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Role of Bone Marrow Derived Macrophages and Stromal Cells in Irradiation-Induced Pulmonary Fibrosis
S470
I. J. Radiation Oncology
2404
● Biology ● Physics
Volume 63, Number 2, Supplement, 2005
Possible Fractionation Regimens for the Treatment of Large-size Arteriovenous Malformation Using IMRT
X. Qi, C.J. Schultz, X. Li Medical College of Wisconsin, Milwaukee, WI Purpose/Objective: It is not feasible to use single fraction Stereotactic Radiosurgery (SRS) to deliver therapeutic doses for large size (⬎ 35 cc) intracranial arteriovenous malformations (AVMs) due to the risk of complications. Clinical studies demonstrate obliteration rates increase with dose; though so do normal tissue complications. Image guided intensity modulated radiation therapy (IG-IMRT), such as Helical Tomotherapy (HT), may allow delivery of high doses to large intracranial lesions while sparing critical structures. Because of the non-invasive image guidance, accurate multiple-fractionation treatment can be reliably carried out with HT. The purpose of this work is to determine possible fractionation regimens suitable for IG-IMRT of large-size AVMs. Materials/Methods: The LQ formalism and the Poisson TCP model were used to analyze a series of reported clinical outcomes from SRS for AVMs. The obliteration rates at 3-year angiographic follow-up observed at many institutes were compiled and evaluated to derive radiobiological parameters, such as ␣/ ratio. Such determined parameters were used to calculate possible fractionation regimens for IMRT based on the concept of biologically effective dose (BED) and equivalent uniform dose (EUD). The dose heterogeneities of SRS with LINAC and Gamma knife and of helical tomotherapy (HiArt, Tomotherapy Inc.) were considered by using representative dose volume histograms (DVHs) of target and normal structures (e.g., brain) for each of these modalities (Fig. 2). Normal tissue complications measured by EUD and NTCP were considered in the calculation. The possible new regimens are those with equal or lower complication rates than those reported for SRS. The biological effectiveness, as measured by a figure-of-merit index (fEUD) based on EUD, for those possible regimens were compared with the existing standard SRT regimens. The sensitivity of parameters on the calculation was also studied. Results: The radiobiological analysis of a series of clinical studies is shown in Fig. 1. This analysis yields a ␣/ ratio of 2.1 ⫾ 7.6 (Gy) for AVMs, indicating that AVM has a typical late response to radiation. Using this value, possible fractionation regimens with 2, 4, 6, 8, 10 or 20 fractions are tabulated (Tab. 1). The values of EUDs and fEUD for these regimens are included in Tab. 2. It is seen that the multi-fractionation treatments by the IMRT result in higher treatment effectiveness as compared with the Linac-based stereotactic radiotherapy (SRT). Calculation with different ␣/ ratios showed the results were moderately dependent on the parameter used. Conclusions: Clinically relevant radiobiological parameter, ␣/ ratio is determined to be 2.1 Gy for AVM based on the analysis of a series clinical studies. Possible fractionation regimens which are suitable for image-guide IMRT are derived for large size AVMs. The tomotherapy can potentially deliver more effective treatment for large-size AVMs than currently used Linac-based SRT schemes. Clinical trials are needed to confirm the results.
2405
Role of Bone Marrow Derived Macrophages and Stromal Cells in Irradiation-Induced Pulmonary Fibrosis
Y. Niu,1 M.W. Epperly,1 T. Carlos,2 X. Zhang,1 J.S. Greenberger1 Radiation Oncology, University of Pittsburgh, Pittsburgh, PA, 2Medicine, University of Pittsburgh, Pittsburgh, PA
1
Purpose/Objective: In the C57BL/6NHsd mouse marrow chimera model of pulmonary irradiation fibrosis/organizing alveolitis, bone marrow derived macrophages and fibroblasts migrate into the lungs 80 to 120 days after 20 Gy lung irradiation. Fibroblasts proliferate resulting in deposition of collagen and the development of fibrosis. A detectable increase in TNF␣ and TGF expression occurs before migration of fibroblasts into the lungs. To determine the role of macrophages in the development of flung fibrosis, we blocked pulmonary migration of monocyte/macrophages using antibodies to mouse macrophages. To determine the role of TGF in attracting marrow myofibroblasts into the lung we used clonal bone marrow stromal cells lines derived from Smad3⫺/⫺ knockout mice, which have the TGF signal transduction pathway altered by removal of the Smad3 gene, compared to cell lines from control Smad3⫹/⫹ mice.
