Characteristics of Rodeo Injuries and Suggestions for Injury Prevention: A Systematic Review.

Background: Rodeo is a globally popular sport, with its athletes prone to various types of injuries. There is no systematic review discussing rodeo injuries across all age groups. Purpose: To (1) review the published literature on incidence, types of injuries, and factors leading to injuries in rodeo athletes; (2) provide prevention recommendations for health care providers; and (3) identify gaps in the research. Study Design: Systematic review; Level of evidence, 4. Methods: A comprehensive search of available literature was electronically performed through MEDLINE, Embase, and SPORTDiscus databases using the key terms "rodeo" and "injury" or "trauma" between 1995 and 2021. A systematic review was performed using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, which identified 116 eligible studies. Outcome data included frequency of injuries, risk factors for injury, and types of injury. Results: A total of 23 studies met the inclusion criteria (N = 2105 athletes), of which 13 were retrospective studies. In the included studies, the injury rate per competition exposure (CE) ranged from 4.2 to 19.1 injuries per 1000 CE. Sprains and strains accounted for the highest percentage of injury types, ranging from 15% to 34%. The knee was the most common location of injury, making up 11.1% to 17% of injuries. Concussions occurred in up to 15.3% of injuries for all events and up to 77% of injuries in roughstock events. Of all rodeo events reported, bull riding caused the highest percentage of injuries, making up 19.4% to 58.4% of injuries, and bareback had the second highest at 15.3% to 28.8% of injuries. Conclusion: There was a high prevalence of various injury types and mechanisms in rodeo. Improved injury surveillance and the introduction of a comprehensive standardized injury reporting system would be helpful in the future prevention, diagnosis, and treatment of rodeo injuries.

Mitochondrial Inhibitor Atovaquone Increases Tumor Oxygenation and Inhibits Hypoxic Gene Expression in Patients with Non-Small Cell Lung Cancer.

PURPOSE: Tumor hypoxia fuels an aggressive tumor phenotype and confers resistance to anticancer treatments. We conducted a clinical trial to determine whether the antimalarial drug atovaquone, a known mitochondrial inhibitor, reduces hypoxia in non-small cell lung cancer (NSCLC). PATIENTS AND METHODS: Patients with NSCLC scheduled for surgery were recruited sequentially into two cohorts: cohort 1 received oral atovaquone at the standard clinical dose of 750 mg twice daily, while cohort 2 did not. Primary imaging endpoint was change in tumor hypoxic volume (HV) measured by hypoxia PET-CT. Intercohort comparison of hypoxia gene expression signatures using RNA sequencing from resected tumors was performed. RESULTS: Thirty patients were evaluable for hypoxia PET-CT analysis, 15 per cohort. Median treatment duration was 12 days. Eleven (73.3%) atovaquone-treated patients had meaningful HV reduction, with median change -28% [95% confidence interval (CI), -58.2 to -4.4]. In contrast, median change in untreated patients was +15.5% (95% CI, -6.5 to 35.5). Linear regression estimated the expected mean HV was 55% (95% CI, 24%-74%) lower in cohort 1 compared with cohort 2 (P = 0.004), adjusting for cohort, tumor volume, and baseline HV. A key pharmacodynamics endpoint was reduction in hypoxia-regulated genes, which were significantly downregulated in atovaquone-treated tumors. Data from multiple additional measures of tumor hypoxia and perfusion are presented. No atovaquone-related adverse events were reported. CONCLUSIONS: This is the first clinical evidence that targeting tumor mitochondrial metabolism can reduce hypoxia and produce relevant antitumor effects at the mRNA level. Repurposing atovaquone for this purpose may improve treatment outcomes for NSCLC.

Impacts of combining anti-PD-L1 immunotherapy and radiotherapy on the tumour immune microenvironment in a murine prostate cancer model.

