- Email: [email protected]
Evaluation of Folate-targeted Nanoparticle Formulation of Docetaxel as a Radiosensitizer in Head and Neck Cancer
I. J. Radiation Oncology d Biology d Physics
S114
Volume 78, Number 3, Supplement, 2010
conjugate + radiation or a PSMA aptamer-scrambled siRNA conjugate + radiation, resulted in a modest tumor growth delay relative to control groups (23.7 days to 4X; p \ 0.05). Tumors treated with the PSMA aptamer-DNA-pK siRNA conjugate + radiation resulted in a significant growth delay relative to all conjugates alone and to control conjugates plus radiation (89.7 days to 4X; p \ 0.000001 compared to all groups). Conclusions: We believe this is the first report of in vivo radiation sensitization and tumor control via targeted, prostate-specific siRNAs. We document significant DNA-pK protein reduction in PCa tumors injected with a PSMA aptamer-DNA-pK siRNA conjugate. We also show that reductions in target protein result in substantial radiation sensitization and tumor control, nearly quadrupling the time to 4X. These data support continued development of this technology as a path to enhance radiotherapeutic outcomes for men with PCa. Author Disclosure: T.L. DeWeese, None; X. Ni, None; Y. Zhang, None; M. Hedayati, None; S. Lupold, None.
243
Evaluation of Folate-targeted Nanoparticle Formulation of Docetaxel as a Radiosensitizer in Head and Neck Cancer
Z. Wang, M. Werner, J. A. Copp, S. Karve, R. C. Chen, A. D. Cox University of North Carolina School of Medicine, Chapel Hill, NC Purpose/Objective(s): Nanoparticle (NP) therapeutics is poised to make a major impact on cancer treatment. NPs have been shown to preferentially accumulate in tumors, which leads to superior biodistribution and lower toxicity when compared to conventional small molecule chemotherapeutics. The next generation of NP chemotherapeutics are biologically targeted and composed of biodegradable materials that allow controlled release of drugs. Although they hold high promise as radiosensitizers, preclinical evaluation is necessary given NPs’ different mode of cell entry and drug release profile compared to that of free drugs. In this study, we evaluated the effectiveness of a model targeted NP therapeutic, folate-targeted NP docetaxel (Dtxl), as radiosensitizer in vitro in a head and neck cancer cell line. We also studied the optimal timing of radiotherapy after drug incubation. Materials/Methods: Folate targeted polymer-lipid nanoparticle platform was synthesized by a nanoprecipitation method. The resulting nanoparticles have a hydrophobic polymeric core (PLGA) covered by a self-assembled monolayer of lipid and lipid-PEG and lipid-PEG-folate. Dtxl is encapsulated within the polymeric core. The DSPE-PEG-Folate allows targeting of folate receptor on tumor cells. Folate receptor expressing KB head and neck cancer cell line was used as the model tumor. Using clonogenic assay, we studied the optimal timing for radiotherapy to achieve maximal radiosensitization as well as the comparative effectiveness of folatetargeted NPs encapsulating Dtxl vs. non-targeted NPs and free Dtxl. Results: Characterization of the folate-targeted NPs containing Dtxl showed particle size of 70+/ 5 nm and 60% Dtxl encapsulation efficiency. Drug release study showed controlled release with more than 95% of Dtxl released at 24 hours. We found that maximal radiosensitization occurred when cells were radiated at 24 hrs post NP incubation; unlike that for free Dtxl where maximal radiosensitization occurred immediately following drug incubation. We also compared the effectiveness of folate-NP-Dtxl, NPDtxl and free Dtxl as radiosensitizers in KB cells. We demonstrated that folate-NP-Dtxl is more effective than NP-Dtxl and is as effective as free Dtxl. Conclusions: We have demonstrated that a biologically targeted NP, folate-NP-Dtxl, is an effective radiosensitizer of head and neck cells in vitro. We have shown that the optimal timing for radiotherapy to achieve maximal radiosensitization for this NP is at 24 hours. We have also shown the targeted NPs are more effective as radiosensitizers than non-targeted NPs. We plan to validate our in data in vivo. We believe the next generation of biologically targeted nanoparticles holds great promise as radiosensitizers. Author Disclosure: Z. Wang, None; M. Werner, None; J.A. Copp, None; S. Karve, None; R.C. Chen, None; A.D. Cox, None.
