Predictive Signatures Inform the Effective Repurposing of Decitabine to Treat KRAS-Dependent Pancreatic Ductal Adenocarcinoma

Mutated KRAS protein is a pivotal tumor driver in pancreatic cancer. However, despite comprehensive efforts, effective therapeutics that can target oncogenic KRAS are still under investigation or awaiting clinical approval. Using a specific KRAS-dependent gene signature, we implemented a computer-assisted inspection of a drug-gene network to in silico repurpose drugs that work like inhibitors of oncogenic KRAS. We identified and validated decitabine, an FDA-approved drug, as a potent inhibitor of growth in pancreatic cancer cells and patient-derived xenograft models that showed KRAS dependency. Mechanistically, decitabine efficacy was linked to KRAS-driven dependency on nucleotide metabolism and its ability to specifically impair pyrimidine biosynthesis in KRAS-dependent tumors cells. These findings also showed that gene signatures related to KRAS dependency might be prospectively used to inform on decitabine sensitivity in a selected subset of patients with KRAS-mutated pancreatic cancer. Overall, the repurposing of decitabine emerged as an intriguing option for treating pancreatic tumors that are addicted to mutant KRAS, thus offering opportunities for improving the arsenal of therapeutics for this extremely deadly disease. SIGNIFICANCE: Decitabine is a promising drug for cancer cells dependent on RAS signaling.

Abstract 2627: Inhibition of TGFβ in colorectal cancer cells is associated with a compensatory activation of AXL and p38 MAPK signaling pathways

According to the consensus molecular subtypes (CMS), almost 23% of human colorectal cancer (CRC) are classified in the CMS4 group, characterized by a mesenchymal signature and the activation of transforming growth factor β (TGF-β) signaling. AXL is a tyrosine kinase receptor involved in epithelial to mesenchymal transition, angiogenesis and immune modulation in CRC. We have previously demonstrated that AXL gene is amplified in approximately 5% of human CRC, and that AXL inhibition causes a significant blockade of CRC cell proliferation and migration. Here we have evaluated the role of TGF-β signaling and the potential interaction between TGF-β and AXL in human CRC cell lines. We assessed the expression and activation of TGF-β and AXL in a panel of six human CRC cell lines by western blot (WB) and real time PCR. We tested the sensitivity of HCT116 and LOVO cells to treatment with galunisertib ( LY21209761), a selective TGF-β R1 inhibitor, by MTT, cell invasion, wound healing and soft-agar colony forming assays. Further, intracellular CRC cell signaling was evaluated following galunisertib treatment by WB. TGF-β receptors 1 and 2 were expressed in all human CRC cell lines (HCT116, SW480, LOVO, LIM 1215, SW48 and CaCo2), whereas AXL expression was restricted to HCT116, SW480, LOVO cells. Treatment with galunisertib had little or no effect on cancer cell growth, whereas it partially reduced TGF-β induced cell migration, invasion and colony formation in HCT116 and LOVO cells (that co-expressed both TGF-β receptors and AXL). Interestingly, TGF-β inhibition resulted in a concomitant significant activation of AXL and p38 MAPK in both cell lines, that could represent a cancer cell adaptive mechanism of resistance to galunisertib treatment. These results suggest a potential functional cross talk between TGF-β, AXL and p38 MAPK signals in human CRC cells. In this respect, further experiments are ongoing to better understand this interaction with the aim of identifying potential novel anti-AXL and anti-TGF-β therapeutic strategies.

Citation Format: Davide Ciardiello, Pietro Paolo Vitiello, Nunzia Matrone, Valentina Belli, Claudia Cardone, Luca Poliero, Carola Borrelli, Gianluca Arrichiello, Giulia Martini, Vincenza Ciaramella, Giusi Barra, Floriana Morgillo, Teresa Troiani, Davide Melisi, Fortunato Ciardiello, Erika Martinelli. Inhibition of TGFβ in colorectal cancer cells is associated with a compensatory activation of AXL and p38 MAPK signaling pathways [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2627.

Abstract 295: Synergism between oxaliplatin or irinotecan with the PARP inhibitor niraparib in a preclinical model of KRAS/BRAF mutated colorectal cancer is associated with MSI status

DNA damage response (DDR) is crucial in a variety of tumors and several new drugs that interfere with this mechanism are already available or in advanced clinical testing. RAS-MAPK pathway activation, induced by either RAS or BRAF mutation, is a frequent feature of colorectal cancers (CRCs) and is strongly associated to mitotic stress and dependency upon DDR. Among the drugs used for CRC, oxaliplatin and irinotecan are known to induce DNA damage in form of single or double strand breaks (SSB/DSBs) and thus require active DDR systems in cancer cells to be tolerated. The poly-ADP-Ribose Polymerase (PARP) inhibitor Niraparib (MK-4827) is an FDA-approved orally bioavailable drug with strong PARP1-trapping activity, a feature ofted associated with synergism in combination with platinum salts, while synergism with other DNA damaging agents is independent of the PARP1-trapping activity. We tested the activity of niraparib used in combination with oxaliplatin or irinotecan (in the form of its active metabolite SN38) in a panel of 8 KRAS or BRAF mutated CRC cell lines (LOVO, HCT15, SW1116, LS1034, SW948, WiDr, SW480, HCT116) with different microsatellite and CIMP status. Combination index (CI) analysis was performed in order to evaluate the synergism between niraparib and the chemotherapeutics. Cell cycle distribution and apoptosis assays were performed in order to further characterize the effects of the combinations.

