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Image reconstruction of low-count positron emission tomography (PET) data is challenging. Kernel methods address the challenge by incorporating image prior information in the forward model of iterative PET image reconstruction. The kernelized expectation-maximization (KEM) algorithm has been developed and demonstrated to be effective and easy to implement. A common approach for a further improvement of the kernel method would be adding an explicit regularization, which however leads to a complex optimization problem. In this paper, we propose an implicit regularization for the kernel method by using a deep coefficient prior, which represents the kernel coefficient image in the PET forward model using a convolutional neural-network. To solve the maximum-likelihood neural network-based reconstruction problem, we apply the principle of optimization transfer to derive a neural KEM algorithm. Each iteration of the algorithm consists of two separate steps: a KEM step for image update from the projection data and a deep-learning step in the image domain for updating the kernel coefficient image using the neural network. This optimization algorithm is guaranteed to monotonically increase the data likelihood. The results from computer simulations and real patient data have demonstrated that the neural KEM can outperform existing KEM and deep image prior methods.

Colorectal cancer (CRC) is a heterogeneous and complex disease with limited treatment options. Targeting transforming growth factor β (TGF-β) and programmed death ligand 1 pathways may enhance antitumor efficacy. Bintrafusp alfa is a first-in-class bifunctional fusion protein composed of the extracellular domain of TGF-β receptor II (a TGF-β "trap") fused to a human IgG1 monoclonal antibody blocking programmed cell death ligand 1. We report results from an expansion cohort of a phase I study (NCT02517398) in patients with heavily pretreated advanced CRC treated with bintrafusp alfa. As of May 15, 2020, 32 patients with advanced CRC had received bintrafusp alfa for a median duration of 7.1 weeks. The objective response rate was 3.1% and the disease control rate was 6.3% (1 partial response, 1 stable disease); 2 patients were not evaluable. The safety profile was consistent with previously reported data.

PurposeAurora Kinase A (AKA) inhibition with gemcitabine represents a potentially synergistic cancer treatment strategy via mitotic catastrophe. The feasibility, safety, and preliminary efficacy of alisertib (MLN8237), an oral AKA inhibitor, with gemcitabine was evaluated in this open-label phase I trial with dose escalation and expansion.MethodsKey inclusion criteria included advanced solid tumor with any number of prior chemotherapy regimens in the dose escalation phase, and advanced pancreatic adenocarcinoma with up to two prior chemotherapy regimens. Four dose levels (DLs 1-4) of alisertib (20, 30, 40, or 50 mg) were evaluated in 3 + 3 design with gemcitabine 1000 mg/m2 on days 1, 8, and 15 in 28-day cycles.ResultsIn total, 21 subjects were treated in dose escalation and 5 subjects were treated in dose expansion at DL4. Dose-limiting toxicities were observed in 1 of 6 subjects each in DL3 and DL4. All subjects experienced treatment-related adverse events. Grade ≥ 3 treatment-related adverse events were observed in 73% of subjects, with neutropenia observed in 54%. Out of 22 subjects evaluable for response, 2 subjects (9%) had partial response and 14 subjects (64%) had stable disease. Median PFS was 4.1 months (95% CI 2.1-4.5). No significant changes in pharmacokinetic parameters for gemcitabine or its metabolite dFdU were observed with alisertib co-administration.ConclusionsThis trial established the recommended phase 2 dose of alisertib 50 mg to be combined with gemcitabine. Gemcitabine and alisertib are a feasible strategy with potential for disease control in multiple heavily pre-treated tumors, though gastrointestinal and hematologic toxicity was apparent.

TAS-102 is approved for treatment of refractory metastatic gastroesophageal carcinoma (mGEC). This study sought to determine whether the combination of TAS-102 with irinotecan (TASIRI) was safe and effective in previously treated mGEC. This was a single-arm phase 1b study for patients (pts) with mGEC previously treated with at least one line of fluoropyrimidine and platinum-containing regimen. TAS-102 was given at 25 mg/m2 twice daily on days 1 to 5 with irinotecan 180 mg/m2 on day 1 of a 14-day cycle. The primary endpoint was progression-free survival at 6 months ≥ 35% (PFS-6). 20 Pts were enrolled. The study met its primary endpoint. PFS-6 is 40% (95% CI 19.3-60.0). Median PFS and overall survival are 5.3 months and not reached, respectively. 17 of 20 pts had measurable disease by RECIST criteria. Of the 17, 13 had stable disease and 4 had progressive disease as best response (8 pts had tumor shrinkage  5% of pts were anemia (20%) and neutropenia (10%). 2 serious TRAE were reported: G4 febrile neutropenia (n = 1) and G3 hypotension (n = 1). There was no G5 TRAE. The combination of TASIRI showed encouraging clinical activity with a meaningful improvement in PFS-6 compared to historic controls.

