A phase I trial of concurrent sorafenib and stereotactic radiosurgery for patients with brain metastases.

We hypothesized that sorafenib (BAY 43-9006), an oral multi-kinase inhibitor, used in combination with SRS will improve overall intracranial control. This Phase I study assesses the safety, tolerability, and maximal tolerated dose of sorafenib administered with SRS to treat 1-4 brain metastases. This was an open label phase I dose escalation study with an expansion cohort. Eligible adults had 1-4 brain metastases from solid malignancies. Sorafenib was begun 5-7 days prior to SRS and continued for 14 days thereafter. Dose escalation of sorafenib was conducted via a "3 + 3" dose escalation design. Dose limiting toxicities (DLT) were determined 1 month after SRS and defined as ≥grade 3 neurologic toxicities. Twenty-three patients were enrolled. There were no DLTs at dose level 1 (400 mg per day) or dose level 2 (400 mg twice per day). An expansion cohort of 17 patients was treated at dose level 2. There were six grade 3 toxicities: hypertension (n = 2), rash (n = 1), lymphopenia (n = 1), hypokalemia (n = 1), fatigue (n = 1) and hand-foot syndrome (n = 1). All of these were attributable to sorafenib and not to the combination with SRS. The median time to CNS progression was 10 months, 1 year CNS progression-free survival was 46%, the median overall survival was 11.6 months and the 1 year overall survival was 46%. The use of sorafenib concurrent with SRS for the treatment of 1-4 brain metastases is safe and well tolerated at 400 mg twice a day. Our recommended phase II dose of concurrent sorafenib with SRS would be 400 mg twice daily.

Feasibility and Tolerability of Adjuvant Capecitabine-Based Chemoradiation in Patients With Breast Cancer and Residual Disease After Neoadjuvant Chemotherapy: A Prospective Clinical Trial.

PURPOSE: Addition of adjuvant capecitabine improves overall survival for patients with breast cancer lacking pathologic complete response to standard-of-care neoadjuvant chemotherapy. Combining radiosensitizing capecitabine concurrent with radiation may further improve disease control, although the feasibility and tolerability of chemoradiation in this setting is unknown. This study aimed to determine the feasibility of this combination. Secondary objectives included the effect of chemoradiation on physician-reported toxicity, patient-reported skin dermatitis, and patient-reported quality of life compared with patients with breast cancer treated with adjuvant radiation. METHODS AND MATERIALS: Twenty patients with residual disease following standard neoadjuvant chemotherapy were enrolled in a prospective single-arm trial and treated with adjuvant capecitabine-based chemoradiation. Feasibility was defined as ≥75% of patients completing chemoradiation as planned. Toxicity was assessed using Common Terminology Criteria for Adverse Events version 5.0 and the patient-reported radiation-induced skin reaction scale. Quality of life was measured using the RAND Short-Form 36-Item Health Survey. RESULTS: Eighteen patients (90%) completed chemoradiation without interruption or dose reduction. The incidence of grade ≥3 radiation dermatitis was 5% (1 of 20 patients). Patient-reported radiation dermatitis did not show a clinically meaningful difference following chemoradiation (mean increase, 55 points) compared with published reports of patients with breast cancer treated with adjuvant radiation alone (mean increase, 47 points). On the other hand, patient-reported quality of life demonstrated a clinically meaningful decline at the end of chemoradiation (mean, 46; SD, 7) compared with the reference population of patients treated with adjuvant radiation alone (mean, 50; SD, 6). CONCLUSIONS: Adjuvant chemoradiation with capecitabine is feasible and tolerable in patients with breast cancer. Although current studies using adjuvant capecitabine for residual disease following neoadjuvant chemotherapy have specified sequential treatment of capecitabine and radiation, these results support the conduct of randomized trials in this setting to investigate the efficacy of concurrent radiation with capecitabine and provide patient-reported toxicity estimates for trial design.

PREVLAR: Phase 2a Randomized Trial to Assess the Safety and Efficacy of RRx-001 in the Attenuation of Oral Mucositis in Patients Receiving Head and Neck Chemoradiotherapy.

