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1.
Clin Colorectal Cancer ; 22(1): 92-99, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36529613

RESUMO

INTRODUCTION: RRx-001 is a novel cysteine-targeted alkylating agent that releases nitric oxide (NO). The primary biological activities of this hybrid molecule include macrophage repolarizing and vascular normalization. The purpose of this clinical trial (ROCKET) (NCT02096354) was to compare the safety and efficacy of the combination therapy RRx-001 + irinotecan vs. regorafenib in third/fourth line colorectal cancer that previously received treatment with irinotecan. PATIENTS AND METHODS: A total of 34 patients were randomized (24 to RRx-001 + irinotecan (RxI) and 10 to single-agent regorafenib (RegI)) and were the basis for the intention-to-treat analysis (ITT, comprising all 34 patients). RRx-001 treatment was administered as an up-to-2-month "primer" followed by irinotecan for patients randomized to the RRx-001 arm (24). The efficacy and safety data are presented for the 34 patients in the (ITT) efficacy analysis. Therapy consisted of intravenous administration of RRx-001 at 4 mg once weekly for up to 2 months, at which point RRx-001 was discontinued, followed by intravenous infusion of irinotecan at 180 mg/m2 on day 1 in a 21-day cycle vs. 160 mg oral regorafenib daily for 3/4 weeks followed at progression, if applicable, by irinotecan 180 mg/m2 on day 1 in a 21-day cycle. There were 3 patients (3/24 = 12.5%) with prior single agent irinotecan on the RRx-001 randomized arm and 2 (2/10 = 20%) on the regorafenib randomized arm. Numerous patients had irinotecan combination therapies prior to randomized treatment. There were 15 patients on RRx-001 arm that received irinotecan post-RRx-001 in the randomized trial. There were 5 PRs on RRx-001 plus irinotecan leading to an overall response of 20.8% (5/24). There were 37.5% (9/24) of RRx-001 randomized patients with KRAS mutant type while 60% (6/10) regorafenib randomized patients were of KRAS type mutant. There were only 4 patients with available QOL and Edmonton Symptom Assessment System, an insufficient sample size to allow for any meaningful analysis. RESULTS: Median patient follow-up was approximately 14.5 months (SD 4.5 months). Median overall survival was 8.6 months for RxI and 4.7 months for RegI. Median progression free survival was 6.1 months for RxI vs. 1.7 months for RegI (a statistically significant result, 2-sided log-rank test, P = .0030). The toxicity profile of RxI was substantially improved compared with RegI. CONCLUSION: The results of this trial demonstrate improved efficacy of RxI compared with RegI in patients with metastatic colorectal cancer after previous treatment with irinotecan, and late-stage clinical development in this indication is planned on the strength of the observed "signal" accompanied by a sufficient safety profile.


Assuntos
Neoplasias Colorretais , Humanos , Irinotecano , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/genética , Proteínas Proto-Oncogênicas p21(ras) , Qualidade de Vida , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Fluoruracila , Camptotecina
2.
Int J Radiat Oncol Biol Phys ; 113(4): 719-726, 2022 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-35367328

RESUMO

In 2017, the American Society for Radiation Oncology (ASTRO) board of directors prioritized radiopharmaceutical therapy (RPT) as a leading area for new therapeutic development, and the ASTRO RPT workgroup was created. Herein, the workgroup has developed a framework for RPT curriculum development upon which education leaders can build to integrate this modality into radiation oncology resident education. Through this effort, the workgroup aims to provide a guide to ensure robust training in an emerging therapeutic area within the context of existing radiation oncology training in radiation biology, medical physics, and clinical radiation oncology. The framework first determines the core RPT knowledge required to select patients, prescribe, safely administer, and manage related adverse events. Then, it defines the most important topics for preparing residents for clinical RPT planning and delivery. This framework is designed as a tool to supplement the current training that exists for radiation oncology residents. The final document was approved by the ASTRO board of directors in the fall of 2021.