BACKGROUND: Radiotherapy enhances innate and adaptive anti-tumour immunity. It is unclear whether this effect may be harnessed by combining immunotherapy with radiotherapy fractions used to treat prostate cancer. We investigated tumour immune microenvironment responses of pre-clinical prostate cancer models to radiotherapy. Having defined this landscape, we tested whether radiotherapy-induced tumour growth delay could be enhanced with anti-PD-L1. METHODS: Hypofractionated radiotherapy was delivered to TRAMP-C1 and MyC-CaP flank allografts. Tumour growth delay, tumour immune microenvironment flow-cytometry, and immune gene expression were analysed. TRAMP-C1 allografts were then treated with 3 × 5 Gy ± anti-PD-L1. RESULTS: 3 × 5 Gy caused tumour growth delay in TRAMP-C1 and MyC-CaP. Tumour immune microenvironment changes in TRAMP-C1 at 7 days post-radiotherapy included increased tumour-associated macrophages and dendritic cells and upregulation of PD-1/PD-L1, CD8+ T-cell, dendritic cell, and regulatory T-cell genes. At tumour regrowth post-3 × 5 Gy the tumour immune microenvironment flow-cytometry was similar to control tumours, however CD8+, natural killer and dendritic cell gene transcripts were reduced. PD-L1 inhibition plus 3 × 5 Gy in TRAMP-C1 did not enhance tumour growth delay versus monotherapy. CONCLUSION: 3 × 5 Gy hypofractionated radiotherapy can result in tumour growth delay and immune cell changes in allograft prostate cancer models. Adjuncts beyond immunomodulation may be necessary to improve the radiotherapy-induced anti-tumour response.

Buparlisib with thoracic radiotherapy and its effect on tumour hypoxia: A phase I study in patients with advanced non-small cell lung carcinoma.

BACKGROUND: Pre-clinically, phosphoinositide 3-kinase (PI3K) inhibition radiosensitises tumours by increasing intrinsic radiosensitivity and by reducing tumour hypoxia. We assessed whether buparlisib, a class 1 PI3K inhibitor, can be safely combined with radiotherapy in patients with non-small cell lung carcinoma (NSCLC) and investigated its effect on tumour hypoxia. METHODS: This was a 3 + 3 dose escalation and dose expansion phase I trial in patients with advanced NSCLC. Buparlisib dose levels were 50 mg, 80 mg and 100 mg once daily orally for 2 weeks, with palliative thoracic radiotherapy (20 Gy in 5 fractions) delivered during week 2. Tumour hypoxic volume (HV) was measured using 18F-fluoromisonidazole positron-emission tomography-computed tomography at baseline and following 1 week of buparlisib. RESULTS: Twenty-one patients were recruited with 9 patients evaluable for maximum tolerated dose (MTD) analysis. No dose-limiting toxicity was reported; therefore, 100 mg was declared the MTD, and 10 patients received this dose in the expansion phase. Ninety-four percent of treatment-related adverse events were ≤grade 2 with fatigue (67%), nausea (24%) and decreased appetite (19%) most common per patient. One serious adverse event (grade 3 hypoalbuminaemia) was possibly related to buparlisib. No unexpected radiotherapy toxicity was reported. Ten (67%) of 15 patients evaluable for imaging analysis were responders with 20% median reduction in HV at the MTD. CONCLUSION: This is the first clinical trial to combine a PI3K inhibitor with radiotherapy in NSCLC and investigate the effects of PI3K inhibition on tumour hypoxia. This combination was well tolerated and PI3K inhibition reduced hypoxia, warranting investigation into whether this novel class of radiosensitisers can improve radiotherapy outcomes.

Loss-of-function desmoplakin I and II mutations underlie dominant arrhythmogenic cardiomyopathy with a hair and skin phenotype.