PURPOSE: No Food and Drug Administration-approved intervention exists for oral mucositis (OM) from chemoradiotherapy (CRT) used to treat head and neck cancers. RRx-001 is a hypoxia-activated, cysteine-directed molecule that affects key pathways involved in OM pathogenesis. This phase 2a, multi-institutional trial was designed to assess the safety and feasibility of 3 schedules of a fixed concentration of RRx-001; a standard-of-care arm was included to identify potential signals of efficacy for further study. METHODS AND MATERIALS: This study enrolled patients with oral cavity and oropharynx squamous cell carcinoma receiving definitive or postoperative cisplatin-based CRT. Patients were randomized into 4 cohorts. In arms 1 to 3, RRx-001 was coinfused with patients' blood at differing intervals. Arm 4 was a control cohort of patients treated with CRT alone. Trained evaluators assessed OM using a standardized data collection instrument twice weekly during treatment and then until resolution. OM severity was scored centrally using World Health Organization criteria. Safety outcomes were assessed using National Cancer Institute - Common Terminology Criteriav4 benchmarks. Long-term tumor response was defined by Response evaluation criteria in solid tumors v1.1 criteria. RESULTS: Fifty-three patients were enrolled, with 46 and 45 individuals contributing safety and efficacy data, respectively. There were no severe adverse events attributed to the study drug. Across all 3 active arms, the study drug was infused fully per protocol in 86% of patients. All 3 RRx-001 treatment cohorts appeared to demonstrate a similar or lower OM duration relative to control; arm 1 had the lowest median duration of severe oral mucositis (SOM), 8.5 days versus 24 days in controls among patients who developed at least 1 day of SOM. There were no locoregional failures in any patient. CONCLUSIONS: Our results support the safety and feasibility of RRx-001 as an intervention to mitigate SOM. Additional studies are planned to confirm its efficacy.

Whole Scalp Radiation Therapy for Recurrent Benign Cylindromas.

Cylindromas are a rare benign pathology that can manifest as multiple lesions on a patient's scalp. Standard of care is resection of lesions. We report a case of a 74-year-old man with a known diagnosis of Brooke-Spiegler syndrome which is a genetic syndrome that results in multiple recurrent cylindromas. He had approximately 70 prior resections to remove recurrent lesions with multiple grafts. After a large scalp recurrence, with multiple satellite areas, he preferred radiation to the largest site for no-surgical management. After an excellent clinical response, this led to him electing for total scalp irradiation to the remaining sites. He now has a complete response to all remaining sites.

Validity Testing of the Head and Neck Lymphedema and Fibrosis Symptom Inventory.

Background: Lack of reliable and valid tools significantly impacts early identification and timely treatment of lymphedema and fibrosis (LEF) in the head and neck cancer population. To address this need, we developed and reported a patient-reported outcome measure (Head and Neck Lymphedema and Fibrosis Symptom Inventory [HN-LEF SI]). This article reports the construct validity (convergent and divergent validity) testing of the tool. Materials and Methods: A prospective, longitudinal, instrument validation study was conducted in patients with a newly diagnosed oral cavity or oropharyngeal cancer. Participants completed the HN-LEF SI and six carefully selected self-report measures at pretreatment, end-of-treatment, and every 3 months up to 12 months after treatment. Spearman correlations were used. Results: A total of 117 patients completed the study. Patterns of correlations of the HN-LEF SI scores with the established self-report measure scores were consistent with expected convergent and divergent validity. Conclusion: Evidence from this work supports the construct validity of the HN-LEF SI.

Refinement and Validation of the Head and Neck Lymphedema and Fibrosis Symptom Inventory.

