Combined MEK and STAT3 Inhibition Uncovers Stromal Plasticity by Enriching for Cancer-Associated Fibroblasts With Mesenchymal Stem Cell-Like Features to Overcome Immunotherapy Resistance in Pancreatic Cancer.

BACKGROUND & AIMS: We have shown that reciprocally activated rat sarcoma (RAS)/mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK) and Janus kinase/signal transducer and activator of transcription 3 (STAT3) pathways mediate therapeutic resistance in pancreatic ductal adenocarcinoma (PDAC), while combined MEK and STAT3 inhibition (MEKi+STAT3i) overcomes such resistance and alters stromal architecture. We now determine whether MEKi+STAT3i reprograms the cancer-associated fibroblast (CAF) and immune microenvironment to overcome resistance to immune checkpoint inhibition in PDAC. METHODS: CAF and immune cell transcriptomes in MEKi (trametinib)+STAT3i (ruxolitinib)-treated vs vehicle-treated Ptf1aCre/+;LSL-KrasG12D/+;Tgfbr2flox/flox (PKT) tumors were examined via single-cell RNA sequencing (scRNAseq). Clustered regularly interspaced short palindromic repeats/clustered regularly interspaced short palindromic repeats associated protein 9 silencing of CAF-restricted Map2k1/Mek1 or Stat3, or both, enabled interrogation of CAF-dependent effects on immunologic remodeling in orthotopic models. Tumor growth, survival, and immune profiling via mass cytometry by time-of-flight were examined in PKT mice treated with vehicle, anti-programmed cell death protein 1 (PD-1) monotherapy, and MEKi+STAT3i combined with anti-PD1. RESULTS: MEKi+STAT3i attenuates Il6/Cxcl1-expressing proinflammatory and Lrrc15-expressing myofibroblastic CAF phenotypes while enriching for Ly6a/Cd34-expressing CAFs exhibiting mesenchymal stem cell-like features via scRNAseq in PKT mice. This CAF plasticity is associated with M2-to-M1 reprogramming of tumor-associated macrophages, and enhanced trafficking of cluster of differentiation 8+ T cells, which exhibit distinct effector transcriptional programs. These MEKi+STAT3i-induced effects appear CAF-dependent, because CAF-restricted Mek1/Stat3 silencing mitigates inflammatory-CAF polarization and myeloid infiltration in vivo. Addition of MEKi+STAT3i to PD-1 blockade not only dramatically improves antitumor responses and survival in PKT mice but also augments recruitment of activated/memory T cells while improving their degranulating and cytotoxic capacity compared with anti-PD-1 monotherapy. Importantly, treatment of a patient who has chemotherapy-refractory metastatic PDAC with MEKi (trametinib), STAT3i (ruxolitinib), and PD-1 inhibitor (nivolumab) yielded clinical benefit. CONCLUSIONS: Combined MEKi+STAT3i mitigates stromal inflammation and enriches for CAF phenotypes with mesenchymal stem cell-like properties to overcome immunotherapy resistance in PDAC.

Urolithin A attenuates severity of chronic pancreatitis associated with continued alcohol intake by inhibiting PI3K/AKT/mTOR signaling.

Heavy alcohol consumption is the dominant risk factor for chronic pancreatitis (CP); however, treatment and prevention strategies for alcoholic chronic pancreatitis (ACP) remains limited. The present study demonstrates that ACP induction in C57BL/6 mice causes significant acinar cell injury, pancreatic stellate cell (PSC) activation, exocrine function insufficiency, and an increased fibroinflammatory response when compared with alcohol or CP alone. Although the withdrawal of alcohol during ACP recovery led to reversion of pancreatic damage, continued alcohol consumption with established ACP perpetuated pancreatic injury. In addition, phosphokinase array and Western blot analysis of ACP-induced mice pancreata revealed activation of the phosphatidylinositol 3 kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) and cyclic AMP response element binding protein (CREB) signaling pathways possibly orchestrating the fibroinflammatory program of ACP pathogenesis. Mice treated with urolithin A (Uro A, a gut-derived microbial metabolite) in the setting of ACP with continued alcohol intake (during the recovery period) showed suppression of AKT and P70S6K activation, and acinar damage was significantly reduced with a parallel reduction in pancreas-infiltrating macrophages and proinflammatory cytokine accumulation. These results collectively provide mechanistic insight into the impact of Uro A on attenuation of ACP severity through suppression of PI3K/AKT/mTOR signaling pathways and can be a useful therapeutic approach in patients with ACP with continuous alcohol intake.NEW & NOTEWORTHY Our novel findings presented here demonstrate the utility of Uro A as an effective therapeutic agent in attenuating alcoholic chronic pancreatitis (ACP) severity with alcohol continuation after established disease, through suppression of the PI3K/AKT/mTOR signaling pathway.

