernosal pressure (ICP) measurements were then conducted at 2 weeks, 1 month, and 2 months after irradiation. For bioassay, the number of erections and yawns (a control behavior) were counted through recorded monitoring in a dimly lit, quiet isolated area over a 30-minute period after the administration of apomorphine (100mg/kg). Results were compared between groups using a Mann-Whitney rank sum test. ICP was measured under general anesthesia using electrical stimulation of the cavernous nerve (2, 4, 6, and 8 volts) with continuous monitoring of mean arterial pressure (MAP). After ICP measurements, penile shaft, bulb, and prostate tissues were harvested for histological and molecular analyses. Means of peak ICP and ICP/MAP ratio were evaluated by the Student’s t-test. Results: All treatment rats tolerated radiation very well with no toxicities during the observation period. There was no difference in the mean frequency of the control bioassay behavior between T and C animals at any time point (p = 0.11, 0.88, and 0.46, respectively). Bioassay did not find a reduction in erection frequency 2 weeks after radiation (p = 0.64), but a decrease in the mean number of erections was noted at both the 1 and 2 month endpoints (p \ 0.001). Peak ICP in T and C groups at 2 weeks, 1month, and 2 months were 43.4, 36.5, and 21.2 mm Hg and 42.1, 67.3, and 69.4 mm Hg, respectively. Results were significantly different for 1 and 2 month endpoints (2 week, p = 0.710; 1 month, p = 0.049; and 2 month, p = 0.014). As well as, the ICP/MAP ratio in T and C groups at 2 weeks, 1month, and 2 months were 0.51, 0.51, and 0.27 mm Hg and 0.56, 0.80, and 0.97 mm Hg, respectively. Results were significantly different for 1 and 2 month endpoints (2 week, p = 0.623; 1 month, p = 0.006; and 2 month, p \ 0.001). Conclusions: This is the first animal model to document use a highly conformal treatment technique to study normal tissue injury after prostate irradiation. We demonstrate time dependence of ED development, similar to that noted in clinical practice. Future pathological and molecular investigation of downstream tissues will be conducted, including analysis of endothelial and neural function, apoptotic and fibrotic changes, and oxidative stress. Author Disclosure: M. Kimura, None; B.F. Koontz, None; H. Yan, None; Z. Rabbani, None; T. Satoh, None; S. Baba, None; F. Yin, None; C.F. Donatucci, None; T.J. Polascik, None; Z. Vujaskovic, None.
S40
Volume 78, Number 3, Supplement, 2010
Such findings support the concept that bSOD protein might be a potential candidate for further, accelerated development as a therapeutic agent for use in deliberate or accidental radiation exposure. Acknowledgements: NIH-5U19AI-067798-04(ZNR)/RO1CA098452 (ZV). Author Disclosure: Z. Rabbani, None; I. Jackson, None; X. Zhang, None; P. Xu, None; Z. Vujaskovic, None.
84
Attenuation and Reversal of Radiation-induced Pulmonary Fibrosis in a Murine Model by an Anti-CTGF Monoclonal Antibody
S. Bickelhaupt1, P. Peschke1, C. Erbel2, A. Tietz1, C. Timke1, U. Wirkner1, J. Debus1, K. Lipson3, P. E. Huber1 1 3
Radiation Oncology dkfz/University Hospital, Heidelberg, Germany, 2Cardiology University Hospital, Heidelberg, Germany, FibroGen, San Francisco, CA
Purpose/Objective(s): Connective tissue growth factor (CTGF) is a matricellular protein that is a central mediator of tissue remodeling. CTGF expression is elevated in patients with idiopathic pulmonary fibrosis. Several studies in different organs have suggested that CTGF is essential for sustained fibrosis. Therefore, inhibition of CTGF may be therapeutically beneficial to fibrosis patients. Radiation induced lung fibrosis is a dose limiting side effect. Here we investigated this concept in a murine model of radiation induced lung fibrosis. Materials/Methods: Pulmonary fibrosis was initiated with a single, full thorax irradiation (20 Gy) to 6 groups of 25 mice. One group of mice remained untreated, while the other 5 groups received 8 weeks of control human IgG or an anti-CTGF monoclonal antibody (FG-3019). Administration of FG-3019 began 2 days before or after irradiation, or 20 days, or 16 weeks after irradiation. Two additional groups were not irradiated, but received 8 weeks of human IgG or FG-3019. Lung density of all surviving mice was monitored by computed tomography (CT). 