Bryan Allen - Academia.edu (original) (raw)
Papers by Bryan Allen
Nature Protocols, 2006
Bacteriophage phiC31 makes the enzyme integrase that allows the insertion of the phage genome int... more Bacteriophage phiC31 makes the enzyme integrase that allows the insertion of the phage genome into its bacterial host. The enzyme recognizes a specific DNA sequence in the phage (attP) and a different sequence in the bacteria (attB). Recombination between these sites leads to integration in a reaction that requires no accessory factors. Seminal studies carried out by M. Calos and co-workers demonstrated that the phiC31 integrase was capable of integrating plasmid with an attB site into mammalian genomes at sites that approximated the attP site. We describe the use of attB containing plasmids with insulated reporter genes for successful integration of DNA into Xenopus embryos. The method offers a way to produce transgenic embryos without manipulation of sperm nuclei using microinjection methods standard for experiments in Xenopus laevis. The method aims to allow the non-mosaic controlled expression of new genetic material in the injected embryo and compares favorably with the time normally taken to analyze embryos injected with mRNAs, plasmids, morpholinos or oligonucleotides.
Nature Communications
Although machine learning (ML) has shown promise across disciplines, out-of-sample generalizabili... more Although machine learning (ML) has shown promise across disciplines, out-of-sample generalizability is concerning. This is currently addressed by sharing multi-site data, but such centralization is challenging/infeasible to scale due to various limitations. Federated ML (FL) provides an alternative paradigm for accurate and generalizable ML, by only sharing numerical model updates. Here we present the largest FL study to-date, involving data from 71 sites across 6 continents, to generate an automatic tumor boundary detector for the rare disease of glioblastoma, reporting the largest such dataset in the literature (n = 6, 314). We demonstrate a 33% delineation improvement for the surgically targetable tumor, and 23% for the complete tumor extent, over a publicly trained model. We anticipate our study to: 1) enable more healthcare studies informed by large diverse data, ensuring meaningful results for rare diseases and underrepresented populations, 2) facilitate further analyses for g...
International Journal of Molecular Sciences
Polyoxometalate nanoparticles (POMs) are a class of compounds made up of multiple transition meta... more Polyoxometalate nanoparticles (POMs) are a class of compounds made up of multiple transition metals linked together using oxygen atoms. POMs commonly include group 6 transition metals, with two of the most common forms using molybdenum and tungsten. POMs are suggested to exhibit antimicrobial effects. In this study, we developed two POM preparations to study anti-cancer activity. We found that Mo-POM (NH4)Mo7O24) and W-POM (H3PW12O40) have anti-cancer effects on glioblastoma cells. Both POMs induced morphological changes marked by membrane swelling and the presence of multinucleated cells that may indicate apoptosis induction along with impaired cell division. We also observed significant increases in lipid oxidation events, suggesting that POMs are redox-active and can catalyze detrimental oxidation events in glioblastoma cells. Here, we present preliminary indications that molybdenum polyoxometalate nanoparticles may act like ferrous iron to catalyze the oxidation of phospholipids...
Antioxidants, 2021
Cisplatin is a chemotherapy agent commonly used to treat a wide variety of cancers. Despite the p... more Cisplatin is a chemotherapy agent commonly used to treat a wide variety of cancers. Despite the potential for both severe acute and chronic side effects, it remains a preferred therapeutic option for many malignancies due to its potent anti-tumor activity. Common cisplatin-associated side-effects include acute kidney injury (AKI) and chronic kidney disease (CKD). These renal injuries may cause delays and potentially cessation of cisplatin therapy and have long-term effects on renal function reserve. Thus, developing mechanism-based interventional strategies that minimize cisplatin-associated kidney injury without reducing efficacy would be of great benefit. In addition to its action of cross-linking DNA, cisplatin has been shown to affect mitochondrial metabolism, resulting in mitochondrially derived reactive oxygen species (ROS). Increased ROS formation in renal proximal convoluted tubule cells is associated with cisplatin-induced AKI and CKD. We review the mechanisms by which cisp...
International Journal of Molecular Sciences, 2021
Interest in the use of pharmacological ascorbate as a treatment for cancer has increased consider... more Interest in the use of pharmacological ascorbate as a treatment for cancer has increased considerably since it was introduced by Cameron and Pauling in the 1970s. Recently, pharmacological ascorbate has been used in preclinical and early-phase clinical trials as a selective radiation sensitizer in cancer. The results of these studies are promising. This review summarizes data on pharmacological ascorbate (1) as a safe and efficacious adjuvant to cancer therapy; (2) as a selective radiosensitizer of cancer via a mechanism involving hydrogen peroxide; and (3) as a radioprotector in normal tissues. Additionally, we present new data demonstrating the ability of pharmacological ascorbate to enhance radiation-induced DNA damage in glioblastoma cells, facilitating cancer cell death. We propose that pharmacological ascorbate may be a general radiosensitizer in cancer therapy and simultaneously a radioprotector of normal tissue.