Nonaccidental Trauma Is an Independent Risk Factor for Mortality Among Injured Infants.

OBJECTIVES: The Centers for Disease Control disclosed over 600,000 cases of child abuse or neglect in 2016. Single-institution studies have shown that nonaccidental trauma (NAT) has higher complication rates than accidental trauma (AT). Nonaccidental trauma is disproportionately represented in infants. We hypothesized that NAT would increase the risk of mortality in infants. This study aims to provide a contemporary descriptive analysis for infant trauma patients and determine the association between NAT and mortality. METHODS: Infants (<1 year of age) within the Pediatric Trauma Quality Improvement Program database (2014-2016) were identified. Descriptive statistics (χ2 and t test) were used to compare NAT infants to AT infants. A multivariable logistic regression was used to determine the risk of mortality associated with select variables including NAT. RESULTS: From 14,965 infant traumas, most presented to a level I pediatric trauma center (53.5%) with a median injury severity score of 9. The most common mechanism was falls (48.6%), followed by NAT (14.5%). Overall mortality was 2.1%. Although most NAT infants were white (60.2%), black infants were overrepresented (23.6% vs 18.3%; P < 0.0001) compared with AT infants. The incidence of mortality was higher in NAT infants (41.6% vs 13.9%; P < 0.0001), and they were more likely to have traumatic brain injury (TBI) (63.1% vs 50.6%; P < 0.001). Nonaccidental trauma [odds ratio (OR), 2.48; P < 0.001], hypotension within 24 hours (OR, 8.93; P < 0.001), injury severity score (OR, 1.12; P < 0.001), and severe abbreviated injury scale-head (OR 1.62, P = 0.014) had the highest association with mortality. CONCLUSIONS: This study confirms the incidence of TBI and NAT in infants. Although providers should be vigilant for NAT, suspicion of NAT should prompt close surveillance, as there is a 2-fold increased risk of mortality independent of injury or TBI.

Minimally Invasive Surgery is Associated with an Increased Risk of Postoperative Venous Thromboembolism After Distal Pancreatectomy.

BACKGROUND: Venous thromboembolism (VTE) is a major cause of morbidity and mortality following distal pancreatectomy (DP). However, the influence of operative technique on VTE risk after DP is unknown. OBJECTIVE: The purpose of this study was to examine the association between the MIS technique versus the open technique and the development of postoperative VTE after DP. METHODS: Patients who underwent DP from 2014 to 2015 were identified in the American College of Surgeons National Surgical Quality Improvement Program pancreas-specific database. Multivariable logistic regression was then used to identify independent associations with the development of postoperative VTE after DP. RESULTS: A total of 3558 patients underwent DP during this time period. Of these cases, 47.8% (n = 1702) were performed via the MIS approach. After adjusting for significant covariates, the MIS approach was independently associated with the development of any VTE (odds ratio [OR] 1.60, 95% confidence interval [CI] 1.06-2.40; p = 0.025), as well as increasing the risk of developing a postdischarge VTE (OR 1.80, 95% CI 1.05-3.08; p = 0.033) when compared with the open approach. There was an association between VTE and the development of numerous postoperative complications, including pneumonia, unplanned intubation, need for prolonged mechanical ventilation, and cardiac arrest. CONCLUSION: Compared with the open approach, the MIS approach is associated with higher rates of postoperative VTE in patients undergoing DP. The majority of these events are diagnosed after hospital discharge.

Perioperative blood transfusion is associated with an increased risk for post-surgical infection following pancreaticoduodenectomy.