BACKGROUND: Arrhythmogenic cardiomyopathy (AC) is an inherited, frequently underdiagnosed disorder, which can predispose individuals to sudden cardiac death. Rare, recessive forms of AC can be associated with woolly hair and palmoplantar keratoderma, but most autosomal dominant AC forms have been reported to be cardiac specific. Causative mutations frequently occur in desmosomal genes including desmoplakin (DSP). OBJECTIVES: In this study, we systematically investigated the presence of a skin and hair phenotype in heterozygous DSP mutation carriers with AC. METHODS: Six AC pedigrees with 38 carriers of a dominant loss-of-function (nonsense or frameshift) mutation in DSP were evaluated by detailed clinical examination (cardiac, hair and skin) and molecular phenotyping. RESULTS: All carriers with mutations affecting both major DSP isoforms (DSPI and II) were observed to have curly or wavy hair in the pedigrees examined, except for members of Family 6, where the position of the mutation only affected the cardiac-specific isoform DSPI. A mild palmoplantar keratoderma was also present in many carriers. Sanger sequencing of cDNA from nonlesional carrier skin suggested degradation of the mutant allele. Immunohistochemistry of patient skin demonstrated mislocalization of DSP and other junctional proteins (plakoglobin, connexin 43) in the basal epidermis. However, in Family 6, DSP localization was comparable with control skin. CONCLUSIONS: This study identifies a highly recognizable cutaneous phenotype associated with dominant loss-of-function DSPI/II mutations underlying AC. Increased awareness of this phenotype among healthcare workers could facilitate a timely diagnosis of AC in the absence of overt cardiac features.

CDK1 inhibition sensitizes normal cells to DNA damage in a cell cycle dependent manner.

Cyclin-dependent kinase 1 (CDK1) orchestrates the transition from the G2 phase into mitosis and as cancer cells often display enhanced CDK1 activity, it has been proposed as a tumor specific anti-cancer target. Here we show that the effects of CDK1 inhibition are not restricted to tumor cells but can also reduce viability in non-cancer cells and sensitize them to radiation in a cell cycle dependent manner. Radiosensitization by the specific CDK1 inhibitor, RO-3306, was determined by colony formation assays in three tumor lines (HeLa, T24, SQ20B) and three non-cancer lines (HFL1, MRC-5, RPE). Initial results showed that CDK1 inhibition radiosensitized tumor cells, but did not sensitize normal fibroblasts and epithelial cells in colony formation assays despite effective inhibition of CDK1 signaling. Further investigation showed that normal cells were less sensitive to CDK1 inhibition because they remained predominantly in G1 for a prolonged period when plated in colony formation assays. In contrast, inhibiting CDK1 a day after plating, when the cells were going through G2/M phase, reduced their clonogenic survival both with and without radiation. Our finding that inhibition of CDK1 can damage normal cells in a cell cycle dependent manner indicates that targeting CDK1 in cancer patients may lead to toxicity in normal proliferating cells. Furthermore, our finding that cell cycle progression becomes easily stalled in non-cancer cells under normal culture conditions has general implications for testing anti-cancer agents in these cells.

Nucleoporin 54 contributes to homologous recombination repair and post-replicative DNA integrity.

The nuclear pore complex (NPC) machinery is emerging as an important determinant in the maintenance of genome integrity and sensitivity to DNA double-strand break (DSB)-inducing agents, such as ionising radiation (IR). In this study, using a high-throughput siRNA screen, we identified the central channel NPC protein Nup54, and concomitantly its molecular partners Nup62 and Nup58, as novel factors implicated in radiosensitivity. Nup54 depletion caused an increase in cell death by mitotic catastrophe after IR, and specifically enhanced both the duration of the G2 arrest and the radiosensitivity of cells that contained replicated DNA at the time of IR exposure. Nup54-depleted cells also exhibited increased formation of chromosome aberrations arisen from replicated DNA. Interestingly, we found that Nup54 is epistatic with the homologous recombination (HR) factor Rad51. Moreover, using specific DNA damage repair reporters, we observed a decreased HR repair activity upon Nup54 knockdown. In agreement with a role in HR repair, we also demonstrated a decreased formation of HR-linked DNA synthesis foci and sister chromatid exchanges after IR in cells depleted of Nup54. Our study reveals a novel role for Nup54 in the response to IR and the maintenance of HR-mediated genome integrity.

STING-Dependent Interferon-λ1 Induction in HT29 Cells, a Human Colorectal Cancer Cell Line, After Gamma-Radiation.