To date, driver genes for pancreatic cancer treatment are difficult to pursue therapeutically. Targeting mutated KRAS, the most renowned driver gene in pancreatic cancer, is an active area of study. We discovered a gene named SEMA3C was highly expressed in pancreatic cancer cell lines and patients with a G12D mutation in KRAS. High expression of SEMA3C in patients was significantly associated with the decreased survival of pancreatic cancer patients based on the TCGA database. In pancreatic cancer cells, SEMA3C knockdown or inhibition exhibited growth/colony inhibition and cell cycle arrest. In addition, SEMA3C inhibition sensitized KRAS or MEK1/2 inhibition in pancreatic cancer cells. Overexpression of SEMA3C resulted in the induction of autophagy, whereas depletion of SEMA3C compromised induction of autophagy. SEMA3C modified the PD-L1 expression in tumor and immune cells and is correlated with the M2-like macrophage marker ARG1/CD163 expression, which could reshape the tumor microenvironment. Inhibition of SEMA3C decreased tumor formation in the xenograft model in vivo. Taken together, our data suggest that SEMA3C plays a substantial role in promoting cancer cell survival by regulating the autophagy process and impacting the tumor environment immune response. SEMA3C can be used as a novel target or marker with therapeutic or diagnostic potential in pancreatic cancer especially in tumors harboring the specific KRAS G12D mutation.

BACKGROUNDMEK inhibitors have limited activity in biliary tract cancers (BTCs) as monotherapy but are hypothesized to enhance responses to programmed death ligand 1 (PD-L1) inhibition.METHODSThis open-label phase II study randomized patients with BTC to atezolizumab (anti-PD-L1) as monotherapy or in combination with cobimetinib (MEK inhibitor). Eligible patients had unresectable BTC with 1 to 2 lines of prior therapy in the metastatic setting, measurable disease, and Eastern Cooperative Oncology Group (ECOG) performance status less than or equal to 1. The primary endpoint was progression-free survival (PFS).RESULTSSeventy-seven patients were randomized and received study therapy. The trial met its primary endpoint, with a median PFS of 3.65 months in the combination arm versus 1.87 months in the monotherapy arm (HR 0.58, 90% CI 0.35-0.93, 1-tail P = 0.027). One patient in the combination arm (3.3%) and 1 patient in the monotherapy arm (2.8%) had a partial response. Combination therapy was associated with more rash, gastrointestinal events, CPK elevations, and thrombocytopenia. Exploratory analysis of tumor biopsies revealed enhanced expression of antigen processing and presentation genes and an increase in CD8/FoxP3 ratios with combination treatment. Patients with higher baseline or lower fold changes in expression of certain inhibitory ligands (LAG3, BTLA, VISTA) on circulating T cells had evidence of greater clinical benefit from the combination.CONCLUSIONThe combination of atezolizumab plus cobimetinib prolonged PFS as compared with atezolizumab monotherapy, but the low response rate in both arms highlights the immune-resistant nature of BTCs.TRIAL REGISTRATIONClinicalTrials.gov NCT03201458.FUNDINGNational Cancer Institute (NCI) Experimental Therapeutics Clinical Trials Network (ETCTN); F. Hoffmann-La Roche, Ltd.; NCI, NIH (R01 CA228414-01 and UM1CA186691); NCI's Specialized Program of Research Excellence (SPORE) in Gastrointestinal Cancers (P50 CA062924); NIH Center Core Grant (P30 CA006973); and the Passano Foundation.

PurposeAurora kinases are overexpressed or amplified in numerous malignancies. This study was designed to determine the safety and tolerability of the Aurora A kinase inhibitor alisertib (MLN8237) when combined with weekly irinotecan.MethodsIn this single-center phase 1 study, adult patients with refractory advanced solid tumors received 100 mg/m2 irinotecan intravenously on day 1 and 8 of a 21-day cycle. Alisertib at planned escalating dose levels of 20-60 mg was administered orally twice per day on days 1-3 and 8-10. Patients homozygous for UGT1A1*28 were excluded. The primary objective was the safety of alisertib when combined with irinotecan to determine the maximum tolerated dose (MTD). Secondary objectives included overall response rate by RECIST and pharmacokinetics in a planned expansion cohort of patients with colorectal cancer treated at the MTD.ResultsA total of 17 patients enrolled at three dose levels. Dose-limiting toxicities included diarrhea, dehydration, and neutropenia. The MTD of alisertib combined with weekly irinotecan was 20 mg twice per day on days 1-3 and 8-10. One fatal cardiac arrest at the highest dose level tested was deemed possibly related to drug treatment. One partial response in 11 efficacy evaluable patients (9%) occurred in a patient with small cell lung cancer. The study was terminated prior to the planned expansion in patients with colorectal cancer.ConclusionIn contrast to prior results in a pediatric population, adult patients did not tolerate alisertib combined with irinotecan at clinically meaningful doses due to hematologic and gastrointestinal toxicities. The study was registered with ClinicalTrials.gov under study number NCT01923337 on Aug 15, 2013.