BACKGROUND/PURPOSE: Perioperative blood transfusion is common after pancreaticoduodenectomy (PD) and may predispose patients to infectious complications. The purpose of this study is to examine the association between perioperative blood transfusion and the development of post-surgical infection after PD. METHODS: Patients who underwent PD from 2014 to 2015 were identified in the NSQIP pancreas-specific database. Logistic regression analysis was used to compute adjusted odds ratios (aOR) to identify an independent association between perioperative red blood cell transfusion (within 72 h of surgery) and the development of post-operative infection after 72 h. RESULTS: A total of 6869 patients underwent PD during this time period. Of these, 1372 (20.0%) patients received a perioperative blood transfusion. Patients receiving transfusion had a higher rate of post-operative infection (34.7% vs 26.5%, p < 0.001). After adjusting for significant covariates, perioperative transfusion was independently associated the subsequent development of any post-operative infection (aOR 1.41 [1.23-1.62], p < 0.001), including pneumonia (aOR 2.01 [1.48-2.74], p < 0.001), sepsis (aOR 1.62 [1.29-2.04], p < 0.001), and septic shock (aOR 1.92 [1.38-2.68], p < 0.001). CONCLUSION: There is a strong independent association between perioperative blood transfusion and the development of subsequent post-operative infection following PD.

Long-term Quality of Life and Gastrointestinal Functional Outcomes After Pancreaticoduodenectomy.

OBJECTIVE: To perform a comprehensive assessment of long-term quality of life (QOL) and gastrointestinal (GI) function in patients following pancreaticoduodenectomy (PD). SUMMARY OF BACKGROUND DATA: Survival after PD has greatly improved and thus has resulted in a larger population of survivors, yet long-term QOL and GI function after PD is largely unknown. METHODS: Patients were identified from a global online support group. QOL was measured using the Short Form-36, while GI function was assessed using the Gastrointestinal Symptom Rating Scale. QOL and GI function were analyzed across subgroups based on time after PD. QOL was compared with preoperative measurements and with established values of a general healthy population (GHP). Multivariate linear regression was used to identify predictors of QOL. RESULTS: Of the 7605 members of the online support group, 1102 responded to the questionnaire with 927 responders meeting inclusion criteria. Seven hundred seventeen (77.3%) of these responders underwent PD for malignancy. Mean age was 57 ±â€Š12 years and 327 (35%) were male. At the time of survey, patients were 2.0 (0.7, 4.3) years out from surgery, with a maximum 30.7-year response following PD. Emotional and physical domains of QOL improved with time and surpassed preoperative levels between 6 months and 1 year after PD (both P < 0.001). Each GI symptom worsened over time (all P < 0.001). Independent predictors of general QOL in long-term survivors (> 5 years) included total GSRS score [ß = -1.70 (-1.91, -1.50)], female sex [ß = 3.58 (0.67, 6.46)], and being a cancer survivor [ß = 3.93 (0.60, 7.25)]. CONCLUSIONS: Long-term QOL following PD improves over time, however never approaches that of a GHP. GI dysfunction persists in long-term survivors and is an independent predictor of poor QOL. Long-term physical, psychosocial, and GI functional support after PD is encouraged.

Racial and ethnic disparities in the diagnosis of breast cancer: changes in presenting stage in minority populations in Florida during 1981-2009.

We assessed whether presenting breast cancer stage has changed over time in Florida, and whether there is variation in this change with respect to race, ethnicity, and socioeconomic status (SES). Data were obtained from the Florida Cancer Data System. We included females with invasive breast cancer and complete information on race, ethnicity, and SES during 1981-2009 (n = 226,651). Associations between categorical variables were examined using Chi-square tests. Predictors of SEER stage at diagnosis (local, regional, and distant) were modeled with multinomial ordinal logistic regression models. There was a significant increase in local disease and a decrease in regional and distant disease at presentation (p < 0.0001) over the time period assessed. Compared to whites, black patients continue to have lower odds of local presentation (OR 0.73, 95% CI 0.63, 0.85), as do Hispanic patients (OR 0.80, 95% CI 0.76, 0.84) compared to non-Hispanics. The increase in local stage at diagnosis was greater for black than white patients, as was the decrease in regional and distant disease (p < 0.001). Hispanic women also had significant increase in localized disease and decrease in regional and distant disease (p < 0.001), but there was little difference in the change compared to non-Hispanic women. Localized breast cancer stage at diagnosis has become more common over time in all groups. Significant disparity persists, with black and Hispanic patients being less likely to present with localized disease than white patients overall. There was a greater change for black versus white patients, resulting in a narrowing in the racial gap in stage at diagnosis.