Cancers, 2021
Sarcoma is a widely varied and devastating oncological subtype, with overall five-year survival o... more Sarcoma is a widely varied and devastating oncological subtype, with overall five-year survival of 65% that drops to 16% with the presence of metastatic disease at diagnosis. Standard of care for localized sarcomas is predicated on local control with wide-local resection and radiation therapy, or, less commonly, chemotherapy, depending on tumor subtype. Verteporfin has the potential to be incorporated into this standard of care due to its unique molecular properties: inhibition of the upregulated Hippo pathway that frequently drives soft tissue sarcoma and photodynamic therapy-mediated necrosis due to oxidative damage. The initial anti-proliferative effect of verteporfin is mediated via binding and dissociation of YAP/TEAD proteins from the nucleus, ultimately leading to decreased cell proliferation as demonstrated in multiple in vitro studies. This effect has the potential to be compounded with use of photodynamic therapy to directly induce cellular necrosis with use of a clinical ...
Neuro-Oncology Advances, 2021
Pharmacological ascorbate (P-AscH-; high dose intravenous infusions of vitamin C generating milli... more Pharmacological ascorbate (P-AscH-; high dose intravenous infusions of vitamin C generating milli-molar plasma concentrations) has re-emerged as an anti-cancer therapy. Phase 1 clinical trials combining P-AscH- with chemotherapy and ionizing radiation demonstrate safety and promising clinical outcomes in a variety of malignancies. In a first-in-human trial, subjects with newly diagnosed glioblastoma (GBM) and undetectable MGMT promoter methylation were treated with P-AscH-, ionizing radiation, and temozolomide. Results demonstrate median progression-free survival (PFS) of 10 months and median overall survival (OS) of 23 months, comparing favorably to historical GBM patients expressing MGMT. P-AscH-‘s anti-cancer mechanism is dependent upon the presence of redox active labile iron. In the presence of redox active iron, the formation of hydrogen peroxide, which causes oxidative stress and eventual cell death, selectively forms in cancer cells. Treatment with P-AscH- increased cancer c...
Redox Biology, 2021
Pharmacological ascorbate (P-AscH-) combined with standard of care (SOC) radiation and temozolomi... more Pharmacological ascorbate (P-AscH-) combined with standard of care (SOC) radiation and temozolomide is being evaluated in a phase 2 clinical trial (NCT02344355) in the treatment of glioblastoma (GBM). Previously published data demonstrated that paramagnetic iron (Fe 3+) catalyzes ascorbate's oxidation to form diamagnetic iron (Fe 2+). Because paramagnetic Fe 3+ may influence relaxation times observed in MR imaging, quantitative MR imaging of P-AscH-induced changes in redox-active Fe was assessed as a biomarker for therapy response. Gel phantoms containing either Fe 3+ or Fe 2+ were imaged with T2* and quantitative susceptibility mapping (QSM). Fifteen subjects receiving P-AscHplus SOC underwent T2* and QSM imaging four weeks into treatment. Subjects were scanned: pre-P-AscHinfusion, post-P-AscHinfusion, and post-radiation (3-4 h between scans). Changes in T2* and QSM relaxation times in tumor and normal tissue were calculated and compared to changes in Fe 3+ and Fe 2+ gel phantoms. A GBM mouse model was used to study the relationship between the imaging findings and the labile iron pool. Phantoms containing Fe 3+ demonstrated detectable changes in T2* and QSM relaxation times relative to Fe 2+ phantoms. Compared to pre-P-AscH-, GBM T2* and QSM imaging were significantly changed post-P-AscHinfusion consistent with conversion of Fe 3+ to Fe 2+. No significant changes in T2* or QSM were observed in normal brain tissue. There was moderate concordance between T2* and QSM changes in both progression free survival and overall survival. The GBM mouse model showed similar results with P-AscHinducing greater changes in tumor labile iron pools compared to the normal tissue. Conclusions: T2* and QSM MR-imaging responses are consistent with P-AscHreducing Fe 3+ to Fe 2+ , selectively in GBM tumor volumes and represent a potential biomarker of response. This study is the first application using MR imaging in humans to measure P-AscH-induced changes in redox-active iron.
Antioxidants, 2021
Cancer cells preferentially accumulate iron (Fe) relative to non-malignant cells; however, the un... more Cancer cells preferentially accumulate iron (Fe) relative to non-malignant cells; however, the underlying rationale remains elusive. Iron–sulfur (Fe–S) clusters are critical cofactors that aid in a wide variety of cellular functions (e.g., DNA metabolism and electron transport). In this article, we theorize that a differential need for Fe–S biogenesis in tumor versus non-malignant cells underlies the Fe-dependent cell growth demand of cancer cells to promote cell division and survival by promoting genomic stability via Fe–S containing DNA metabolic enzymes. In this review, we outline the complex Fe–S biogenesis process and its potential upregulation in cancer. We also discuss three therapeutic strategies to target Fe–S biogenesis: (i) redox manipulation, (ii) Fe chelation, and (iii) Fe mimicry.
Journal for ImmunoTherapy of Cancer, 2021
BackgroundSoft-tissue sarcomas (STS) in the extremities and trunk treated with standard-of-care p... more BackgroundSoft-tissue sarcomas (STS) in the extremities and trunk treated with standard-of-care preoperative external beam radiation therapy (EBRT) followed by surgical resection are associated with local and distant relapses. In preclinical studies, oncolytic virotherapy in sarcoma has demonstrated antitumor effects via direct intratumoral oncolysis and cytotoxic T-cell–mediated immune responses. Talimogene laherparepvec (TVEC) is a replication-competent, immune-enhanced, oncolytic herpes simplex virus type 1 engineered for intratumoral injection; it has been approved by the FDA for the treatment of locally advanced and metastatic melanoma.MethodsWe explored a novel combination of TVEC with standard-of-care EBRT administered preoperatively in patients with locally advanced STS of the extremities and trunk in a phase IB/II clinical trial. Thirty patients with primary STS >5 cm for which EBRT was indicated to achieve negative margins were enrolled. FDA-approved TVEC doses were use...