PURPOSE: Lymphedema and fibrosis (LEF) are common yet overlooked late effects of head and neck cancer and its therapy. Lack of reliable and valid measures of head and neck LEF is a critical barrier to the timely identification and management of head and neck LEF. To fill this gap, we developed and pilot tested a 64-item patient-reported outcome measure ( Lymphedema Symptom Intensity and Distress Survey-Head and Neck, LSIDS-H&N). This article aims to report the process of further validation and refinement of the tool. METHODS AND MATERIALS: A prospective, longitudinal study was conducted, and 120 patients with oral cavity and oropharyngeal cancer were recruited. Participants completed the LSIDS-H&N at pretreatment, end of treatment, and every 3 months up to 12 months after treatment. SAS PROC VARCLUS was used to generate preliminary clusters of item responses. Internal consistency of the item responses within each cluster was assessed using Cronbach's alpha. RESULTS: A total of 117 patients completed the study. The participants reported that the LSIDS-H&N was easy to understand and captured their symptoms and medical conditions. However, >50% of participants indicated that the survey was burdensome due to length. Thus, we proceeded with item reduction, and the shortened tool (33-item) was named Head and Neck Lymphedema and Fibrosis Symptom Inventory (HN-LEF Symptom Inventory). The subsequent exploration of symptom clusters identified 7 symptom domain clusters (eg, soft tissue and neurologic toxicity), all of which demonstrated good internal consistency. CONCLUSIONS: The HN-LEF Symptom Inventory has been carefully developed and refined to allow clinicians and researchers to capture LEF-associated symptom burden and function impairments. Additional rigorous psychometric testing of the tool is ongoing to further validate the strength and internal validity of this tool.

Combining registration and active shape models for the automatic segmentation of the lymph node regions in head and neck CT images.

PURPOSE: Intensity-modulated radiation therapy (IMRT) is the state of the art technique for head and neck cancer treatment. It requires precise delineation of the target to be treated and structures to be spared, which is currently done manually. The process is a time-consuming task of which the delineation of lymph node regions is often the longest step. Atlas-based delineation has been proposed as an alternative, but, in the authors' experience, this approach is not accurate enough for routine clinical use. Here, the authors improve atlas-based segmentation results obtained for level II-IV lymph node regions using an active shape model (ASM) approach. METHODS: An average image volume was first created from a set of head and neck patient images with minimally enlarged nodes. The average image volume was then registered using affine, global, and local nonrigid transformations to the other volumes to establish a correspondence between surface points in the atlas and surface points in each of the other volumes. Once the correspondence was established, the ASMs were created for each node level. The models were then used to first constrain the results obtained with an atlas-based approach and then to iteratively refine the solution. RESULTS: The method was evaluated through a leave-one-out experiment. The ASM- and atlas-based segmentations were compared to manual delineations via the Dice similarity coefficient (DSC) for volume overlap and the Euclidean distance between manual and automatic 3D surfaces. The mean DSC value obtained with the ASM-based approach is 10.7% higher than with the atlas-based approach; the mean and median surface errors were decreased by 13.6% and 12.0%, respectively. CONCLUSIONS: The ASM approach is effective in reducing segmentation errors in areas of low CT contrast where purely atlas-based methods are challenged. Statistical analysis shows that the improvements brought by this approach are significant.

Differential efficacy of combined therapy with radiation and AEE788 in high and low EGFR-expressing androgen-independent prostate tumor models.

PURPOSE: To determine the efficacy of combining radiation (XRT) with a dual epidermal growth factor receptor (EGFR)/vascular endothelial growth factor receptor inhibitor, AEE788, in prostate cancer models with different levels of EGFR expression. METHODS AND MATERIALS: Immunoblotting was performed for EGFR, phosphorylated-EGFR, and phosphorylated-AKT in prostate cancer cells. Clonogenic assays were performed on DU145, PC-3, and human umbilical vein endothelial cells treated with XRT +/- AEE788. Tumor xenografts were established for DU145 and PC-3 on hind limbs of athymic nude mice assigned to four treatment groups: (1) control, (2) AEE788, (3) XRT, and (4) AEE788 + XRT. Tumor blood flow and growth measurements were performed using immunohistochemistry and imaging. RESULTS: AEE788 effectively decreased phosphorylated-EGFR and phosphorylated-AKT levels in DU145 and PC-3 cells. Clonogenic assays showed no radiosensitization for DU145 and PC-3 colonies treated with AEE788 + XRT. However, AEE788 caused decreased proliferation in DU145 cells. AEE788 showed a radiosensitization effect in human umbilical vein endothelial cells and increased apoptosis susceptibility. Concurrent AEE788 + XRT compared with either alone led to significant tumor growth delay in DU145 tumors. Conversely, PC-3 tumors derived no added benefit from combined-modality therapy. In DU145 tumors, a significant decrease in tumor blood flow with combination therapy was shown by using power Doppler sonography and tumor blood vessel destruction on immunohistochemistry. Maldi-spectrometry (MS) imaging showed that AEE788 is bioavailable and heterogeneously distributed in DU145 tumors undergoing therapy. CONCLUSIONS: AEE788 + XRT showed efficacy in vitro/in vivo with DU145-based cell models, whereas PC-3-based models were adequately treated with XRT alone without added benefit from combination therapy. These findings correlated with differences in EGFR expression and showed effects on both tumor cell proliferation and vascular destruction.