Tumor Cell-Intrinsic p38 MAPK Signaling Promotes IL1α-Mediated Stromal Inflammation and Therapeutic Resistance in Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a KRAS-driven inflammatory program and a desmoplastic stroma, which contribute to the profoundly chemoresistant phenotype. The tumor stroma contains an abundance of cancer-associated fibroblasts (CAF), which engage in extensive paracrine cross-talk with tumor cells to perpetuate protumorigenic inflammation. IL1α, a pleiotropic, tumor cell-derived cytokine, plays a critical role in shaping the stromal landscape. To provide insights into the molecular mechanisms regulating IL1A expression in PDAC, we performed transcriptional profiling of The Cancer Genome Atlas datasets and pharmacologic screening in PDAC cells and identified p38α MAPK as a key positive regulator of IL1A expression. Both genetic and pharmacologic inhibition of p38 MAPK significantly diminished IL1α production in vitro. Chromatin- and coimmunoprecipitation analyses revealed that p38 MAPK coordinates the transcription factors Sp1 and the p65 subunit of NFκB to drive IL1A overexpression. Single-cell RNA sequencing of a highly desmoplastic murine PDAC model, Ptf1aCre/+; LSL-KrasG12D/+; Tgfbr2flox/flox (PKT), confirmed that p38 MAPK inhibition significantly decreases tumor cell-derived Il1a and attenuates the inflammatory CAF phenotype in a paracrine IL1α-dependent manner. Furthermore, p38 MAPK inhibition favorably modulated intratumoral immunosuppressive myeloid populations and augmented chemotherapeutic efficacy to substantially reduce tumor burden and improve overall survival in PKT mice. These findings illustrate a cellular mechanism of tumor cell-intrinsic p38-p65/Sp1-IL1α signaling that is responsible for sustaining stromal inflammation and CAF activation, offering an attractive therapeutic approach to enhance chemosensitivity in PDAC. SIGNIFICANCE: Inhibition of p38 MAPK suppresses tumor cell-derived IL1α and attenuates the inflammatory stroma and immunosuppressive tumor microenvironment to overcome chemotherapeutic resistance in pancreatic cancer.

CREB activation drives acinar to ductal reprogramming and promote pancreatic cancer progression in animal models of alcoholic chronic pancreatitis.

BACKGROUND AND AIMS: In vivo induction of alcoholic chronic pancreatitis (ACP) causes significant acinar damage, increased fibroinflammatory response, and heightened activation of cyclic response element binding protein 1 (CREB) when compared with alcohol (A) or chronic pancreatitis (CP) mediated pancreatic damage. However, the study elucidating the cooperative interaction between CREB and the oncogenic Kras G12D/+ (Kras*) in promoting pancreatic cancer progression with ACP remains unexplored. METHODS: Experimental ACP induction was established in multiple mouse models, followed by euthanization of the animals at various time intervals during the recovery periods. Tumor latency was determined in these mice cohorts. Here, we established CREB deletion (Creb fl/fl ) in Ptf1a CreERTM/+ ;LSL-Kras G12D+/-(KC) genetic mouse models (KCC-/-). Western blot, phosphokinase array, and qPCR were used to analyze the pancreata of Ptf1a CreERTM+/-, KC and KCC -/- mice. The pancreata of ACP-induced KC mice were subjected to single-cell RNA sequencing (scRNAseq). Further studies involved conducting lineage tracing and acinar cell explant cultures. RESULTS: ACP induction in KC mice had detrimental effects on the pancreatic damage repair mechanism. The persistent existence of acinar cell-derived ductal lesions demonstrated a prolonged state of hyperactivated CREB. Persistent CREB activation leads to acinar cell reprogramming and increased pro-fibrotic inflammation in KC mice. Acinar-specific Creb ablation reduced advanced PanINs lesions, hindered tumor progression, and restored acinar cell function in ACP-induced mouse models. CONCLUSIONS: Our findings demonstrate that CREB cooperates with Kras* to perpetuate an irreversible ADM and PanIN formation. Moreover, CREB sustains oncogenic activity to promote the progression of premalignant lesions toward cancer in the presence of ACP.

