Search

A quality assurance (QA) CT scans are usually acquired during cancer radiotherapy to assess for any anatomical changes, which may cause an unacceptable dose deviation and therefore warrant a replan. Accurate and rapid deformable image registration (DIR) is needed to support contour propagation from the planning CT (pCT) to the QA CT to facilitate dose volume histogram (DVH) review. Further, the generated deformation maps are used to track the anatomical variations throughout the treatment course and calculate the corresponding accumulated dose from one or more treatment plans.In this study, we aim to develop a deep learning (DL)-based method for automatic deformable registration to align the pCT and the QA CT. Our proposed method, named dual-feasible framework, was implemented by a mutual network that functions as both a forward module and a backward module. The mutual network was trained to predict two deformation vector fields (DVFs) simultaneously, which were then used to register the pCT and QA CT in both directions. A novel dual feasible loss was proposed to train the mutual network. The dual-feasible framework was able to provide additional DVF regularization during network training, which preserves the topology and reduces folding problems. We conducted experiments on 65 head-and-neck cancer patients (228 CTs in total), each with 1 pCT and 2-6 QA CTs. For evaluations, we calculated the mean absolute error (MAE), peak-signal-to-noise ratio (PSNR), structural similarity index (SSIM), target registration error (TRE) between the deformed and target images and the Jacobian determinant of the predicted DVFs.Within the body contour, the mean MAE, PSNR, SSIM, and TRE are 122.7 HU, 21.8 dB, 0.62 and 4.1 mm before registration and are 40.6 HU, 30.8 dB, 0.94, and 2.0 mm after registration using the proposed method. These results demonstrate the feasibility and efficacy of our proposed method for pCT and QA CT DIR.In summary, we proposed a DL-based method for automatic DIR to match the pCT to the QA CT. Such DIR method would not only benefit current workflow of evaluating DVHs on QA CTs but may also facilitate studies of treatment response assessment and radiomics that depend heavily on the accurate localization of tissues across longitudinal images.

The RNA exosome is a ribonuclease complex that mediates both RNA processing and degradation. This complex is evolutionarily conserved, ubiquitously expressed, and required for fundamental cellular functions, including rRNA processing. The RNA exosome plays roles in regulating gene expression and protecting the genome, including modulating the accumulation of RNA-DNA hybrids (R-loops). The function of the RNA exosome is facilitated by cofactors, such as the RNA helicase MTR4, which binds/remodels RNAs. Recently, missense mutations in RNA exosome subunit genes have been linked to neurological diseases. One possibility to explain why missense mutations in genes encoding RNA exosome subunits lead to neurological diseases is that the complex may interact with cell- or tissue-specific cofactors that are impacted by these changes. To begin addressing this question, we performed immunoprecipitation of the RNA exosome subunit, EXOSC3, in a neuronal cell line (N2A) followed by proteomic analyses to identify novel interactors. We identified the putative RNA helicase, DDX1, as an interactor. DDX1 plays roles in double-strand break repair, rRNA processing, and R-loop modulation. To explore the functional connections between EXOSC3 and DDX1, we examined the interaction following double-strand breaks, and analyzed changes in R-loops in N2A cells depleted for EXOSC3 or DDX1 by DNA/RNA immunoprecipitation followed by sequencing (DRIP-Seq). We find that EXOSC3 interaction with DDX1 is decreased in the presence of DNA damage and that loss of EXOSC3 or DDX1 alters R-loops. These results suggest EXOSC3 and DDX1 interact during events of cellular homeostasis and potentially suppress unscrupulous expression of genes promoting neuronal projection.

PDF file - 981KB, Representative Immunohistochemistry for CHD7 Expression in Primary Tumor Tissue (S1). Network Analysis via MetaCore ExPlain Process Network Analysis for genes involved in CHK1, CDC25A, AURKB, PLK1, HUS1 pathway (S2). CHD7 Knockdown Causes Gemcitabine Sensitization (S3). Mice with Xenograft Tumors Showed No Significant Difference in Body Weight (S4). CHD7 Knockdown Effect on Cell Cycle (S5). Gemcitabine Does Not Significantly Change CHD7 Protein Levels in Cells (S6).

PDF file - 70KB

XLS file - 675KB, Full Results of Primary Gemcitabine Sensitivity Screen (S1). Known DNA Damage Response Genes Identified as Hits in Gemcitabine Sensitivity Screen (S2). Dysregulation, Differential Expression, and Literature RNAi Cross-Reference for Known DDR Genes and Select Hits (S3). Selected Top 15% of Gemcitabine Sensitivity Genes Tested on Secondary Screen (S4).