Vanderbilt head and neck symptom survey, version 2.0: Clinical and research utility for identification of symptom clusters and changes in symptoms over time.

OBJECTIVES: The symptoms and functional defects following treatment for head and neck cancer (HNC) have been poorly defined. The purpose of this study was to examine the utility of the Vanderbilt Head and Neck Symptom Survey (VHNSS) version 2.0 to identify symptom clusters experienced by patients with HNC as well as assess reliability and sensitivity to change. MATERIALS AND METHODS: The VHNSS 2.0 questionnaire was completed by 150 patients over three studies. Two studies utilized the survey at multiple time points. RESULTS: Cluster analysis identified ten multi-item clusters and three single items. The internal consistency was good to excellent, with Cronbach's alpha coefficient above 0.90 in five symptom clusters and above 0.70 in remaining clusters. Clusters demonstrated convergent and divergent validity with other measures. Symptom burden was lowest at baseline, peaked at the end of treatment then subsided over the following months. CONCLUSIONS: The VHNSS 2.0 is a reliable and valid measure of acute and late toxicities in patients treated for HNC. The tool may be used in research and clinical practice to screen, to evaluate treatments, and to compare side effects of treatment regimens.

A Randomized Feasibility Trial to Evaluate Use of the Jaw Dynasplint to Prevent Trismus in Patients With Head and Neck Cancer Receiving Primary or Adjuvant Radiation-Based Therapy.

OBJECTIVE: This study was designed to assess the feasibility of using the Jaw Dynasplint System as an adjunct to conventional stretching exercises as a preventative measure against trismus in patients undergoing radiotherapy. METHODS: Study participants (n = 40) were randomized using a permuted block design to conventional stretching or stretching plus use of the Jaw Dynasplint 3 times per day for 30 minutes. Patients were instructed to record maximum interincisal opening each day as well as logging use of the Jaw Dynasplint. RESULTS: At 6 months after initiation of the preventative regimen, 50% of patients in the Dynasplint arm and 75% in the conventional stretching arm remained on their assigned therapy. Trismus was diagnosed in 2 patients in the control arm and in 4 patients in the Dynasplint arm. Only 25% (95% confidence interval = 11.1, 46.9) of patients in the Dynasplint arm used the device as prescribed. CONCLUSIONS: The addition of the Jaw Dynasplint decreased compliance compared with conventional stretching. It is unlikely that the prescribed regimen will prove efficacious as a preventative measure due to low compliance.

Evaluation of CT Changes in the Head and Neck After Cancer Treatment: Development of a Measurement Tool.

BACKGROUND: The late effect continuum of lymphedema and fibrosis (LEF) affects more than 70% of patients after treatment for head and neck cancer (HNC). LEF is associated with symptom burden and decreased function and quality of life. Although surveillance imaging is common posttreatment, objective assessment of soft tissues is not, likely due to the lack of objective evaluation methods and understanding of the significance of LEF. We undertook the development of a tool to measure LEF using CT scans in HNC patients. METHODS AND RESULTS: We developed a CT measurement tool assessing sites of soft tissue damage secondary to tumor, surgery, or radiation. The tool was applied to pre- and posttreatment CT scans for 10 HNC patients. The data were reviewed, and the initial tool was modified. Ten additional patients' scans were assessed using the revised tool. The tool was modified further after data review by an expert panel and was then applied to scans from all 20 patients. The final tool included 11 items as follows: grading of fat stranding at 6 sites (axial reconstruction images, scale 0-2), measurement of epiglottic thickness (sagittal images, scale mm), and measurement of prevertebral soft tissue thickness at C3 (sagittal images, scale mm). A total of 176 CT scans were evaluated from 20 patients (range 4-14 examinations/patient). Preliminary data demonstrated face validity. CONCLUSIONS: The final LEF assessment tool (CT-LEFAT) provides a standardized method for assessing critical sites that are involved by LEF. Studies to assess reliability and validity are ongoing.