Remodeling of Stromal Immune Microenvironment by Urolithin A Improves Survival with Immune Checkpoint Blockade in Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) is a significant contributor to cancer-related morbidity and mortality, and it is known for its resistance to conventional treatment regimens, including chemotherapy and immune checkpoint blockade (ICB)-based therapies. We have previously shown that Urolithin A (Uro A), a gut microbial metabolite derived from pomegranates, can target and inhibit KRAS-dependent PI3K/AKT/mTOR signaling pathways to overcome therapeutic resistance and improve survival in PDAC. However, the effect of Uro A on the tumor immune microenvironment and its ability to enhance ICB efficacy has not been explored. This study demonstrates that Uro A treatment reduces stromal fibrosis and reinvigorates the adaptive T-cell immune response to overcome resistance to PD-1 blockade in a genetically engineered mouse model (GEMM) of PDAC. Flow cytometric-based analysis of Uro A-treated mouse tumors revealed a significant attenuation of immunosuppressive tumor-associated M2-like macrophages with a concurrent increase in the infiltration of CD4+ and CD8+ T cells with memory-like phenotype along with reduced expression of the exhaustion-associated protein, PD-1. Importantly, the combination of Uro A treatment with anti-PD-1 immunotherapy promoted enhancement of the antitumor response with increased infiltration of CD4+ Th1 cells, ultimately resulting in a remarkable improvement in overall survival in GEMM of PDAC. Overall, our findings provide preclinical evidence for the potential of Uro A as a novel therapeutic agent to increase sensitivity to immunotherapy in PDAC and warrant further mechanistic exploration in preclinical and clinical studies. Significance: Immunotherapeutic agents are ineffective against pancreatic cancer, mainly due to the immunosuppressive tumor microenvironment and stromal desmoplasia. Our current study demonstrates the therapeutic utility of a novel gut microbial metabolite, Uro A, to remodel the stromal-immune microenvironment and improve overall survival with anti-PD-1 therapy in pancreatic cancer.

Cell-Autonomous Cxcl1 Sustains Tolerogenic Circuitries and Stromal Inflammation via Neutrophil-Derived TNF in Pancreatic Cancer.

We have shown that KRAS-TP53 genomic coalteration is associated with immune-excluded microenvironments, chemoresistance, and poor survival in pancreatic ductal adenocarcinoma (PDAC) patients. By treating KRAS-TP53 cooperativity as a model for high-risk biology, we now identify cell-autonomous Cxcl1 as a key mediator of spatial T-cell restriction via interactions with CXCR2+ neutrophilic myeloid-derived suppressor cells in human PDAC using imaging mass cytometry. Silencing of cell-intrinsic Cxcl1 in LSL-KrasG12D/+;Trp53R172H/+;Pdx-1Cre/+(KPC) cells reprograms the trafficking and functional dynamics of neutrophils to overcome T-cell exclusion and controls tumor growth in a T cell-dependent manner. Mechanistically, neutrophil-derived TNF is a central regulator of this immunologic rewiring, instigating feed-forward Cxcl1 overproduction from tumor cells and cancer-associated fibroblasts (CAF), T-cell dysfunction, and inflammatory CAF polarization via transmembrane TNF-TNFR2 interactions. TNFR2 inhibition disrupts this circuitry and improves sensitivity to chemotherapy in vivo. Our results uncover cancer cell-neutrophil cross-talk in which context-dependent TNF signaling amplifies stromal inflammation and immune tolerance to promote therapeutic resistance in PDAC. SIGNIFICANCE: By decoding connections between high-risk tumor genotypes, cell-autonomous inflammatory programs, and myeloid-enriched/T cell-excluded contexts, we identify a novel role for neutrophil-derived TNF in sustaining immunosuppression and stromal inflammation in pancreatic tumor microenvironments. This work offers a conceptual framework by which targeting context-dependent TNF signaling may overcome hallmarks of chemoresistance in pancreatic cancer. This article is highlighted in the In This Issue feature, p. 1275.

Interleukin-1 signaling in solid organ malignancies.

As inflammation plays a critical role in the development and progression of cancer, therapeutic targeting of cytokine pathways involved in both tumorigenesis and dictating response to clinical treatments are of significant interest. Recent evidence has highlighted the importance of the pro-inflammatory cytokine interleukin-1 (IL-1) as a key mediator of tumor growth, metastatic disease spread, immunosuppression, and drug resistance in cancer. IL-1 promotes tumorigenesis through diverse mechanisms, including the activation of oncogenic signaling pathways directly in tumor cells and via orchestrating crosstalk between the cellular constituents of the tumor microenvironment (TME), thereby driving cancer growth. This review will provide an overview of IL-1 signaling and physiology and summarize the disparate mechanisms involving IL-1 in tumorigenesis and cancer progression. Additionally, clinical studies targeting IL-1 signaling in the management of solid organ tumors will be summarized herein.