244
Enhancing Tumor Chemo-radio-sensitization using Ketogenic Diets
B. G. Allen1, M. A. Fath2, A. L. Simons2, S. K. Bhatia1, J. M. Buatti1, D. R. Spitz2 1
University of Iowa Hospitals and Clinics, Iowa City, IA, 2University of Iowa, Iowa City, IA
Purpose/Objective(s): Ketogenic diets (high fat, low protein and carbohydrates) force cells to rely more on mitochondrial oxidation of ketoacids for energy production. It has been hypothesized that cancer cells exist in a state of chronic oxidative stress with the site of pro-oxidant production being mitochondrial electron transport chains. Since cancer cells may have defective mitochondrial O2 metabolism, then ketogenic diets may increase cellular oxidative stress and further sensitize cancer cells to conventional therapeutic agents. Materials/Methods: In order to determine if ketogenic diets (KD) enhance cancer therapy, MIA PaCa-2 pancreatic cancer cells and FaDu head and neck carcinoma cells were grown in the flanks of nude mice and fed either KD (KetoCal 4:1 fat:carbohydrates + protein) or standard rodent chow (SD) ad libitum during therapy. Mice were treated with either cisplatin (CIS; 2mg/kg QOD) and/or ionizing radiation (IR; 2 Gy x6 fractions) for 2 weeks. Tumor growth rates were assessed daily with calipers. Mice were sacrificed once tumors had diameters greater than 1.5cm. Results: Mice with MIA PaCa-2 pancreatic xenograft tumors treated with KD+IR demonstrated a significantly longer median survival (147 days; 95% confidence interval:141-152 days) compared to mice receiving SD+IR (91 days; 95% CI: 61-120), KD (93 days; 95% CI: 67-120) or SD alone (91 days; 95% CI 67-115) . Mice with FaDu head and neck tumors treated with KD+IR also demonstrated a prolonged median survival (61 days: 95% CI: 39-83) compared to mice receiving SD (25 days; 95% CI: 20-30), KD (23 days; 95% CI: 19-27), SD+IR (35 days; 95% CI: 25-45), SD+CIS (27 days: 95% CI: 24-30), KD+CIS (32 days: 95% CI: 2242). Mice treated with SD+CIS+IR had a median survival of 45 days (95% CI: 39-51) while mice treated with KD+CIS+IR had a median survival of 55 days (95% CI: 42-68). Western blots of plasma harvested from KD+IR animals provide evidence of increased protein oxidation compared to SD+IR animals. Conclusions: These experiments support the hypothesis that ketogenic diets may increase systemic oxidative stress and enhance tumor chemo-radio-sensitization.
S114
Volume 78, Number 3, Supplement, 2010
conjugate + radiation or a PSMA aptamer-scrambled siRNA conjugate + radiation, resulted in a modest tumor growth delay relative to control groups (23.7 days to 4X; p \ 0.05). Tumors treated with the PSMA aptamer-DNA-pK siRNA conjugate + radiation resulted in a significant growth delay relative to all conjugates alone and to control conjugates plus radiation (89.7 days to 4X; p \ 0.000001 compared to all groups). Conclusions: We believe this is the first report of in vivo radiation sensitization and tumor control via targeted, prostate-specific siRNAs. We document significant DNA-pK protein reduction in PCa tumors injected with a PSMA aptamer-DNA-pK siRNA conjugate. We also show that reductions in target protein result in substantial radiation sensitization and tumor control, nearly quadrupling the time to 4X. These data support continued development of this technology as a path to enhance radiotherapeutic outcomes for men with PCa. Author Disclosure: T.L. DeWeese, None; X. Ni, None; Y. Zhang, None; M. Hedayati, None; S. Lupold, None.