Background Preclinical evidence has suggested that a subset of pancreatic cancers with the G12R mutational isoform of the KRAS oncogene is more sensitive to MAPK pathway blockade than pancreatic tumors with other KRAS isoforms. We conducted a biomarker-driven trial of selumetinib (KOSELUGO™; ARRY-142886), an orally active, allosteric mitogen-activated protein kinase 1 and 2 (MEK1/2) inhibitor, in pancreas cancer patients with somatic KRASG12R mutations. Methods In this two-stage, phase II study (NCT03040986) patients with advanced pancreas cancer harboring somatic KRASG12R variants who had received at least one standard-of-care systemic therapy regimen received 75 mg selumetinib orally twice a day until disease progression or unacceptable toxicity occurred. The primary outcome of the study was best objective response (BOR). Results From August 2017 to February 2018 a total of 8 patients with confirmed somatic KRASG12R mutations and a median age of 61.5 years were treated with selumetinib. Seven out of eight (87.5%) had received two or more lines of prior systemic chemotherapy. After a median follow-up period of 8.5 months (range 2 to 20), three patients had stable disease for more than 6 months while receiving selumetinib. No patients achieved an objective partial response. Median progression-free survival (PFS) was 3.0 months (95% CI, 0.8-8.2) and median overall survival (OS) 9 months (95% CI, 2.5-20.9). Conclusion This study in heavily pre-treated pancreatic adenocarcinoma patients suggests alternative strategies beyond single agent MEK inhibition are required for this unique, molecular subset of pancreatic cancer patients. The trial was registered on February 2nd, 2017 under identifier NCT03040986 with ClinicalTrials.gov .

Cancer cells are dysregulated and addicted to continuous supply and metabolism of nutritional glucose and amino acids (e.g., arginine) to drive the synthesis of critical macromolecules for uncontrolled growth. Recent studies have revealed that genome-derived microRNA (miRNA or miR)-1291-5p (miR-1291-5p or miR-1291) may modulate the expression of argininosuccinate synthase (ASS1) and glucose transporter protein type 1 (GLUT1). We also developed a novel approach to produce recombinant miR-1291 agents for research, which are distinguished from conventional chemo-engineered miRNA mimics. Herein, we firstly demonstrated that bioengineered miR-1291 agent was selectively processed to high levels of target miR-1291-5p in human pancreatic cancer (PC) cells. After the suppression of ASS1 protein levels, miR-1291 perturbed arginine homeostasis and preferably sensitized ASS1-abundant L3.3 cells to arginine deprivation therapy. In addition, miR-1291 treatment reduced the protein levels of GLUT1 in both AsPC-1 and PANC-1 cells, leading to a lower glucose uptake (deceased > 40%) and glycolysis capacity (reduced approximately 50%). As a result, miR-1291 largely improved cisplatin efficacy in the inhibition of PC cell viability. Our results demonstrated that miR-1291 was effective to sensitize PC cells to arginine deprivation treatment and chemotherapy through targeting ASS1- and GLUT1-mediated arginolysis and glycolysis, respectively, which may provide insights into understanding miRNA signaling underlying cancer cell metabolism and development of new strategies for the treatment of lethal PC. SIGNIFICANCE STATEMENT: Many anticancer drugs in clinical use and under investigation exert pharmacological effects or improve efficacy of coadministered medications by targeting cancer cell metabolism. Using new recombinant miR-1291 agent, we revealed that miR-1291 acts as a metabolism modulator in pancreatic carcinoma cells through the regulation of argininosuccinate synthase- and glucose transporter protein type 1-mediated arginolysis and glycolysis. Consequently, miR-1291 effectively enhanced the efficacy of arginine deprivation (pegylated arginine deiminase) and chemotherapy (cisplatin), offering new insights into development of rational combination therapies.