Distinct mechanisms of innate and adaptive immune regulation underlie poor oncologic outcomes associated with KRAS-TP53 co-alteration in pancreatic cancer.

Co-occurrent KRAS and TP53 mutations define a majority of patients with pancreatic ductal adenocarcinoma (PDAC) and define its pro-metastatic proclivity. Here, we demonstrate that KRAS-TP53 co-alteration is associated with worse survival compared with either KRAS-alone or TP53-alone altered PDAC in 245 patients with metastatic disease treated at a tertiary referral cancer center, and validate this observation in two independent molecularly annotated datasets. Compared with non-TP53 mutated KRAS-altered tumors, KRAS-TP53 co-alteration engenders disproportionately innate immune-enriched and CD8+ T-cell-excluded immune signatures. Leveraging in silico, in vitro, and in vivo models of human and murine PDAC, we discover a novel intersection between KRAS-TP53 co-altered transcriptomes, TP63-defined squamous trans-differentiation, and myeloid-cell migration into the tumor microenvironment. Comparison of single-cell transcriptomes between KRAS-TP53 co-altered and KRAS-altered/TP53WT tumors revealed cancer cell-autonomous transcriptional programs that orchestrate innate immune trafficking and function. Moreover, we uncover granulocyte-derived inflammasome activation and TNF signaling as putative paracrine mediators of innate immunoregulatory transcriptional programs in KRAS-TP53 co-altered PDAC. Immune subtyping of KRAS-TP53 co-altered PDAC reveals conflation of intratumor heterogeneity with progenitor-like stemness properties. Coalescing these distinct molecular characteristics into a KRAS-TP53 co-altered "immunoregulatory program" predicts chemoresistance in metastatic PDAC patients enrolled in the COMPASS trial, as well as worse overall survival.

The Role of Perioperative Chemotherapy in the Management of Colloid Carcinoma of the Pancreas.

OBJECTIVES: Colloid carcinoma (CC) of the pancreas is associated with an improved prognosis compared with pancreatic ductal adenocarcinoma (PDAC), yet studies on the optimal management of these rare lesions are lacking. METHODS: Patients with CC or PDAC treated from 2004 to 2014 were identified in the National Cancer Database. Clinicopathologic characteristics were compared between groups and stratified by disease stage. Survival analysis evaluating the role of perioperative chemotherapy was performed. RESULTS: A total of 1295 CC patients (11%) and 10,855 PDAC patients (89%) were identified. Pancreatic ductal adenocarcinoma was associated with a higher likelihood of mortality compared with CC (hazard ratio, 1.35; 95% confidence interval, 1.25-1.45; P < 0.001). When stratifying by stage, perioperative chemoradiation improved overall survival in early stage (I/IIA) PDAC but had no effect in CC patients. However, for node-positive disease (stage IIB), median overall survival was improved with adjuvant chemoradiation for both CC patients (22 vs 13 months; P < 0.001) and PDAC patients (20 vs 11 months; P < 0.001) compared with surgery alone. CONCLUSIONS: Surgery alone may be sufficient for the management of node-negative (I/IIA) CC lesions in contrast to conventional PDAC, whereas CC patients with stage IIB disease have a survival benefit from perioperative chemoradiation.

Ras-p53 genomic cooperativity as a model to investigate mechanisms of innate immune regulation in gastrointestinal cancers.