Assuntos
Internato e Residência , Radioterapia (Especialidade) , Currículo , Humanos , Radioterapia (Especialidade)/educação , Radiobiologia/educação , Compostos Radiofarmacêuticos/uso terapêutico , Sociedades Médicas , Estados Unidos
3.
Drugs R D ; 21(2): 169-178, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33866531

RESUMO

BACKGROUND: Selenite is a radiosensitizer and inhibitor of androgen receptor expression and function. In a phase I study (NCT02184533) in 15 subjects with metastatic cancer receiving daily oral sodium selenite with palliative radiation therapy, disease stabilization was observed, as evidenced by tumor regression, marked reduction in pain symptoms, and decreased prostate-specific antigen levels (only patients with castrate-resistant prostate cancer). OBJECTIVE: The aim of this work was to characterize the pharmacokinetics of selenite to suggest dosing strategies and to propose a study design for further investigation. METHODS: With selenium plasma concentrations obtained from five dosing cohorts (5.5, 11, 16.5, 33, and 49.5 mg), a population pharmacokinetic model was constructed using NONMEM. The model described externally administered selenite (inorganic) with a baseline component for endogenous selenium levels. Using the pharmacokinetic model, simulations were performed to suggest dosing regimens that achieved in vitro target selenite levels, and optimal pharmacokinetic sampling times for a subsequent study were proposed using PopED. RESULTS: A one-compartment model characterized selenite pharmacokinetics. Parameter estimates were absorption rate constant (0.64 h-1), apparent clearance (1.58 L/h), apparent volume of distribution (42.3 L), and baseline selenium amount (5270 µg). A logarithmic function characterized the inverse relationship between dose level and bioavailability. Four regimens to reach in vitro target selenite levels were proposed: 33 mg daily, 16.5 mg twice daily (BID), 11 mg BID, and 5.5 mg thrice daily (TID). Optimal sampling times were 1, 2, 6, and 24 h. DISCUSSION: The population model described the pharmacokinetic data well. Three regimens (33 mg daily, 11 mg BID, 5.5 mg TID) achieved in vitro target selenite levels after one dose. The model and optimal sampling times may inform future studies evaluating the efficacy of selenite for metastatic cancer treatment.


Assuntos
Neoplasias , Selenito de Sódio , Administração Oral , Disponibilidade Biológica , Humanos , Masculino , Neoplasias/tratamento farmacológico , Ácido Selenioso
4.
Semin Radiat Oncol ; 31(1): 20-27, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33246632

RESUMO

Radiopharmaceutical therapy or targeted radionuclide therapy (TRT) is a well-established class of cancer therapeutics that includes a growing number of FDA-approved drugs and a promising pipeline of experimental therapeutics. Radiobiology is fundamental to a mechanistic understanding of the therapeutic capacity of these agents and their potential toxicities. However, the field of radiobiology has historically focused on external beam radiation. Critical differences exist between TRT and external beam radiotherapy with respect to dosimetry, dose rate, linear energy transfer, duration of treatment delivery, fractionation, range, and target volume. These distinctions simultaneously make it difficult to extrapolate from the radiobiology of external beam radiation to that of TRT and pose considerable challenges for preclinical and clinical studies investigating TRT. Here, we discuss these challenges and explore the current understanding of the radiobiology of radiopharmaceuticals.


Assuntos
Neoplasias , Compostos Radiofarmacêuticos , Humanos , Transferência Linear de Energia , Neoplasias/tratamento farmacológico , Neoplasias/radioterapia , Radiobiologia , Radiometria , Compostos Radiofarmacêuticos/uso terapêutico
5.
Radiat Oncol J ; 38(4): 226-235, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33233031

RESUMO

Radiotherapy is used as definitive treatment in approximately two-thirds of all cancers. However, like any treatment, radiation has significant acute and long-term side effects including secondary malignancies. Even when similar radiation parameters are used, 5%-10% of patients will experience adverse radiation side effects. Genomic susceptibility is thought to be responsible for approximately 40% of the clinical variability observed. In the era of precision medicine, the link between genetic susceptibility and radiation-induced side effects is further strengthening. Genome-wide association studies (GWAS) have begun to identify single-nucleotide polymorphisms (SNPs) attributed to overall and tissue-specific toxicity following radiation for treatment of breast cancer, prostate cancer, and other cancers. Here, we review the use of GWAS in identifying polymorphisms that are predictive of acute and long-term radiation-induced side effects with a focus on chest, pelvic, and head-and-neck irradiation. Integration of GWAS studies with "omic" data, patient characteristics, and clinical correlates into predictive models could decrease radiation-induced side effects while increasing therapeutic efficacy.