Cancers, 2020
Ionizing radiation is a common and effective therapeutic option for the treatment of glioblastoma... more Ionizing radiation is a common and effective therapeutic option for the treatment of glioblastoma (GBM). Unfortunately, some GBMs are relatively radioresistant and patients have worse outcomes after radiation treatment. The mechanisms underlying intrinsic radioresistance in GBM has been rigorously investigated over the past several years, but the complex interaction of the cellular molecules and signaling pathways involved in radioresistance remains incompletely defined. A clinically effective radiosensitizer that overcomes radioresistance has yet to be identified. In this review, we discuss the current status of radiation treatment in GBM, including advances in imaging techniques that have facilitated more accurate diagnosis, and the identified mechanisms of GBM radioresistance. In addition, we provide a summary of the candidate GBM radiosensitizers being investigated, including an update of subjects enrolled in clinical trials. Overall, this review highlights the importance of und...
Redox Biology, 2021
There is a rapidly growing body of literature supporting the notion that differential oxidative m... more There is a rapidly growing body of literature supporting the notion that differential oxidative metabolism in cancer versus normal cells represents a metabolic frailty that can be exploited to open a therapeutic window into cancer therapy. These cancer cell-specific metabolic frailties may be amenable to manipulation with non-toxic small molecule redox active compounds traditionally thought to be antioxidants. In this review we describe the potential mechanisms and clinical applicability in cancer therapy of four small molecule redox active agents: melatonin, vitamin E, selenium, and vitamin C. Each has shown the potential to have pro-oxidant effects in cancer cells while retaining antioxidant activity in normal cells. This dichotomy can be exploited to improve responses to radiation and chemotherapy by opening a therapeutic window based on a testable biochemical rationale amenable to confirmation with biomarker studies during clinical trials. Thus, the unique pro-oxidant/ antioxidant properties of melatonin, vitamin E, selenium, and vitamin C have the potential to act as effective adjuvants to traditional cancer therapies, thereby improving cancer patient outcomes.
Cancers, 2020
Historically, patients with localized soft tissue sarcomas (STS) of the extremities would undergo... more Historically, patients with localized soft tissue sarcomas (STS) of the extremities would undergo limb amputation. It was subsequently determined that the addition of radiation therapy (RT) delivered prior to (neoadjuvant) or after (adjuvant) a limb-sparing surgical resection yielded equivalent survival outcomes to amputation in appropriate patients. Generally, neoadjuvant radiation offers decreased volume and dose of high-intensity radiation to normal tissue and increased chance of achieving negative surgical margins—but also increases wound healing complications when compared to adjuvant radiotherapy. This review elaborates on the current neoadjuvant/adjuvant RT approaches, wound healing complications in STS, and the potential application of novel radioprotective agents to minimize radiation-induced normal tissue toxicity.
Cancers, 2019
Iron (Fe) is an essential element that plays a fundamental role in a wide range of cellular funct... more Iron (Fe) is an essential element that plays a fundamental role in a wide range of cellular functions, including cellular proliferation, DNA synthesis, as well as DNA damage and repair. Because of these connections, iron has been strongly implicated in cancer development. Cancer cells frequently have changes in the expression of iron regulatory proteins. For example, cancer cells frequently upregulate transferrin (increasing uptake of iron) and down regulate ferroportin (decreasing efflux of intracellular iron). These changes increase the steady-state level of intracellular redox active iron, known as the labile iron pool (LIP). The LIP typically contains approximately 2% intracellular iron, which primarily exists as ferrous iron (Fe2+). The LIP can readily contribute to oxidative distress within the cell through Fe2+-dioxygen and Fenton chemistries, generating the highly reactive hydroxyl radical (HO•). Due to the reactive nature of the LIP, it can contribute to increased DNA damag...
Journal of thoracic disease, 2018
The optimal surgery for resectable pulmonary typical carcinoid (TC), e.g., lobar resection (L-R) ... more The optimal surgery for resectable pulmonary typical carcinoid (TC), e.g., lobar resection (L-R) sub-lobar resection (SL-R), is controversial. This is further explored in this population-based study. The Surveillance, Epidemiology, and End Results (SEER) Program was used to select patients ≥66 years old, and diagnosed between 2000 and 2012 with pulmonary TC. A similar cohort was developed using the SEER-Medicare database (diagnosed from 2000-2007) to identify chemotherapy (CTX) use and co-morbidity. Five-year survival was calculated using univariate and multivariate analysis. A total of 1,506 and 512 patients were identified from SEER and SEER-Medicare, respectively. In the SEER cohort, 49%, 29% and 21% received L-R, SL-R, and no surgery (NS), respectively. Those who received NS were older (P<0.001), had a higher stage (P<0.001), greater comorbidity (P<0.001), and were more likely to receive radiotherapy (XRT) (P<0.001) and CTX (P<0.001). Relative survival was nearly ...
