Using Holistic Residency Applicant Review and Selection in Radiation Oncology to Enhance Diversity and Inclusion, an ASTRO SCAROP-ADROP-ARRO Collaboration

Disproportionate gender, racial, and ethnic diversity remains in the radiation oncology physician workforce despite widespread awareness and longitudinal efforts to improve representation. In this collaborative review, we define the rationale and components of holistic review and how it can be best utilized to provide a comprehensive evaluation of applicants to residency programs in radiation oncology. We initially discuss the current state of diversity in the field of radiation oncology and highlight the components of the residency selection process that may serve to perpetuate existing biases. Subsequently, the ACGME and AAMC holistic review framework is reviewed in detail to demonstrate the balanced assessment of potential applicants. The implementation of holistic review in medical school and residency selection to-date are examined to underscore the potential value of holistic review in the radiation oncology residency selection process. Finally, recommendations for the practical implementation of holistic review in radiation oncology trainee selection are outlined.

Academic patterns of practice regarding CT simulation scans and radiology review

OBJECTIVE

Currently, there are no consensus guidelines about handling incidental radiological findings on radiotherapy planning CT simulation scans. Retrospective studies analyzing incidental findings on CT simulations show a small, but not insignificant, rate of both oncologic and non-oncologic findings. These findings may have medico-legal, financial, and clinical implications. Given a lack of guidelines, we obtained a formal survey of multiple academic institutions to evaluate how CT simulations are handled in regard to incidental findings.

METHODS

A formal survey was developed consisting of 12 questions related to institutional practices regarding CT simulation scans. From 7/18/21 to 8/27/21 and 5/6/22 to 5/24/22, the survey was administered electronically by REDCap to key personnel at Academic Radiation Oncology Programs identified through the American Society for Radiation Oncology (ASTRO) with inclusion criteria including an active ACGME approved Radiation Oncology residency program.

RESULTS

In total, 88 academic radiation oncology programs were surveyed with total of 45 responses (51%). 1 out of 45 departments who responded has formal guidelines regarding workup of incidental findings. There is variability about sending CT simulation scans for official radiology review if an incidental finding is identified.

CONCLUSIONS

Based on a measurable rate of incidental findings on radiotherapy planning CT simulations and their possible implications, our survey illustrates a likely need for consensus recommendations for handling such findings to improve patient care and safety.

Patient Reported Quality of Life Outcomes After Definitive Radiation Therapy With Absorbable Spacer Hydrogel for Prostate Cancer

Purpose

SpaceOAR is a device approved for conventional radiation in prostate cancer. We sought to observe prospectively how SpaceOAR Hydrogel effected quality of life and dosimetry to organs at risk at our institution.

Methods and Materials

We prospectively enrolled patients with low risk or favorable-intermediate risk localized prostate cancer. Baseline Expanded Prostate Cancer Index Composite (EPIC-26) scores along with baseline American Urology Association Symptom Index (AUA-SI) scores were collected. SpaceOAR was placed for all patients who then received stereotactic body radiation therapy, low dose rate brachytherapy, conventionally fractionated radiation therapy, or moderately hypofractionated radiation therapy. We evaluated postimplant dosimetry to critical structures, and prospectively collected follow-up EPIC-26 and AUA-SI scores. We performed a repeated measures analysis of variance to compare patient-specific responses and correlated survey data with dosimetric metrics by generating linear regression models.

Results

We enrolled 59 patients in this study with a median follow-up of 366 days (interquartile range, 507). At final follow-up, the "?>prostate-specific antigen had a significant decline compared with baseline (P < .0001). There were no grade 3 toxicities on treatment. There were no significant changes in the AUA-SI score (P = .69) at final follow-up compared with baseline, nor was there any change in EPIC-26 domain scores (P = .19) during the course of the study period. There were no significant associations between AUA scores and EPIC-26 scores and the dose to the rectum, bladder, or urethra with the exception being dose to the 2 mL rectum correlated with decline in EPIC-26 rectal score (β, −0.002; P = .006). Patient-reported declines in bowel domains were less than previously reported data.

Conclusions

Use of SpaceOAR results in favorable dosimetry to the organs at risk and portends excellent short-term quality of life as measured by the association with the patient reported outcome measures. Longer-term follow-up is ongoing and necessary to assess the long-term effect and association of the hydrogel.

Novel Workflow for Conversion of Catheter-Based Electroanatomic Mapping to DICOM Imaging for Noninvasive Radioablation of Ventricular Tachycardia

PURPOSE

A recent clinical trial has demonstrated that noninvasive radioablation (NIRA) has the potential to reduce recurrent ventricular tachycardia (VT) that is refractory to drugs and standard catheter ablation. Electroanatomic mapping (EAM) that would be useful for planning is obtained during catheter ablation, but incompatibility between EAM and DICOM formats required for radiation planning has impeded the use of existing catheter-based mapping to guide NIRA and is an important hurdle for its wider adoption. In this paper we define a process to facilitate the fusion of catheter-based EAM with DICOM imaging for radiation planning.

METHOD AND MATERIALS

The raw data export of the CARTO3 EAM system (version 6.0.45.171, ".mesh" file) was processed with a MATLAB script to generate 3-dimensional (3D) visual took kit files containing X, Y, Z coordinates obtained during mapping and corresponding impedance, voltage, and other point-based information. The image could then be visualized with standard image processing software (3D Slicer) and the target outlined on the image surface. This structure was in turn converted to a DICOM image and fused with patient thoracic imaging using anatomic landmarks. Robustness of the workflow was assessed through implementation with a second magnetic resonance imaging based VT ablation planning system, ADAS-VT.

RESULTS

This process facilitated the fusion of EAM and DICOM imaging to inform selection of NIRA targets. The workflow was found to be robust and compatible with a second VT ablation planning system.

CONCLUSIONS

The conversion of catheter-based EAM to a DICOM compatible format permits the fusion of images for radiation planning and provides an avenue for the wider application of NIRA. Further improvements in the compatibility of these imaging formats would be expected to improve quality and reproducibility of image fusion.

Consensus and controversies regarding the treatment of rhabdomyosarcoma

Optimal treatment of rhabdomyosarcoma (RMS) requires multidisciplinary approach, incorporating chemotherapy with local control. Although current therapies are built on cooperative group trials, a comprehensive standard of care to guide clinical decision making has been lacking, especially for relapsed patients. Therefore, we assembled a panel of pediatric and adolescent and young adult sarcoma experts to develop treatment guidelines for managing RMS and to identify areas in which further research is needed. We created algorithms incorporating evidence-based care for patients with RMS, emphasizing the importance of clinical trials and close integration of all specialties involved in the care of these patients.