6.
Sci Rep ; 10(1): 17327, 2020 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-33060741

RESUMO

Oral mucositis refers to lesions of the oral mucosa observed in patients with cancer being treated with radiation with or without chemotherapy, and can significantly affect quality of life. There is a large unmet medical need to prevent oral mucositis that can occur with radiation either alone or in combination with chemotherapy. We investigated the efficacy of locally administered heparin-binding epidermal growth factor-like growth factor (HB-EGF), a potent epithelial proliferation and migration stimulator of the oral mucosa as a potential therapy to prevent radiation induced oral mucositis. Using a single dose (20 Gy) of radiation to the oral cavity of female C57BL/6 J mice, we evaluated the efficacy of HB-EGF treatment (5 µl of 10 µg/ml) solution. The results show that HB-EGF delivered post radiation, significantly increased the area of epithelial thickness on the tongue (dorsal tongue (42,106 vs 53,493 µm2, p < 0.01), ventral tongue (30,793 vs 39,095 µm2, *p < 0.05)) compared to vehicle control, enhanced new epithelial cell division, and increased the quality and quantity of desmosomes in the oral mucosa measured in the tongue and buccal mucosa. This data provides the proof of concept that local administration of HB-EGF has the potential to be developed as a topical treatment to mitigate oral mucositis following radiation.


Assuntos
Fator de Crescimento Semelhante a EGF de Ligação à Heparina/administração & dosagem , Radioterapia/efeitos adversos , Estomatite/prevenção & controle , Administração Tópica , Animais , Camundongos , Camundongos Endogâmicos C57BL , Estomatite/etiologia , Língua/efeitos da radiação
7.
Semin Oncol ; 47(2-3): 117-124, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32517874

RESUMO

The mammalian immune system consists of two distinct arms, nonspecific innate and more specific adaptive, with the innate immune response as the first line of defense and protection, which primes and amplifies subsequent adaptive responses. On the basis of this binary immune interplay, stimulation of T cells through checkpoint inhibitors (CIs), which bypasses innate involvement, seems likely to engender suboptimal or incomplete anticancer immunity, given that the successful induction of effect or responses depends on two-way innate/adaptive coordination. Indeed, the majority of patients-70%-80%, do not respond to CIs, which is potentially problematic if access to more optimal standard therapies is withheld or delayed in favor of ineffective or only marginally effective anti-PD-1/PD-L1 treatment. Therefore, stimulation of the innate immune response in combination with CIs (or other inducers of T cell cytotoxicity) has the potential to make the immune system "whole" and thereby to enhance and broaden the anti-tumor activity of PD-1/PD-L1 inhibitors for example, in relatively nonimmunogenic or "cold" tumor types. A critical innate macrophage immune checkpoint and druggable target is the antiphagocytic and "marker of self" CD47-SIRPα pathway, which is co-opted by cancer cells to mediate escape from immune-mediated clearance and checkpoint inhibition. This review summarizes the status of key CD47 antagonists in clinical trials, including the biologics, Hu5F9-G4 (5F9), TTI-621, and ALX148, as well as the small molecule, RRx-001, now in a Phase 3 clinical trial, which has not been previously included in CD47-SIRPα reviews focused on biologics. Hu5F9-G4 (5F9), TTI-621, ALX148, and RRx-001 are chosen as compounds with potentially promising data that have advanced the farthest in clinical development.


Assuntos
Antineoplásicos Imunológicos/farmacologia , Antígeno CD47/antagonistas & inibidores , Imunidade Inata/efeitos dos fármacos , Imunoterapia/métodos , Receptores Imunológicos/antagonistas & inibidores , Animais , Antígenos de Diferenciação , Humanos , Neoplasias/tratamento farmacológico
8.
Melanoma Manag ; 7(1): MMT36, 2020 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-32399174

RESUMO

AIM: We previously reported a prospective trial evaluating the safety and efficacy of combining ipilimumab and radiation therapy in patients with metastatic melanoma. Herein, we provide a long-term update on patients with complete response (CR) or partial response (PR). PATIENTS & METHODS: We continued to follow these patients with serial imaging including computed tomography, PET or MRI. RESULTS: Two of the three patients with CR are still alive and without evidence of melanoma but with chronic treatment-induced hypophysitis. The third patient died of hepatocellular carcinoma, but with no evidence of melanoma. Among the three patients with PR, two achieved CR after pembrolizumab monotherapy. CONCLUSION: This long-term follow up reveals the striking durability of the CRs, which appears to correlate with a grade 2-3 hypophysitis.