Cancer research, Jan 25, 2018
Chemoradiation therapy is the mainstay for treatment of locally advanced, borderline resectable p... more Chemoradiation therapy is the mainstay for treatment of locally advanced, borderline resectable pancreatic cancer. Pharmacological ascorbate (P-AscH-, i.e., intravenous infusions of ascorbic acid, vitamin C), but not oral ascorbate, produces high plasma concentrations capable of selective cytotoxicity to tumor cells. In doses achievable in humans, P-AscH- decreases the viability and proliferative capacity of pancreatic cancer via a hydrogen peroxide (H2O2)-mediated mechanism. In this study, we demonstrate that P-AscH- radiosensitizes pancreatic cancer cells but inhibits radiation-induced damage to normal cells. Specifically, radiation-induced decreases in clonogenic survival and double-stranded DNA breaks in tumor cells, but not in normal cells, were enhanced by P-AscH-, while radiation-induced intestinal damage, collagen deposition, and oxidative stress were also reduced with P-AscH- in normal tissue. We also report on our first-in-human phase 1 trial that infused P-AscH- during th...
Annals of radiation therapy and oncology, 2017
Review of our experience in treating thymic carcinoma patients using a combination of surgery, ch... more Review of our experience in treating thymic carcinoma patients using a combination of surgery, chemotherapy and radiation therapy. An institutional review of thymic carcinoma patients treated between 2007 and 2014 was performed analyzing clinical characteristics, treatment intent, surgical margin status, and radiation treatment dose. Survival curves were generated using the Kaplan-Meier method. Nine individuals were treated for newly diagnosed thymic carcinoma. Three patients had unresectable disease at presentation; two of these were treated with definitive chemoradiation therapy while another received neoadjuvant chemotherapy. Seven subjects underwent surgical resection (one after neoadjuvant chemotherapy) with pathological staging ranging from IIa - IVb disease. Patients were planned for adjuvant radiotherapy followed by chemotherapy; however, one developed liver metastases prior to initiating radiotherapy and was therefore treated with palliative chemotherapy alone. A second pat...
Radiation research, May 1, 2018
Gastric adenocarcinoma most often presents at an advanced stage and overall five-year survival of... more Gastric adenocarcinoma most often presents at an advanced stage and overall five-year survival of ∼30%. Pharmacological ascorbate (high-dose IV ascorbate) has been proposed as a promising nontoxic adjuvant to standard radio-chemotherapies in several cancer types. In the current study, pharmacological ascorbate (0.5-2 m M) caused a dose-dependent decrease (70-85% at 2 m M) in clonogenic survival of gastric adenocarcinoma cells (AGS and MNK-45), but was relatively nontoxic to a small intestinal epithelial nonimmortalized human cell isolate (FHs 74 Int). The addition of pharmacological ascorbate (1 m M) to standard radio-chemotherapies [i.e., 5-FU (5 μ M); cisplatin (0.5 μ M); irinotecan (2.5 μ M); carboplatin (5 μ M); paclitaxel (2-4 n M); and X rays (1.8 Gy)] also potentiated gastric cancer clonogenic cell killing [additional decreases were noted with: ascorbate plus 5-FU/radiation (1%); ascorbate plus cisplatin/irinotecan (9-19%); and ascorbate plus paclitaxel/carboplatin (6-7%)]. T...
Antioxidants (Basel, Switzerland), Jan 19, 2018
Lung cancer, together with head and neck cancer, accounts for more than one-fourth of cancer deat... more Lung cancer, together with head and neck cancer, accounts for more than one-fourth of cancer deaths worldwide. New, non-toxic therapeutic approaches are needed. High-dose IV vitamin C (aka, pharmacological ascorbate; P-AscH) represents a promising adjuvant to radiochemotherapy that exerts its anti-cancer effects via metal-catalyzed oxidation to form H₂O₂. Mn(III)-porphyrins possessing superoxide dismutase (SOD) mimetic activity have been shown to increase the rate of oxidation of AscH, enhancing the anti-tumor effects of AscH in several cancer types. The current study demonstrates that the Mn(II)-containing pentaazamacrocyclic selective SOD mimetic GC4419 may serve as an AscH/O₂ oxidoreductase as evidenced by the increased rate of oxygen consumption, steady-state concentrations of ascorbate radical, and H₂O₂ production in complete cell culture media. GC4419, but not CuZnSOD, was shown to significantly enhance the toxicity of AscH in H1299, SCC25, SQ20B, and Cal27 cancer cell lines. ...
Redox biology, Apr 28, 2017
Soft tissue sarcomas are a histologically heterogeneous group of rare mesenchymal cancers for whi... more Soft tissue sarcomas are a histologically heterogeneous group of rare mesenchymal cancers for which treatment options leading to increased overall survival have not improved in over two decades. The current study shows that pharmacological ascorbate (systemic high dose vitamin C achieving ≥ 20mM plasma levels) is a potentially efficacious and easily integrable addition to current standard of care treatment strategies in preclinical models of fibrosarcoma and liposarcoma both in vitro and in vivo. Furthermore, enhanced ascorbate-mediated toxicity and DNA damage in these sarcoma models were found to be dependent upon H2O2 and intracellular labile iron. Together, these data support the hypothesis that pharmacological ascorbate may represent an easily implementable and non-toxic addition to conventional sarcoma therapies based on taking advantage of fundamental differences in cancer cell oxidative metabolism.