Treatment pathway of bone sarcoma in children, adolescents, and young adults

When pediatric, adolescent, and young adult patients present with a bone sarcoma, treatment decisions, especially after relapse, are complex and require a multidisciplinary approach. This review presents scenarios commonly encountered in the therapy of bone sarcomas with the goal of objectively presenting a consensus, multidisciplinary management approach. Little variation was found in the authors' group with respect to local control or systemic therapy. Clinical trials were universally prioritized in all settings. Decisions regarding relapse therapies in the absence of a clinical trial had very minor variations initially, but a consensus was reached after a literature review and discussion. This review presents a concise document and figures as a starting point for evidence‐based care for patients with these rare diseases. This framework allows prospective decision making and prioritization of clinical trials. It is hoped that this framework will inspire and focus future clinical research and thus lead to new trials to improve efficacy and reduce toxicity. Cancer 2017;123:2206–2218. © 2017 American Cancer Society.

This review presents a pathway for the management of common clinical scenarios that arise in the treatment of bone sarcomas in children, adolescents, and young adults. Clinical trials should be prioritized when they are available, and for those times when trials are unavailable, a consensus, multidisciplinary management approach to bone sarcomas is presented.

The Use of Gene Therapy in Cancer Research and Treatment

Gene therapy involves identifying a gene of interest and then manipulating the expression of this gene through a variety of techniques. Here we specifically address gene therapy's role in cancer research. This paper will encompass thoroughly investigated techniques such as cancer vaccines and suicide gene therapy and the latest advancements in and applications of these techniques. It will also cover newer techniques such as Antisense Oligonucleotides and small interfering RNAs and how these technologies are being developed and used. The use of gene therapy continues to expand in cancer research and has an integral role in the advancement of cancer treatment.

The Use of Tyrosine Kinase Inhibitors in Modifying the Response of Tumor Microvasculature to Radiotherapy

The response of the tumor microvasculature to ionizing radiation can be modified to improve tumor control in preclinical mouse models of cancer. Recent studies have shown that a variety of cancer drugs can improve the response of cancers to radiotherapy. Protein tyrosine kinase inhibitors (TKIs) have been shown to enhance radiation-induced destruction of tumor blood vessels. Among these compounds are inhibitors of a broad spectrum of receptor tyrosine kinases (RTKs). Inhibition of RTKs attenuates downstream signaling from various angiogenic growth factors, including vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), and fibroblast growth factor (FGF). RTK inhibitors with various specificities against the receptors for VEGF, PDGF, and FGF manifest significant antiangiogenic activities as well. We have shown using tumor vascular window model and tumor growth delay assays that these compounds can enhance tumor radiation response by attacking tumor microvasculature. Furthermore, we have shown that radiation and RTK inhibitors exert their antiangiogenic effect through inhibition of the PI3K/Akt signaling pathway, which results in induction of apoptosis. Our studies have provided a basis for future clinical investigations of combining radiotherapy and RTK inhibitors.

The utilization of chemotherapy and radiation at the end of life in individuals with metastatic non-small cell lung cancer

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Background: Advancements in the diagnosis and treatment of metastatic non-small cell lung cancer (NSCLC) have contributed to improved quality of life and survival. However, these successes are matched with rising healthcare costs and a growing debate over the appropriate utilization of medical resources near the end of life. To date, the majority of utilization studies report outcomes based on single institution or Medicare models. This may lead to significant bias due to individual physician preferences, narrow age groups or single payer systems. The purpose of this study is to analyze the broader trends and variables impacting the use of chemotherapy (CHT) and radiation (XRT) in the final months of life. Methods: The Florida Cancer Data System (FCDS) was used to evaluate patients with Stage IV (M1) NCLC from 1995 to 2010. Logistic Regression was used to determine the association between insurance types, census-based socioeconomic status (SES) and demographic variables with XRT received or CHT received. Results: 48,858 patients were identified within the FCDS and eligible for this study. The median age was 69 years. The median survival was 4.8 months. The overall use of XRT decreased between 1995 and 2010 from 52% to 37%, while the use of CHT increased from 35% to 49%. The utilization of treatment during the final 60, 30 and 14 days of death was 28%, 13% and 5% respectively for XRT, and 18%, 8% and 4% for CHT. Neither insurance status (OR, 0.852; 95% CI, 0.721 -1.174) nor poverty status (OR, 1.026; 95% CI, 0.950 -1.109) was predictive for XRT received. Those classified as low SES (OR, 0.685, 95% CI, 0.633-0.741) or not insured (OR, 0.678, 95% CI, 0.572-0.804) were less likely to receive CHT. Older-unmarried-females were less likely to receive CHT and XRT compared to their younger-married-male counterparts. Conclusions: When examining a broader demographic and insurance mix, the utilization of XRT and CHT in the final 30 and 14 days of death remain low at 13% and 5% for radiation and 8% and 4% for chemotherapy consistent with previously reported studies. Younger-married-males were more likely to receive palliative treatments. Insurance and SES did not influence the delivery of XRT while they did impact the use of CHT.

The Refusal of Palliative Radiation in Metastatic Non-Small Cell Lung Cancer and Its Prognostic Implications

CONTEXT

Patients with metastatic non-small cell lung cancer (NSCLC) have limited survival. Population studies have evaluated the impact of radiation refusal in the curative setting; however, no data exist concerning the prognostic impact of radiation refusal in the palliative care setting.

OBJECTIVES

To investigate the patterns of radiation refusal in newly diagnosed patients with metastatic NSCLC.

METHODS

Patients with Stage IV NSCLC diagnosed between 1988 and 2010 were identified in the Surveillance, Epidemiology, and End Results database. Univariate and multivariate analyses were used to identify predictors for refusal of radiation and the impact of radiation and refusal on survival in the palliative setting.

RESULTS

A total of 285,641 patients were initially included in the analysis. Palliative radiation was recommended in 42% and refused by 3.1% of patients. Refusal rates remained consistent across included years of study. On multivariate analysis, older, nonblack/nonwhite, unmarried females were more likely to refuse radiation (P < 0.001 in all cases). Median survival for patients refusing radiation was three months vs. five months for those receiving radiation and two months for those whom radiation was not recommended.

CONCLUSION

Patients with metastatic NSCLC who refuse recommended palliative radiation have a poor survival. Radiation refusal or the recommendation against treatment can serve as a trigger for integrating palliative care services sooner and contributes greatly to prognostic awareness. Further investigation into this survival difference and the factors behind refusal are warranted.