9.
Expert Opin Ther Targets ; 24(5): 427-438, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32228232

RESUMO

Introduction: Transforming Growth Factor-Beta (TGF-ß) is a master regulator of numerous cellular functions including cellular immunity. In cancer, TGF-ß can function as a tumor promoter via several mechanisms including immunosuppression. Since the immune checkpoint pathways are co-opted in cancer to induce T cell tolerance, this review posits that TGF-ß is a master checkpoint in cancer, whose negative regulatory influence overrides and controls that of other immune checkpoints.Areas Covered: This review examines therapeutic agents that target TGF-ß and its signaling pathways for the treatment of cancer which may be classifiable as checkpoint inhibitors in the broadest sense. This concept is supported by the observations that 1) only a subset of patients benefit from current checkpoint inhibitor therapies, 2) the presence of TGF-ß in the tumor microenvironment is associated with excluded or cold tumors, and resistance to checkpoint inhibitors, and 3) existing biomarkers such as PD-1, PD-L1, microsatellite instability and tumor mutational burden are inadequate to reliably and adequately identify immuno-responsive patients. By contrast, TGF-ß overexpression is a widespread and profoundly negative molecular hallmark in multiple tumor types.Expert Opinion: TGF-ß status may serve as a biomarker to predict responsiveness and as a therapeutic target to increase the activity of immunotherapies.


Assuntos
Terapia de Alvo Molecular , Neoplasias/terapia , Fator de Crescimento Transformador beta/imunologia , Animais , Regulação Neoplásica da Expressão Gênica , Humanos , Inibidores de Checkpoint Imunológico/farmacologia , Imunidade Celular , Imunoterapia/métodos , Neoplasias/imunologia , Neoplasias/patologia , Transdução de Sinais , Fator de Crescimento Transformador beta/genética , Microambiente Tumoral
10.
Clin Cancer Res ; 26(13): 3193-3201, 2020 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-32205463

RESUMO

PURPOSE: Preclinical data suggest that radiotherapy (RT) is beneficial in combination with immune checkpoint blockade. Clinical trials have explored RT with single-agent immune checkpoint blockade, but no trials have reported RT with the combination of nivolumab and ipilimumab. PATIENTS AND METHODS: We conducted a phase 1 study of patients with stage IV melanoma receiving nivolumab and ipilimumab with two different dose-fractionation schemes of RT. Patients had at least one melanoma metastasis that would benefit from palliative RT and one metastasis that would not be irradiated. Nivolumab 1 mg/kg + ipilimumab 3 mg/kg and extracranial RT with a dose of 30 Gy in 10 fractions was administered in Cohort A, and then 27 Gy in 3 fractions was administered in Cohort B. The primary outcome was safety. RESULTS: Twenty patients were treated (10 in each cohort). The rates of treatment-related grade 3-4 adverse events in Cohort A and B were 40% and 30%, respectively. There were no grade ≥3 adverse events attributed to RT. Patients responded to treatment outside of the irradiated volume (Cohort A 5/10; Cohort B 1/9). No evaluable patients had progression of irradiated metastases. Immunologic changes were seen in the peripheral blood with increases in T-cell receptor diversity in some responding patients. CONCLUSIONS: RT with nivolumab and ipilimumab was safe compared with historical data of nivolumab and ipilimumab alone. Immunologic effects were observed in the peripheral blood. Randomized studies are ongoing to assess whether RT increases the efficacy of nivolumab and ipilimumab.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Melanoma/patologia , Melanoma/terapia , Terapia Neoadjuvante , Adulto , Idoso , Idoso de 80 Anos ou mais , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Biomarcadores , Quimiorradioterapia , Feminino , Humanos , Ipilimumab/administração & dosagem , Masculino , Melanoma/etiologia , Melanoma/mortalidade , Pessoa de Meia-Idade , Terapia Neoadjuvante/métodos , Metástase Neoplásica , Estadiamento de Neoplasias , Nivolumabe/administração & dosagem , Prognóstico , Resultado do Tratamento
11.
Semin Oncol ; 47(1): 85-92, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32147127