PURPOSE: To investigate the induction of type III interferons (IFNs) in human cancer cells by gamma-rays. METHODS AND MATERIALS: Type III IFN expression in human cancer cell lines after gamma-ray irradiation in vitro was assessed by reverse transcription-quantitative polymerase chain reaction and enzyme-linked immunosorbent assay. Signaling pathways mediating type III IFN induction were examined by a variety of means, including immunoblotting, flow cytometry, confocal imaging, and reverse transcription-quantitative polymerase chain reaction. Key mediators in these pathways were further explored and validated using gene CRISPR knockout or short hairpin RNA knockdown. RESULTS: Exposure to gamma-rays directly induced type III IFNs (mainly IFNL1) in human cancer cell lines in dose- and time-dependent fashions. The induction of IFNL1 was primarily mediated by the cytosolic DNA sensors-STING-TBK1-IRF1 signaling axis, with a lesser contribution from the nuclear factor kappa b signaling in HT29 cells. In addition, type III IFN signaling through its receptors serves as a positive feedback loop, further enhancing IFN expression via up-regulation of the kinases in the STING-TBK1 signaling axis. CONCLUSIONS: Our results suggest that IFNL1 can be up-regulated in human cancer cell lines after gamma-ray treatment. In HT29 cells this induction occurs via the STING pathway, adding another layer of complexity to the understanding of radiation-induced antitumor immunity, and may provide novel insights into IFN-based cancer treatment.

Oxidative Phosphorylation as an Emerging Target in Cancer Therapy.

Cancer cells have upregulated glycolysis compared with normal cells, which has led many to the assumption that oxidative phosphorylation (OXPHOS) is downregulated in all cancers. However, recent studies have shown that OXPHOS can be also upregulated in certain cancers, including leukemias, lymphomas, pancreatic ductal adenocarcinoma, high OXPHOS subtype melanoma, and endometrial carcinoma, and that this can occur even in the face of active glycolysis. OXPHOS inhibitors could therefore be used to target cancer subtypes in which OXPHOS is upregulated and to alleviate therapeutically adverse tumor hypoxia. Several drugs including metformin, atovaquone, and arsenic trioxide are used clinically for non-oncologic indications, but emerging data demonstrate their potential use as OXPHOS inhibitors. We highlight novel applications of OXPHOS inhibitors with a suitable therapeutic index to target cancer cell metabolism. Clin Cancer Res; 24(11); 2482-90. ©2018 AACR.

Gemcitabine-Induced TIMP1 Attenuates Therapy Response and Promotes Tumor Growth and Liver Metastasis in Pancreatic Cancer.

Gemcitabine constitutes one of the backbones for chemotherapy treatment in pancreatic ductal adenocarcinoma (PDAC), but patients often respond poorly to this agent. Molecular markers downstream of gemcitabine treatment in preclinical models may provide an insight into resistance mechanisms. Using cytokine arrays, we identified potential secretory biomarkers of gemcitabine resistance (response) in the transgenic KRasG12D; Trp53R172H; Pdx-1 Cre (KPC) mouse model of PDAC. We verified the oncogenic role of the cytokine tissue inhibitor of matrix metalloproteinases 1 (TIMP1) in primary pancreatic tumors and metastases using both in vitro techniques and animal models. We identified potential pathways affected downstream of TIMP1 using the Illumina Human H12 array. Our findings were validated in both primary and metastatic models of pancreatic cancer. Gemcitabine increased inflammatory cytokines including TIMP1 in the KPC mouse model. TIMP1 was upregulated in patients with pancreatic intraepithelial neoplasias grade 3 and PDAC lesions relative to matched normal pancreatic tissue. In addition, TIMP1 played a role in tumor clonogenic survival and vascular density, while TIMP1 inhibition resensitized tumors to gemcitabine and radiotherapy. We observed a linear relationship between TIMP-1 expression, liver metastatic burden, and infiltration by CD11b+Gr1+ myeloid cells and CD4+CD25+FOXP3+ Tregs, whereas the presence of tumor cells was required for immune cell infiltration. Overall, our results identify TIMP1 upregulation as a resistance mechanism to gemcitabine and provide a rationale for combining chemo/radiotherapy with TIMP1 inhibitors in PDAC. Cancer Res; 77(21); 5952-62. ©2017 AACR.