Long-term outcomes and late effects for childhood and young adulthood intracranial germinomas

BACKGROUND

Pediatric and young adult central nervous system (CNS) germinomas have favorable cure rates. However, long-term follow-up data are limited because of the rarity of this tumor. We report the long-term overall survival (OS) and causes of late mortality for these patients.

METHODS

Data between 1973 and 2005 from the Surveillance, Epidemiology, and End Results (SEER) database were analyzed. Kaplan Meier survival analysis was performed on 5-year survivors of childhood CNS germinomatous germ cell tumors (GGCTs) and nongerminomatous germ cell tumors (NGGCTs). Standardized mortality ratios (SMRs) were calculated using US population data to compare observed versus expected all-cause death and death from stroke. Cumulative incidence was calculated using a competing risk model.

RESULTS

Four hundred five GGCTs and 94 NGGCTs cases were eligible. OS at 20 and 30 years for GGCTs was 84.1% and 61.9%, respectively, and was 86.7% for NGGCTs at both time points. Five-year survivors of GGCTs and NGGCTs experienced a 10-fold increase in mortality risk compared with their peers (SMR, 10.41; 95% confidence interval [CI], 7.71-13.76 vs SMR, 10.39;95% CI, 4.83-19.73, respectively). Five-year survivors GGCTs also experienced a nearly 59-fold increase in risk of death from stroke (SMR, 58.93; 95% CI, 18.72-142.10). At 25 years, the cumulative incidence of death due to cancer and subsequent malignancy was 16% and 6.0%, respectively.

CONCLUSION

Although CNS germinomas have favorable cure rates, late recurrences, subsequent malignancies, and stroke significantly affect long-term survival. Close attention to long-term follow-up with assessment of stroke risk factors is recommended.

Outcome for children with metastatic solid tumors over the last four decades

Background

Outcomes for pediatric solid tumors have significantly improved over the last 30 years. However, much of this improvement is due to improved outcome for patients with localized disease. Here we evaluate overall survival (OS) for pediatric patients with metastatic disease over the last 40 years.

Procedure

The United States Surveillance, Epidemiology, and End Results (SEER) database was used to conduct this study. Patients diagnosed between 0 and 18 years of age with metastatic Ewings sarcoma, neuroblastoma, osteosarcoma, rhabdomyosarcoma or Wilms tumor were included in the analysis.

Results

3,009 patients diagnosed between 1973–2010 met inclusion criteria for analysis. OS at 10 years for patients diagnosed between 1973–1979, 1980–1989, 1990–1999 and 2000–2010 was 28.3%, 37.2%, 44.7% and 49.3%, respectively (p<0.001). For patients diagnosed between 2000–2010, 10-year OS for patients with Ewing sarcoma, neuroblastoma, osteosarcoma, rhabdomyosarcoma and Wilms tumor was 30.6%, 54.4%, 29.3%, 27.5%, and 76.6%, respectively, as compared to 13.8%, 25.1%, 13.6%, 17.9% and 57.1%, respectively, for patients diagnosed between 1973–1979. OS for neuroblastoma significantly increased with each decade. For patients with osteosarcoma and Ewing sarcoma, there was no improvement in OS over the last two decades. There was no improvement in outcome for patients with rhabdomyosarcoma or Wilms tumor over the last 30 years.

Conclusions

OS for pediatric patients with metastatic solid tumors has significantly improved since the 1970s. However, outcome has changed little for some malignancies in the last 20–30 years. These data underscore the importance of continued collaboration and studies to improve outcome for these patients.

Subsequent malignancies and their effect on survival in patients with retinoblastoma

BACKGROUND

As cure rates for retinoblastoma have improved, it is clear that patients with hereditary retinoblastoma experience increased risk of subsequent malignant neoplasms (SMNs).

METHODS

Using the Surveillance, Epidemiology and End Results (SEER) database, we evaluated risk of SMNs in survivors or retinoblastoma. Standardized mortality ratios (SMRs) were calculated to compare number of deaths observed to the expected number for the cohort. Cumulative incidence of SMNs and standardized incidence ratios (SIRs) of observed to expected SMNs were calculated

RESULTS

A total of 595 patients were included in the analysis. Cumulative incidence of secondary malignancy at 30 years for patients with unilateral and bilateral disease was 1.7% and 28.5%, respectively (P < 0.001). SIRs of subsequent malignancies for patients with unilateral and bilateral disease were 2.1 (95% CI = 0.6-5.4) and 38.3 (95% CI = 24.3-57.5), respectively. Patients with bilateral disease treated with and without radiotherapy both experienced an increased risk of SMNs (SIRs = 45.9, 95% CI = 26.8-73.6 and 27.3, 95% CI = 10.0-59.4, respectively). The most common cause of death for the patients with bilateral disease was subsequent malignancy (52% of deaths). Beginning in the 1990s, there was a significant decrease in the use of radiotherapy as 30.5% of patients received radiotherapy in the 1980s compared to 2.6% after 1999 (P < 0.001).

CONCLUSIONS

Survivors of bilateral retinoblastoma experience an increased risk of SMNs which adversely affects survival. The use of radiotherapy in the management of retinoblastoma has declined; however, patients with bilateral disease remain at an increased risk of subsequent cancers.

Late causes of death in children treated for CNS malignancies

As the outcome for pediatric central nervous system (CNS) malignancies improves, data regarding long term effects and risk of early mortality are needed. Using the Surveillance, Epidemiology, and End Results database, we evaluated the causes of mortality in 5-year survivors of a CNS tumor diagnosed prior to the age of 20 years. Using United States population data, standardized mortality ratios (SMRs) were calculated to compare number of deaths observed to the expected number for the cohort. Cumulative incidence of subsequent malignant neoplasms (SMNs) and standardized incidence ratios of observed to expected SMNs were calculated. 3,627 patients were included in the study. 20-year overall survival (OS) was 85.7 % compared to an expected rate of 98.5 % (p < 0.001). Death from the primary brain tumor accounted for 51 % of deaths, while death from a SMN accounted for 10 % of deaths. Patients were at an increased risk of death due to cardiovascular and cerebrovascular disease (SMRs = 2.5, 95 % confidence interval (CI) 1.2-4.8 and 7.9, 2.6-19.0, respectively). Cumulative incidence of SMN at 30 years was 6.4 % (95 % CI 4.8-7.7). Patients treated after 1986 enjoyed a small improvement in mortality (20-year OS 86.5 vs 83.8 %, p = 0.005). Five-year survivors of a childhood CNS tumor experienced a nearly 13-fold increased risk of death compared to their peers. Patients were at an increased risk of death due to recurrent disease, SMNs, cerebrovascular and cardiovascular events.