RESUMO

From a series of clinical trials in the last several decades, current treatment paradigms for locally advanced rectal cancer include: (1) preoperative long-course radiotherapy (RT) combined with radiosensitizing chemotherapy; (2) preoperative short-course RT alone followed by adjuvant postoperative chemotherapy; and (3) total neoadjuvant therapy with induction chemotherapy followed by chemoradiotherapy. Other strategies under active investigation in both institutional and cooperative trials include neoadjuvant chemotherapy alone without RT in select patients, total neoadjuvant therapy, watchful waiting after a clinical complete response as an alternative to surgical resection, and the use of different chemotherapeutic and targeted agents. The focus of this review is on established and novel therapeutic strategies for locally advanced rectal cancer.


Assuntos
Neoplasias Retais/diagnóstico , Neoplasias Retais/terapia , Ensaios Clínicos como Assunto , Terapia Combinada/efeitos adversos , Terapia Combinada/métodos , Gerenciamento Clínico , Humanos , Estadiamento de Neoplasias/métodos , Neoplasias Retais/etiologia , Resultado do Tratamento
12.
Front Oncol ; 10: 574012, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33614476

RESUMO

Glioblastoma is an aggressive and inevitably recurrent primary intra-axial brain tumor with a dismal prognosis. The current mainstay of treatment involves maximally safe surgical resection followed by radiotherapy over a 6-week period with concomitant temozolomide chemotherapy followed by temozolomide maintenance. This review provides a summary of the epidemiological, clinical, histologic and genetic characteristics of newly diagnosed disease as well as the current standard of care and potential future therapeutic prospects.

13.
Int J Radiat Biol ; 96(1): 22-34, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-30605362

RESUMO

Purpose: In a significant nuclear event, hundreds of thousands of individuals will require rapid triage for absorbed radiation to ensure effective medical treatment and efficient use of medical resources. We are developing a rapid screening method to assess whether an individual received an absorbed dose of ≥2 Gy based on the analysis of a specific panel of blood proteins in a fingerstick blood sample.Materials and methods: We studied a data set of 1051 human blood samples obtained from radiotherapy patients, normal healthy individuals, and several special population groups. We compared the findings in humans with those from irradiation studies in non-human primates (NHPs).Results: We identified a panel of three protein biomarkers, salivary alpha amylase (AMY1), Flt3 ligand (FLT3L), and monocyte chemotactic protein 1 (MCP1), which are upregulated in human patients receiving fractionated doses of total body irradiation (TBI) therapy as a treatment for cancer. These proteins exhibited a similar radiation response in NHPs after single acute or fractionated doses of ionizing radiation.Conclusion: Our work provides confidence in this biomarker panel for biodosimetry triage using fingerstick blood samples and in the use of NHPs as a model for irradiated humans.


Assuntos
Proteínas Sanguíneas/análise , Radiometria/métodos , Triagem/métodos , Adolescente , Adulto , Idoso , Animais , Biomarcadores/sangue , Criança , Feminino , Humanos , Imunoensaio , Macaca mulatta , Masculino , Pessoa de Meia-Idade , Adulto Jovem
14.
Transl Oncol ; 12(11): 1525-1531, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31454725

RESUMO

In preclinical studies, selenite had single agent activity and radiosensitized tumors in vivo. Here we report results from a Phase 1 trial in 15 patients with metastatic cancer treated with selenite (5.5 to 49.5 mg) orally as a single dose 2 hours before each radiation therapy (RT) treatment. Patients received RT regimens that were standard of care. The primary objective of the study was to assess the safety of this combination therapy. Secondary objectives included measurement of pharmacokinetics (PK) and evaluation of efficacy. Endpoints included assessment of PK, toxicity, tumor response, and pain before and after treatment. The half-life of selenite was 18.5 hours. There were no adverse events attributable to selenite until the 33 mg dose level, at which the primary toxicities were grade 1 GI side effects. One patient treated with 49.5 mg had grade 2 GI toxicity. Although this was not a DLT, it was felt that the highest acceptable dose in this patient population was 33 mg. Most patients had stabilization of disease within the RT fields, with some demonstrating objective evidence of tumor regression. Most patients had a marked improvement in pain and seven out of nine patients with prostate cancer had a decrease in PSA ranging from 11-78%. Doses up to 33 mg selenite were well tolerated in combination with RT. A randomized, well controlled study is needed at the 33 mg dose level to determine if selenite results in clinically meaningful improvements in the response to palliative RT.