Despite increasingly thorough mechanistic understanding of the dominant genetic drivers of gastrointestinal (GI) tumorigenesis (e.g., Ras/Raf, TP53, etc.), only a small proportion of these molecular alterations are therapeutically actionable. In an attempt to address this therapeutic impasse, our group has proposed an innovative extreme outlier model to identify novel cooperative molecular vulnerabilities in high-risk GI cancers which dictate prognosis, correlate with distinct patterns of metastasis, and define therapeutic sensitivity or resistance. Our model also proposes comprehensive investigation of their downstream transcriptomic, immunomic, metabolic, or upstream epigenomic cellular consequences to reveal novel therapeutic targets in previously "undruggable" tumors with high-risk genomic features. Leveraging this methodology, our and others' data reveal that the genomic cooperativity between Ras and p53 alterations is not only prognostically relevant in GI malignancy, but may also represent the incipient molecular events that initiate and sustain innate immunoregulatory signaling networks within the GI tumor microenvironment, driving T-cell exclusion and therapeutic resistance in these cancers. As such, deciphering the unique transcriptional programs encoded by Ras-p53 cooperativity that promote innate immune trafficking and chronic inflammatory tumor-stromal-immune crosstalk may uncover immunologic vulnerabilities that could be exploited to develop novel therapeutic strategies for these difficult-to-treat malignancies.

Revisiting the Surgical Infection Society Delphi Analysis of the Research Agenda in Surgical Infections: Advancements and Unanswered Questions.

Background: In 2006, the Surgical Infection Society (SIS) used a modified Delphi process to enlist SIS member-experts to identify 15 research priorities in the field of surgical infectious diseases; it was intended to serve as a research road map for the next one to two decades. We sought to evaluate the progress made in each of these priority areas. Hypothesis: We examined the progress achieved with respect to the 15 research areas identified by the Delphi process at that time, hypothesizing that advances in knowledge would be achieved in most domains, if not all. Methods: Surgical Infection Society members were surveyed to determine whether each priority area question had been satisfactorily answered in the last 14 years; to assess the quality of evidence answering each question (1-3 scale); and to delineate whether there is a current unmet need for continued research in each area. Randomized controlled trials (RCTs) regarding these initiatives were also identified via literature search and their citations in the literature were tabulated. Results: Sixty-six members of the SIS responded to the survey. Thirteen of 15 research priority areas saw an increase in data perceived to be available as adjudged by experts, as well an increase in the number of RCTs addressing that topic. However, there were only six questions that were deemed by experts to be answered sufficiently, primarily regarding antibiotic duration for certain conditions and the impact of glycemic control on infection. The questions that remained unanswered related to nosocomial infections, sepsis/septic shock, prevention of SSI, and antimicrobial pharmacokinetics. For a majority of the questions that experts believed were not answered sufficiently (8/9), respondents opined that continued research into these areas was warranted. Conclusion: Whereas 40% (6/15) of the research questions prioritized by the SIS in 2006 were answered to the satisfaction of member-experts, there are many questions that remain unanswered despite an increase of available data. Revisiting these research priorities highlights advancements made in the field of surgical infections, but also helps identify the areas that would benefit from continued study. That a majority of questions remain unanswered underscores an opportunity for member-experts to collaborate on SIS-managed or -endorsed RCTs.

Combined Blockade of MEK and CDK4/6 Pathways Induces Senescence to Improve Survival in Pancreatic Ductal Adenocarcinoma.

Activating KRAS mutations, a defining feature of pancreatic ductal adenocarcinoma (PDAC), promote tumor growth in part through the activation of cyclin-dependent kinases (CDK) that induce cell-cycle progression. p16INK4a (p16), encoded by the gene CDKN2A, is a potent inhibitor of CDK4/6 and serves as a critical checkpoint of cell proliferation. Mutations in and subsequent loss of the p16 gene occur in PDAC at a rate higher than that reported in any other tumor type and results in Rb inactivation and unrestricted cellular growth. Therefore, strategies targeting downstream RAS pathway effectors combined with CDK4/6 inhibition (CDK4/6i) may have the potential to improve outcomes in this disease. Herein, we show that expression of p16 is markedly reduced in PDAC tumors compared with normal pancreatic or pre-neoplastic tissues. Combined MEK inhibition (MEKi) and CDK4/6i results in sustained downregulation of both ERK and Rb phosphorylation and a significant reduction in cell proliferation compared with monotherapy in human PDAC cells. MEKi with CDK4/6i reduces tumor cell proliferation by promoting senescence-mediated growth arrest, independent of apoptosis in vitro We show that combined MEKi and CDK4/6i treatment attenuates tumor growth in xenograft models of PDAC and improves overall survival over 200% compared with treatment with vehicle or individual agents alone in Ptf1acre/+ ;LSL-KRASG12D/+ ;Tgfbr2flox/flox (PKT) mice. Histologic analysis of PKT tumor lysates reveal a significant decrease in markers of cell proliferation and an increase in senescence-associated markers without any significant change in apoptosis. These results demonstrate that combined targeting of both MEK and CDK4/6 represents a novel therapeutic strategy to synergistically reduce tumor growth through induction of cellular senescence in PDAC.