Patterns of care and outcomes of patients with pleomorphic xanthoastrocytoma: a SEER analysis

To study the clinical characteristics, treatment approach and outcome of pleomorphic xanthoastrocytoma (PXA), patients were identified using the National Cancer Intitute's Surveillance, Epidemiology, and End Results (SEER) database. A total of 214 patients were identified with PXA using the November 2010 submission. Patient demographics, tumor characteristics, extent of surgical resection, the use of radiotherapy, and overall survival were evaluated. Overall survival for PXA was then compared to that of pilocytic astrocytoma, oligodendroglioma, ependymom and glioblastoma also using the SEER database. Kaplan-Meier, univariate and multivariate analyses were performed. The majority of patients were found to be young adults with the most common tumor location being temporal lobe. Surgery was performed on most (95 %) patients, while 25 % of patients received radiation therapy. Five and 10 year overall survival rates were 75 and 67 %, respectively. Grade was only available for a limited number of patients but appeared to affect prognosis. Patients with grade IV tumors had a median overall survival of 45 months, whereas median survival was not reached for grade I-III patients. On multivariate analysis, male gender and increasing age were associated with worse overall survival (p values 0.05 and <0.006, respectively). Extent of resection trended towards significance in favor of gross total resection. PXA is a rare diagnosis that affects young adults. Surgical resection is the primary modality of treatment with an overall good prognosis. Elderly patients, those with higher grade disease and patients with incomplete resections may have a worse prognosis. The role of radiation therapy for PXA remains unclear but is more often used for patients with high grade tumors. Compared to other common brain tumors, PXA's appear to fare worse than pilocytic astrocytoma and oligodendroglioma, especially in younger patients. However, even high grade PXA patients have significantly better overall survival compared to glioblastoma.

Feasibility of electromagnetic transponder use to monitor inter- and intrafractional motion in locally advanced pancreatic cancer patients

PURPOSE

The primary objective of this study was to determine the feasibility of electromagnetic transponder implantation in patients with locally advanced unresectable pancreatic cancer. Secondarily, the use of transponders to monitor inter- and intrafractional motion, and the efficacy of breath holding for limiting target motion, were examined.

METHODS AND MATERIALS

During routine screening laparoscopy, 5 patients without metastatic disease were implanted with transponders peri-tumorally. The Calypso System's localization and tracking modes were used to monitor inter- and intrafractional motion, respectively. Intrafractional motion, with and without breath holding, was also examined using Calypso tracking mode.

RESULTS

Transponder implantation was well tolerated in all patients, with minimal migration, aside from 1 patient who expulsed a single transponder. Interfractional motion based on mean shifts from setup using tattoos/orthogonal imaging to transponder based localization from 164 treatments was significant in all dimensions. Mean shift (in millimeters), followed by the standard deviation and p value, were as follows: X-axis: 4.5 mm (1.0, p = 0.01); Y axis: 6.4 mm (1.9, p = 0.03); and Z-axis 3.9 mm (0.6, p = 0.002). Mean intrafractional motion was also found to be significant in all directions: superior, 7.2 mm (0.9, p = 0.01); inferior, 11.9 mm (0.9, p < 0.01); anterior: 4.9 mm (0.5, p = 0.01); posterior, 2.9 mm (0.5, p = 0.02); left, 2.2 mm (0.4, p = 0.02); and right, 3.1 mm (0.6, p = 0.04). Breath holding during treatment significantly decreased tumor motion in all directions.

CONCLUSIONS

Electromagnetic transponder implantation appears to be safe and effective for monitoring inter- and intrafractional motion. Based on these results a larger clinical trial is underway.

Brachytherapy in the treatment of cholangiocarcinoma

PURPOSE

To examine the role of brachytherapy in the treatment of cholangiocarcinomas in a relatively large group of patients.

METHODS AND MATERIALS

Using the Surveillance, Epidemiology and End Results database, a total of 193 patients with cholangiocarcinoma treated with brachytherapy were identified for the period 1988-2003. The primary analysis compared patients treated with brachytherapy (with or without external-beam radiation) with those who did not receive radiation. To try to account for confounding variables, propensity score and sensitivity analyses were used.

RESULTS

There was a significant difference between patients who received radiation (n = 193) and those who did not (n = 6859) with regard to surgery (p < 0.0001), race (p < 0.0001), stage (p < 0.0001), and year of diagnosis (p <0.0001). Median survival for patients treated with brachytherapy was 11 months (95% confidence interval [CI] 9-13 months), compared with 4 months for patients who received no radiation (p < 0.0001). On multivariable analysis (hazard ratio [95% CI]) brachytherapy (0.79 [0.66-0.95]), surgery (0.50 [0.46-0.53]), year of diagnosis (1998-2003: 0.66 [0.60-0.73]; 1993-1997: (0.96 [0.89-1.03; NS], baseline 1988-1992), and extrahepatic disease (0.84 [0.79-0.89]) were associated with better overall survival.

CONCLUSIONS

To the authors' knowledge, this is the largest dataset reported for the treatment of cholangiocarcinomas with brachytherapy. The results of this retrospective analysis suggest that brachytherapy may improve overall survival. However, because of the limitations of the Surveillance, Epidemiology and End Results database, these results should be interpreted cautiously, and future prospective studies are needed.

Sirolimus as a potential radiosensitizer in squamous cell cancer of the head and neck

BACKGROUND

An estimated 34,000 cases of squamous cell carcinomas of the head and neck (HNSCC) will be diagnosed in 2007 with 7500 estimated deaths. Radiation is commonly used to treat these patients. Preclinical studies have suggested that sirolimus may be an effective radiosensitizer in HNSCC.

METHODS

The present case report describes a patient, status post liver transplant, who was switched to sirolimus for immunosupression. The patient subsequently underwent radiation therapy for a T2N0M0 SCC of the larynx.

RESULTS

The patient had an unusually early response to radiation, with a clinical complete response after 7 fractions of radiation. However, the patients also had toxicity earlier than expected and required a break from radiation after 11 fractions.

CONCLUSIONS

To the authors' knowledge, this is the first observation to suggest that sirolimus is an effective radiosensitizer in patients with HNSCC. We hope that our results will create interest in future clinical studies.

The role of mTOR inhibition in augmenting radiation induced autophagy

Radiation affects both tumor and normal tissues, limiting the total delivered radiation dose. Therefore, novel ways to exploit molecular targets and improve the therapeutic ratio are continually being investigated. Autophagy plays an important role in cancer cell death decisions, particularly in solid tumors. This is counterbalanced by its function in cellular energy preservation. Recent studies have attempted to exploit autophagy in order to improve therapeutic ratio. However, direct inhibition of autophagy has been demonstrated to promote cancer cell death or survival dependent on cell type and condition. The mammalian target of rapamycin (mTOR) also regulates autophagy, as well as cell survival and proliferation pathways. Therefore, inhibition at this level of signaling would represent an excellent therapeutic target as it would limit cell growth, decrease cell proliferation, and boost autophagocytosis. Current investigations of mTOR inhibitors in combination with radiation appear to potentiate radiation's ability to induce autophagy. Further studies are necessary to fully elucidate which tumors have the most robust induction of autophagy in response to mTOR inhibition and radiation.