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease with poor outcomes with current therapies. Gemcitabine is the primary adjuvant drug used clinically, but its effectiveness is limited. In this study, our objective was to use a rationale-driven approach to identify novel biomarkers for outcome in patients with early-stage resected PDAC treated with adjuvant gemcitabine. Using a synthetic lethal screen in human PDAC cells, we identified 93 genes, including 55 genes linked to DNA damage responses (DDR), that demonstrated gemcitabine sensitization when silenced, including CHD7, which functions in chromatin remodeling. CHD7 depletion sensitized PDAC cells to gemcitabine and delayed their growth in tumor xenografts. Moreover, CHD7 silencing impaired ATR-dependent phosphorylation of CHK1 and increased DNA damage induced by gemcitabine. CHD7 was dysregulated, ranking above the 90th percentile in differential expression in a panel of PDAC clinical specimens, highlighting its potential as a biomarker. Immunohistochemical analysis of specimens from 59 patients with resected PDAC receiving adjuvant gemcitabine revealed that low CHD7 expression was associated with increased recurrence-free survival (RFS) and overall survival (OS), in univariate and multivariate analyses. Notably, CHD7 expression was not associated with RFS or OS for patients not receiving gemcitabine. Thus, low CHD7 expression was correlated selectively with gemcitabine sensitivity in this patient population. These results supported our rationale-driven strategy to exploit dysregulated DDR pathways in PDAC to identify genetic determinants of gemcitabine sensitivity, identifying CHD7 as a novel biomarker candidate to evaluate further for individualizing PDAC treatment. Cancer Res; 74(10); 2677–87. ©2014 AACR.

Objective. Chronic cancer pain and depressive symptoms are interrelated in clinical settings. As local data is lacking, this study aimed to determine the prevalence of depressive symptoms among chronic cancer pain patients seen at the Philippine General Hospital - Pain Clinic (PGH-PC).Methods. In this retrospective, descriptive, cross-sectional study, data were collected from the charts of chroniccancer pain patients seen at the PGH-PC. The Pain Clinic Self-Report Questionnaire (SRQ) tool was used to assess depressive symptoms. Clinico-demographic data were obtained and analyzed using descriptive statistics.Results. Of the 129 patients included in the study, 61 had depressive symptoms corresponding to a prevalence of 47.29% (38.72 - 56.01 95% CI). Overall, a more significant number of patients included in the study were female, belonged to age 41-50, were married, attained secondary education, and were unemployed. Demographically, there were no statistically significant differences between chronic cancer pain patients who exhibited depressive symptoms and those who did not. The cancer type showed a statistically significant difference among those cancer patients with or without depressive symptoms (p = 0.016). Breast and gynecologic malignancies comprised more than half of the patients studied. Neither the cancer stage nor the pain scores had a statistically significant difference among those cancer patients with or without symptoms of depression.Conclusion. Almost 1 in every two chronic cancer pain patients studied had depressive symptoms. Routine screening of patients for depressive symptoms could identify patients and may initiate interventions in this vulnerable population

Small cell lung cancer (SCLC) is a highly aggressive malignancy with poor outcomes associated with resistance to cisplatin-based chemotherapy. Enhancer of Zeste Homolog 2 (EZH2) is the catalytic subunit of Polycomb Repressive Complex 2 (PRC2), which silences transcription through trimethylation of histone H3 lysine 27 (H3K27me3) and has emerged as an important therapeutic target with inhibitors targeting its methyltransferase activity under clinical investigation. Here, we show that EZH2 has a non-catalytic and PRC2 independent role in stabilizing DDB2 to promote nucleotide excision repair (NER) and govern cisplatin resistance in SCLC. Using a synthetic lethality screen, we identified important regulators of cisplatin resistance in SCLC cells, including EZH2. EZH2 depletion causes cellular cisplatin and UV hypersensitivity in an epistatic manner with DDB1-DDB2. EZH2 complexes with DDB1-DDB2 and promotes DDB2 stability by impairing its ubiquitination independent of methyltransferase activity or PRC2, thereby facilitating DDB2 localization to cyclobutane pyrimidine dimer (CPD) crosslinks to govern their repair. Furthermore, targeting EZH2 for depletion with DZNep strongly sensitizes SCLC cells and tumors to cisplatin. Our findings reveal a non-catalytic and PRC2-independent function for EZH2 in promoting NER through DDB2 stabilization, suggesting a rationale for targeting EZH2 beyond its catalytic activity for overcoming cisplatin resistance in SCLC.