Proceedings of the 47th Annual ASTRO Meeting
Materials/Methods: C57BL/6NHsd mice were irradiated to 20 Gy to the pulmonary cavity. Bone marrow stromal cell lines were isolated from Smad3⫹/⫹ or Smad3⫺/⫺ mice and transfected with a retrovirus containing DS-red or GFP transgene, respectively. At 80 days after irradiation, subgroups of mice were injected intravenously (IV) with cells from the DS-redSmad3⫹/⫹ or GFP-Smad3⫺/⫺ bone marrow stromal cell line. In other subgroups, mice were injected intraperitoneally (IP) for 15 days (Monday-Friday for 3 weeks) with monoclonal rat anti-mouse antibodies to either T-cells (T1B-207) or macrophages (M1/70). All mice were followed for the development of irradiation-induced fibrosis. Results: In areas of organizing alveolitis/fibrosis, we detected both GFP Smad3⫺/⫺ cells and DS-red Smad3⫹/⫹ cells. However, there was increased accumulation of Smad3⫹/⫹ DS-red cells compared to GFP Smad3⫺/⫺ cells. In mice treated with anti-macrophage antibody, M1/70 antibody treated animals had increased survival compared to mice that received irradiation only (p ⫽ 0.0225) or T1B-207 antibody. Conclusions: Migration of both marrow origin macrophages and fibroblasts play a critical role in the development of pulmonary irradiation fibrosis. Disruption in the migration of one cell phenotype or altering their response to TGF impairs the development of irradiation-induced fibrosis.
2406
Does a p53 Inhibitor Protect Mice Against the Toxicity of High-Dose Abdominal Radiotherapy?
L. Cai,1 W.A. Weber,2 N.H. Andratschke,1 S. Schill,1 M. Molls,1 C. Nieder1 Dept. of Radiation Oncology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany, 2Dept. of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
1
Purpose/Objective: To test whether the chemical inhibitor of p53 1-(4-Methylphenyl)-2-(4,5,6,7-tetrahydro-2-imino-3(2H)benzo) ethanone hydrobromide, also known as pififthrin-alpha, prevents radiation-induced bowel and kidney toxicity. Materials/Methods: Thirty-three adult female C3H mice were treated with single-fraction radiotherapy of 15 Gy to the right middle abdomen either with or without pififthrin-alpha injection before irradiation. The kidney function was assessed prior to radiotherapy and 19 weeks thereafter by means of 99mTc-dimercaptosuccinat (DMSA) scans (static scintigraphy). The mice were followed until death and autopsy was performed to confirm the cause of death. Results: At baseline, the right kidney had a median proportion of total function of 54⫾2% in control mice and 51⫾3% in mice treated with pififthrin-alpha. After 19 weeks, the function of the irradiated right kidney declined to 41⫾9% vs. 43⫾3%. The difference in radiation-induced kidney dysfunction between both groups was not statistically significant (t-test, p⬎0.1). Radiation treatment induced lethal bowel toxicity, confirmed by autopsy, in 89% of controls and 100% of pififthrin-alphatreated mice. Actuarial median survival (Kaplan-Meier analysis) was 89 vs. 85 days from radiation treatment (difference not statistically significant, log-rank-test, p⬎0.1). Conclusions: In contrast to an earlier publication (Science 1999; 285: 1733ff), where different mouse strains (Balb/c and C57BL) received total body irradiation with lower doses with or without pififthrin-alpha and where the compound improved survival, pififthrin-alpha had no significant protective effect when given before high-dose local abdominal radiotherapy. Thus, the hypothesis that abrogation of p53 signaling induces radioresistance of normal tissues has to undergo further critical examination.