Esophageal cancer in a young woman with bulimia nervosa: a case report

Adenocarcinoma of the esophagus has increased dramatically within the United States and continues to have a poor prognosis despite aggressive treatment. Identifying potential risk factors is critical for the early detection and treatment of this disease. The present case report describes a very young woman who developed adenocarcinoma of the esophagus after only a brief history of bulimia. These findings suggest that even in very young patients, bulimia may represent a risk factor for adenocarcinoma of the esophagus.

Inhibition of survivin and aurora B kinase sensitizes mesothelioma cells by enhancing mitotic arrests

PURPOSE

Survivin, a member of the inhibitor of apoptosis gene family, has also been shown to regulate mitosis. It binds Aurora B kinase and the inner centromere protein to form the chromosome passenger complex. Both Aurora B and survivin are overexpressed in many tumors. In this study, we examined whether irradiation affected survivin and Aurora B expression in mesothelioma cells, and how inhibition of these molecules affected radiosensitivity.

METHODS AND MATERIALS

ZM447439 and survivin antisense oligonucleotides were used to inhibit survivin and Aurora B kinase respectively. Western blot was performed to determine the expression of survivin, Aurora B, phosphorylated-histone H3 (Ser 10), and caspase cleavage. Multinucleated cells were counted using flow cytometry, and cell survival after treatment was determined using clonogenic assay.

RESULTS

At 3-Gy irradiation an increase was observed in levels of survivin and Aurora B as well as the kinase activity of Aurora B, with an increase in G2/M phase. The radiation-induced upregulation of these molecules was effectively attenuated by antisense oligonucleotides against survivin and a small-molecule inhibitor of Aurora B, ZM447439. Dual inhibition of survivin and Aurora B synergistically radiosensitized mesothelioma cells with a dose enhancement ratio of 2.55. This treatment resulted in increased formation of multinucleated cells after irradiation but did not increase levels of cleaved caspase 3.

CONCLUSION

Inhibition of survivin and Aurora B induces mitotic cell arrest in mesothelioma cells after irradiation. These two proteins may be potential therapeutic targets for the enhancement of radiotherapy in malignant pleural mesothelioma.

Active integration: new strategies for transgenesis

This paper presents novel methods for producing transgenic animals, with a further emphasis on how these techniques may someday be applied in gene therapy. There are several passive methods for transgenesis, such as pronuclear microinjection (PNI) and Intracytoplasmic Sperm Injection-Mediated Transgenesis (ICSI-Tr), which rely on the repair mechanisms of the host for transgene (tg) insertion. ICSI-Tr has been shown to be an effective means of creating transgenic animals with a transfection efficiency of approximately 45% of animals born. Furthermore, because this involves the injection of the transgene into the cytoplasm of oocytes during fertilization, limited mosaicism has traditionally occurred using this technique. Current active transgenesis techniques involve the use of viruses, such as disarmed retroviruses which can insert genes into the host genome. However, these methods are limited by the size of the sequence that can be inserted, high embryo mortality, and randomness of insertion. A novel active method has been developed which combines ICSI-Tr with recombinases or transposases to increase transfection efficiency. This technique has been termed "Active Transgenesis" to imply that the tg is inserted into the host genome by enzymes supplied into the oocyte during tg introduction. DNA based methods alleviate many of the costs and time associated with purifying enzyme. Further studies have shown that RNA can be used for the transposase source. Using RNA may prevent problems with continued transposase activity that can occur if a DNA transposase is integrated into the host genome. At present piggyBac is the most effective transposon for stable integration in mammalian systems and as further studies are done to elucidate modifications which improve piggyBac's specificity and efficacy, efficiency in creating transgenic animals should improve further. Subsequently, these methods may someday be used for gene therapy in humans.

PDGFR-beta expression in small cell lung cancer patients

BACKGROUND

Platelet derived growth factor (PDGF) and PDGFR-beta are expressed and have been found to have prognostic value in several human cancers. Data in non-small-cell cancer cell lines have suggested that PDGFR is a therapeutic target for drug development. In the current study PDGFR-beta expression and prognostic value in small cell lung cancer (SCLC) was investigated.

METHODS AND MATERIALS

Paraffin-embedded tissue blocks from 53 patients with limited and extensive stage SCLC were obtained for immunohistochemical staining. Tumors from each patient were sampled 3 times and stained with PDGFR-beta specific antibody. Patients were divided into low and high staining groups based on intensity.

RESULTS

There was high intensity PDGFR-beta staining in 20 patients with SCLC. Another 29 expressed low intensity PDGFR-beta staining, with only 4 patients showing no PDGFR-beta staining. There was no statistically significant difference in 5 year overall survival between patients with low levels of PDGFR-beta staining vs. those with high level staining SCLC tumors (p = 0.538).

CONCLUSIONS

The present study found that the majority of SCLC patients express, at least, a low level of PDGF-beta. However, the level of PDGFR-beta expression was not a statistically significant predictor of 5 year overall survival in SCLC.

Inhibition of signal transducer and activator of transcription 3 activity results in down-regulation of Survivin following irradiation

Signal transducer and activator of transcription 3 (Stat3) and Survivin are constitutively up-regulated in various human tumor cells. We previously found Survivin to be significantly reduced in response to radiation in human umbilical vein endothelial cells (HUVEC) but not in tumor cell lines. In this study, we examined the effect of Stat3 on Survivin expression in irradiated HUVECs and breast cancer cells. We also studied how inhibition of Stat3 and Survivin activity affects cell survival and angiogenesis following irradiation. We determined that Survivin was significantly increased by overexpression of an active Stat3 (Stat3-C). Following irradiation, the level of phospho-Stat3 Tyr(705), but not phospho-Stat3 Ser(727), was reduced in HUVECs, whereas it remained unchanged in irradiated breast cancer cells. Correspondingly, Stat3 DNA-binding activity following irradiation was specifically down-regulated in HUVECs but not in breast cancer cells. Mutation of Tyr(705) abolished radiation-induced down-regulation of Survivin. Clonogenic and endothelial cell morphogenesis assays suggested that DN-Stat3 and DN-Survivin together resulted in the greatest radiosensitization of MDA-MB-231, decreasing angiogenesis and cell survival. In summary, Stat3 modulates Survivin, and both are potential therapeutic targets for radiation sensitization in breast cancer.