BackgroundThe rationale for the evaluation of trametinib in advanced biliary cancer (BC) is based on the presence of mitogen-activated protein kinase alterations and on earlier promising results with MEK inhibitors in BC.MethodsPatients with histologically proven BC who progressed on gemcitabine/platinum were randomised to trametinib daily (arm 1) versus fluoropyrimidine therapy (infusional 5-fluorouracil or oral capecitabine, arm 2). The primary end-point was overall survival (OS). Secondary end-points included progression free survival (PFS) and response rate. A planned interim futility analysis of objective response was performed on the first 14 patients registered to the trametinib arm.ResultsThe study was stopped early based on the lack of measurable response in the trametinib arm. A total of 44 eligible patients were randomised (24 patients in arm 1 and 20 patients in arm 2). Median age was 62 years and the primary sites of tumour were cholangiocarcinoma (68%) and gallbladder (32%). The overall response rate was 8% (95% CI 0%-19%) in arm 1 versus 10% (95% CI 0%-23%) in arm 2 (p > .99) Median OS was 4.3 months for arm 1 and 6.6 months for arm 2. The median PFS was 1.4 months for arm 1 and 3.3 months for arm 2.ConclusionsThis is the first prospective randomised study of a targeted agent versus chemotherapy for the second-line treatment of BC. In this unselected population, the interim analysis result of unlikely benefit with trametinib resulted in early closure.

FOLFOX is one of the most effective treatments for advanced colorectal cancer. However, cumulative oxaliplatin neurotoxicity often results in halting the therapy. Oxaliplatin functions predominantly via the formation of toxic covalent drug-DNA adducts. We hypothesize that oxaliplatin-DNA adduct levels formed in vivo in peripheral blood mononuclear cells (PBMC) are proportional to tumor shrinkage caused by FOLFOX therapy. We further hypothesize that adducts induced by subtherapeutic "diagnostic microdoses" are proportional to those induced by therapeutic doses and are also predictive of response to FOLFOX therapy. These hypotheses were tested in colorectal cancer cell lines and a pilot clinical study. Four colorectal cancer cell lines were cultured with therapeutically relevant (100 μmol/L) or diagnostic microdose (1 μmol/L) concentrations of [14C]oxaliplatin. The C-14 label enabled quantification of oxaliplatin-DNA adduct level with accelerator mass spectrometry (AMS). Oxaliplatin-DNA adduct formation was correlated with oxaliplatin cytotoxicity for each cell line as measured by the MTT viability assay. Six colorectal cancer patients received by intravenous route a diagnostic microdose containing [14C]oxaliplatin prior to treatment, as well as a second [14C]oxaliplatin dose during FOLFOX chemotherapy, termed a "therapeutic dose." Oxaliplatin-DNA adduct levels from PBMC correlated significantly to mean tumor volume change of evaluable target lesions (5 of the 6 patients had measurable disease). Oxaliplatin-DNA adduct levels were linearly proportional between microdose and therapeutically relevant concentrations in cell culture experiments and patient samples, as was plasma pharmacokinetics, indicating potential utility of diagnostic microdosing.

Accurate snow depth observations are critical to assess water resources. More than a billion people rely on water from snow, most of which originates in the Northern Hemisphere mountain ranges. Yet, remote sensing observations of mountain snow depth are still lacking at the large scale. Here, we show the ability of Sentinel-1 to map snow depth in the Northern Hemisphere mountains at 1 km² resolution using an empirical change detection approach. An evaluation with measurements from ~4000 sites and reanalysis data demonstrates that the Sentinel-1 retrievals capture the spatial variability between and within mountain ranges, as well as their inter-annual differences. This is showcased with the contrasting snow depths between 2017 and 2018 in the US Sierra Nevada and European Alps. With Sentinel-1 continuity ensured until 2030 and likely beyond, these findings lay a foundation for quantifying the long-term vulnerability of mountain snow-water resources to climate change.

The BCL-2 family of proteins, including anti-apoptotic members BCL-2, BCL-XL and MCL-1, are part of a complex network that controls apoptosis. BH3-mimetics such as ABT-263 inhibit anti-apoptotic BCL-2 proteins and have been developed as potential cancer therapeutics. Aurora Kinase A (AKA) is over-expressed in pancreatic cancer (PC) and controls G2-M transition during mitosis and AKA inhibitors have been developed that induce mitotic arrest. We hypothesized that mitotic arrest induced by AKA inhibition may sensitize PC to accelerated apoptosis by a BH3-mimetic. Our results demonstrated that ABT-263 plus MLN8237 treatment showed greater activity than either single drug alone, as well as strong synergism, in the inhibition of growth of pancreatic cell lines (AsPC-1, PANC-1, MIA PaCa-2, HPAF-II) and PC patient-derived organoids (PDOs). The higher efficacy of combination treatment was attributable to the higher levels of induction of apoptosis and reduction of MCL-1 in PC cells and PDOs. In addition, combination therapy was more effective than single drug in the suppression of tumor growth in AsPC-1 xenograft mouse models. Together, our findings suggest that combination therapy with ABT-263 and MLN8237 should be considered for further exploration as a novel treatment of deadly PC disease.