Lysine acetylation is an important post-translational modification that is used in multiple cellular pathways, such as the regulation of gene expression at the histone level. The purpose of this assay is to test for putative substrates of class III deacetylases using an

Sirtuin 2 (SIRT2) is a NAD+-dependent deacetylase, which regulates multiple biological processes, including genome maintenance, aging, tumor suppression, and metabolism. While a number of substrates involved in these processes have been identified, the global landscape of the SIRT2 acetylome remains unclear. Using a label-free quantitative proteomic approach following enrichment for acetylated peptides from SIRT2-depleted and SIRT2-overexpressing HCT116 human colorectal cancer cells, we identified a total of 2,846 unique acetylation sites from 1414 proteins. 896 sites from 610 proteins showed a > 1.5-fold increase in acetylation with SIRT2 knockdown, and 509 sites from 361 proteins showed a > 1.5-fold decrease in acetylation with SIRT2 overexpression, with 184 proteins meeting both criteria. Sequence motif analyses identified several site-specific consensus sequence motifs preferentially recognized by SIRT2, most commonly KxxxxK(ac). Gene Ontology, KEGG, and MetaCore pathway analyses identified SIRT2 substrates involved in diverse pathways, including carbon metabolism, glycolysis, spliceosome, RNA transport, RNA binding, transcription, DNA damage response, the cell cycle, and colorectal cancer. Collectively, our findings expand on the number of known acetylation sites, substrates, and cellular pathways targeted by SIRT2, providing support for SIRT2 in regulating networks of proteins in diverse pathways and opening new avenues of investigation into SIRT2 function.

Elevated intracellular levels of dNTPs have been shown to be a biochemical marker of cancer cells. Recently, a series of mutations in the multifunctional dNTP triphosphohydrolase (dNTPase), sterile alpha motif and histidine–aspartate domain–containing protein 1 (SAMHD1), have been reported in various cancers. Here, we investigated the structure and functions of SAMHD1 R366C/H mutants, found in colon cancer and leukemia. Unlike many other cancer-specific mutations, the SAMHD1 R366 mutations do not alter cellular protein levels of the enzyme. However, R366C/H mutant proteins exhibit a loss of dNTPase activity, and their X-ray structures demonstrate the absence of dGTP substrate in their active site, likely because of a loss of interaction with the γ-phosphate of the substrate. The R366C/H mutants failed to reduce intracellular dNTP levels and restrict HIV-1 replication, functions of SAMHD1 that are dependent on the ability of the enzyme to hydrolyze dNTPs. However, these mutants retain dNTPase-independent functions, including mediating dsDNA break repair, interacting with CtIP and cyclin A2, and suppressing innate immune responses. Finally, SAMHD1 degradation in human primary-activated/dividing CD4+ T cells further elevates cellular dNTP levels. This study suggests that the loss of SAMHD1 dNTPase activity induced by R366 mutations can mechanistically contribute to the elevated dNTP levels commonly found in cancer cells.

Elevated intracellular dNTP level is a biochemical marker of cancer cells. Recently, a series of mutations in a highly multi-functional dNTPase, SAMHD1, have been reported in various cancers. Here we investigated the role of SAMHD1 in cancer by characterizing cancer-specific SAMHD1 mutations. R366C/H mutants, which were found in two cancer types, lost dNTPase activity and their X-ray structures demonstrate the absence of dGTP substrate in their active site, likely due to loss of interaction with γ-phosphate of the substrate. The R366C/H mutants failed to reduce intracellular dNTP levels and restrict HIV-1. However, these mutants retain dNTPase-independent functions including mediating dsDNA break repair, interacting with CtIP and Cyclin A2, and suppressing innate immune responses.Finally, SAMHD1 degradation in human primary activated/dividing CD4+ T cells further elevates cellular dNTP levels. This study supports that the loss of SAMHD1 dNTPase activity mechanistically contributes to the elevated dNTP levels commonly found in cancer cells.

In contrast to the vast majority of research that has focused on the immediate effects of ionizing radiation, this work concentrates on the molecular mechanism driving delayed effects that emerge in the progeny of the exposed cells. We employed functional protein arrays to identify molecular changes induced in a human bronchial epithelial cell line (HBEC3-KT) and osteosarcoma cell line (U2OS) and evaluated their impact on outcomes associated with radiation induced genomic instability (RIGI) at day 5 and 7 post-exposure to a 2Gy X-ray dose, which revealed replication stress in the context of increased FOXM1 expression. Irradiated cells had reduced DNA replication rate detected by the DNA fiber assay and increased DNA resection detected by RPA foci and phosphorylation. Irradiated cells increased utilization of homologous recombination-dependent repair detected by a gene conversion assay and DNA damage at mitosis reflected by RPA positive chromosomal bridges, micronuclei formation and 53BP1 positive bodies in G1, all known outcomes of replication stress. Interference with the function of FOXM1, a transcription factor widely expressed in cancer, employing an aptamer, decreased radiation-induced micronuclei formation and cell transformation while plasmid-driven overexpression of FOXM1b was sufficient to induce replication stress, micronuclei formation and cell transformation.