2407
A Model of Experimental Kidney Irradiation for Screening of Response Modifiers: Evaluation of Insulinlike Growth Factor-1 (IGF-1) and Erythropoietin (EPO)
A. Schnaiter,1 L. Cai,1 N.H. Andratschke,1 S. Schill,1 W.A. Weber,2 M. Molls,1 C. Nieder1 Dept. of Radiation Oncology, Klinikum rechts der Isar, TU Munich, Munich, Germany, 2Dept. of Nuclear Medicine, Klinikum rechts der Isar, TU Munich, Munich, Germany
1
Purpose/Objective: The kidney is one of the most radiosensitive abdominal organs. Therefore, modification of its radiation response might improve the therapeutic ratio in a variety of common tumors treated with radiotherapy. Growth factors are increasingly being studied as response modifiers. To evaluate their role in conjunction with irradiation of the kidney, we established an experimental mouse model. Materials/Methods: Adult female C3H mice were treated with single-fraction radiotherapy to the right kidney with doses of 6 –17 Gy and with or without two different growth factors, i.e. IGF-1 and EPO. The kidney function was assessed prior to radiotherapy, 19 weeks thereafter and then every 6 weeks by means of 99mTc-dimercaptosuccinat scans, i.e. static scintigraphy. Maximum follow-up was 12 months. IGF-1 was given subcutaneously either concomitant to radiotherapy or after deterioration of the kidney function, i.e. after 5– 6 months. Delayed treatment after deterioration of the kidney function was administered over 4 weeks, immediately followed by repeat scans every 6 weeks. Doses of IGF-1 were 0.5-25 g per injection. EPO was given concomitant to radiotherapy in a dose of 500 IU or 2000 IU/kg body weight. Results: The function of the irradiated kidney continuously declined during follow-up in all control groups in a dose-dependent fashion. Very accurate and reproducible results were obtained when examining the same control animals several times before the development of kidney dysfunction with this method of static scintigraphy. Concomitant treatment with IGF-1 significantly reduced the decline of the median kidney function. The best dose of IGF-1 was 5 g per injection, administered over 2 weeks. Delayed treatment after deterioration of the kidney function was unable to restore the function regardless of the IGF-1 dose. Very few animals in the groups with delayed IGF-1 showed at least stabilisation of the compromised kidney function. EPO actually increased the degree of radiation-induced kidney dysfunction significantly. The higher dose of EPO caused more damage than the lower dose. Conclusions: We have developed a relatively simple, accurate method for screening of response modifiers in the context of mouse kidney irradiation. Our results demonstrate that administration of growth factors concomitant to radiotherapy causes
S471
I. J. Radiation Oncology
2404
● Biology ● Physics
Volume 63, Number 2, Supplement, 2005
Possible Fractionation Regimens for the Treatment of Large-size Arteriovenous Malformation Using IMRT
X. Qi, C.J. Schultz, X. Li Medical College of Wisconsin, Milwaukee, WI Purpose/Objective: It is not feasible to use single fraction Stereotactic Radiosurgery (SRS) to deliver therapeutic doses for large size (⬎ 35 cc) intracranial arteriovenous malformations (AVMs) due to the risk of complications. Clinical studies demonstrate obliteration rates increase with dose; though so do normal tissue complications. Image guided intensity modulated radiation therapy (IG-IMRT), such as Helical Tomotherapy (HT), may allow delivery of high doses to large intracranial lesions while sparing critical structures. Because of the non-invasive image guidance, accurate multiple-fractionation treatment can be reliably carried out with HT. The purpose of this work is to determine possible fractionation regimens suitable for IG-IMRT of large-size AVMs. Materials/Methods: The LQ formalism and the Poisson TCP model were used to analyze a series of reported clinical outcomes from SRS for AVMs. The obliteration rates at 3-year angiographic follow-up observed at many institutes were compiled and evaluated to derive radiobiological parameters, such as ␣/ ratio. Such determined parameters were used to calculate possible fractionation regimens for IMRT based on the concept of biologically effective dose (BED) and equivalent uniform dose (EUD). The dose heterogeneities of SRS with LINAC and Gamma knife and of helical tomotherapy (HiArt, Tomotherapy Inc.) were considered by using representative dose volume histograms (DVHs) of target and normal structures (e.g., brain) for each of these modalities (Fig. 2). Normal tissue complications measured by EUD and NTCP were considered in the calculation. The possible new regimens are those with equal or lower complication rates than those reported for SRS. The biological effectiveness, as measured by a figure-of-merit index (fEUD) based on EUD, for those possible regimens were compared with the existing standard SRT regimens. The sensitivity of parameters on the calculation was also studied. Results: The radiobiological analysis of a series of clinical studies is shown in Fig. 1. This analysis yields a ␣/ ratio of 2.1 ⫾ 7.6 (Gy) for AVMs, indicating that AVM has a typical late response to radiation. Using this value, possible fractionation regimens with 2, 4, 6, 8, 10 or 20 fractions are tabulated (Tab. 1). The values of EUDs and fEUD for these regimens are included in Tab. 2. It is seen that the multi-fractionation treatments by the IMRT result in higher treatment effectiveness as compared with the Linac-based stereotactic radiotherapy (SRT). Calculation with different ␣/ ratios showed the results were moderately dependent on the parameter used. Conclusions: Clinically relevant radiobiological parameter, ␣/ ratio is determined to be 2.1 Gy for AVM based on the analysis of a series clinical studies. Possible fractionation regimens which are suitable for image-guide IMRT are derived for large size AVMs. The tomotherapy can potentially deliver more effective treatment for large-size AVMs than currently used Linac-based SRT schemes. Clinical trials are needed to confirm the results.