PurposeThe study was undertaken to develop and evaluate the potential of an integrin αvβ6-binding peptide (αvβ6-BP) for noninvasive imaging of a diverse range of malignancies with PET.Experimental designThe peptide αvβ6-BP was prepared on solid phase and radiolabeled with 4-[18F]fluorobenzoic acid. In vitro testing included ELISA, serum stability, and cell binding studies using paired αvβ6-expressing and αvβ6-null cell lines. In vivo evaluation (PET/CT, biodistribution, and autoradiography) was performed in a mouse model bearing the same paired αvβ6-expressing and αvβ6-null cell xenografts. A first-in-human PET/CT imaging study was performed in patients with metastatic lung, colon, breast, or pancreatic cancer.Results[18F]αvβ6-BP displayed excellent affinity and selectivity for the integrin αvβ6 in vitro [IC50(αvβ6) = 1.2 nmol/L vs IC50(αvβ3) >10 μmol/L] in addition to rapid target-specific cell binding and internalization (72.5% ± 0.9% binding and 52.5% ± 1.8%, respectively). Favorable tumor affinity and selectivity were retained in the mouse model and excretion of unbound [18F]αvβ6-BP was rapid, primarily via the kidneys. In patients, [18F]αvβ6-BP was well tolerated without noticeable adverse side effects. PET images showed significant uptake of [18F]αvβ6-BP in both the primary lesion and metastases, including metastasis to brain, bone, liver, and lung.ConclusionsThe clinical impact of [18F]αvβ6-BP PET imaging demonstrated in this first-in-human study is immediate for a broad spectrum of malignancies.

Our recent studies have revealed that microRNA-1291 (miR-1291) is downregulated in pancreatic cancer (PC) specimens and restoration of miR-1291 inhibits tumorigenesis of PC cells. This study is to assess the efficacy and underlying mechanism of our bioengineered miR-1291 prodrug monotherapy and combined treatment with chemotherapy. AT-rich interacting domain protein 3B (ARID3B) was verified as a new target for miR-1291, and miR-1291 prodrug was processed to mature miR-1291 in PC cells which surprisingly upregulated ARID3B mRNA and protein levels. Co-administration of miR-1291 with gemcitabine plus nab-paclitaxel (Gem-nP) largely increased the levels of apoptosis, DNA damage and mitotic arrest in PC cells, compared to mono-drug treatment. Consequently, miR-1291 prodrug improved cell sensitivity to Gem-nP. Furthermore, systemic administration of in vivo-jetPEI-formulated miR-1291 prodrug suppressed tumor growth in both PANC-1 xenograft and PC patients derived xenograft (PDX) mouse models to comparable degrees as Gem-nP alone, while combination treatment reduced tumor growth more ubiquitously and to the greatest degrees (70-90%), compared to monotherapy. All treatments were well tolerated in mice. In conclusion, biologic miR-1291 prodrug has therapeutic potential as a monotherapy for PC, and a sensitizing agent to chemotherapy.

ObjectivesCombinations of gemcitabine, 5-fluorouracil (5-FU), and platinum have demonstrated improved outcomes compared with singlet chemotherapy in pancreatic and biliary cancers. This phase II study examined efficacy and safety of a novel schedule of cisplatin, fixed-dose-rate gemcitabine and infusional 5-FU.Materials and methodsPatients with metastatic adenocarcinoma of the pancreas or biliary tract, previously untreated or having received 1 cytotoxic regimen for advanced disease, were treated with gemcitabine 1000 mg/m intravenously (IV) over 100 minutes, cisplatin 35 mg/m IV over 30 minutes, and 5-FU 2400 mg/m IV over 48 hours on day 1 of a 14-day cycle. Patients were treated until disease progression or for 12 cycles. After 12 cycles, patients with stable or responding disease could continue gemcitabine and 5-FU. The primary endpoint was objective response.ResultsThirty-nine patients were treated: 8 with biliary cancer (all untreated) and 31 with pancreatic cancer (17 untreated, 14 previously treated). Best response in 25 untreated patients was partial response in 40%, stable disease in 40%, and progressive disease in 20%. In 14 previously treated pancreatic patients, best response was partial response in 7%, stable disease in 50%, and progressive disease in 43%. Median overall survival in untreated patients was 10.3 versus 4.9 months in previously treated patients. Adverse events were primarily uncomplicated hematologic toxicity, ≥grade 3 neutropenia (54%), anemia (21%), and thrombocytopenia (13%).ConclusionBiweekly cisplatin, fixed-dose-rate gemcitabine, and infusional 5-FU demonstrated a high response rate and were well tolerated, encouraging further investigation of this regimen in metastatic pancreatic and biliary cancers.