Nature Protocols, 2006
Bacteriophage phiC31 makes the enzyme integrase that allows the insertion of the phage genome int... more Bacteriophage phiC31 makes the enzyme integrase that allows the insertion of the phage genome into its bacterial host. The enzyme recognizes a specific DNA sequence in the phage (attP) and a different sequence in the bacteria (attB). Recombination between these sites leads to integration in a reaction that requires no accessory factors. Seminal studies carried out by M. Calos and co-workers demonstrated that the phiC31 integrase was capable of integrating plasmid with an attB site into mammalian genomes at sites that approximated the attP site. We describe the use of attB containing plasmids with insulated reporter genes for successful integration of DNA into Xenopus embryos. The method offers a way to produce transgenic embryos without manipulation of sperm nuclei using microinjection methods standard for experiments in Xenopus laevis. The method aims to allow the non-mosaic controlled expression of new genetic material in the injected embryo and compares favorably with the time normally taken to analyze embryos injected with mRNAs, plasmids, morpholinos or oligonucleotides.
Nature Communications
Although machine learning (ML) has shown promise across disciplines, out-of-sample generalizabili... more Although machine learning (ML) has shown promise across disciplines, out-of-sample generalizability is concerning. This is currently addressed by sharing multi-site data, but such centralization is challenging/infeasible to scale due to various limitations. Federated ML (FL) provides an alternative paradigm for accurate and generalizable ML, by only sharing numerical model updates. Here we present the largest FL study to-date, involving data from 71 sites across 6 continents, to generate an automatic tumor boundary detector for the rare disease of glioblastoma, reporting the largest such dataset in the literature (n = 6, 314). We demonstrate a 33% delineation improvement for the surgically targetable tumor, and 23% for the complete tumor extent, over a publicly trained model. We anticipate our study to: 1) enable more healthcare studies informed by large diverse data, ensuring meaningful results for rare diseases and underrepresented populations, 2) facilitate further analyses for g...
International Journal of Molecular Sciences
Polyoxometalate nanoparticles (POMs) are a class of compounds made up of multiple transition meta... more Polyoxometalate nanoparticles (POMs) are a class of compounds made up of multiple transition metals linked together using oxygen atoms. POMs commonly include group 6 transition metals, with two of the most common forms using molybdenum and tungsten. POMs are suggested to exhibit antimicrobial effects. In this study, we developed two POM preparations to study anti-cancer activity. We found that Mo-POM (NH4)Mo7O24) and W-POM (H3PW12O40) have anti-cancer effects on glioblastoma cells. Both POMs induced morphological changes marked by membrane swelling and the presence of multinucleated cells that may indicate apoptosis induction along with impaired cell division. We also observed significant increases in lipid oxidation events, suggesting that POMs are redox-active and can catalyze detrimental oxidation events in glioblastoma cells. Here, we present preliminary indications that molybdenum polyoxometalate nanoparticles may act like ferrous iron to catalyze the oxidation of phospholipids...
Antioxidants, 2021
Cisplatin is a chemotherapy agent commonly used to treat a wide variety of cancers. Despite the p... more Cisplatin is a chemotherapy agent commonly used to treat a wide variety of cancers. Despite the potential for both severe acute and chronic side effects, it remains a preferred therapeutic option for many malignancies due to its potent anti-tumor activity. Common cisplatin-associated side-effects include acute kidney injury (AKI) and chronic kidney disease (CKD). These renal injuries may cause delays and potentially cessation of cisplatin therapy and have long-term effects on renal function reserve. Thus, developing mechanism-based interventional strategies that minimize cisplatin-associated kidney injury without reducing efficacy would be of great benefit. In addition to its action of cross-linking DNA, cisplatin has been shown to affect mitochondrial metabolism, resulting in mitochondrially derived reactive oxygen species (ROS). Increased ROS formation in renal proximal convoluted tubule cells is associated with cisplatin-induced AKI and CKD. We review the mechanisms by which cisp...
International Journal of Molecular Sciences, 2021
Interest in the use of pharmacological ascorbate as a treatment for cancer has increased consider... more Interest in the use of pharmacological ascorbate as a treatment for cancer has increased considerably since it was introduced by Cameron and Pauling in the 1970s. Recently, pharmacological ascorbate has been used in preclinical and early-phase clinical trials as a selective radiation sensitizer in cancer. The results of these studies are promising. This review summarizes data on pharmacological ascorbate (1) as a safe and efficacious adjuvant to cancer therapy; (2) as a selective radiosensitizer of cancer via a mechanism involving hydrogen peroxide; and (3) as a radioprotector in normal tissues. Additionally, we present new data demonstrating the ability of pharmacological ascorbate to enhance radiation-induced DNA damage in glioblastoma cells, facilitating cancer cell death. We propose that pharmacological ascorbate may be a general radiosensitizer in cancer therapy and simultaneously a radioprotector of normal tissue.