We are constantly exposed to a variety of both external and internal DNA damaging agents, such as UV light from the sun and reactive oxygen species created as by-products of aerobic respiration. As a result, our DNA accumulates thousands of instances of damage per cell per day. DNA damage response (DDR) pathways, which include DNA repair and cell-cycle checkpoints, are responsible for the repair of DNA damage and are critical for protecting against mutagenesis and maintaining genome integrity. DNA double-stranded breaks (DSBs) are the most deleterious type of DNA damage and are repaired by one of two pathways: Non-homologous end-joining (NHEJ), an error-prone mechanism of repair active throughout the entire cell cycle, or homologous recombination (HR), considered to be an 'error-free' method for DSB repair that occurs in the S and G2 phases of the cell cycle. Deficiencies in NHEJ or HR can result in genomic instability via genomic incorporation of chromosomal aberrations, which can ultimately lead to an increased risk of cancer. However, in many cases, the mechanisms by which defects in these pathways lead to an increased risk of developing cancer is unknown, making preventative care and treatment of resulting cancers more difficult. Breast Cancer 1 (BRCA1), an established tumor suppressor, is a protein necessary for the proper repair of DNA DSBs through the HR pathway. Defects in BRCA1, whether genetically inherited or spontaneously developed, have been linked to different types of cancer in both men and women, including breast, ovarian, and pancreatic cancer. Yet, the regulation of BRCA1 in HR is not well understood and thus highlights a major a gap in our understanding of how deficiencies in HR contribute to the development of cancer. Our lab has discovered that SIRT2, a class III NAD+ dependent histone deacetylase and putative human tumor suppressor, plays a crucial role in the DDR and repair of DNA DSBs. We have shown that depletion of SIRT2 impairs HR and increases cell sensitivity to ionizing radiation in a deacetylase-dependent manner. A mass spectrometry analysis showed SIRT2 interacts with several proteins involved in DDR, including BRCA1. We validated the interaction between SIRT2 and BRCA1 and found SIRT2 deacetylates BRCA1 both in vitro and in cells. Depletion of SIRT2 and subsequent deacetylation of BRCA1 decreases BRCA1 protein levels in cells, impairing HR. Our results show SIRT2 is a novel regulator of BRCA1 and is critical for the repair of DNA DSBs through HR. These findings provide invaluable insights into how to exploit the interplay between SIRT2 and BRCA1 as a novel therapeutic approach for the prevention and treatment of cancer. Citation Format: Minten EV, Zhang H, Li C, Head PE, Yu DS. Regulation of BRCA1 by SIRT2 [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-06-01.

Objectives The patterns of care for salivary gland adenoid cystic carcinomas (ACC) are unknown. We sought to assess predictors of receiving postoperative radiation and/or chemotherapy for patients with nonmetastatic, definitively resected ACC, as well as report unexpected nodal disease. Methods The National Cancer Data Base was queried for definitively resected nonmetastatic ACC from 2004 to 2014. Logistic regression, Kaplan-Meier, and Cox proportional-hazard models were utilized. Propensity-score matched analysis was employed to reduce confounding variables. Results A total of 3,136 patients met entry criteria: 2,252 (71.8%) received postoperative radiation, with 223 (7.4%) also receiving concurrent chemotherapy. Median follow-up was 4.87 years. In clinically lymph node negative (cN0) patients, 7.4% had pathologically positive lymph nodes (pN) + after elective neck dissection. Patients who lived closer to their treatment facility and had positive margins were more likely to receive postoperative radiation. Black patients and uninsured patients were less likely to receive radiation. Older age, male sex, advancing stage, and positive surgical margins were associated with worse overall survival (OS). With limited follow-up, receipt of radiation or chemotherapy was not associated with OS. Conclusion Postoperative radiation was frequently given for resected ACC, with a minority receiving chemotherapy. Black patients and uninsured patients were less likely to receive radiation. Postoperative radiation and/or chemotherapy had no association with OS but were given in greater frequency in more advanced disease, and our series is limited by short follow-up. The disparity findings for this rare disease need to be addressed in future studies. Level of evidence 2c Laryngoscope, 129:377-386, 2019.