2405
Role of Bone Marrow Derived Macrophages and Stromal Cells in Irradiation-Induced Pulmonary Fibrosis
Y. Niu,1 M.W. Epperly,1 T. Carlos,2 X. Zhang,1 J.S. Greenberger1 Radiation Oncology, University of Pittsburgh, Pittsburgh, PA, 2Medicine, University of Pittsburgh, Pittsburgh, PA
1
Purpose/Objective: In the C57BL/6NHsd mouse marrow chimera model of pulmonary irradiation fibrosis/organizing alveolitis, bone marrow derived macrophages and fibroblasts migrate into the lungs 80 to 120 days after 20 Gy lung irradiation. Fibroblasts proliferate resulting in deposition of collagen and the development of fibrosis. A detectable increase in TNF␣ and TGF expression occurs before migration of fibroblasts into the lungs. To determine the role of macrophages in the development of flung fibrosis, we blocked pulmonary migration of monocyte/macrophages using antibodies to mouse macrophages. To determine the role of TGF in attracting marrow myofibroblasts into the lung we used clonal bone marrow stromal cells lines derived from Smad3⫺/⫺ knockout mice, which have the TGF signal transduction pathway altered by removal of the Smad3 gene, compared to cell lines from control Smad3⫹/⫹ mice.
Proceedings of the 47th Annual ASTRO Meeting
Materials/Methods: C57BL/6NHsd mice were irradiated to 20 Gy to the pulmonary cavity. Bone marrow stromal cell lines were isolated from Smad3⫹/⫹ or Smad3⫺/⫺ mice and transfected with a retrovirus containing DS-red or GFP transgene, respectively. At 80 days after irradiation, subgroups of mice were injected intravenously (IV) with cells from the DS-redSmad3⫹/⫹ or GFP-Smad3⫺/⫺ bone marrow stromal cell line. In other subgroups, mice were injected intraperitoneally (IP) for 15 days (Monday-Friday for 3 weeks) with monoclonal rat anti-mouse antibodies to either T-cells (T1B-207) or macrophages (M1/70). All mice were followed for the development of irradiation-induced fibrosis. Results: In areas of organizing alveolitis/fibrosis, we detected both GFP Smad3⫺/⫺ cells and DS-red Smad3⫹/⫹ cells. However, there was increased accumulation of Smad3⫹/⫹ DS-red cells compared to GFP Smad3⫺/⫺ cells. In mice treated with anti-macrophage antibody, M1/70 antibody treated animals had increased survival compared to mice that received irradiation only (p ⫽ 0.0225) or T1B-207 antibody. Conclusions: Migration of both marrow origin macrophages and fibroblasts play a critical role in the development of pulmonary irradiation fibrosis. Disruption in the migration of one cell phenotype or altering their response to TGF impairs the development of irradiation-induced fibrosis.
2406
Does a p53 Inhibitor Protect Mice Against the Toxicity of High-Dose Abdominal Radiotherapy?