15.
J Extracell Vesicles ; 8(1): 1597603, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31258878

RESUMO

Biological nanoparticles, including viruses and extracellular vesicles (EVs), are of interest to many fields of medicine as biomarkers and mediators of or treatments for disease. However, exosomes and small viruses fall below the detection limits of conventional flow cytometers due to the overlap of particle-associated scattered light signals with the detection of background instrument noise from diffusely scattered light. To identify, sort, and study distinct subsets of EVs and other nanoparticles, as individual particles, we developed nanoscale Fluorescence Analysis and Cytometric Sorting (nanoFACS) methods to maximise information and material that can be obtained with high speed, high resolution flow cytometers. This nanoFACS method requires analysis of the instrument background noise (herein defined as the "reference noise"). With these methods, we demonstrate detection of tumour cell-derived EVs with specific tumour antigens using both fluorescence and scattered light parameters. We further validated the performance of nanoFACS by sorting two distinct HIV strains to >95% purity and confirmed the viability (infectivity) and molecular specificity (specific cell tropism) of biological nanomaterials sorted with nanoFACS. This nanoFACS method provides a unique way to analyse and sort functional EV- and viral-subsets with preservation of vesicular structure, surface protein specificity and RNA cargo activity.

16.
Cureus ; 10(12): e3723, 2018 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-30788205

RESUMO

The combined use of immunotherapy and radiation therapy is emerging as a potentially effective treatment for patients with immunogenic tumors such as melanoma; however, evidence for long-term treatment outcomes is lacking. Herein, we summarize our previously described case study of a patient with metastatic melanoma treated with two cycles of ipilimumab, followed by stereotactic body radiotherapy to two of seven liver metastases, with two additional cycles of ipilimumab. In the longest follow-up to date, we report a successful treatment outcome at 6.5 years. Our patient remains in complete remission, with no evidence of disease or recurrence 6.5 years after treatment. He continues to manage chronic hypophysitis developed secondary to immunotherapy and has developed osteopenia from prolonged systemic glucocorticoid use. The use of radiotherapy in combination with targeted immune therapy appears to be an effective treatment strategy, with long-lasting efficacy.

17.
Cureus ; 9(6): e1414, 2017 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-28861331

RESUMO

The effects of high dose gamma radiation on brain tissue are poorly understood, with both limited and major changes reported. The present study compared the effects of gamma irradiation on the expression of interneuron markers within the hippocampal cornu ammonis 1 (CA1) region with expression in control matched rats. This area was chosen for study because of its well-characterized circuitry. Male Sprague-Dawley rats were exposed to 60 Gy of whole brain gamma radiation and after 24 or 48 hours, the brains were removed, fixed and sectioned to quantitate expression of parvalbumin (PV), calbindin-D28K (CB), reelin, neuropeptide-Y (NPY), and somatostatin. All of these markers increased in expression over the first 48 hours, except NPY, which decreased. This provides novel information on changes in gene expression in the hippocampal interneurons following radiation. Staining for Beclin 1, a marker of autophagy, increased most strongly in the subgranular zone (SGZ) of the dentate gyrus (DG). Overall, the results are consistent with the hypothesis that increased intracellular calcium follows irradiation, leading to an increased expression of calcium binding proteins. Increased autophagy occurs in the neurogenic zone of the dentate hilus, consistent with reduced effective neurogenesis after irradiation.