Pancreatic ductal adenocarcinoma (PDA) is one of the most lethal human malignancies, owing in part to its propensity for metastasis. Here, we used an organoid culture system to investigate how transcription and the enhancer landscape become altered during discrete stages of disease progression in a PDA mouse model. This approach revealed that the metastatic transition is accompanied by massive and recurrent alterations in enhancer activity. We implicate the pioneer factor FOXA1 as a driver of enhancer activation in this system, a mechanism that renders PDA cells more invasive and less anchorage-dependent for growth in vitro, as well as more metastatic in vivo. In this context, FOXA1-dependent enhancer reprogramming activates a transcriptional program of embryonic foregut endoderm. Collectively, our study implicates enhancer reprogramming, FOXA1 upregulation, and a retrograde developmental transition in PDA metastasis.

Background Cabozantinib and gemcitabine improve tumor control in pancreatic ductal adenocarcinoma (PDAC) in preclinical models through c-Met inhibition. We sought to determine the maximum tolerated dose (MTD) of this combination in patients with advanced PDAC. Methods Patients with ≤1 prior treatment and adequate performance status were eligible. Cabozantinib was given orally once daily, beginning day (-)7 and continued with gemcitabine given intravenously on days 1, 8, and 15 every 28 days. Dose level was assigned using Time to Event Continual Reassessment Method (TITE-CRM). Primary endpoint was MTD, defined as the highest dose level at which ≤25 % of patients incurred a dose-limiting toxicity (DLT). Secondary endpoints included response rate, progression-free survival (PFS), overall survival (OS) and urinary biomarker assessment. Results Twelve patients were enrolled and treated with 10 patients evaluable for DLT. The probability of DLT was >25 % for all dose levels tested, and thus an MTD was not determined. DLTs included grade 3 ALT/AST elevations and thrombocytopenia. Three patients had partial responses, but each discontinued therapy due to toxicity. Median PFS and OS were 4.7 (95 % CI: 1.4-9.7) and 10.1 months (95 % CI: 3.6-20.6). Exploratory biomarker analysis showed correlation of c-Met and VEGF levels with response. Conclusions An MTD for the combination was not established. Cabozantinib and gemcitabine appear impractical for further development due to DLT at low doses and continuing toxicities with ongoing therapy. Acknowledging the small sample size, responses were seen suggesting further investigation of c-Met inhibition in PDAC may be warranted.

Pancreatic cancer is the fourth leading cause of cancer death in the United States. Better understanding of pancreatic cancer biology may help identify new oncotargets towards more effective therapies. This study investigated the mechanistic actions of microRNA-1291 (miR-1291) in the suppression of pancreatic tumorigenesis. Our data showed that miR-1291 was downregulated in a set of clinical pancreatic carcinoma specimens and human pancreatic cancer cell lines. Restoration of miR-1291 expression inhibited pancreatic cancer cell proliferation, which was associated with cell cycle arrest and enhanced apoptosis. Furthermore, miR-1291 sharply suppressed the tumorigenicity of PANC-1 cells in mouse models. A proteomic profiling study revealed 32 proteins altered over 2-fold in miR-1291-expressing PANC-1 cells that could be assembled into multiple critical pathways for cancer. Among them anterior gradient 2 (AGR2) was reduced to the greatest degree. Through computational and experimental studies we further identified that forkhead box protein A2 (FOXA2), a transcription factor governing AGR2 expression, was a direct target of miR-1291. These results connect miR-1291 to the FOXA2-AGR2 regulatory pathway in the suppression of pancreatic cancer cell proliferation and tumorigenesis, providing new insight into the development of miRNA-based therapy to combat pancreatic cancer.

