Injectable Thermogelling Nanostructured Ink as Simultaneous Optical and Magnetic Resonance Imaging Contrast Agent for Image-Guided Surgery.

The development of efficient and biocompatible contrast agents is particularly urgent for modern clinical surgery. Nanostructured materials raised great interest as contrast agents for different imaging techniques, for which essential features are high contrasts, and in the case of precise clinical surgery, minimization of the signal spatial dispersion when embedded in biological tissues. This study deals with the development of a multimodal contrast agent based on an injectable hydrogel nanocomposite containing a lanthanide-activated layered double hydroxide coupled to a biocompatible dye (indocyanine green), emitting in the first biological window. This novel nanostructured thermogelling hydrogel behaves as an efficient tissue marker for optical and magnetic resonance imaging because the particular formulation strongly limits its spatial diffusion in biological tissue by exploiting a simple injection. The synergistic combination of these properties permits to employ the hydrogel ink simultaneously for both optical and magnetic resonance imaging, easy monitoring of the biological target, and, at the same time, increasing the spatial resolution during a clinical surgery. The biocompatibility and excellent performance as contrast agents are very promising for possible use in image-guided surgery, which is currently one of the most challenging topics in clinical research.

Autotaxin Secretion Is a Stromal Mechanism of Adaptive Resistance to TGFß Inhibition in Pancreatic Ductal Adenocarcinoma.

The TGFß receptor inhibitor galunisertib demonstrated efficacy in patients with pancreatic ductal adenocarcinoma (PDAC) in the randomized phase II H9H-MC-JBAJ study, which compared galunisertib plus the chemotherapeutic agent gemcitabine with gemcitabine alone. However, additional stromal paracrine signals might confer adaptive resistance that limits the efficacy of this therapeutic strategy. Here, we found that autotaxin, a secreted enzyme that promotes inflammation and fibrosis by generating lysophosphatidic acid (LPA), mediates adaptive resistance to TGFß receptor inhibition. Blocking TGFß signaling prompted the skewing of cancer-associated fibroblasts (CAF) toward an inflammatory (iCAF) phenotype. iCAFs were responsible for a significant secretion of autotaxin. Paracrine autotaxin increased LPA-NFκB signaling in tumor cells that triggered treatment resistance. The autotaxin inhibitor IOA-289 suppressed NFκB activation in PDAC cells and overcame resistance to galunisertib and gemcitabine. In immunocompetent orthotopic murine models, IOA-289 synergized with galunisertib in restoring sensitivity to gemcitabine. Most importantly, treatment with galunisertib significantly increased plasma levels of autotaxin in patients enrolled in the H9H-MC-JBAJ study, and median progression-free survival was significantly longer in patients without an increase of autotaxin upon treatment with galunisertib compared with those with increased autotaxin. These results establish that autotaxin secretion by CAFs is increased by TGFß inhibition and that circulating autotaxin levels predict response to the combination treatment approach of gemcitabine plus galunisertib. SIGNIFICANCE: TGFß inhibition skews cancer-associated fibroblasts toward an inflammatory phenotype that secretes autotaxin to drive adaptive resistance in PDAC, revealing autotaxin as a therapeutic target and biomarker of galunisertib response.

YAP Activation Is Associated with a Worse Prognosis of Poorly Cohesive Gastric Cancer.

Poorly cohesive (PC) gastric cancer (GC) is extremely aggressive in progression, and there is an urgent need to identify the molecular pathways involved. We hypothesized the essential role of the RhoA-YAP axis in these mechanisms. The present observational multicenter retrospective study included 133 patients with PC GC treated at two dedicated European surgical centers between 2004 and 2014. YAP nuclear localization was measured by immunohistochemical (IHC) analysis of tissue biopsies. The complete absence of nuclear reactivity was coded as negative expression; we considered "any positive" as low nuclear expression (>0% but <10% of cells) and high nuclear expression (≥10% of cells). Women represented about half of the present series (52%), and the median age was 64 years (p25-p75 range: 53-75). Neoadjuvant and adjuvant treatments were administered to 10% and 54% of the cases, respectively. Extended systemic lymphadenectomy (D2) was the most common (54%). In nearly all cases, the number of retrieved nodes was ≥15, i.e., adequate for tumor staging (94%). An R0 resection was achieved in 80% of the cases. Most patients were pathological T stage 3 and 4 (pT3/pT4 = 79.0%) and pathological N stage 2, 3a, and 3b (pN2/pN3a/pN3b = 47.0%) at the pathological examination. Twenty patients (15%) presented distant metastases. Five-year overall survival (OS) was significantly higher (p = 0.029) in patients with negative YAP (46%, 95% CI 31.1-60.0%) than in the other patients (27%, 17.5-38.1%). Moreover, when controlling for sex, age, pT, pN, and percentage of signet ring cells in the multivariable analysis, YAP expression was a significant predictor of OS (HR 2.03, 95% CI: 1.18-3.51, p = 0.011). Our results provide new insights into the role of the YAP signaling cascade, as its activation was associated with a worse prognosis in PC GC.

