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Molecular Imaging Biomarkers of Response to Radiation Therapy in Canines With Spontaneously-Occurring Nasal Tumors
Digital Poster Discussion Abstracts S195
Volume 90 Number 1S Supplement 2014 Technology Commission of Shanghai (81272506, 61227017) from National Natural Science Foundation of China.
1089 WITHDRAWN
1090 Molecular Imaging Biomarkers of Response to Radiation Therapy in Canines With Spontaneously-Occurring Nasal Tumors R. Jeraj, T. Bradshaw, L. Forrest, and R. Chappell; University of Wisconsin, Madison, WI Purpose/Objective(s): Imaging biomarkers of response can inform and guide treatment management. Most studies so far have focused on assessing a single imaging biomarker, often driven by general availability of a particular imaging modality (e.g., FDG PET/CT). The main goal of this study was to systematically explore a number of different molecular imaging biomarkers as surrogates of resistance to RT. Materials/Methods: Twenty-two canine patients with spontaneouslyoccurring nasal tumors were treated with the accelerated hypofractionated RT to either 10 4.2 Gy (N Z 10) or 10 5.0 Gy (N Z 12) to the GTV. All patients were imaged with FDG, FLT, and CuATSM PET/CT before therapy and with FLT and Cu-ATSM PET/CT during therapy (after 2 and 3 fractions, respectively). Follow-up CT scans were obtained at 3, 6, and 9 months after treatment, or when patients presented with clinical signs of recurrence. Progression-free survival was assessed according to RECIST. Pre-treatment SUVmean and SUVmax were calculated for each scan, as well as the FLT and Cu-ATSM SUV changes from pre- to mid-treatment. Univariate Cox proportional hazards regression was performed for all PET measures, as well as volume, stage, histology, age, sex, and dose. Significant variables from univariate analysis were included in multivariate analysis with two predictor variables. The best model was selected according to Pseudo R2. Results: The following variables were significant positive predictors of poor clinical outcome according to univariate analysis: tumor volume (p Z 0.011), mid-treatment FLT SUVmean (p Z 0.018), and mid-treatment FLT SUVmax (p Z 0.006). Large decreases in FLT SUVmean from pre- to mid-treatment resulted in worse clinical outcome (p Z 0.013). In the multivariate model, the best two-variable combination for predicting poor survival were high mid-treatment FLT SUVmax (p Z 0.022) and large FLT response from pre- to mid-treatment (p Z 0.041). Conclusions: In addition to tumor volume, which is a known prognostic factor, rapid tumor proliferative response measured with FLT PET, especially when associated with high residual FLT PET at mid-treatment, is a negative predictive biomarker of response to RT. Neither FDG PET nor Cu-ATSM PET was predictive of response. Author Disclosure: R. Jeraj: None. T. Bradshaw: None. L. Forrest: None. R. Chappell: None.
1091 Heat Shock Protein 90 (HSP90) Is Preferentially Overexpressed in P16-Negative Oropharyngeal Squamous Cell Carcinoma, and its Inhibition In Vitro Potentiates the Effects of Chemoradiation K. Patel, J. Wen, K. Magliocca, S. Muller, Y. Liu, G. Chen, N. Saba, and R. Diaz; Emory University, Atlanta, GA Purpose/Objective(s): Despite treatment advances, 5-year overall survival for squamous cell carcinoma of the head and neck (SCCHN) is close to 50%. Cisplatin and radiation therapy remain the current standard for treating locally advanced SCCHN. Novel treatment approaches are urgently needed, especially in patients with human papillomavirus (HPV) negative disease who have worse outcomes despite multimodality therapy.
Materials/Methods: Using our IRB approved head and neck cancer data base, squamous cell carcinoma (SCC) tissue samples were obtained: 10 p16 positive, 10 p16 negative. HSP90 protein levels in these samples were analyzed via immunohistochemistry, Using HPV-positive and HPV-negative SCC cell lines, baseline HSP90 expression levels and the effect of the HSP90 inhibitor ganetespib on proliferation and apoptosis were compared. Clonogenic survival of HPV-negative and positive cells treated with ganetespib, radiation therapy, and/or cisplatin was then investigated. Last, the effects of ganetespib on proteins that are thought to drive DNA damage resistance in HPVnegative cells are characterized. Results: HSP90 expression was significantly higher in p16 negative compared to p16 positive samples (p Z 0.016) and in HPV-negative cell lines compared to positive cells. Ganetespib decreased proliferation and induced apoptosis in HPV-negative more than positive cells. Adding ganetespib to cisplatin and/or radiation therapy in HPV-negative cells further decreased clonogenic survival. Interestingly, while HPV-positive cells demonstrated greater sensitivity to radiation therapy, ganetespib still further sensitized HPV-positive cells to radiation therapy. Finally, ganetespib downregulated expression of EGFR, ERK, AKT, p53, and HIF-1a in HPV-negative tumor cells. Conclusions: Ganetespib inhibited HPV-negative SCCHN proliferation and potentiated cell kill when combined with cisplatin or radiation therapy in vitro. With HSP90 expression higher in HPV-negative cells and in p16 negative patients, further exploration of the clinical activity of HSP90 inhibitors in SCCHN is warranted. Author Disclosure: K. Patel: None. J. Wen: None. K. Magliocca: None. S. Muller: None. Y. Liu: None. G. Chen: None. N. Saba: None. R. Diaz: None.