Colorectal cancer (CRC) is a leading cause of cancer death in the United States. In recent years, therapeutic advances have prolonged the survival of patients with advanced disease. Along with the addition of new treatments, an increasing body of literature explores the potential benefit of using molecular testing to define tumor, circulating, or host biomarkers of benefit to specific treatment strategies. At present, testing for specific mutations in exons 2, 3, and 4 of KRAS and NRAS has become accepted practice to select patients for treatment with epidermal growth factor receptor (EGFR)-targeted agents. Additionally, testing for the BRAF V600E mutation is used to refine decisions based on patient prognosis. The presence of the uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) *28 polymorphism is associated with toxicity from irinotecan, although it has not been universally applied. Nonetheless, molecular markers to predict response and toxicity of cytotoxic therapy are evolving. While the development of selection biomarkers for anti-angiogenic treatments has not proved fruitful to date, improved development strategies and novel targeted agents are anticipated to revolutionize the approach to treatment of advanced CRC in the near future. This review summarizes currently available data to select treatment strategies in patients with advanced CRC.

IntroductionDespite some recent advances in treatment options, pancreatic cancer remains a devastating disease with poor outcomes. In a trend contrary to most malignancies, both incidence and mortality continue to rise due to pancreatic cancer. The majority of patients present with advanced disease and there are no treatment options for this stage that have demonstrated a median survival > 1 year. As the penultimate step prior to Phase III studies involving hundreds of patients, Phase II clinical trials provide an early opportunity to evaluate the efficacy of new treatments that are desperately needed for this disease.Areas coveredThis review covers the results of published Phase II clinical trials in advanced pancreatic adenocarcinoma published within the past 5 years. The treatment results are framed in the context of the current standards of care and the historic challenge of predicting Phase III success from Phase II trial results.Expert opinionPromising therapies remain elusive in pancreatic cancer based on recent Phase II clinical trial results. Optimization and standardization of clinical trial design in the Phase II setting, with consistent incorporation of biomarkers, is needed to more accurately identify promising therapies that warrant Phase III evaluation.

PurposeErlotinib marginally improves survival when administered continuously with gemcitabine to patients with advanced pancreatic cancer; however, preclinical data suggest that there is antagonism between chemotherapy and epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors when these are delivered concurrently. We tested a pharmacodynamic separation approach for erlotinib plus gemcitabine and interrogated EGFR signaling intermediates as potential surrogates for the efficacy of this strategy.MethodsPatients with measurable, previously untreated locally advanced unresectable or metastatic pancreatic cancer were treated with gemcitabine 1000 mg/m(2) as an intravenous infusion over 30-min on days 1, 8, 15 and erlotinib 150 mg/day on days 2-5, 9-12, 16-26 of each 28-day cycle. The primary endpoint was progression-free survival (PFS); secondary endpoints included RECIST objective response rate (ORR) and safety. The study was terminated after thirty patients due to funding considerations.ResultsThe median PFS was 2.07 months (95% CI; 1.87-5.50 months) and the ORR was 11%. No unexpected safety signals were seen: the most common grade 3 or higher adverse events were neutropenia (23%), lymphopenia (23%), and fatigue (13%). Patients with mutant plasma Kirsten rat sarcoma virus (KRAS) had significantly lower median PFS (1.8 vs. 4.6 months, p = 0.014) and overall survival (3.0 vs. 10.5 months, p = 0.003) than those without detected plasma KRAS mutations.ConclusionsAlthough pharmacodynamically separated erlotinib and gemcitabine were feasible and tolerable in patients with advanced pancreatic cancer, no signal for increased efficacy was seen in this molecularly unselected cohort. Detection of a KRAS mutation in circulating cell-free DNA was a strong predictor of survival.

This article examines how Chinese citizens perceived the relationship between wealth and achievement among their former middle school classmates. It draws on a survey of 503 respondents in their late twenties and early thirties (who have been followed since 1999, when they were eighth or ninth graders in Dalian City, China) and on interviews with 60 of them. Most believed their former classmates from "poorer" families "studied better" than those from "wealthier" families. Interviewees elaborated that wealthier classmates were more likely than poorer classmates to lack motivation, have poor study habits, and be distracted by material pursuits. Interviewees also suggested that parental involvement was a key factor in shaping achievement, with more involved and educated "poorer" parents' children doing better than children of "wealthier" business-owner parents who were too busy to get involved in their children's education. Among these young adults, associations between wealth and achievement differ from those documented in Western societies.