Targeting Tumor-Stromal IL6/STAT3 Signaling through IL1 Receptor Inhibition in Pancreatic Cancer.

A hallmark of pancreatic ductal adenocarcinoma (PDAC) is the presence of a dense, desmoplastic stroma and the consequent altered interactions between cancer cells and their surrounding tumor microenvironment (TME) that promote disease progression, metastasis, and chemoresistance. We have previously shown that IL6 secreted from pancreatic stellate cells (PSC) stimulates the activation of STAT3 signaling in tumor cells, an established mechanism of therapeutic resistance in PDAC. We have now identified the tumor cell-derived cytokine IL1α as an upstream mediator of IL6 release from PSCs that is involved in STAT3 activation within the TME. Herein, we show that IL1α is overexpressed in both murine and human PDAC tumors and engages with its cognate receptor IL1R1, which is strongly expressed on stromal cells. Further, we show that IL1R1 inhibition using anakinra (recombinant IL1 receptor antagonist) significantly reduces stromal-derived IL6, thereby suppressing IL6-dependent STAT3 activation in human PDAC cell lines. Anakinra treatment results in significant reduction in IL6 and activated STAT3 levels in pancreatic tumors from Ptf1aCre/+;LSL-KrasG12D/+; Tgfbr2flox/flox (PKT) mice. Additionally, the combination of anakinra with cytotoxic chemotherapy significantly extends overall survival compared with vehicle treatment or anakinra monotherapy in this aggressive genetic mouse model of PDAC. These data highlight the importance of IL1 in mediating tumor-stromal IL6/STAT3 cross-talk in the TME and provide a preclinical rationale for targeting IL1 signaling as a therapeutic strategy in PDAC.

Combined Src/EGFR Inhibition Targets STAT3 Signaling and Induces Stromal Remodeling to Improve Survival in Pancreatic Cancer.

Lack of durable response to cytotoxic chemotherapy is a major contributor to the dismal outcomes seen in pancreatic ductal adenocarcinoma (PDAC). Extensive tumor desmoplasia and poor vascular supply are two predominant characteristics which hinder the delivery of chemotherapeutic drugs into PDAC tumors and mediate resistance to therapy. Previously, we have shown that STAT3 is a key biomarker of therapeutic resistance to gemcitabine treatment in PDAC, which can be overcome by combined inhibition of the Src and EGFR pathways. Although it is well-established that concurrent EGFR and Src inhibition exert these antineoplastic properties through direct inhibition of mitogenic pathways in tumor cells, the influence of this combined therapy on stromal constituents in PDAC tumors remains unknown. In this study, we demonstrate in both orthotopic tumor xenograft and Ptf1acre/+;LSL-KrasG12D/+;Tgfbr2flox/flox (PKT) mouse models that concurrent EGFR and Src inhibition abrogates STAT3 activation, increases microvessel density, and prevents tissue fibrosis in vivo. Furthermore, the stromal changes induced by parallel EGFR and Src pathway inhibition resulted in improved overall survival in PKT mice when combined with gemcitabine. As a phase I clinical trial utilizing concurrent EGFR and Src inhibition with gemcitabine has recently concluded, these data provide timely translational insight into the novel mechanism of action of this regimen and expand our understanding into the phenomenon of stromal-mediated therapeutic resistance. IMPLICATIONS: These findings demonstrate that Src/EGFR inhibition targets STAT3, remodels the tumor stroma, and results in enhanced delivery of gemcitabine to improve overall survival in a mouse model of PDAC.

Bile Metabolism and Lithogenesis: An Update.

Bile is composed of multiple macromolecules, including bile acids, free cholesterol, phospholipids, bilirubin, and inorganic ions that aid in digestion, nutrient absorption, and disposal of the insoluble products of heme catabolism. The synthesis and release of bile acids is tightly controlled and dependent on feedback mechanisms that regulate enterohepatic circulation. Alterations in bile composition, impaired gallbladder relaxation, and accelerated nucleation are the principal mechanisms leading to biliary stone formation. Various physiologic conditions and disease states alter bile composition and metabolism, thus increasing the risk of developing gallstones.