DNA double-strand breaks (DSBs) are mainly repaired either by homologous recombination (HR) or by nonhomologous end-joining (NHEJ) pathways. Here, we showed that myeloid cell leukemia sequence 1 (Mcl-1) acts as a functional switch in selecting between HR and NHEJ pathways. Mcl-1 was cell cycle–regulated during HR, with its expression peaking in S/G2 phase. While endogenous Mcl-1 depletion reduced HR and enhanced NHEJ, Mcl-1 overexpression resulted in a net increase in HR over NHEJ. Mcl-1 directly interacted with the dimeric Ku protein complex via its Bcl-2 homology 1 and 3 (BH1 and BH3) domains, which are required for Mcl-1 to inhibit Ku-mediated NHEJ. Mcl-1 also promoted DNA resection mediated by the Mre11 complex and HR-dependent DSB repair. Using the Mcl-1 BH1 domain as a docking site, we identified a small molecule, MI-223, that directly bound to BH1 and blocked Mcl-1–stimulated HR DNA repair, leading to sensitization of cancer cells to hydroxyurea- or olaparib-induced DNA replication stress. Combined treatment with MI-223 and hydroxyurea or olaparib exhibited a strong synergy against lung cancer in vivo. This mechanism-driven combination of agents provides a highly attractive therapeutic strategy to improve lung cancer outcomes.

Sirtuin 2 (SIRT2) is a sirtuin family deacetylase, which maintains genome integrity and prevents tumorigenesis. Although Sirt2 deficiency in mice leads to tumorigenesis, the functional significance of somatic SIRT2 mutations in human tumors is unclear. Using structural insight combined with bioinformatics and functional analyses, we show that naturally occurring cancer-associated SIRT2 mutations at evolutionarily conserved sites disrupt its deacetylation of DNA-damage response proteins by impairing SIRT2 catalytic activity or protein levels but not its localization or binding with substrate. We observed that these SIRT2 mutant proteins fail to restore the replication stress sensitivity, impairment in recovery from replication stress, and impairment in ATR-interacting protein (ATRIP) focus accumulation of SIRT2 deficiency. Moreover, the SIRT2 mutant proteins failed to rescue the spontaneous induction of DNA damage and micronuclei of SIRT2 deficiency in cancer cells. Our findings support a model for SIRT2's tumor-suppressive function in which somatic mutations in SIRT2 contribute to genomic instability by impairing its deacetylase activity or diminishing its protein levels in the DNA-damage response. In conclusion, our work provides a mechanistic basis for understanding the biological and clinical significance of SIRT2 mutations in genome maintenance and tumor suppression.

DNA double-strand break (DSB) repair by homologous recombination (HR) is initiated by CtIP/MRN-mediated DNA end resection to maintain genome integrity. SAMHD1 is a dNTP triphosphohydrolase, which restricts HIV-1 infection, and mutations are associated with Aicardi-Goutières syndrome and cancer. We show that SAMHD1 has a dNTPase-independent function in promoting DNA end resection to facilitate DSB repair by HR. SAMHD1 deficiency or Vpx-mediated degradation causes hypersensitivity to DSB-inducing agents, and SAMHD1 is recruited to DSBs. SAMHD1 complexes with CtIP via a conserved carboxyl-terminal domain and recruits CtIP to DSBs to facilitate end resection and HR. Significantly, a cancer-associated mutant with impaired CtIP interaction but not dNTPase-inactive SAMHD1 fails to rescue the end resection impairment of SAMHD1 depletion. Our findings define a dNTPase-independent function for SAMHD1 in HR-mediated DSB repair by facilitating CtIP accrual to promote DNA end resection, providing insight into how SAMHD1 promotes genome integrity and prevents disease, including cancer.

The breast cancer type I susceptibility protein (BRCA1) and BRCA1-associated RING domain protein I (BARD1) heterodimer promotes genome integrity through pleiotropic functions, including DNA double-strand break (DSB) repair by homologous recombination (HR). BRCA1-BARD1 heterodimerization is required for their mutual stability, HR function, and role in tumor suppression; however, the upstream signaling events governing BRCA1-BARD1 heterodimerization are unclear. Here, we show that SIRT2, a sirtuin deacetylase and breast tumor suppressor, promotes BRCA1-BARD1 heterodimerization through deacetylation. SIRT2 complexes with BRCA1-BARD1 and deacetylates conserved lysines in the BARD1 RING domain, interfacing BRCA1, which promotes BRCA1-BARD1 heterodimerization and consequently BRCA1-BARD1 stability, nuclear retention, and localization to DNA damage sites, as well as efficient HR. Our findings define a mechanism for regulation of BRCA1-BARD1 heterodimerization through SIRT2 deacetylation, elucidating a critical upstream signaling event directing BRCA1-BARD1 heterodimerization, which facilitates HR and tumor suppression, and delineating a role for SIRT2 in directing DSB repair by HR. Citation Format: Elizabeth V. Minten, Priya Kappor-Vazirani, Chunyang Li, Hui Zhang, Kamakshi Balakrishnan, David S. Yu. SIRT2 promotes BRCA1-BARD1 heterodimerization through deacetylation [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr PR-002.