PurposeThe hedgehog (HH) signaling pathway is a key regulator in tumorigenesis of pancreatic adenocarcinoma and is upregulated in pancreatic adenocarcinoma cancer stem cells (CSCs). GDC-0449 is an oral small-molecule inhibitor of the HH pathway. This study assessed the effect of GDC-0449-mediated HH inhibition in paired biopsies, followed by combined treatment with gemcitabine, in patients with metastatic pancreatic adenocarcinoma.Experimental designTwenty-five patients were enrolled of which 23 underwent core biopsies at baseline and following 3 weeks of GDC-0449. On day 29, 23 patients started weekly gemcitabine while continuing GDC-0449. We evaluated GLI1 and PTCH1 inhibition, change in CSCs, Ki-67, fibrosis, and assessed tumor response, survival and toxicity.ResultsOn pretreatment biopsy, 75% of patients had elevated sonic hedgehog (SHH) expression. On posttreatment biopsy, GLI1 and PTCH1 decreased in 95.6% and 82.6% of 23 patients, fibrosis decreased in 45.4% of 22, and Ki-67 in 52.9% of 17 evaluable patients. No significant changes were detected in CSCs pre- and postbiopsy. The median progression-free and overall survival for all treated patients were 2.8 and 5.3 months. The response and disease control rate was 21.7% and 65.2%. No significant correlation was noted between CSCs, fibrosis, SHH, Ki-67, GLI1, PTCH1 (baseline values or relative change on posttreatment biopsy), and survival. Grade ≥ 3 adverse events were noted in 56% of patients.ConclusionWe show that GDC-0449 for 3 weeks leads to downmodulation of GLI1 and PTCH1, without significant changes in CSCs compared with baseline. GDC-0449 and gemcitabine were not superior to gemcitabine alone in the treatment of metastatic pancreatic cancer.

BackgroundPancreatic cancer stem cells (CSCs) represent a small subpopulation of pancreatic cancer cells that have the capacity to initiate and propagate tumor formation. However, the mechanisms by which pancreatic CSCs are maintained are not well understood or characterized.MethodsExpression of Notch receptors, ligands, and Notch signaling target genes was quantitated in the CSC and non-CSC populations from 8 primary human pancreatic xenografts. A gamma secretase inhibitor (GSI) that inhibits the Notch pathway and a shRNA targeting the Notch target gene Hes1 were used to assess the role of the Notch pathway in CSC population maintenance and pancreatic tumor growth.ResultsNotch pathway components were found to be upregulated in pancreatic CSCs. Inhibition of the Notch pathway using either a gamma secretase inhibitor or Hes1 shRNA in pancreatic cancer cells reduced the percentage of CSCs and tumorsphere formation. Conversely, activation of the Notch pathway with an exogenous Notch peptide ligand increased the percentage of CSCs as well as tumorsphere formation. In vivo treatment of orthotopic pancreatic tumors in NOD/SCID mice with GSI blocked tumor growth and reduced the CSC population.ConclusionThe Notch signaling pathway is important in maintaining the pancreatic CSC population and is a potential therapeutic target in pancreatic cancer.

Pancreatic neuroendocrine tumors (PNETs) are relatively rare tumors that arise in the endocrine cells of the pancreas. Historically, somatostatin analogues have been used in this disease primarily for symptom control and, to a limited extent, disease stability. More recently, sunitinib and everolimus have been approved for advanced stage PNETs based on a survival benefit. However, both agents have a

Measurements of radar backscatter are sensitive to snow water equivalent (SWE) across a wide range of frequencies, motivating proposals for satellite missions to measure global distributions of SWE. However, radar backscatter measurements are also sensitive to snow stratigraphy, to microstructure, and to ground surface roughness, complicating SWE retrieval. A number of recent advances have created new tools and datasets with which to address the retrieval problem, including a parameterized relationship between SWE, microstructure, and radar backscatter, and methods to characterize ground surface scattering. Although many algorithms also introduce external (prior) information on SWE or snow microstructure, the precision of the prior datasets used must be high in some cases in order to achieve accurate SWE retrieval. We hypothesize that a time series of radar measurements can be used to solve this problem and demonstrate that SWE retrieval with acceptable error characteristics is achievable by using previous retrievals as priors for subsequent retrievals. We demonstrate the accuracy of three configurations of prior information: using a global SWE model, using the previously retrieved SWE, and using a weighted average of the model and the previous retrieval. We assess the robustness of the approach by quantifying the sensitivity of the SWE retrieval accuracy to SWE biases artificially introduced in the prior. We find that the retrieval with the weighted averaged prior demonstrates SWE accuracy better than 20 % and an error increase of only 3 % relative RMSE per 10 % change in prior bias; the algorithm is thus both accurate and robust. This finding strengthens the case for future radar-based satellite missions to map SWE globally. [ABSTRACT FROM AUTHOR]