Cancers, 2021
Sarcoma is a widely varied and devastating oncological subtype, with overall five-year survival o... more Sarcoma is a widely varied and devastating oncological subtype, with overall five-year survival of 65% that drops to 16% with the presence of metastatic disease at diagnosis. Standard of care for localized sarcomas is predicated on local control with wide-local resection and radiation therapy, or, less commonly, chemotherapy, depending on tumor subtype. Verteporfin has the potential to be incorporated into this standard of care due to its unique molecular properties: inhibition of the upregulated Hippo pathway that frequently drives soft tissue sarcoma and photodynamic therapy-mediated necrosis due to oxidative damage. The initial anti-proliferative effect of verteporfin is mediated via binding and dissociation of YAP/TEAD proteins from the nucleus, ultimately leading to decreased cell proliferation as demonstrated in multiple in vitro studies. This effect has the potential to be compounded with use of photodynamic therapy to directly induce cellular necrosis with use of a clinical ...
Neuro-Oncology Advances, 2021
Pharmacological ascorbate (P-AscH-; high dose intravenous infusions of vitamin C generating milli... more Pharmacological ascorbate (P-AscH-; high dose intravenous infusions of vitamin C generating milli-molar plasma concentrations) has re-emerged as an anti-cancer therapy. Phase 1 clinical trials combining P-AscH- with chemotherapy and ionizing radiation demonstrate safety and promising clinical outcomes in a variety of malignancies. In a first-in-human trial, subjects with newly diagnosed glioblastoma (GBM) and undetectable MGMT promoter methylation were treated with P-AscH-, ionizing radiation, and temozolomide. Results demonstrate median progression-free survival (PFS) of 10 months and median overall survival (OS) of 23 months, comparing favorably to historical GBM patients expressing MGMT. P-AscH-‘s anti-cancer mechanism is dependent upon the presence of redox active labile iron. In the presence of redox active iron, the formation of hydrogen peroxide, which causes oxidative stress and eventual cell death, selectively forms in cancer cells. Treatment with P-AscH- increased cancer c...
Redox Biology, 2021
Pharmacological ascorbate (P-AscH-) combined with standard of care (SOC) radiation and temozolomi... more Pharmacological ascorbate (P-AscH-) combined with standard of care (SOC) radiation and temozolomide is being evaluated in a phase 2 clinical trial (NCT02344355) in the treatment of glioblastoma (GBM). Previously published data demonstrated that paramagnetic iron (Fe 3+) catalyzes ascorbate's oxidation to form diamagnetic iron (Fe 2+). Because paramagnetic Fe 3+ may influence relaxation times observed in MR imaging, quantitative MR imaging of P-AscH-induced changes in redox-active Fe was assessed as a biomarker for therapy response. Gel phantoms containing either Fe 3+ or Fe 2+ were imaged with T2* and quantitative susceptibility mapping (QSM). Fifteen subjects receiving P-AscHplus SOC underwent T2* and QSM imaging four weeks into treatment. Subjects were scanned: pre-P-AscHinfusion, post-P-AscHinfusion, and post-radiation (3-4 h between scans). Changes in T2* and QSM relaxation times in tumor and normal tissue were calculated and compared to changes in Fe 3+ and Fe 2+ gel phantoms. A GBM mouse model was used to study the relationship between the imaging findings and the labile iron pool. Phantoms containing Fe 3+ demonstrated detectable changes in T2* and QSM relaxation times relative to Fe 2+ phantoms. Compared to pre-P-AscH-, GBM T2* and QSM imaging were significantly changed post-P-AscHinfusion consistent with conversion of Fe 3+ to Fe 2+. No significant changes in T2* or QSM were observed in normal brain tissue. There was moderate concordance between T2* and QSM changes in both progression free survival and overall survival. The GBM mouse model showed similar results with P-AscHinducing greater changes in tumor labile iron pools compared to the normal tissue. Conclusions: T2* and QSM MR-imaging responses are consistent with P-AscHreducing Fe 3+ to Fe 2+ , selectively in GBM tumor volumes and represent a potential biomarker of response. This study is the first application using MR imaging in humans to measure P-AscH-induced changes in redox-active iron.
Antioxidants, 2021
Cancer cells preferentially accumulate iron (Fe) relative to non-malignant cells; however, the un... more Cancer cells preferentially accumulate iron (Fe) relative to non-malignant cells; however, the underlying rationale remains elusive. Iron–sulfur (Fe–S) clusters are critical cofactors that aid in a wide variety of cellular functions (e.g., DNA metabolism and electron transport). In this article, we theorize that a differential need for Fe–S biogenesis in tumor versus non-malignant cells underlies the Fe-dependent cell growth demand of cancer cells to promote cell division and survival by promoting genomic stability via Fe–S containing DNA metabolic enzymes. In this review, we outline the complex Fe–S biogenesis process and its potential upregulation in cancer. We also discuss three therapeutic strategies to target Fe–S biogenesis: (i) redox manipulation, (ii) Fe chelation, and (iii) Fe mimicry.
Journal for ImmunoTherapy of Cancer, 2021
BackgroundSoft-tissue sarcomas (STS) in the extremities and trunk treated with standard-of-care p... more BackgroundSoft-tissue sarcomas (STS) in the extremities and trunk treated with standard-of-care preoperative external beam radiation therapy (EBRT) followed by surgical resection are associated with local and distant relapses. In preclinical studies, oncolytic virotherapy in sarcoma has demonstrated antitumor effects via direct intratumoral oncolysis and cytotoxic T-cell–mediated immune responses. Talimogene laherparepvec (TVEC) is a replication-competent, immune-enhanced, oncolytic herpes simplex virus type 1 engineered for intratumoral injection; it has been approved by the FDA for the treatment of locally advanced and metastatic melanoma.MethodsWe explored a novel combination of TVEC with standard-of-care EBRT administered preoperatively in patients with locally advanced STS of the extremities and trunk in a phase IB/II clinical trial. Thirty patients with primary STS >5 cm for which EBRT was indicated to achieve negative margins were enrolled. FDA-approved TVEC doses were use...