Integration of quantitative DCE-MRI and ADC mapping to monitor treatment response in human breast cancer: initial results.

PURPOSE: The objective of this study was to assess changes in the water apparent diffusion coefficient (ADC) and in pharmacokinetic parameters obtained from the fast-exchange regime (FXR) modeling of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) during neoadjuvant chemotherapy in breast cancer. MATERIALS AND METHODS: Eleven patients with locally advanced breast cancer underwent MRI examination prior to and after chemotherapy but prior to surgery. A 1.5-T scanner was used to obtain T1, ADC and DCE-MRI data. DCE-MRI data were analyzed by the FXR model returning estimates of K(trans) (volume transfer constant), v(e) (extravascular extracellular volume fraction) and tau(i) (average intracellular water lifetime). Histogram and correlation analyses assessed parameter changes post-treatment. RESULTS: Significant (P < .05) changes or trends towards significance (P < .10) were seen in all parameters except tau(i), although there was qualitative reduction in tau(i) values post-treatment. In particular, there was reduction (P < .035) in voxels with K(trans) values in the range 0.2-0.5 min(-1) and a decrease (P < .05) in voxels with ADC values in the range 0.99 x 10(-3) to 1.35 x 10(-3) mm2/s. ADC and v(e) were negatively correlated (r = -.60, P < .02). Parameters sensitive to water distribution and geometry (T(1), v(e), tau(i) and ADC) correlated with a multivariable linear regression model. CONCLUSION: The analysis presented here is sensitive to longitudinal changes in breast tumor status; K(trans) and ADC are most sensitive to these changes. Relationships between parameters provide information on water distribution and geometry in the tumor environment.

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.

A Prospective Study of the Lymphedema and Fibrosis Continuum in Patients with Head and Neck Cancer.

BACKGROUND: The purpose of this study was to determine the prevalence and nature of internal, external, and combined lymphedema and fibrosis in patients with head and neck cancer (HNC). MATERIALS AND METHODS: We obtained consent from 100 patients newly diagnosed with having cancer of the head and neck for a 4-year, prospective, longitudinal descriptive study. Recruitment began in August 23, 2010, and the study was completed in April 24, 2014. Eighty-three were evaluated at regular intervals from preradiation therapy to 18 months post-treatment. Percentage developing external, internal, or both types of lymphedema and/or fibrosis and trajectories of the severity of external, internal, or both types of lymphedema and/or fibrosis were determined. RESULTS: Before treatment, lymphedema rates were the following: external: 62.7%, internal: 41.7%, or combined: 29.2%, and/or fibrosis: 42.2%. Ranges of lymphedema late-effect rates were even higher: external: 81.9%-90.1%, internal: 80.4%-89.4%, combined: 70.6%-80.9%, and fibrosis: 66.7%-77.4%. Approximately 75% had a late-effect trajectory characterized by moderate to severe external or internal lymphedema; ∼47% had moderate to severe fibrosis. CONCLUSION: Lymphatic and soft tissue complications of HNC occur not only post-treatment but also before treatment. They are ubiquitous throughout the first 18 months post-treatment, with greater than 90% of patients in our study experiencing some form of internal, external, or combined lymphedema, and over half of those patients developing fibrosis. Further research regarding these conditions is indicated.

The controversial abscopal effect.

The abscopal effect is potentially important for tumor control and is mediated through cytokines and/or the immune system, mainly cell-mediated immunity. It results from loss of growth stimulatory and/or immunosuppressive factors from the tumor. Until recently, the abscopal effect referred to the distant effects seen after local radiation therapy. However, the term should now be used interchangeably with distant bystander effect. Through analysis of distant bystander effects of other local therapies, we discuss the poorly understood and researched radiation-induced abscopal effect. Although the abscopal effect has been described in various malignancies, it is a rarely recognized clinical event. The abscopal effect is still extremely controversial with known data that both support and refute the concept.