18 F-fluoromisonidazole uptake in advanced stage non-small cell lung cancer: A voxel-by-voxel PET kinetics study.

PURPOSE: The aim of this study was to determine the relative abilities of compartment models to describe time-courses of 18 F-fluoromisonidazole (FMISO) uptake in tumor voxels of patients with non-small cell lung cancer (NSCLC) imaged using dynamic positron emission tomography. Also to use fits of the best-performing model to investigate changes in fitted rate-constants with distance from the tumor edge. METHODS: Reversible and irreversible two- and three-tissue compartment models were fitted to 24 662 individual voxel time activity curves (TACs) obtained from tumors in nine patients, each imaged twice. Descriptions of the TACs provided by the models were compared using the Akaike and Bayesian information criteria (AIC and BIC). Two different models (two- and three-tissue) were fitted to 30 measured voxel TACs to provide ground-truth TACs for a statistical simulation study. Appropriately scaled noise was added to each of the resulting ground-truth TACs, generating 1000 simulated noisy TACs for each ground-truth TAC. The simulation study was carried out to provide estimates of the accuracy and precision with which parameter values are determined, the estimates being obtained for both assumptions about the ground-truth kinetics. A BIC clustering technique was used to group the fitted rate-constants, taking into consideration the underlying uncertainties on the fitted rate-constants. Voxels were also categorized according to their distance from the tumor edge. RESULTS: For uptake time-courses of individual voxels an irreversible two-tissue compartment model was found to be most precise. The simulation study indicated that this model had a one standard deviation precision of 39% for tumor fractional blood volumes and 37% for the FMISO binding rate-constant. Weighted means of fitted FMISO binding rate-constants of voxels in all tumors rose significantly with increasing distance from the tumor edge, whereas fitted fractional blood volumes fell significantly. When grouped using the BIC clustering, many centrally located voxels had high-fitted FMISO binding rate-constants and low rate-constants for tracer flow between the vasculature and tumor, both indicative of hypoxia. Nevertheless, many of these voxels had tumor-to-blood (TBR) values lower than the 1.4 level commonly expected for hypoxic tissues, possibly due to the low rate-constants for tracer flow between the vasculature and tumor cells in these voxels. CONCLUSIONS: Time-courses of FMISO uptake in NSCLC tumor voxels are best analyzed using an irreversible two-tissue compartment model, fits of which provide more precise parameter values than those of a three-tissue model. Changes in fitted model parameter values indicate that levels of hypoxia rise with increasing distance from tumor edges. The average FMISO binding rate-constant is higher for voxels in tumor centers than in the next tumor layer out, but the average value of the more simplistic TBR metric is lower in tumor centers. For both metrics, higher values might be considered indicative of hypoxia, and the mismatch in this case is likely to be due to poor perfusion at the tumor center. Kinetics analysis of dynamic PET images may therefore provide more accurate measures of the hypoxic status of such regions than the simpler TBR metric, a hypothesis we are presently exploring in a study of tumor imaging versus histopathology.

Depletion of signal recognition particle 72kDa increases radiosensitivity.

The identification of genetic determinants that underpin tumor radioresistance can help the development of targeted radiosensitizers or aid personalization of radiotherapy treatment. Here we identify signal recognition particle 72kDa (SRP72) as a novel gene involved in radioresistance. Knockdown of SRP72 resulted in significant radiosensitization of HeLa (cervical), PSN-1 (pancreatic), and T24 (bladder), BT-549 (breast) and MCF7 (breast) tumor lines as measured by colony formation assays. SRP72 depletion also resulted in the radiosensitization of normal lung fibroblast cell lines (HFL1 and MRC-5), demonstrating that the effect is not restricted to tumor cells. Increased radiosensitivity was not due to impaired DNA damage signaling or repair as assessed by γ-H2AX foci formation. Instead SRP72 depletion was associated with elevated levels of apoptosis after irradiation, as measured by caspase 3/7 activity, PARP-cleavage and Annexin-V staining, and with an induction of the unfolded protein response. Together, our results show that SRP72 is a novel gene involved in radioresistance.