E-cadherin promoter polymorphisms are not associated with the aggressiveness of prostate cancer in Caucasian patients

BACKGROUND

-160C-->A and -347G-->GA polymorphisms in the promoter region decrease E-cadherin gene transcription. Decreased E-cadherin expression predicts poor outcome among patients with cancer. We sought to investigate whether -160C-->A and/or -347G-->GA polymorphisms were associated with the aggressiveness of prostate cancer.

METHODS

TaqMan single nucleotide polymorphism genotyping assay (Applied Biosystems, Foster City, CA) was used to detect -160C-->A and -347G-->GA polymorphisms in deoxyribonucleic acid from the paraffin-embedded prostate tissues of 98 Caucasian patients.

RESULTS

The genotype frequencies were -160C/C: 48% (47 of 98); -160C/A: 44% (43 of 98); -160A/A: 8% (8 of 98); -347G/G: 68% (67 of 98); -347G/GA: 28% (27 of 98); and -347GA/GA: 4% (4 of 98). Using the chi-square test, we found that the polymorphisms -160C-->A and -347G-->GA were not related to other clinical and pathologic parameters (i.e., age, prostate-specific antigen level, Gleason grade, and clinical stage) (P > 0.05). In combination analysis, there was no significant relationship between patients with both -160C/C and -347G/G, and these same parameters (P > 0.05). Using the log-rank test, we found no significant difference in relapse-free survival and overall survival between patients with -160C/C and those with -160A/C or -160A/A (P = 0.0764 and 0.2746, respectively), and also no significant difference between patients with -347G/G and those with -347GA/G or -347GA/GA (P = 0.9416 and 0.7367, respectively). There was also no significant difference in relapse-free survival and overall survival between patients with homozygosities of -160C/-347G and patients with other genotypes (P = 0.1418 and 0.2434, respectively).

CONCLUSION

We conclude that E-cadherin -160C-->A and/or -347G-->GA polymorphisms are not associated with the aggressiveness of prostate cancer in Caucasian patients.

Lithium Treatment Prevents Neurocognitive Deficit Resulting from Cranial Irradiation

Curative cancer treatment regimens often require cranial irradiation, resulting in lifelong neurocognitive deficiency in cancer survivors. This deficiency is in part related to radiation-induced apoptosis and decreased neurogenesis in the subgranular zone of the hippocampus. We show that lithium treatment protects irradiated hippocampal neurons from apoptosis and improves cognitive performance of irradiated mice. The molecular mechanism of this effect is mediated through multiple pathways, including Akt/glycogen synthase kinase-3beta (GSK-3beta) and Bcl-2/Bax. Lithium treatment of the cultured mouse hippocampal neurons HT-22 induced activation of Akt (1.5-fold), inhibition of GSK-3beta (2.2-fold), and an increase in Bcl-2 protein expression (2-fold). These effects were sustained when cells were treated with lithium in combination with ionizing radiation. In addition, this combined treatment led to decreased expression (40%) of the apoptotic protein Bax. The additional genes regulated by lithium were identified by microarray, such as decorin and Birc1f. In summary, we propose lithium treatment as a novel therapy for prevention of deleterious neurocognitive consequences of cranial irradiation.

ATM polymorphism IVS62+60G>A is not associated with disease aggressiveness in prostate cancer

OBJECTIVES

ATM is an important protein that protects the genome from double-stranded DNA breaks. Mutations and polymorphisms in the ATM gene have been associated with an increased risk of certain types of malignancies, especially breast cancer.

METHODS

We analyzed tissue from 98 white patients with prostate cancer for the presence of IVS62+60G>A polymorphism in the ATM gene.

RESULTS

The frequency of the homozygous IVS62+60G/G, heterozygous IVS62+60G/A, and homozygous IVS62+60A/A was 18.37% (18 of 98), 30.61% (30 of 98), and 51.02% (50 of 98), respectively. Using Fisher's exact test, we found the polymorphism IVS62+60G>A was not significantly related to age, tumor grade, prostate-specific antigen level, or clinical stage (P >0.05). No difference was found in relapse-free survival between patients with IVS62+60G/G and those with IVS62+60G/A or IVS62+60A/A (P = 0.4533).

CONCLUSIONS

The results of our study indicate that this ATM polymorphism is not associated with the aggressiveness of prostate cancer in white men.

Radiosensitization of lung cancer by nutlin, an inhibitor of murine double minute 2

p53 plays a critical role in cell cycle arrest and induction of apoptosis. Certain malignancies carry wild-type p53, which is frequently down-regulated by murine double minute 2 (MDM2) overexpression. Availability of a small-molecule inhibitor against MDM2, nutlin, has made it feasible to evaluate the anti-MDM2-based therapeutic strategies. The rationale for the current study is that functional p53 has been linked with improved responses to radiation treatment. Hence, this study evaluates the use of nutlin, a small-molecule inhibitor that blocks the interaction of p53 and MDM2, in sensitizing cancer cells to radiation. Expression of MDM2, p53, and p21 in both p53 wild-type and p53-defective lung cancer cell lines was examined. Clonogenic and 7-amino-actinomycin D studies were used to determine possible mechanisms of cell death. The combined effect of MDM2 inhibition and radiation on cell cycle was also studied. We found that radiosensitization by nutlin occurs in lung cancer cells with wild-type p53. There were increased apoptosis and cell cycle arrest following administration of nutlin and radiation. Furthermore, the combination of nutlin and radiation decreased the ability of endothelial cells to form vasculature, as shown by Matrigel assays. Our data suggest that nutlin is an effective radiosensitizer of p53 wild-type cells. The radiosensitizing effect seems to be at least partially due to induction of apoptosis and cell cycle arrest. In addition, nutlin may be an effective radiosensitizer of tumor vasculature.

Plasminogen Activator Inhibitor-1 Promoter Polymorphism is Not Associated With the Aggressiveness of Disease in Prostate Cancer

AIMS

PAI-1 (plasminogen activator inhibitors-1) regulates plasminogen activation, and is related to tumour development. This study aims to test whether the promoter polymorphism in the PAI-1 gene is related to the aggressiveness of disease in prostate cancer.

MATERIALS AND METHODS

In the present study, Taqman SNP genotyping assay was used to detect PAI-1 4G/5G polymorphism in DNA from paraffin-embedded tissues of 98 Caucasian patients with prostate cancer.