e14027 Background: Accurate staging is critical in determining treatment strategies in the management of breast cancer (BC) patients. FDG PET/CT is used to identify the presence of metastatic disease. The criteria for FDG PET/CT utilization is variable, including in any patient with nodal positivity, any patients with systemic symptoms, to those with Stage III disease or higher.. This practice variation has results in different patterns of ordering FDG PET/CT. The preliminary results of a Quality Oncology Practice Initiative (QOPI) audit performed in our Cancer Center in 2017 prompted concern for the over utilization of FDG PET/CT in our BC patients. We performed an initial audit of these practices in 2017 and confirmed these findings. The goal of this study was to re-measure our adherence to NCCN guidelines in 2019 after an educational session complimented by use of a checklist. Methods: A retrospective review was conducted for all BC patients who had FDG PET/CT ordered as initial treatment planning from 1/2017-12/2017. This revealed a 33% rate of failure to meet NCCN guidelines. We then educated our team about the NCCN guidelines for initial PET/CT ordering during our weekly multi-disciplinary conferences, created a test ordering checklist and compared the effect of this education on the use of PET/CT in patients treated at our institution from 1/2019-12/2019. Results: 65 female BC patients had an FDG PET/CT ordered to assist in initial treatment recommendation in 2017. Overall, 66.2% (n = 43) of patients met NCCN indications while 33.8% (n = 22) did not. In comparison to 2017 data, 71 female breast cancer patients had an FDG PET/CT ordered in 2019. Overall, 67 patients (94.4%) met NCCN criteria indications for undergoing FDG PET/CT while only 5 patients (5.6%) did not. Conclusions: Review of FDG PET/CT scans ordered for initial treatment in 2017 revealed that about one third of scans were ordered outside of NCCN guideline recommendations. After an educational session and implementation of a test ordering checklist, we found a marked reduction in the use of FDG PET/CT outside of NCCN guideline recommendations. Although our study is limited by small sample sizes, we identified a practice area that deviated from national recommendations and were able to improve our internal compliance in national guidelines through education and system modification.

BACKGROUND The prognostic relevance of human papillomavirus (HPV) status in patients with nonoropharyngeal (OPX) squamous cell cancer (SCC) of the head and neck is controversial. In the current study, the authors evaluated the impact of high-risk HPV status on overall survival (OS) in patients with non-OPX SCC using a large database approach. METHODS The National Cancer Data Base was queried to identify patients diagnosed from 2004 through 2014 with SCC of the OPX, hypopharynx (HPX), larynx, and oral cavity (OC) with known HPV status. Survival was estimated using Kaplan-Meier methods; distributions were compared using log-rank tests. Propensity score-matching and inverse probability of treatment weighing (IPTW) methods were used; cohorts were matched based on age, sex, Charlson-Deyo score, clinical American Joint Committee on Cancer (AJCC) group stage, treatments received, and anatomic subsite. Propensity analyses were stratified by group stage of disease. RESULTS A total of 24,740 patients diagnosed from 2010 through 2013 were analyzed: 1085 patients with HPX, 4804 with laryngeal, 4,018 with OC, and 14,833 with OPX SCC. The percentages of HPV-positive cases by disease site were 17.7% for HPX, 11% for larynx, 10.6% for OC, and 62.9% for OPX. HPV status was found to be prognostic in multiple unadjusted and propensity-adjusted non-OPX populations. HPV positivity was associated with superior OS in patients with HPX SCC with a hazard ratio (HR) of 0.61 (P

To investigate the feasibility of ultrasound Nakagami imaging to quantitatively assess radiation-induced neck fibrosis, a common sequela of radiation therapy (RT) to the head and neck.In a pilot study, 40 study participants were enrolled and classified into 3 subgroups: (1) a control group of 12 healthy volunteers; (2) an asymptomatic group of 11 patients who had received intensity modulated RT for head and neck cancer and had experienced no neck fibrosis; and (3) a symptomatic group of 17 post-RT patients with neck fibrosis. Each study participant underwent 1 ultrasound study in which scans were performed in the longitudinal orientation of the bilateral neck. Three Nakagami parameters were calculated to quantify radiation-induced tissue injury: Nakagami probability distribution function, shape, and scaling parameters. Physician-based assessments of the neck fibrosis were performed according to the Radiation Therapy Oncology Group late morbidity scoring scheme, and patient-based fibrosis assessments were rated based on symptoms such as pain and stiffness.Major discrepancies existed between physician-based and patient-based assessments of radiation-induced fibrosis. Significant differences in all Nakagami parameters were observed between the control group and 2 post-RT groups. Moreover, significant differences in Nakagami shape and scaling parameters were observed among asymptomatic and symptomatic groups. Compared with the control group, the average Nakagami shape parameter value increased by 32.1% (P.001), and the average Nakagami scaling parameter increased by 55.7% (P.001) for the asymptomatic group, whereas the Nakagami shape parameter increased by 74.1% (P.001) and the Nakagami scaling parameter increased by 83.5% (P.001) for the symptomatic group.Ultrasonic Nakagami imaging is a potential quantitative tool to characterize radiation-induced asymptomatic and symptomatic neck fibrosis.