Sonographic depiction of changes of tumor vascularity in response to various therapies.

PURPOSE: To evaluate the diagnostic accuracy of power Doppler sonography for the depiction of changes in tumor vascularity with various therapeutic regimens. MATERIALS AND METHODS: Tumor cells were implanted subcutaneously in thirty-two mice and assigned to four treatment groups: control, radiation therapy, antiangiogenesis therapy (VEGF [vascular endothelial growth factor] receptor antagonist, SU11248), or combined antiangiogenesis and radiation therapy. Twenty of these mice were scanned with power Doppler sonography at two time points over the course of treatment, and power-weighted pixel densities were assessed. The other twelve mice each underwent subcutaneous placement of a dorsal skin-fold window over the tumor site, allowing for daily angiogenesis assessment of vascular length density. All tumor specimens had correlative histologic analyses performed, including immunohistochemical stains for microvasculature. RESULTS: Sonographic measurements revealed significant longitudinal differences in tumor vascularity among the four treatment groups: control mice receiving no treatment demonstrated a doubling in intra-tumor color pixel density (P < 0.02); those receiving radiation alone increased by 68% (P < 0.04); those receiving oral therapy alone increased by 44% (P = 0.016); and those receiving combination therapy decreased by 38% (P < 0.02). Tumor vascularity independently measured in the twelve mice with the skin-fold windows revealed a similar response to each type of treatment. Post-mortem tumor histology was consistent with both sonographic and skin-fold window measurements. CONCLUSION: Power Doppler sonography was accurate and reliable in measuring tumor vascularity changes in this model. These results were independently confirmed by a quantitative method relying on direct visualization of the microvasculature. Because it is rapid and non-invasive, sonographic quantification is beneficial in assessing the anti-angiogenic effects of various treatment strategies for cancer.

MLN8054, a small molecule inhibitor of aurora kinase a, sensitizes androgen-resistant prostate cancer to radiation.

PURPOSE: To determine whether MLN8054, an Aurora kinase A (Aurora-A) inhibitor causes radiosensitization in androgen-insensitive prostate cancer cells in vitro and in vivo. METHODS AND MATERIALS: In vitro studies consisted of culturing PC3 and DU145 prostate cancer cells and then immunoblotting Aurora A and phospho-Aurora A after radiation and/or nocodazole with MLN8054. Phases of the cell cycle were measured with flow cytometry. PC3 and DU145 cell lines were measured for survival after treatment with MLN8054 and radiation. Immunofluorescence measured γ-H2AX in the PC3 and DU145 cells after treatment. In vivo studies looked at growth delay of PC3 tumor cells in athymic nude mice. PC3 cells grew for 6 to 8 days in mice treated with radiation, MLN8054, or combined for 7 more days. Tumors were resected and fixed on paraffin and stained for von Willebrand factor, Ki67, and caspase-3. RESULTS: In vitro inhibition of Aurora-A by MLN8054 sensitized prostate cancer cells, as determined by dose enhancement ratios in clonogenic assays. These effects were associated with sustained DNA double-strand breaks, as evidenced by increased immunofluorescence for γ-H2AX and significant G2/M accumulation and polyploidy. In vivo, the addition of MLN8054 (30 mg/kg/day) to radiation in mouse prostate cancer xenografts (PC3 cells) significantly increased tumor growth delay and apoptosis (caspase-3 staining), with reduction in cell proliferation (Ki67 staining) and vascular density (von Willebrand factor staining). CONCLUSION: MLN8054, a novel small molecule Aurora-A inhibitor showed radiation sensitization in androgen-insensitive prostate cancer in vitro and in vivo. This warrants the clinical development of MLN8054 with radiation for prostate cancer patients.

Targeting the mechanisms of resistance to chemotherapy and radiotherapy with the cancer stem cell hypothesis.