PD-L1 blockade enhances response of pancreatic ductal adenocarcinoma to radiotherapy.

Pancreatic ductal adenocarcinoma (PDAC) is considered a non-immunogenic tumor, and immune checkpoint inhibitor monotherapy lacks efficacy in this disease. Radiotherapy (RT) can stimulate the immune system. Here, we show that treatment of KPC and Pan02 murine PDAC cells with RT and gemcitabine upregulated PD-L1 expression in a JAK/Stat1-dependent manner. In vitro, PD-L1 inhibition did not alter radio- and chemosensitivity. In vivo, addition of anti-PD-L1 to high (12, 5 × 3, 20 Gy) but not low (6, 5 × 2 Gy) RT doses significantly improved tumor response in KPC and Pan02 allografts. Radiosensitization after PD-L1 blockade was associated with reduced CD11b+Gr1+ myeloid cell infiltration and enhanced CD45+CD8+ T-cell infiltration with concomitant upregulation of T-cell activation markers including CD69, CD44, and FasL, and increased CD8:Treg ratio. Depletion of CD8+ T cells abrogated radiosensitization by anti-PD-L1. Blockade of PD-L1 further augmented the effect of high RT doses (12 Gy) in preventing development of liver metastases. Exploring multiple mathematical models reveals a mechanism able to explain the observed synergy between RT and anti-PD-L1 therapy. Our findings provide a rationale for testing the use of immune checkpoint inhibitors with RT in PDAC.

Prognostic role and correlation of CA9, CD31, CD68 and CD20 with the desmoplastic stroma in pancreatic ductal adenocarcinoma.

We assessed the prognostic value of hypoxia (carbonic anhydrase 9; CA9), vessel density (CD31), with macrophages (CD68) and B cells (CD20) that can interact and lead to immune suppression and disease progression using scanning and histological mapping of whole-mount FFPE pancreatectomy tissue sections from 141 primarily resectable pancreatic ductal adenocarcinoma (PDAC) samples treated with surgery and adjuvant chemotherapy. Their expression was correlated with clinicopathological characteristics, and overall survival (OS), progression-free survival (PFS), local progression-free survival (LPFS) and distant metastases free-survival (DMFS), also in the context of stroma density (haematoxylin-eosin) and activity (alpha-smooth muscle actin). The median OS was 21 months after a mean follow-up of 20 months (range, 2-69 months). The median tumor surface area positive for CA9 and CD31 was 7.8% and 8.1%, respectively. Although total expression of these markers lacked prognostic value in the entire cohort, nevertheless, high tumor compartment CD68 expression correlated with worse PFS (p = 0.033) and DMFS (p = 0.047). Also, high CD31 expression predicted for worse OS (p = 0.004), PFS (p = 0.008), LPFS (p = 0.014) and DMFS (p = 0.004) in patients with moderate density stroma. High stromal and peripheral compartment CD68 expression predicted for significantly worse outcome in patients with loose and moderate stroma density, respectively. Altogether, in contrast to the current notion, hypoxia levels in PDAC appear to be comparable to other malignancies. CD31 and CD68 constitute prognostic markers in patient subgroups that vary according to tumor compartment and stromal density. Our study provides important insight on the pathophysiology of PDAC and should be exploited for future treatments.

Comments on potential health effects of MRI-induced DNA lesions: quality is more important to consider than quantity.