Protein kinases play a vital role in the regulation of pathways that control cell growth, proliferation, survival, and differentiation. Epidermal growth factor receptor (EGFR) is a key protein kinase that when dysregulated, disrupts these pathways and, accordingly, is associated with several cancers. Thus, EGFR has been a focus of investigation as a therapeutic target for cancer treatment for the past several decades, with fair success. Despite this success, EGFR-targeted therapies are not universally effective across cancers, and improving the specificity and efficiency of EGFR-targeted therapies is an area of continued investigation. This chapter discusses recent progress made in understanding the role of EGFR in cancer and how the knowledge have been used to develop more precise EGFR-based therapeutic regimens for cancer patients.

This case is about a 35-week neonate diagnosed with harlequin ichthyosis. The neonate was managed by a multidisciplinary team composed of specialists from neonatology, genetics, dermatology, plastic surgery, ophthalmology, rehabilitation medicine, and anesthesiology. Harlequin ichthyosis is characterized by defective keratinization and desquamation of the epidermis which is very painful. Pain management in the neonate entails a proper balance between pain relief and avoidance of serious adverse effects which is a major challenge for caregivers.

Xerostomia (dry mouth) is a common, often permanent, and debilitating morbidity of radiotherapy (RT) for head-and-neck malignancies (1,2). Patients with severe xerostomia have thick secretions, difficulty in swallowing and speaking, and are at high risk for oral infection and dental caries (3). This symptom burden impairs the quality of life (QoL) of many head-and-neck cancer survivors for months, even years, after treatment (4). It is well established that the main cause of RT-induced xerostomia is irradiation of parotid glands—the major salivary glands producing ~60% of total saliva (1). Recent clinical studies indicate that intensity-modulated radiotherapy (IMRT) provides a significant advantage in sparing the parotid glands and reducing xerostomia. However, even with the new technology, 17%–30% of patients treated with IMRT still develop permanent xerostomia. There is substantial heterogeneity in parotid gland injury after radiation (5–7). In the clinic, radiation-induced xerostomia is assessed using patient-based or physician-based grading systems. For example, the Radiation Therapy Oncology Group (RTOG) and the European Organization for Research and Treatment of Cancer (EORTC) established a morbidity scale to evaluate post-RT salivary glands. Specifically, salivary gland toxicity was divided into two categories: acute (≤3 months after RT) toxicity and late (>3 months after RT) toxicity. Physicians assign a score of grade 1 (slight dryness) to grade 4 (necrosis or fibrosis) for acute or late salivary toxicity (8). Such subjective measures of radiation toxicity are prone to intraobserver and interobserver variability. In recent years, many groups have been investigating imaging technologies to evaluate parotid gland injury induced by radiation. Studies using computed tomography (CT), magnetic resonance imaging (MRI), MR sialography, and single-photon emission computed tomography scintigraphy have shown some degree of success in assessing the severity of parotid gland injury and documenting normal tissue response to RT (9–17). However, the high cost, the technical complexity, and the need for dedicated imaging expertise (CT, MRI, or nuclear medicine) preclude their use in routine clinical assessment of xerostomia. The concept of ultrasound imaging to evaluate parotid gland injury is especially attractive because ultrasound is safe, portable, widely available, easy to use, and cost effective. In particular, because parotid glands are superficial structures wrapping around the mandible, they are readily amenable to ultrasound examination. Ultrasound, therefore, is the standard imaging modality in the assessment of salivary gland diseases such as neoplasms, Sjogren syndrome, sialadenitis, and sialolothiasis. However, there is limited information in the literature about evaluation of radiation-induced parotid gland injury or xerostomia using ultrasound (9). Previously, we have proposed an ultrasound technology based on quantitative analysis of echo-intensity histogram to assess RT-associated parotid gland injury (18). A family of sonographic features was derived from the echo histogram to quantify the echogenicity and heterogeneity of parotid glands, which is used to assess the morphologic and architectural integrity of post-RT parotids. In a pilot study of 12 patients, we demonstrated the clinical feasibility of using these echo histogram features in evaluating parotid gland toxicity after RT (18). Another appealing factor of ultrasound histogram evaluation of RT-related parotid gland toxicity is that it could eliminate variations in subjective radiologic interpretations of ultrasound images. To further explore this ultrasound technology in the evaluation of RT-induced parotid gland injury, we embarked on this clinical study. The primary objective was to determine the diagnostic accuracy of echo-intensity histogram parameters in the assessment of RT-induced parotid gland injury. In addition, we compared the quantitative ultrasound examination with radiologists’ evaluation of acute and late toxicities of RT to parotid glands. Special emphasis was placed on acute toxicity for patients within 3 months of cancer treatment. We want to emphasize the importance of developing safe and easy ultrasound technology to detect acute toxicity because early detection of parotid gland injury could enable early interventions to minimize long-term morbidity.