18.
Cureus ; 9(3): e1076, 2017 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-28401026

RESUMO

Studies on the effects of gamma radiation on brain tissue have produced markedly differing results, ranging from little effect to major pathology, following irradiation. The present study used control-matched animals to compare effects on a well characterized brain region following gamma irradiation. Male Sprague-Dawley rats were exposed to 60 Gy of whole brain gamma radiation and, after 24-hours, 48-hours, and one-week periods, hippocampal brain slices were isolated and measured for anatomical and physiological differences. There were no major changes observed in tissue appearance or evoked synaptic responses at any post-irradiation time point. However, exposure to 60 Gy of irradiation resulted in a small, but statistically significant (14% change; ANOVA p < 0.005; n = 9) reduction in synaptic inhibition seen at 100 ms, indicating a selective depression of the gamma-aminobutyric acid (GABAA) slow form of inhibition. Population spike (PS) amplitudes also transiently declined by ~ 10% (p < 0.005; n = 9) when comparing the 24-hour group to sham group. Effects on PS amplitude recovered to baseline 48 hour and one week later. There were no obvious negative pathological effects; however, a subtle depression in circuit level inhibition was observed and provides evidence for 'radiomodulation' of brain circuits.

19.
Clin Epigenetics ; 9: 4, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28149332

RESUMO

BACKGROUND: RRx-001, a dinitroazetidine derivative, is a novel anticancer agent currently in phase II clinical trials. It mediates immunomodulatory effects either directly through polarization of tumor associated macrophages or indirectly through vascular normalization and increased T-lymphocyte infiltration. With multiple additional mechanisms of action including upregulation of oxidative stress, depletion of GSH and NADPH, anti-angiogenesis and epigenetic modulation, RRx-001 is being studied as a radio- and chemo-sensitizer to resensitize tumors to prior therapy and to prime tumors to respond to radiation, chemotherapy and immunotherapy in combination therapy studies. Here, we identified another mechanism, viral mimicry, which refers to the "unsilencing" of epigenetically repressed viral genes present in the tumor that provokes an immune response and may contribute to the anticancer activity of RRx-001. RESULTS: RRx-001 inhibited the growth of colon cancer cells (HCT 116) and decreased levels of the DNA methyltransferases DNMT1 and DNMT3a in a time and dose-dependent manner. Treatment of HCT 116 cells with 0.5 µM RRx-001 for 24 h significantly increased transcripts of interferon (IFN)-responsive genes and this induction was sustained for up to 4 weeks after transient exposure to RRx-001. ELISA assays showed that RRx-001 increased secretion of type I and III IFNs by HCT 116 cells, and these IFNs were confirmed to be bioactive. Transcription of endogenous retrovirus ERV-Fc2 and LTRs from the ERV-L family (MLT2B4 and MLT1C49) was induced by RRx-001. The induction of ERV-Fc2-env was through demethylation of ERV-Fc2 LTR as determined by methylation-specific polymerase chain reaction and combined bisulfite restriction analysis. Immunofluorescence staining with J2 antibody confirmed induction of double-stranded RNA. CONCLUSIONS: Transient exposure of HCT 116 cells to low-dose RRx-001 induced transcription of silenced retroviral genes present in the cancer cell DNA with subsequent synthesis of IFN in response to this "pseudo-pathogenic" stimulus, mimicking an antiviral defense. RRx-001-mediated IFN induction may have the potential to improve the efficacy of immunotherapies as well as radiotherapy, standard chemotherapies and molecularly targeted agents when used in combination. The striking safety profile of RRx-001 in comparison to other more toxic epigenetic and immunomodulatory agents such as azacitidine makes it a leading candidate for such clinical applications.


Assuntos
Azetidinas/farmacologia , Neoplasias do Colo/tratamento farmacológico , Neoplasias do Colo/imunologia , Interferons/imunologia , Nitrocompostos/farmacologia , Antineoplásicos/farmacologia , Azacitidina/farmacologia , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Neoplasias do Colo/enzimologia , Neoplasias do Colo/genética , DNA (Citosina-5-)-Metiltransferase 1 , DNA (Citosina-5-)-Metiltransferases/metabolismo , DNA Metiltransferase 3A , Relação Dose-Resposta a Droga , Regulação para Baixo/efeitos dos fármacos , Retrovirus Endógenos/genética , Retrovirus Endógenos/imunologia , Epigênese Genética/efeitos dos fármacos , Células HCT116 , Humanos , Fatores Imunológicos/farmacologia , Interferons/biossíntese , Interferons/genética , Mimetismo Molecular , Transcrição Gênica , Proteínas do Envelope Viral/genética , Proteínas do Envelope Viral/imunologia
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