Cancers, 2020
Ionizing radiation is a common and effective therapeutic option for the treatment of glioblastoma... more Ionizing radiation is a common and effective therapeutic option for the treatment of glioblastoma (GBM). Unfortunately, some GBMs are relatively radioresistant and patients have worse outcomes after radiation treatment. The mechanisms underlying intrinsic radioresistance in GBM has been rigorously investigated over the past several years, but the complex interaction of the cellular molecules and signaling pathways involved in radioresistance remains incompletely defined. A clinically effective radiosensitizer that overcomes radioresistance has yet to be identified. In this review, we discuss the current status of radiation treatment in GBM, including advances in imaging techniques that have facilitated more accurate diagnosis, and the identified mechanisms of GBM radioresistance. In addition, we provide a summary of the candidate GBM radiosensitizers being investigated, including an update of subjects enrolled in clinical trials. Overall, this review highlights the importance of und...
Redox Biology, 2021
There is a rapidly growing body of literature supporting the notion that differential oxidative m... more There is a rapidly growing body of literature supporting the notion that differential oxidative metabolism in cancer versus normal cells represents a metabolic frailty that can be exploited to open a therapeutic window into cancer therapy. These cancer cell-specific metabolic frailties may be amenable to manipulation with non-toxic small molecule redox active compounds traditionally thought to be antioxidants. In this review we describe the potential mechanisms and clinical applicability in cancer therapy of four small molecule redox active agents: melatonin, vitamin E, selenium, and vitamin C. Each has shown the potential to have pro-oxidant effects in cancer cells while retaining antioxidant activity in normal cells. This dichotomy can be exploited to improve responses to radiation and chemotherapy by opening a therapeutic window based on a testable biochemical rationale amenable to confirmation with biomarker studies during clinical trials. Thus, the unique pro-oxidant/ antioxidant properties of melatonin, vitamin E, selenium, and vitamin C have the potential to act as effective adjuvants to traditional cancer therapies, thereby improving cancer patient outcomes.
Cancers, 2020
Historically, patients with localized soft tissue sarcomas (STS) of the extremities would undergo... more Historically, patients with localized soft tissue sarcomas (STS) of the extremities would undergo limb amputation. It was subsequently determined that the addition of radiation therapy (RT) delivered prior to (neoadjuvant) or after (adjuvant) a limb-sparing surgical resection yielded equivalent survival outcomes to amputation in appropriate patients. Generally, neoadjuvant radiation offers decreased volume and dose of high-intensity radiation to normal tissue and increased chance of achieving negative surgical margins—but also increases wound healing complications when compared to adjuvant radiotherapy. This review elaborates on the current neoadjuvant/adjuvant RT approaches, wound healing complications in STS, and the potential application of novel radioprotective agents to minimize radiation-induced normal tissue toxicity.
Cancers, 2019
Iron (Fe) is an essential element that plays a fundamental role in a wide range of cellular funct... more Iron (Fe) is an essential element that plays a fundamental role in a wide range of cellular functions, including cellular proliferation, DNA synthesis, as well as DNA damage and repair. Because of these connections, iron has been strongly implicated in cancer development. Cancer cells frequently have changes in the expression of iron regulatory proteins. For example, cancer cells frequently upregulate transferrin (increasing uptake of iron) and down regulate ferroportin (decreasing efflux of intracellular iron). These changes increase the steady-state level of intracellular redox active iron, known as the labile iron pool (LIP). The LIP typically contains approximately 2% intracellular iron, which primarily exists as ferrous iron (Fe2+). The LIP can readily contribute to oxidative distress within the cell through Fe2+-dioxygen and Fenton chemistries, generating the highly reactive hydroxyl radical (HO•). Due to the reactive nature of the LIP, it can contribute to increased DNA damag...
Journal of thoracic disease, 2018
The optimal surgery for resectable pulmonary typical carcinoid (TC), e.g., lobar resection (L-R) ... more The optimal surgery for resectable pulmonary typical carcinoid (TC), e.g., lobar resection (L-R) sub-lobar resection (SL-R), is controversial. This is further explored in this population-based study. The Surveillance, Epidemiology, and End Results (SEER) Program was used to select patients ≥66 years old, and diagnosed between 2000 and 2012 with pulmonary TC. A similar cohort was developed using the SEER-Medicare database (diagnosed from 2000-2007) to identify chemotherapy (CTX) use and co-morbidity. Five-year survival was calculated using univariate and multivariate analysis. A total of 1,506 and 512 patients were identified from SEER and SEER-Medicare, respectively. In the SEER cohort, 49%, 29% and 21% received L-R, SL-R, and no surgery (NS), respectively. Those who received NS were older (P<0.001), had a higher stage (P<0.001), greater comorbidity (P<0.001), and were more likely to receive radiotherapy (XRT) (P<0.001) and CTX (P<0.001). Relative survival was nearly ...