L. Cai,1 W.A. Weber,2 N.H. Andratschke,1 S. Schill,1 M. Molls,1 C. Nieder1 Dept. of Radiation Oncology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany, 2Dept. of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
1
Purpose/Objective: To test whether the chemical inhibitor of p53 1-(4-Methylphenyl)-2-(4,5,6,7-tetrahydro-2-imino-3(2H)benzo) ethanone hydrobromide, also known as pififthrin-alpha, prevents radiation-induced bowel and kidney toxicity. Materials/Methods: Thirty-three adult female C3H mice were treated with single-fraction radiotherapy of 15 Gy to the right middle abdomen either with or without pififthrin-alpha injection before irradiation. The kidney function was assessed prior to radiotherapy and 19 weeks thereafter by means of 99mTc-dimercaptosuccinat (DMSA) scans (static scintigraphy). The mice were followed until death and autopsy was performed to confirm the cause of death. Results: At baseline, the right kidney had a median proportion of total function of 54⫾2% in control mice and 51⫾3% in mice treated with pififthrin-alpha. After 19 weeks, the function of the irradiated right kidney declined to 41⫾9% vs. 43⫾3%. The difference in radiation-induced kidney dysfunction between both groups was not statistically significant (t-test, p⬎0.1). Radiation treatment induced lethal bowel toxicity, confirmed by autopsy, in 89% of controls and 100% of pififthrin-alphatreated mice. Actuarial median survival (Kaplan-Meier analysis) was 89 vs. 85 days from radiation treatment (difference not statistically significant, log-rank-test, p⬎0.1). Conclusions: In contrast to an earlier publication (Science 1999; 285: 1733ff), where different mouse strains (Balb/c and C57BL) received total body irradiation with lower doses with or without pififthrin-alpha and where the compound improved survival, pififthrin-alpha had no significant protective effect when given before high-dose local abdominal radiotherapy. Thus, the hypothesis that abrogation of p53 signaling induces radioresistance of normal tissues has to undergo further critical examination.
2407
A Model of Experimental Kidney Irradiation for Screening of Response Modifiers: Evaluation of Insulinlike Growth Factor-1 (IGF-1) and Erythropoietin (EPO)
A. Schnaiter,1 L. Cai,1 N.H. Andratschke,1 S. Schill,1 W.A. Weber,2 M. Molls,1 C. Nieder1 Dept. of Radiation Oncology, Klinikum rechts der Isar, TU Munich, Munich, Germany, 2Dept. of Nuclear Medicine, Klinikum rechts der Isar, TU Munich, Munich, Germany
1
Purpose/Objective: The kidney is one of the most radiosensitive abdominal organs. Therefore, modification of its radiation response might improve the therapeutic ratio in a variety of common tumors treated with radiotherapy. Growth factors are increasingly being studied as response modifiers. To evaluate their role in conjunction with irradiation of the kidney, we established an experimental mouse model. Materials/Methods: Adult female C3H mice were treated with single-fraction radiotherapy to the right kidney with doses of 6 –17 Gy and with or without two different growth factors, i.e. IGF-1 and EPO. The kidney function was assessed prior to radiotherapy, 19 weeks thereafter and then every 6 weeks by means of 99mTc-dimercaptosuccinat scans, i.e. static scintigraphy. Maximum follow-up was 12 months. IGF-1 was given subcutaneously either concomitant to radiotherapy or after deterioration of the kidney function, i.e. after 5– 6 months. Delayed treatment after deterioration of the kidney function was administered over 4 weeks, immediately followed by repeat scans every 6 weeks. Doses of IGF-1 were 0.5-25 g per injection. EPO was given concomitant to radiotherapy in a dose of 500 IU or 2000 IU/kg body weight. Results: The function of the irradiated kidney continuously declined during follow-up in all control groups in a dose-dependent fashion. Very accurate and reproducible results were obtained when examining the same control animals several times before the development of kidney dysfunction with this method of static scintigraphy. Concomitant treatment with IGF-1 significantly reduced the decline of the median kidney function. The best dose of IGF-1 was 5 g per injection, administered over 2 weeks. Delayed treatment after deterioration of the kidney function was unable to restore the function regardless of the IGF-1 dose. Very few animals in the groups with delayed IGF-1 showed at least stabilisation of the compromised kidney function. EPO actually increased the degree of radiation-induced kidney dysfunction significantly. The higher dose of EPO caused more damage than the lower dose. Conclusions: We have developed a relatively simple, accurate method for screening of response modifiers in the context of mouse kidney irradiation. Our results demonstrate that administration of growth factors concomitant to radiotherapy causes
S471