RESULTS

The distribution of the genotypes is in Hardy-Weinberg equilibrium. The genotype had no statistically significant relationship with other prognostic factors. Similar risks for recurrence were seen in individuals with the 4G/4G and 4G/5G genotypes compared to those with 5G/5G genotype (odds ratio [OR] 2.65, 95% CI: 0.41-16.94, P = 0.30; OR = 2.19, 95% CI: 0.38-12.49, P = 0.38).

CONCLUSION

We concluded that PAI-1 promoter polymorphism is not associated with the aggressiveness of disease in prostate cancer.

SRC family kinase inhibitor SU6656 enhances antiangiogenic effect of irradiation

PURPOSE

Src family kinases (SFK) have been identified as molecular targets. SU6656 is a small-molecle indolinone that specifically inhibits this family of kinases.

METHODS AND MATERIALS

Human umbilical vein endothelial cells were used to study the effects of SFK inhibition. Western blot analysis was performed to determine the effect of SFK inhibition on the PI3K/Akt pathway and caspase cleavage. Apoptosis was studied by propidium iodide staining of nuclei. Angiogenesis was examined using capillary tubule formation in Matrigel. Tumor response was further studied in vivo using Lewis lung carcinoma cells implanted into the dorsal skin fold of mice in the window model and in the hind limb in the tumor volume model.

RESULTS

Clonogenic survival of endothelial cells was decreased after the combined therapy of SU6656 and radiation compared with radiotherapy alone. Furthermore, SFK inhibition by SU6656 attenuated radiation-induced Akt phosphorylation and increased radiation-induced apoptosis and vascular endothelium destruction. In vivo, SU6656 administered before irradiation significantly enhanced radiation-induced destruction of blood vessels within the tumor windows and enhanced tumor growth delay when administered during fractionated irradiation.

CONCLUSIONS

This study demonstrates the potential use of SFK inhibition to enhance the effects of ionizing radiation during radiotherapy.

STI571 (Gleevec) improves tumor growth delay and survival in irradiated mouse models of glioblastoma

PURPOSE

Glioblastoma multiforme (GBM) is a devastating brain neoplasm that is essentially incurable. Although radiation therapy prolongs survival, GBMs progress within areas of irradiation. Recent studies in invertebrates have shown that STI571 (Gleevec; Novartis, East Hanover, NJ) enhances the cytotoxicity of ionizing radiation. In the present study, the effectiveness of STI571 in combination with radiation was studied in mouse models of GBM.

METHODS AND MATERIALS

Murine GL261 and human D54 GBM cell lines formed tumors in brains and hind limbs of C57BL6 and nude mice, respectively. GL261 and D54 cells were treated with 5 micromol/L of STI571 for 1 h and/or irradiated with 3 Gy. Protein was analyzed by Western immunoblots probed with antibodies to caspase 3, cleaved caspase 3, phospho-Akt, Akt, and platelet-derived growth factor receptor (PDGFR) alpha and beta. Tumor volumes were assessed in mice bearing GL261 or D54 tumors treated with 21 Gy administered in seven fractionated doses. Histologic sections from STI571-treated mice were stained with phospho-Akt and phospho-PDGFR beta antibodies. Kaplan-Meier survival curves were used to study the response of mice bearing intracranial implants of GL261.

RESULTS

STI571 penetrated the blood-brain barrier, which resulted in a reduction in phospho-PDGFR in GBM. STI571-induced apoptosis in GBM was significantly enhanced by irradiation. STI571 combined with irradiation induced caspase 3 cleavage in GBM cells. Glioblastoma multiforme response to therapy correlated with an increase in tumor growth delay and survival when STI571 was administered in conjunction with daily irradiation.

CONCLUSION

These findings suggest that STI571 has the potential to augment radiotherapy and thereby improve median survival.

Clusterin as a therapeutic target for radiation sensitization in a lung cancer model

PURPOSE

Clusterin plays important roles in cell survival and death. Inactivation of clusterin enhances the therapeutic efficacy of chemotherapy in lung cancer models. The purpose of this study was to determine whether inhibition of clusterin by an antisense-based investigative drug enhances radiation sensitization in a lung cancer model.

METHODS AND MATERIALS

Cells were transfected with an antisense oligonucleotide (ASO) against clusterin (OGX-011). Apoptosis was determined by 7-aminoactinomycin D staining. Cell survival was examined by 3-(4, 5-methylthiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide (MTT) and clonogenic assay. Xenograft model was used to demonstrate tumor growth and tumor blood flow.

RESULTS

OGX-011 specifically attenuated the expression of secreted clusterin (prosurvival), with no apparent effect on the expression of nuclear clusterin (proapoptotic). Apoptosis was significantly increased when H460 lung cancer cells were treated with OGX-011 plus radiation. Inhibition of clusterin followed by radiation greatly decreased cell survival. H460 xenografts that were treated with OGX-011 plus radiotherapy demonstrated growth delay beyond 17 days. Doppler studies showed that tumor blood flow was compromised when mice bearing H460 xenografts were treated with OGX-011 and radiation.

CONCLUSION

A combination of radiotherapy and OGX-011 improved control of tumor growth and vascular regression in the H460 lung cancer model.

Murine double minute 2 as a therapeutic target for radiation sensitization of lung cancer

Murine double minute 2 (MDM2) inhibits p53-mediated functions, which are essential for therapies using DNA-damaging agents. The purpose of this study was to determine whether MDM2 inhibition enhances the radiosensitivity of a lung cancer model. The effects of MDM2 inhibition on tumor vasculature were also studied. Transient transfection of H460 lung cancer cells and human umbilical vascular endothelial cells (HUVEC) with antisense oligonucleotides (ASODN) against MDM2 resulted in a reduced level of MDM2 and increased levels of p21 and p53. Clonogenic assays showed that inhibition of MDM2 greatly decreased cell survival following irradiation. Quantification of apoptotic cells by 7-aminoactinomycin D staining and of senescent cells by X-gal staining showed that both processes were significantly increased in H460 cells treated with MDM2-specific ASODN and radiation. H460 xenografts that were treated with MDM2 ASODN plus radiotherapy also showed significant growth delay (P < 0.001) and increased apoptosis by terminal deoxynucleotidyl transferase-mediated nick end labeling staining. HUVECs transfected with MDM2-specific ASODN showed impaired viability and migration with decreased tube formation. Doppler studies showed that tumor blood flow was compromised when H460 xenografts were treated with MDM2-specific ASODN and radiation. A combination of radiotherapy and inhibition of MDM2 through the antisense approach results in improved tumor control in the H460 lung cancer model. This implies that a similar strategy should be investigated among patients with locally advanced lung cancer, receiving thoracic radiotherapy.