Despite advances in treatment, cancer remains the 2nd most common cause of death in the United States. Poor cure rates may result from the ability of cancer to recur and spread after initial therapies have seemingly eliminated detectable signs of disease. A growing body of evidence supports a role for cancer stem cells (CSCs) in tumor regrowth and spread after initial treatment. Thus, targeting CSCs in combination with traditional induction therapies may improve treatment outcomes and survival rates. Unfortunately, CSCs tend to be resistant to chemo- and radiation therapy, and a better understanding of the mechanisms underlying CSC resistance to treatment is necessary. This paper provides an update on evidence that supports a fundamental role for CSCs in cancer progression, summarizes potential mechanisms of CSC resistance to treatment, and discusses classes of drugs currently in preclinical or clinical testing that show promise at targeting CSCs.

Enhanced radiosensitivity of androgen-resistant prostate cancer: AZD1152-mediated Aurora kinase B inhibition.

Aurora kinase B (AURKB) is critical to the process of mitosis, aiding in chromosome condensation by phosphorylating histone H3. We investigated the effects of AZD1152, an AURKB inhibitor, on radiosensitivity of androgen-insensitive prostate cancer cells. The goal of this study was to test whether AZD1152 increases the susceptibility of hormone-refractory prostate cancer cells to radiation-induced DNA damage and to determine the conditions of AZD1152 treatment that maximize radiosensitization. PC3 and DU145 cells were treated with various AZD1152 doses for various durations to elucidate the conditions that yielded maximal increases in G(2)/M-phase and polyploid cells. To assess DNA damage, γ-H2AX phosphorylation was quantified for cells grown under radiosensitizing conditions and subjected to either no radiation or 5 Gy radiation. Radiosensitivity was determined by clonogenic assays. Cell cycle effects in both cell lines were maximized by treatment with 60 nM AZD1152 for 48 h. AZD1152-treated cells exhibited significantly increased DNA damage 30 min postirradiation (PC3: 100% compared to 68%, P  =  0.035; DU145: 100% compared to 69%, P  =  0.034), with additional DNA damage 6 h postirradiation (PC3: 85% compared to 15%, P  =  0.002; DU145: 67% compared to 21%, P  =  0.012). Radiosensitivity was increased in both cell lines, with dose enhancement ratios of 1.53 for PC3 cells (P  =  0.017) and 1.71 for DU145 cells (P  =  0.02). This study identifies the optimal AZD1152 treatment conditions to maximize the radiosensitization of PC3 and DU145 cells. These results suggest a major role for DNA damage and impairment of DNA repair mechanisms in AZD1152-induced radiosensitization of prostate cancer cells.

Enzastaurin (LY317615), a protein kinase C beta selective inhibitor, enhances antiangiogenic effect of radiation.

PURPOSE: Angiogenesis has generated interest in oncology because of its important role in cancer growth and progression, particularly when combined with cytotoxic therapies, such as radiotherapy. Among the numerous pathways influencing vascular growth and stability, inhibition of protein kinase B(Akt) or protein kinase C(PKC) can influence tumor blood vessels within tumor microvasculature. Therefore, we wanted to determine whether PKC inhibition could sensitize lung tumors to radiation. METHODS AND MATERIALS: The combination of the selective PKCbeta inhibitor Enzastaurin (ENZ, LY317615) and ionizing radiation were used in cell culture and a mouse model of lung cancer. Lung cancer cell lines and human umbilical vascular endothelial cells (HUVEC) were examined using immunoblotting, cytotoxic assays including cell proliferation and clonogenic assays, and Matrigel endothelial tubule formation. In vivo, H460 lung cancer xenografts were examined for tumor vasculature and proliferation using immunohistochemistry. RESULTS: ENZ effectively radiosensitizes HUVEC within in vitro models. Furthermore, concurrent ENZ treatment of lung cancer xenografts enhanced radiation-induced destruction of tumor vasculature and proliferation by IHC. However, tumor growth delay was not enhanced with combination treatment compared with either treatment alone. Analysis of downstream effectors revealed that HUVEC and the lung cancer cell lines differed in their response to ENZ and radiation such that only HUVEC demonstrate phosphorylated S6 suppression, which is downstream of mTOR. When ENZ was combined with the mTOR inhibitor, rapamycin, in H460 lung cancer cells, radiosensitization was observed. CONCLUSION: PKC appears to be crucial for angiogenesis, and its inhibition by ENZ has potential to enhance radiotherapy in vivo.