1092 Simultaneous Targeting of Histone Decaetylases (HDAC) and the Hedgehog (HH) Pathway Causes Synergistic p53-Independent p21waf Up-regulation and Radiation Lethality in Head and Neck Cancer S.G. Chun,1 L.S. Li,2 H. Park,2 and J.S. Yordy3; 1UT Southwestern Medical Center, Dallas, TX, 2University of Texas Southwestern, Dallas, TX, 3University of Texas Southwestern Medical Center, Dallas, TX Purpose/Objective(s): Standard combined modality therapy for locally-advanced and recurrent head and neck cancer (HNC) is toxic with suboptimal outcomes, and targeting cancer-specific molecular pathways in combination with radiation may improve the therapeutic ratio. Dysregulation of epigenetic modulators such as histone deacetylases (HDAC) and developmental morphogens, such as the hedgehog (HH)-pathway have been implicated HNC tumor maintenance and progression, but are not aberrantly active in adjacent normal tissues. Recently, HDAC have been found to promote the HHpathway by modifying the lysine acetylation status of Gli-1 and Gli2, providing rationale for combined therapeutic targeting of these pathways. In this translational study, we hypothesized that simultaneous targeting of HDAC and the HH-pathway mediator Smoothened (Smo) represents an opportunity to overcome resistance to radiation therapy in HNC. Materials/Methods: To test the hypothesis that HDAC and HH-pathway can be therapeutically exploited in HNC, the effects of the HDAC inhibitor suberoyl-anilide-hydroxamic acid (SAHA), Smo inhibitor GDC-0449, and ionizing radiation were assessed in multiple HNC cell lines with p53 lossof-function mutations. Effects on cellular proliferation were assessed using tetrazolium assay, automated cell counting, colony formation, and flow cytometry. HDAC and HH pathway activity, cell cycle mediators, and radiation response pathways were analyzed with immunoblotting, quantitative RT-PCR, and cytogenetic analyses. Results: It was shown that SAHA induced hyperacetylation of histones H3 and H4, confirming suppression of HDAC. The HH-pathway mediator patched-1 was cooperatively suppressed by SAHA and GDC-0449.
Volume 90 Number 1S Supplement 2014 Technology Commission of Shanghai (81272506, 61227017) from National Natural Science Foundation of China.
1089 WITHDRAWN
1090 Molecular Imaging Biomarkers of Response to Radiation Therapy in Canines With Spontaneously-Occurring Nasal Tumors R. Jeraj, T. Bradshaw, L. Forrest, and R. Chappell; University of Wisconsin, Madison, WI Purpose/Objective(s): Imaging biomarkers of response can inform and guide treatment management. Most studies so far have focused on assessing a single imaging biomarker, often driven by general availability of a particular imaging modality (e.g., FDG PET/CT). The main goal of this study was to systematically explore a number of different molecular imaging biomarkers as surrogates of resistance to RT. Materials/Methods: Twenty-two canine patients with spontaneouslyoccurring nasal tumors were treated with the accelerated hypofractionated RT to either 10 4.2 Gy (N Z 10) or 10 5.0 Gy (N Z 12) to the GTV. All patients were imaged with FDG, FLT, and CuATSM PET/CT before therapy and with FLT and Cu-ATSM PET/CT during therapy (after 2 and 3 fractions, respectively). Follow-up CT scans were obtained at 3, 6, and 9 months after treatment, or when patients presented with clinical signs of recurrence. Progression-free survival was assessed according to RECIST. Pre-treatment SUVmean and SUVmax were calculated for each scan, as well as the FLT and Cu-ATSM SUV changes from pre- to mid-treatment. Univariate Cox proportional hazards regression was performed for all PET measures, as well as volume, stage, histology, age, sex, and dose. Significant variables from univariate analysis were included in multivariate analysis with two predictor variables. The best model was selected according to Pseudo R2. Results: The following variables were significant positive predictors of poor clinical outcome according to univariate analysis: tumor volume (p Z 0.011), mid-treatment FLT SUVmean (p Z 0.018), and mid-treatment FLT SUVmax (p Z 0.006). Large decreases in FLT SUVmean from pre- to mid-treatment resulted in worse clinical outcome (p Z 0.013). In the multivariate model, the best two-variable combination for predicting poor survival were high mid-treatment FLT SUVmax (p Z 0.022) and large FLT response from pre- to mid-treatment (p Z 0.041). Conclusions: In addition to tumor volume, which is a known prognostic factor, rapid tumor proliferative response measured with FLT PET, especially when associated with high residual FLT PET at mid-treatment, is a negative predictive biomarker of response to RT. Neither FDG PET nor Cu-ATSM PET was predictive of response. Author Disclosure: R. Jeraj: None. T. Bradshaw: None. L. Forrest: None. R. Chappell: None.