Endostatin polymorphism 4349G/A(D104N) is not associated with aggressiveness of disease in prostate [corrected] cancer

Endostatin is an important inhibitory molecule which mediates the sequential steps involved in angiogenesis. Lower level or impaired function of endostatin is associated with a higher risk of developing malignant solid tumors and with a worse prognosis of the disease. The endostatin N104 polymorphism might be associated with an impaired ability to inhibit angiogenesis. We analyzed the tissues from 98 Caucasian prostate cancer patients for the presence of D104N polymorphism. The frequencies of homozygous 4349G/G(104D/D), and heterozygous 4349G/A(104D/N) were 83.67%(82/98) and 16.33%(16/98), respectively; no individuals were homozygous 4349A/A(104N/N). With the Fisher’s exact test we found the genotype of D104N was not significantly related to age, tumor grade, PSA and clinical stage (P > 0.05). There was no difference in relapse free survival(RFS) or overall survival(OS) between patients with 104D/N and those with 104D/D (P = 0.8283, 0.3713 respectively). We concluded that endostatin polymorphism was not associated with the aggressiveness of prostate cancer in Caucasian patients.

DNA-dependent protein kinase is a molecular target for the development of noncytotoxic radiation-sensitizing drugs

DNA-dependent protein kinase (DNA-PK)-defective severe combined immunodeficient (SCID) mice have a greater sensitivity to ionizing radiation compared with wild-type mice due to deficient repair of DNA double-strand break. SCID cells were therefore studied to determine whether radiosensitization by the specific inhibitor of DNA-PK, IC87361, is eliminated in the absence of functional DNA-PK. IC87361 enhanced radiation sensitivity in wild-type C57BL6 endothelial cells but not in SCID cells. The tumor vascular window model was used to assess IC87361-induced radiosensitization of SCID and wild-type tumor microvasculature. Vascular density was 5% in irradiated SCID host compared with 50% in C57BL6 mice (P < 0.05). IC87361 induced radiosensitization of tumor microvasculature in wild-type mice that resembled the radiosensitive phenotype of tumor vessels in SCID mice. Radiosensitization by IC87361 was eliminated in SCID tumor vasculature, which lack functional DNA-PK. Irradiated LLC and B16F0 tumors implanted into SCID mice showed greater tumor growth delay compared with tumors implanted into either wild-type C57BL6 or nude mice. Furthermore, LLC tumors treated with radiation and IC87361 showed tumor growth delay that was significantly greater than tumors treated with radiation alone (P < 0.01 for 3 Gy alone versus 3 Gy + IC87361). DNA-PK inhibitors induced no cytotoxicity and no toxicity in mouse normal tissues. Mouse models deficient in enzyme activity are useful to assess the specificity of novel kinase inhibitors. DNA-PK is an important target for the development of novel radiation-sensitizing drugs that have little intrinsic cytotoxicity.

Nuclear survivin predicts recurrence and poor survival in patients with resected nonsmall cell lung carcinoma

BACKGROUND

Survivin, which is a member of the inhibitor of apoptosis protein gene family, regulates both programmed cell death and mitosis. It has been shown that survivin expression and its subcellular localization both have prognostic value for patients with malignant disease. In this study, the authors investigated whether nuclear or cytoplasmic staining of survivin was a prognostic marker for patients with lung carcinoma.

METHODS

Paraffin-embedded tissue blocks from 144 patients with Stage I and II resected nonsmall cell lung carcinoma (NSCLC) were obtained for immunohistochemical staining. Three specimens from each patient were prepared and stained with a survivin-specific antibody. Nuclear and cytoplasmic staining was graded from 1 to 3 based on intensity.

RESULTS

Patients who had nuclear staining for survivin had a significantly increased risk of disease recurrence (hazard ratio, 2.95; P = 0.0046) and death (hazard ratio, 2.74; P = 0.0086).

CONCLUSIONS

The nuclear presence of survivin may be an independent biomarker for disease recurrence and overall survival in patients with resected Stage I and II NSCLC.

Enhanced radiation damage of tumor vasculature by mTOR inhibitors

It is known that radiation activates the phosphoinositol-3 kinase (PI3K)/Akt pathway and that inhibition of PI3K or Akt sensitizes tumor vasculature to radiotherapy. Mammalian target of rapamycin (mTOR) is a downstream target of Akt, and we hypothesized that irradiation activates mTOR signaling in both glioma and endothelial cells (ECs) and that radiosensitization results from inhibiting mTOR signaling. mTOR inhibitors, rapamycin and RAD001 (everolimus) were found to radiosensitize vascular ECs, but failed to sensitize glioma cells as determined by clonogenic assay. Therefore, we investigated the anti-angiogenic effects of mTOR inhibitors. Increased phospho-mTOR protein was detected in irradiated human umbilical vein endothelial cells (HUVEC), but not in GL261 glioma cells. Phospho-S6, a biomarker for mTOR signaling, was also found to be induced following irradiation in HUVEC and this effect was inhibited by PI3K or mTOR inhibitors. Significant increase in cleaved caspase 3 was detected when Rad001 was combined with radiation. Endothelial tube formation was significantly diminished following treatment with rapamycin and 3 Gy of radiation. Histological sections of GL261 tumors from mice showed a greatly reduced vascular density when treated with RAD001 and radiation. Power Weighted Doppler of glioma xenografts in mice showed a significant reduction in vasculature and blood flow compared with mice treated with 3 Gy or RAD001 alone. We conclude that irradiation activates mTOR signaling in vascular endothelium and that rapamycin and RAD001 increased apoptosis of ECs in response to radiation. To the authors' best knowledge this is the first study which demonstrates that mTOR inhibitors may be a way to target the vasculature by radiosensitizing the vascular endothelium resulting in better tumor control as seen in experiments demonstrating increased tumor growth delay in mice treated with rapamycin with radiation compared with mice treat with either treatment alone. We conclude that mTOR inhibitors have increased efficacy as antiangiogenics when combined with radiation.

The Use of Antisense Oligonucleotides in Evaluating Survivin as a Therapeutic Target for Radiation Sensitization in Lung Cancer

Elucidating the mechanism of over and under expression of proteins is critical in developing a better understanding of cancer. Multiple techniques are used to examine differential expression of proteins in cells and assess changes in protein expression in response to therapies such as radiation. Reduced expression can be caused by protein inactivation, mRNA instability, or reduced transcription. The following protocol was used to determine the mechanism for the reduced expression of an antiapoptotic factor, survivin, in normal tissues in response to radiation and the defect in cancer cells that prevents this reduction. We also examined ways to overcome survivin over expression in cancer cells in order to sensitize them to radiation. We will focus on the use of antisense oligonucleotides, cell cycle analysis, and luciferase reporter genes.