243
Evaluation of Folate-targeted Nanoparticle Formulation of Docetaxel as a Radiosensitizer in Head and Neck Cancer
Z. Wang, M. Werner, J. A. Copp, S. Karve, R. C. Chen, A. D. Cox University of North Carolina School of Medicine, Chapel Hill, NC Purpose/Objective(s): Nanoparticle (NP) therapeutics is poised to make a major impact on cancer treatment. NPs have been shown to preferentially accumulate in tumors, which leads to superior biodistribution and lower toxicity when compared to conventional small molecule chemotherapeutics. The next generation of NP chemotherapeutics are biologically targeted and composed of biodegradable materials that allow controlled release of drugs. Although they hold high promise as radiosensitizers, preclinical evaluation is necessary given NPs’ different mode of cell entry and drug release profile compared to that of free drugs. In this study, we evaluated the effectiveness of a model targeted NP therapeutic, folate-targeted NP docetaxel (Dtxl), as radiosensitizer in vitro in a head and neck cancer cell line. We also studied the optimal timing of radiotherapy after drug incubation. Materials/Methods: Folate targeted polymer-lipid nanoparticle platform was synthesized by a nanoprecipitation method. The resulting nanoparticles have a hydrophobic polymeric core (PLGA) covered by a self-assembled monolayer of lipid and lipid-PEG and lipid-PEG-folate. Dtxl is encapsulated within the polymeric core. The DSPE-PEG-Folate allows targeting of folate receptor on tumor cells. Folate receptor expressing KB head and neck cancer cell line was used as the model tumor. Using clonogenic assay, we studied the optimal timing for radiotherapy to achieve maximal radiosensitization as well as the comparative effectiveness of folatetargeted NPs encapsulating Dtxl vs. non-targeted NPs and free Dtxl. Results: Characterization of the folate-targeted NPs containing Dtxl showed particle size of 70+/ 5 nm and 60% Dtxl encapsulation efficiency. Drug release study showed controlled release with more than 95% of Dtxl released at 24 hours. We found that maximal radiosensitization occurred when cells were radiated at 24 hrs post NP incubation; unlike that for free Dtxl where maximal radiosensitization occurred immediately following drug incubation. We also compared the effectiveness of folate-NP-Dtxl, NPDtxl and free Dtxl as radiosensitizers in KB cells. We demonstrated that folate-NP-Dtxl is more effective than NP-Dtxl and is as effective as free Dtxl. Conclusions: We have demonstrated that a biologically targeted NP, folate-NP-Dtxl, is an effective radiosensitizer of head and neck cells in vitro. We have shown that the optimal timing for radiotherapy to achieve maximal radiosensitization for this NP is at 24 hours. We have also shown the targeted NPs are more effective as radiosensitizers than non-targeted NPs. We plan to validate our in data in vivo. We believe the next generation of biologically targeted nanoparticles holds great promise as radiosensitizers. Author Disclosure: Z. Wang, None; M. Werner, None; J.A. Copp, None; S. Karve, None; R.C. Chen, None; A.D. Cox, None.
244
Enhancing Tumor Chemo-radio-sensitization using Ketogenic Diets
B. G. Allen1, M. A. Fath2, A. L. Simons2, S. K. Bhatia1, J. M. Buatti1, D. R. Spitz2 1
University of Iowa Hospitals and Clinics, Iowa City, IA, 2University of Iowa, Iowa City, IA
Purpose/Objective(s): Ketogenic diets (high fat, low protein and carbohydrates) force cells to rely more on mitochondrial oxidation of ketoacids for energy production. It has been hypothesized that cancer cells exist in a state of chronic oxidative stress with the site of pro-oxidant production being mitochondrial electron transport chains. Since cancer cells may have defective mitochondrial O2 metabolism, then ketogenic diets may increase cellular oxidative stress and further sensitize cancer cells to conventional therapeutic agents. Materials/Methods: In order to determine if ketogenic diets (KD) enhance cancer therapy, MIA PaCa-2 pancreatic cancer cells and FaDu head and neck carcinoma cells were grown in the flanks of nude mice and fed either KD (KetoCal 4:1 fat:carbohydrates + protein) or standard rodent chow (SD) ad libitum during therapy. Mice were treated with either cisplatin (CIS; 2mg/kg QOD) and/or ionizing radiation (IR; 2 Gy x6 fractions) for 2 weeks. Tumor growth rates were assessed daily with calipers. Mice were sacrificed once tumors had diameters greater than 1.5cm. Results: Mice with MIA PaCa-2 pancreatic xenograft tumors treated with KD+IR demonstrated a significantly longer median survival (147 days; 95% confidence interval:141-152 days) compared to mice receiving SD+IR (91 days; 95% CI: 61-120), KD (93 days; 95% CI: 67-120) or SD alone (91 days; 95% CI 67-115) . Mice with FaDu head and neck tumors treated with KD+IR also demonstrated a prolonged median survival (61 days: 95% CI: 39-83) compared to mice receiving SD (25 days; 95% CI: 20-30), KD (23 days; 95% CI: 19-27), SD+IR (35 days; 95% CI: 25-45), SD+CIS (27 days: 95% CI: 24-30), KD+CIS (32 days: 95% CI: 2242). Mice treated with SD+CIS+IR had a median survival of 45 days (95% CI: 39-51) while mice treated with KD+CIS+IR had a median survival of 55 days (95% CI: 42-68). Western blots of plasma harvested from KD+IR animals provide evidence of increased protein oxidation compared to SD+IR animals. Conclusions: These experiments support the hypothesis that ketogenic diets may increase systemic oxidative stress and enhance tumor chemo-radio-sensitization.