Cancer research, Jan 25, 2018
Chemoradiation therapy is the mainstay for treatment of locally advanced, borderline resectable p... more Chemoradiation therapy is the mainstay for treatment of locally advanced, borderline resectable pancreatic cancer. Pharmacological ascorbate (P-AscH-, i.e., intravenous infusions of ascorbic acid, vitamin C), but not oral ascorbate, produces high plasma concentrations capable of selective cytotoxicity to tumor cells. In doses achievable in humans, P-AscH- decreases the viability and proliferative capacity of pancreatic cancer via a hydrogen peroxide (H2O2)-mediated mechanism. In this study, we demonstrate that P-AscH- radiosensitizes pancreatic cancer cells but inhibits radiation-induced damage to normal cells. Specifically, radiation-induced decreases in clonogenic survival and double-stranded DNA breaks in tumor cells, but not in normal cells, were enhanced by P-AscH-, while radiation-induced intestinal damage, collagen deposition, and oxidative stress were also reduced with P-AscH- in normal tissue. We also report on our first-in-human phase 1 trial that infused P-AscH- during th...
Annals of radiation therapy and oncology, 2017
Review of our experience in treating thymic carcinoma patients using a combination of surgery, ch... more Review of our experience in treating thymic carcinoma patients using a combination of surgery, chemotherapy and radiation therapy. An institutional review of thymic carcinoma patients treated between 2007 and 2014 was performed analyzing clinical characteristics, treatment intent, surgical margin status, and radiation treatment dose. Survival curves were generated using the Kaplan-Meier method. Nine individuals were treated for newly diagnosed thymic carcinoma. Three patients had unresectable disease at presentation; two of these were treated with definitive chemoradiation therapy while another received neoadjuvant chemotherapy. Seven subjects underwent surgical resection (one after neoadjuvant chemotherapy) with pathological staging ranging from IIa - IVb disease. Patients were planned for adjuvant radiotherapy followed by chemotherapy; however, one developed liver metastases prior to initiating radiotherapy and was therefore treated with palliative chemotherapy alone. A second pat...
Radiation research, May 1, 2018
Gastric adenocarcinoma most often presents at an advanced stage and overall five-year survival of... more Gastric adenocarcinoma most often presents at an advanced stage and overall five-year survival of ∼30%. Pharmacological ascorbate (high-dose IV ascorbate) has been proposed as a promising nontoxic adjuvant to standard radio-chemotherapies in several cancer types. In the current study, pharmacological ascorbate (0.5-2 m M) caused a dose-dependent decrease (70-85% at 2 m M) in clonogenic survival of gastric adenocarcinoma cells (AGS and MNK-45), but was relatively nontoxic to a small intestinal epithelial nonimmortalized human cell isolate (FHs 74 Int). The addition of pharmacological ascorbate (1 m M) to standard radio-chemotherapies [i.e., 5-FU (5 μ M); cisplatin (0.5 μ M); irinotecan (2.5 μ M); carboplatin (5 μ M); paclitaxel (2-4 n M); and X rays (1.8 Gy)] also potentiated gastric cancer clonogenic cell killing [additional decreases were noted with: ascorbate plus 5-FU/radiation (1%); ascorbate plus cisplatin/irinotecan (9-19%); and ascorbate plus paclitaxel/carboplatin (6-7%)]. T...
Antioxidants (Basel, Switzerland), Jan 19, 2018
Lung cancer, together with head and neck cancer, accounts for more than one-fourth of cancer deat... more Lung cancer, together with head and neck cancer, accounts for more than one-fourth of cancer deaths worldwide. New, non-toxic therapeutic approaches are needed. High-dose IV vitamin C (aka, pharmacological ascorbate; P-AscH) represents a promising adjuvant to radiochemotherapy that exerts its anti-cancer effects via metal-catalyzed oxidation to form H₂O₂. Mn(III)-porphyrins possessing superoxide dismutase (SOD) mimetic activity have been shown to increase the rate of oxidation of AscH, enhancing the anti-tumor effects of AscH in several cancer types. The current study demonstrates that the Mn(II)-containing pentaazamacrocyclic selective SOD mimetic GC4419 may serve as an AscH/O₂ oxidoreductase as evidenced by the increased rate of oxygen consumption, steady-state concentrations of ascorbate radical, and H₂O₂ production in complete cell culture media. GC4419, but not CuZnSOD, was shown to significantly enhance the toxicity of AscH in H1299, SCC25, SQ20B, and Cal27 cancer cell lines. ...
Redox biology, Apr 28, 2017
Soft tissue sarcomas are a histologically heterogeneous group of rare mesenchymal cancers for whi... more Soft tissue sarcomas are a histologically heterogeneous group of rare mesenchymal cancers for which treatment options leading to increased overall survival have not improved in over two decades. The current study shows that pharmacological ascorbate (systemic high dose vitamin C achieving ≥ 20mM plasma levels) is a potentially efficacious and easily integrable addition to current standard of care treatment strategies in preclinical models of fibrosarcoma and liposarcoma both in vitro and in vivo. Furthermore, enhanced ascorbate-mediated toxicity and DNA damage in these sarcoma models were found to be dependent upon H2O2 and intracellular labile iron. Together, these data support the hypothesis that pharmacological ascorbate may represent an easily implementable and non-toxic addition to conventional sarcoma therapies based on taking advantage of fundamental differences in cancer cell oxidative metabolism.