1091 Heat Shock Protein 90 (HSP90) Is Preferentially Overexpressed in P16-Negative Oropharyngeal Squamous Cell Carcinoma, and its Inhibition In Vitro Potentiates the Effects of Chemoradiation K. Patel, J. Wen, K. Magliocca, S. Muller, Y. Liu, G. Chen, N. Saba, and R. Diaz; Emory University, Atlanta, GA Purpose/Objective(s): Despite treatment advances, 5-year overall survival for squamous cell carcinoma of the head and neck (SCCHN) is close to 50%. Cisplatin and radiation therapy remain the current standard for treating locally advanced SCCHN. Novel treatment approaches are urgently needed, especially in patients with human papillomavirus (HPV) negative disease who have worse outcomes despite multimodality therapy.
Materials/Methods: Using our IRB approved head and neck cancer data base, squamous cell carcinoma (SCC) tissue samples were obtained: 10 p16 positive, 10 p16 negative. HSP90 protein levels in these samples were analyzed via immunohistochemistry, Using HPV-positive and HPV-negative SCC cell lines, baseline HSP90 expression levels and the effect of the HSP90 inhibitor ganetespib on proliferation and apoptosis were compared. Clonogenic survival of HPV-negative and positive cells treated with ganetespib, radiation therapy, and/or cisplatin was then investigated. Last, the effects of ganetespib on proteins that are thought to drive DNA damage resistance in HPVnegative cells are characterized. Results: HSP90 expression was significantly higher in p16 negative compared to p16 positive samples (p Z 0.016) and in HPV-negative cell lines compared to positive cells. Ganetespib decreased proliferation and induced apoptosis in HPV-negative more than positive cells. Adding ganetespib to cisplatin and/or radiation therapy in HPV-negative cells further decreased clonogenic survival. Interestingly, while HPV-positive cells demonstrated greater sensitivity to radiation therapy, ganetespib still further sensitized HPV-positive cells to radiation therapy. Finally, ganetespib downregulated expression of EGFR, ERK, AKT, p53, and HIF-1a in HPV-negative tumor cells. Conclusions: Ganetespib inhibited HPV-negative SCCHN proliferation and potentiated cell kill when combined with cisplatin or radiation therapy in vitro. With HSP90 expression higher in HPV-negative cells and in p16 negative patients, further exploration of the clinical activity of HSP90 inhibitors in SCCHN is warranted. Author Disclosure: K. Patel: None. J. Wen: None. K. Magliocca: None. S. Muller: None. Y. Liu: None. G. Chen: None. N. Saba: None. R. Diaz: None.
1092 Simultaneous Targeting of Histone Decaetylases (HDAC) and the Hedgehog (HH) Pathway Causes Synergistic p53-Independent p21waf Up-regulation and Radiation Lethality in Head and Neck Cancer S.G. Chun,1 L.S. Li,2 H. Park,2 and J.S. Yordy3; 1UT Southwestern Medical Center, Dallas, TX, 2University of Texas Southwestern, Dallas, TX, 3University of Texas Southwestern Medical Center, Dallas, TX Purpose/Objective(s): Standard combined modality therapy for locally-advanced and recurrent head and neck cancer (HNC) is toxic with suboptimal outcomes, and targeting cancer-specific molecular pathways in combination with radiation may improve the therapeutic ratio. Dysregulation of epigenetic modulators such as histone deacetylases (HDAC) and developmental morphogens, such as the hedgehog (HH)-pathway have been implicated HNC tumor maintenance and progression, but are not aberrantly active in adjacent normal tissues. Recently, HDAC have been found to promote the HHpathway by modifying the lysine acetylation status of Gli-1 and Gli2, providing rationale for combined therapeutic targeting of these pathways. In this translational study, we hypothesized that simultaneous targeting of HDAC and the HH-pathway mediator Smoothened (Smo) represents an opportunity to overcome resistance to radiation therapy in HNC. Materials/Methods: To test the hypothesis that HDAC and HH-pathway can be therapeutically exploited in HNC, the effects of the HDAC inhibitor suberoyl-anilide-hydroxamic acid (SAHA), Smo inhibitor GDC-0449, and ionizing radiation were assessed in multiple HNC cell lines with p53 lossof-function mutations. Effects on cellular proliferation were assessed using tetrazolium assay, automated cell counting, colony formation, and flow cytometry. HDAC and HH pathway activity, cell cycle mediators, and radiation response pathways were analyzed with immunoblotting, quantitative RT-PCR, and cytogenetic analyses. Results: It was shown that SAHA induced hyperacetylation of histones H3 and H4, confirming suppression of HDAC. The HH-pathway mediator patched-1 was cooperatively suppressed by SAHA and GDC-0449.