Targeting FGFR Pathway Is Not an Effective Therapeutic Strategy in Patients with Unselected Metastatic Esophagogastric Cancer Resistant to Trastuzumab.

Trastuzumab plus chemotherapy is the standard of care for the first-line treatment of patients with HER2+ advanced esophagogastric (EG) cancer. Nevertheless, patients frequently develop resistance. In preclinical models, we identified the overexpression of Fibroblast Growth Factor Receptor (FGFR) 3 as a mechanism potentially involved in trastuzumab-acquired resistance. FGFR inhibition could be a potential mechanism as a second-line treatment. In this Simon's two-stage phase 2, single arm study, patients with advanced EG cancer refractory to trastuzumab-containing therapies received pemigatinib, an inhibitor of FGFR. The primary end point was the 12-week progression-free survival rate. Translational analyses were performed on tissue and plasma samples. Eight patients were enrolled in the first stage. Although the 6-week disease control rate was 25%, only one patient achieved a stable disease after 12 weeks of treatment. The trial was discontinued before the second stage. Two out of six evaluable tumor samples expressed FGFR3. No FGFRs amplification was detected. HER2 amplification was lost in three out of eight patients. Three patients had an high Tumor Mutational Burden, and two of them are significantly long-term survivors. These results do not support the therapeutic efficacy of targeting FGFR in unselected patients with advanced EG cancer, who are refractory to trastuzumab-containing therapies.

p38 MAPK-dependent phosphorylation of transcription factor SOX2 promotes an adaptive response to BRAF inhibitors in melanoma cells.

Despite recent advances in the development of BRAF kinase inhibitors (BRAFi) for BRAF-mutant melanomas, development of resistance remains a major clinical problem. In addition to genetic alterations associated with intrinsic resistance, several adaptive response mechanisms are known to be rapidly activated to allow cell survival in response to treatment, limiting efficacy. A better understanding of the mechanisms driving resistance is urgently needed to improve the success of BRAF-targeted therapies and to make therapeutic intervention more durable. In this study, we identify the mitogen-activated protein kinase (MAPK) p38 as a novel mediator of the adaptive response of melanoma cells to BRAF-targeted therapy. Our findings demonstrate that BRAFi leads to an early increase in p38 activation, which promotes phosphorylation of the transcription factor SOX2 at Ser251, enhancing SOX2 stability, nuclear localization, and transcriptional activity. Furthermore, functional studies show that SOX2 depletion increases sensitivity of melanoma cells to BRAFi, whereas overexpression of a phosphomimetic SOX2-S251E mutant is sufficient to drive resistance and desensitize melanoma cells to BRAFi in vitro and in a zebrafish xenograft model. We also found that SOX2 phosphorylation at Ser251 confers resistance to BRAFi by binding to the promoter and increasing transcriptional activation of the ATP-binding cassette drug efflux transporter ABCG2. In summary, we unveil a p38/SOX2-mediated mechanism of adaptive response to BRAFi, which provides prosurvival signals to melanoma cells against the cytotoxic effects of BRAFi prior to acquiring resistance.

Predictive Biomarkers for a Personalized Approach in Resectable Pancreatic Cancer.

The mainstay treatment for patients with immediate resectable pancreatic cancer remains upfront surgery, which represents the only potentially curative strategy. Nevertheless, the majority of patients surgically resected for pancreatic cancer experiences disease relapse, even when a combination adjuvant therapy is offered. Therefore, aiming at improving disease free survival and overall survival of these patients, there is an increasing interest in evaluating the activity and efficacy of neoadjuvant and perioperative treatments. In this view, it is of utmost importance to find biomarkers able to select patients who may benefit from a preoperative therapy rather than upfront surgical resection. Defined genomic alterations and a dynamic inflammatory microenvironment are the major culprits for disease recurrence and resistance to chemotherapeutic treatments in pancreatic cancer patients. Signal transduction pathways or tumor immune microenvironment could predict early recurrence and response to chemotherapy. In the last decade, distinct molecular subtypes of pancreatic cancer have been described, laying the bases to a tailored therapeutic approach, started firstly in the treatment of advanced disease. Patients with homologous repair deficiency, in particular with mutant germline BRCA genes, represent the first subgroup demonstrating to benefit from specific therapies. A fraction of patients with pancreatic cancer could take advantage of genome sequencing with the aim of identifying possible targetable mutations. These genomic driven strategies could be even more relevant in a potentially curative setting. In this review, we outline putative predictive markers that could help in the next future in tailoring the best therapeutic strategy for pancreatic cancer patients with a potentially curable disease.