Magnetic resonance imaging (MRI) is increasingly being used in cardiology to detect heart disease and guide therapy. It is mooted to be a safer alternative to imaging techniques, such as computed tomography (CT) or coronary angiographic imaging. However, there has recently been an increased interest in the potential long-term health risks of MRI, especially in the light of the controversy resulting from a small number of research studies reporting an increase in DNA damage following exposure, with calls to limit its use and avoid unnecessary examination, according to the precautionary principle. Overall the published data are somewhat limited and inconsistent; the ability of MRI to produce DNA lesions has yet to be robustly demonstrated and future experiments should be carefully designed to optimize sensitivity and benchmarked to validate and assess reproducibility. The majority of the current studies have focussed on the initial induction of DNA damage, and this has led to comparisons between the reported induction of γH2AX and implied double-strand break (DSB) yields produced following MRI with induction by imaging techniques using ionizing radiation. However, γH2AX is not only a marker of classical double-ended DSB, but also a marker of stalled replication forks and in certain circumstances stalled DNA transcription. Additionally, ionizing radiation is efficient at producing complex DNA damage, unique to ionizing radiation, with an associated reduction in repairability. Even if the fields associated with MRI are capable of producing DNA damage, the lesions produced will in general be simple, similar to those produced by endogenous processes. It is therefore inappropriate to try and infer cancer risk by simply comparing the yields of γH2AX foci or DNA lesions potentially produced by MRI to those produced by a given exposure of ionizing radiation, which will generally be more biologically effective and have a greater probability of leading to long-term health effects. As a result, it is important to concentrate on more relevant downstream end points (e.g. chromosome aberration production), along with potential mechanisms by which MRI may lead to DNA lesions. This could potentially involve a perturbation in homeostasis of oxidative stress, modifying the background rate of endogenous DNA damage induction. In summary, what the field needs at the moment is more research and less fear mongering.

Personalized Radiation Oncology: Epidermal Growth Factor Receptor and Other Receptor Tyrosine Kinase Inhibitors.

Molecular biomarkers are currently evaluated in preclinical and clinical studies in order to establish predictors for treatment decisions in radiation oncology. The receptor tyrosine kinases (RTK) are described in the following text. Among them, the most data are available for the epidermal growth factor receptor (EGFR) that plays a major role for prognosis of patients after radiotherapy, but seems also to be involved in mechanisms of radioresistance, specifically in repopulation of tumour cells between radiotherapy fractions. Monoclonal antibodies against the EGFR improve locoregional tumour control and survival when applied during radiotherapy, however, the effects are heterogeneous and biomarkers for patient selection are warranted. Also other RTK´s such as c-Met and IGF-1R seem to play important roles in tumour radioresistance. Beside the potential to select patients for molecular targeting approaches combined with radiotherapy, studies are also needed to evluate radiotherapy adaptation approaches for selected patients, i.e. adaptation of radiation dose, or, more sophisticated, of target volumes.

The radiosensitizing effects of Nelfinavir on pancreatic cancer with and without pancreatic stellate cells.

AIMS: We have previously shown in a phase I trial that nelfinavir (NFV) is safe with chemoradiation in PDAC with good signs for efficacy. Reverse translationally, we aimed to test the influence of PSCs on nelfinavir mediated radiosensitization to PDAC preclinically, because PDAC is very rich in desmoplasia and PSCs are known to mediate radioresistance. METHODS: In a direct co-culture model of several PDAC cell lines with PSC we performed clonogenic assays +/- nelfinavir. This was repeated exposing cells to hypoxic conditions. In xenograft PDAC tumors we tested radiation +/- nelfinavir +/- PSC. RESULTS: NFV sensitized both, PDAC only and PDAC cocultured with PSC (PDAC: Panc-1, MiaPaCa-2, PSN-1). In Panc-1 and PSN-1 this effect was larger +PSC compared to -PSC. Human pancreatic stellate cells (hPSC) were also sensitized by NFV which reduced p-FAK levels in hPSC, an effect that we previously found to sensitize specifically PDAC/PSC coculture. Contrarily, LY294002 reduced p-Akt in PSC (hPSC and LTC-14) but had no impact on PSC radiation survival. In vitro, nelfinavir sensitized Panc-1 and PSN-1 under normoxic and hypoxic conditions. In PSN-1 xenografts, +PSC led to faster tumor regrowth after radiation vs -PSC. The regrowth delay effect of nelfinavir after radiation was dramatically larger +PSC vs -PSC (time to reach 250mm(3) 183% vs 22%). CONCLUSION: NFV mediated radiosensitization in PDAC with stroma is partly mediated by p-FAK inhibition (Chen et al., 2013). In vitro, NFV sensitizes both normoxic and hypoxic PDAC +/- PSC to a roughly similar extent. The dramatic increased effect of xenograft regrowth inhibition by nelfinavir in tumors with PSC is attributed to vascular normalization (Brunner et al., 2014) rather than direct modification of hypoxia as shown by the tumor regrowth after gemcitabine with NFV.