30 weeks after irradiation, oxygen saturation was determined by blood gas analysis of surviving mice. Results: All groups receiving FG-3019 exhibited better survival than irradiated, untreated groups, with the 20-day group demonstrating the best survival. Histological examination demonstrated that significant lung remodeling occurred between 13 and 19 weeks after irradiation. FG-3019 attenuated this remodeling in a schedule-dependent manner, with the 20-day group exhibiting the least remodeling. Increased lung densities observed between 22 and 31 weeks after irradiation were attenuated by FG-3019 beginning 2 days before or after irradiation. Administration of FG-3019 beginning 20 days or 16 weeks after irradiation had also a beneficial effect on lung densities, with a sustained effect after cessation of the drug administration. Since the lung density in the 16-week group had already increased at the time that drug administration began, achieving normal lung density required reversal of the radiation-induced changes. Comparison of oxygen saturation with lung density at 30 weeks demonstrated a good correlation and suggested that reduction in lung density is a good surrogate for improvement in lung function. Conclusions: The anti-CTGF monoclonal antibody FG-3019 can attenuate radiation induced lung fibrosis and reverses established fibrosis, improves lung function, and increases the survival of mice. The data support further research on the role of CTGF in radiation response in general and may suggest a clinical evaluation of blocking CTGF signaling as a new concept for preventing radiation induced lung injury. Author Disclosure: S. Bickelhaupt, None; P. Peschke, None; C. Erbel, None; A. Tietz, None; C. Timke, None; U. Wirkner, None; J. Debus, None; K. Lipson, A, A. Employment; P.E. Huber, B, B. Research Grant.
85
A Modern Animal Model of Radiation-induced Erectile Dysfunction
M. Kimura1, B. F. Koontz1, H. Yan1, Z. Rabbani1, T. Satoh2, S. Baba2, F. Yin1, C. F. Donatucci1, T. J. Polascik1, Z. Vujaskovic1 1
Duke University Medical Center, Durham, NC, 2Kitasato University School of Medicine, Sagamihara, Japan
Purpose/Objective(s): To develop an animal model of radiation-induced erectile dysfunction (ED) mimicking highly conformal modern prostate therapies. Materials/Methods: Sixty young adult male rats aged 70-80 days old were divided into two groups: control (C) and treatment (T). For T animals, a single 20 Gy fraction to the prostate was delivered by 3D dynamic conformal arc using NovalisTX. Bioassay and intracavernosal pressure (ICP) measurements were then conducted at 2 weeks, 1 month, and 2 months after irradiation. For bioassay, the number of erections and yawns (a control behavior) were counted through recorded monitoring in a dimly lit, quiet isolated area over a 30-minute period after the administration of apomorphine (100mg/kg). Results were compared between groups using a Mann-Whitney rank sum test. ICP was measured under general anesthesia using electrical stimulation of the cavernous nerve (2, 4, 6, and 8 volts) with continuous monitoring of mean arterial pressure (MAP). After ICP measurements, penile shaft, bulb, and prostate tissues were harvested for histological and molecular analyses. Means of peak ICP and ICP/MAP ratio were evaluated by the Student’s t-test. Results: All treatment rats tolerated radiation very well with no toxicities during the observation period. There was no difference in the mean frequency of the control bioassay behavior between T and C animals at any time point (p = 0.11, 0.88, and 0.46, respectively). Bioassay did not find a reduction in erection frequency 2 weeks after radiation (p = 0.64), but a decrease in the mean number of erections was noted at both the 1 and 2 month endpoints (p \ 0.001). Peak ICP in T and C groups at 2 weeks, 1month, and 2 months were 43.4, 36.5, and 21.2 mm Hg and 42.1, 67.3, and 69.4 mm Hg, respectively. Results were significantly different for 1 and 2 month endpoints (2 week, p = 0.710; 1 month, p = 0.049; and 2 month, p = 0.014). As well as, the ICP/MAP ratio in T and C groups at 2 weeks, 1month, and 2 months were 0.51, 0.51, and 0.27 mm Hg and 0.56, 0.80, and 0.97 mm Hg, respectively. Results were significantly different for 1 and 2 month endpoints (2 week, p = 0.623; 1 month, p = 0.006; and 2 month, p \ 0.001). Conclusions: This is the first animal model to document use a highly conformal treatment technique to study normal tissue injury after prostate irradiation. We demonstrate time dependence of ED development, similar to that noted in clinical practice. Future pathological and molecular investigation of downstream tissues will be conducted, including analysis of endothelial and neural function, apoptotic and fibrotic changes, and oxidative stress. Author Disclosure: M. Kimura, None; B.F. Koontz, None; H. Yan, None; Z. Rabbani, None; T. Satoh, None; S. Baba, None; F. Yin, None; C.F. Donatucci, None; T.J. Polascik, None; Z. Vujaskovic, None.