High linear energy transfer (LET) radiation from space heavy charged particles or a heavier ion radiotherapy machine kills more cells than low LET radiation, mainly because high LET radiation-induced DNA damage is more difficult to repair. Relative biological effectiveness (RBE) is the ratio of the effects generated by high LET radiation to low LET radiation. Previously, our group and others demonstrated that the cell-killing RBE is involved in the interference of high LET radiation with non-homologous end joining but not homologous recombination repair. This effect is attributable, in part, to the small DNA fragments (≤40 bp) directly produced by high LET radiation, the size of which prevents Ku protein from efficiently binding to the two ends of one fragment at the same time, thereby reducing non-homologous end joining efficiency. Here we demonstrate that Ape1, an enzyme required for processing apurinic/apyrimidinic (known as abasic) sites, is also involved in the generation of small DNA fragments during the repair of high LET radiation-induced base damage, which contributes to the higher RBE of high LET radiation-induced cell killing. This discovery opens a new direction to develop approaches for either protecting astronauts from exposure to space radiation or benefiting cancer patients by sensitizing tumor cells to high LET radiotherapy.

The Replication Stress Response (RSR) is a signaling network that recognizes challenges to DNA replication and coordinates diverse DNA repair and cell-cycle checkpoint pathways. Gemcitabine is a nucleoside analogue that causes cytotoxicity by inducing DNA replication blocks. Using a synthetic lethal screen of a RNAi library of nuclear enzymes to identify genes that when silenced cause gemcitabine sensitization or resistance in human triple-negative breast cancer cells, we identified NIMA (never in mitosis gene A)-related kinase 9 (NEK9) as a key component of the RSR. NEK9 depletion in cells leads to replication stress hypersensitivity, spontaneous accumulation of DNA damage and RPA70 foci, and an impairment in recovery from replication arrest. NEK9 protein levels also increase in response to replication stress. NEK9 complexes with CHK1, and moreover, NEK9 depletion impairs CHK1 autophosphorylation and kinase activity in response to replication stress. Thus, NEK9 is a critical component of the RSR that promotes CHK1 activity, maintaining genome integrity following challenges to DNA replication.

DNA-dependent protein kinase (DNA-PK) plays a critical role in non-homologous end joining (NHEJ), the predominant pathway that repairs DNA double-strand breaks (DSB) in response to ionizing radiation (IR) to govern genome integrity. How DNA-PK is activated in response to DSBs has remained elusive. Here, we show that the SIRT2 sirtuin deacetylase and tumor suppressor directs the activation of DNA-PK through deacetylation of its catalytic subunit (DNA-PKcs). SIRT2 deacetylase activity governs cellular resistance to DSB-inducing agents and promotes NHEJ. SIRT2 furthermore interacts with and deacetylates DNA-PKcs in response to IR, which facilitates its interaction with Ku and recruitment to DSBs, thereby leading to DNA-PKcs autophosphorylation and DNA-PK signaling to downstream NHEJ substrates. Moreover, SIRT2 inhibitor sensitizes resistant cancer cells and tumors to IR. Our findings define a mechanism for DNA-PK activation by SIRT2-mediated deacetylation, elucidating a critical upstream signaling event initiating the repair of DSBs by NHEJ to promote genome integrity and govern IR resistance, which can be exploited for improvements in cancer therapy. Citation Format: PamelaSara E. Head, Nagaraju P. Ganji, Shi-Ya Wang, Duc Duong, Hui Zhang, Waaqo Daddacha, Shuyi Li, Nicholas T. Seyfried, David M. Smalley, Ya Wang, Xingming Deng, William S. Dynan, Bassel El-Rayes, Anthony J. Davis, David S. Yu. DNA-PKCS deacetylation by SIRT2 promotes DNA double-strand break repair by non-homologous end joining [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2561.