Prognostic value, localization and correlation of PD-1/PD-L1, CD8 and FOXP3 with the desmoplastic stroma in pancreatic ductal adenocarcinoma.

We examined the prognostic value of programmed cell death-1 (PD-1) and its ligand (PD-L1) together with CD8+ tumor-infiltrating lymphocytes (TILs) and FOXP3+ Tregs in resectable pancreatic ductal adenocarcinoma (PDAC) samples treated with adjuvant chemotherapy. Whole-mount FFPE tissue sections from 145 pancreatectomies were immunohistochemically stained for PD-1, PD-L1, CD8 and FOXP3. Their expression was correlated with clinicopathological characteristics, and overall survival (OS), progression-free survival (PFS), local progression-free survival (LPFS) and distant metastases free-survival (DMFS), in the context of stroma density (haematoxylin-eosin) and activity (alpha-smooth muscle actin) and in regard to intratumoral lymphoid aggregates. The median OS was 21 months after a mean follow-up of 20 months (range, 2-69 months). In multivariate analysis, high PD-1+ TILs expression was associated with better OS (p = 0.049), LPFS (p = 0.017) and DMFS (p = 0.021). Similar findings were observed for CD8+ TILs, whereas FOXP3 and PD-L1 lacked prognostic significance. Although TIL distribution was heterogeneous, tumors of high stroma density had higher infiltration of CD8+ TILs than loose density stroma and vice versa (p < 0.001), whereas no correlation was found with stromal activity. Sixty (41.4%) tumors contained lymphoid aggregates and the presence of PD-1+ TILs was associated with better OS (p = 0.030), LPFS (p = 0.025) and DMFS (p = 0.033), whereas CD8+ TILs only correlated with superior LPFS (p = 0.039). PD-1+ and CD8+ TILs constitute independent prognostic markers in patients with PDAC treated with adjuvant chemotherapy. Our study provides important insight on the role of PD-1/PD-L1 in the context of desmoplastic stroma and could help guide future immunotherapies in PDAC.

ARCII: A phase II trial of the HIV protease inhibitor Nelfinavir in combination with chemoradiation for locally advanced inoperable pancreatic cancer.

BACKGROUND AND PURPOSE: Nelfinavir can enhance intrinsic radiosensitivity, reduce hypoxia and improve vascularity. We conducted a phase II trial combining nelfinavir with chemoradiotherapy (CRT) for locally advanced inoperable pancreatic cancer (LAPC). MATERIALS AND METHODS: Radiotherapy (50.4Gy/28 fractions; boost to 59.4Gy/33 fractions) was administered with weekly gemcitabine and cisplatin. Nelfinavir started 3-10days before and was continued during CRT. The primary end-point was 1-year overall survival (OS). Secondary end-points included histological downstaging, radiological response, 1-year progression free survival (PFS), overall survival (OS) and treatment toxicity. An imaging sub-study (n=6) evaluated hypoxia ((18)F-Fluoromisonidazole-PET) and perfusion (perfusion CT) during induction nelfinavir. RESULTS: The study closed after recruiting 23 patients, due to non-availability of Nelfinavir in Europe. The 1-year OS was 73.4% (90% CI: 54.5-85.5%) and median OS was 17.4months (90% CI: 12.8-18.8). The 1-year PFS was 21.8% (90% CI: 8.9-38.3%) and median PFS was 5.5months (90% CI: 4.1-8.3). All patients experienced Grade 3/4 toxicity, but many were asymptomatic laboratory abnormalities. Four of 6 patients on the imaging sub-study demonstrated reduced hypoxia and increased perfusion post-nelfinavir. CONCLUSIONS: CRT combined with nelfinavir showed acceptable toxicity and promising survival in pancreatic cancer.