The Multifaceted Role of TGF-ß in Gastrointestinal Tumors.

Transforming growth factor-beta (TGF-ß) is a secreted cytokine that signals via serine/threonine kinase receptors and SMAD effectors. Although TGF-ß acts as a tumor suppressor during the early stages of tumorigenesis, it supports tumor progression in advanced stages. Indeed, TGF-ß can modulate the tumor microenvironment by modifying the extracellular matrix and by sustaining a paracrine interaction between neighboring cells. Due to its critical role in cancer development and progression, a wide range of molecules targeting the TGF-ß signaling pathway are currently under active clinical development in different diseases. Here, we focused on the role of TGF-ß in modulating different pathological processes with a particular emphasis on gastrointestinal tumors.

Targeting KRAS: The Elephant in the Room of Epithelial Cancers.

Mutations of the proto-oncogene KRAS are the most frequent gain-of-function alterations found in cancer. KRAS is mutated in about 30% of all human tumors, but it could reach more than 90% in certain cancer types such as pancreatic adenocarcinoma. Although historically considered to be undruggable, a particular KRAS mutation, the G12C variant, has recently emerged as an actionable alteration especially in non-small cell lung cancer (NSCLC). KRASG12C and pan-KRAS inhibitors are being tested in clinical trials and have recently shown promising activity. Due to the difficulties in direct targeting of KRAS, other approaches are being explored. The inhibition of target upstream activators or downstream effectors of KRAS pathway has shown to be moderately effective given the evidence of emerging mechanisms of resistance. Various synthetic lethal partners of KRAS have recently being identified and the inhibition of some of those might prove to be successful in the future. The study of escape mechanisms to KRAS inhibition could support the utility of combination strategies in overcoming intrinsic and adaptive resistance and enhancing clinical benefit of KRASG12C inhibitors. Considering the role of the microenvironment in influencing tumor initiation and promotion, the immune tumor niche of KRAS mutant tumors has been deeply explored and characterized for its unique immunosuppressive skewing. However, a number of aspects remains to be fully understood, and modulating this tumor niche might revert the immunoresistance of KRAS mutant tumors. Synergistic associations of KRASG12C and immune checkpoint inhibitors are being tested.

Plasma IL8 Is a Biomarker for TAK1 Activation and Predicts Resistance to Nanoliposomal Irinotecan in Patients with Gemcitabine-Refractory Pancreatic Cancer.

PURPOSE: Pancreatic cancer is one of the most lethal solid tumors, mainly because of its intrinsic chemoresistance. We identified TAK1 as a central hub sustaining this resistance. Nanoliposomal irinotecan (nal-IRI) is a novel treatment for metastatic gemcitabine-refractory pancreatic cancer. We endeavored to identify circulating markers for TAK1 activation predicting chemoresistance in this setting. EXPERIMENTAL DESIGN: In vivo activity of nal-IRI was validated in an orthotopic nude murine model expressing TAK1-specific shRNA. Plasma concentration of 20 different cytokines were measured by a multiplex xMAP/Luminex technology in patients prospectively enrolled to receive nal-IRI plus 5-fluorouracil/leucovorin (5-FU/LV). The optimal cutoff thresholds able to significantly predict patients' outcome were obtained on the basis of the maximization of the Youden's statistics. RESULTS: Differential expression profiling revealed the gene coding for IL8 as the most significantly downregulated in shTAK1 pancreatic cancer cell lines. Mice bearing shTAK1 tumors had significantly lower plasma levels of IL8 and experienced a significant reduction in tumor growth if treated with nal-IRI, whereas those bearing TAK1-proficient tumors were resistant to this agent. In a discovery cohort of 77 patients, IL8 was the circulating factor most significantly correlated with survival (plasma levels lower vs higher than cutoff: mPFS 3.4 months vs 2.8 months; hazard ratio [HR], 2.55; 95% CI, 1.39-4.67; P = 0.0017; median overall survival 8.9 months vs 5.3 months; HR, 3.51; 95% CI, 0.84-6.68; P = 4.9e-05). These results were confirmed in a validation cohort of 50 patients. CONCLUSIONS: Our study identified IL8 as the most significant circulating factor for TAK1 pathway activation and candidates IL8 as a potential predictive biomarker of resistance to nal-IRI in gemcitabine-refractory patients with pancreatic cancer.