The combination between niraparib and oxaliplatin resulted synergistic in 6 out of 8 cell lines, with strong synergism (CI < 0,5) in 2 cell lines, while the combination between niraparib and irinotecan (SN38) resulted synergistic in 7 out of 8 cell lines, with strong synergism in 5 cell lines and very strong synergism (CI < 0,1) in 3 cell lines. Interestingly, the only non-synergistic cell line to the combination with irinotecan is also non-synergistic to the combination with oxaliplatin; on the other hand, the cell lines that exhibit strong synergism to the combination with irinotecan do not present strong synergism to the combination with oxaliplatin and vice versa. Moreover, all the microsatellite instable (MSI) cell lines tested resulted synergistic for the two combinations. Finally, the synergistic combinations showed an increased induction of apoptosis and cell cycle arrest compared to non-synergistic combinations.

Taken together, these data investigate the combination between the PARP inhibitor niraparib and the antiproliferative agents oxaliplatin and irinotecan in KRAS/BRAF mutated CRC cell lines, showing how MSI status predicts good synergism with the drug combinations, while MSS status is not a good predictor of synergism. Further studies are needed to identify better predictive biomarker beyond MSI status, in order to optimize the use of these combinations for future development.

Citation Format: Pietro Paolo Vitiello, Davide Ciardiello, Claudia Cardone, Giulia Martini, Valentina Belli, Nunzia Matrone, Luca Poliero, Carola Borrelli, Pasquale Vitale, Nicoletta Zanaletti, Teresa Troiani, Davide Melisi, Fortunato Ciardiello, Erika Martinelli. Synergism between oxaliplatin or irinotecan with the PARP inhibitor niraparib in a preclinical model of KRAS/BRAF mutated colorectal cancer is associated with MSI status [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 295.

A phase Ib dose-escalation and cohort-expansion study of safety and activity of the transforming growth factor (TGF) β receptor I kinase inhibitor galunisertib plus the anti-PD-L1 antibody durvalumab in metastatic pancreatic cancer

4124

Background: Pancreatic cancer (PC) is characterized by a highly immunosuppressive microenvironment, and immune checkpoint inhibitors as monotherapy have been ineffective to date. TGFβ is commonly viewed as a powerful immunosuppressive cytokine, and inhibition of its signaling reverses this suppression and activates adaptive immune responses. A combination of TGFβ and PD-L1 inhibition may act synergistically to induce immune restoration and to improve antitumor responses. This Phase 1b study (NCT02734160) evaluated the combination of galunisertib plus durvalumab in recurrent or refractory metastatic PC. Methods: Eligible patients (pts) were ≥18 years old, had ECOG status ≤1, and had not received treatment with anti-PD-1, anti-PD-L1, or TGFβ R1 kinase inhibitors. The primary objective was to assess the safety and the recommended dose of galunisertib given 14 days on/14 days off in combination with durvalumab 1500 mg every 4 weeks. Four dose levels of galunisertib were tested in the dose escalation portion of the study: 50 mg QD, 50 mg BID, 80 mg BID and 150 mg BID, followed by the cohort expansion portion of the study at the recommended Phase 2 dose (RP2D). Secondary objectives included preliminary assessment of activity by response rate, (RECIST v1.1), median PFS (mPFS), and OS (mOS). Results: 42 pts (25F/17M) were treated in the study (median age 56.5 y; 71.4% had received ≥2 prior systemic regimens). There was no dose limiting toxicity and galunisertib 150 mg BID was chosen as the RP2D. In the 32 pts treated at this dose, Grade ≥3 related AEs included AST and GGT elevations (2 pts each), and ALT and alkaline phosphatase elevations, and neutropenia (1 pt each). One partial response and 7/32 stable diseases were observed (disease control rate 25%); mPFS was 1.9 months (95% CI: 1.5, 2.2) and mOS was NR (95% CI: 3.6, NR). Biomarker data will be presented at the meeting. Conclusions: The combination of galunisertib plus durvalumab had an acceptable tolerability and safety profile. The activity of this combination in second and third line PC patients warrants further consideration. Clinical trial information: NCT02734160.

Adjuvant chemotherapy is associated with improved postoperative survival in specific subtypes of invasive intraductal papillary mucinous neoplasms (IPMN) of the pancreas: it is time for randomized controlled data

BACKGROUND

Very little is known about adjuvant chemotherapy for invasive Intraductal Papillary Mucinous Neoplasms (IPMNs) of the pancreas. The aim was to assess whether adjuvant chemotherapy affects survival.

METHODS

Retrospective evaluation of invasive IPMNs. Patients treated with surgery alone or followed by adjuvant chemotherapy were compared in terms of survival.

RESULTS

A total of 102 invasive IPMNs were analyzed. Median follow-up was 72 (5-318) months and 18.6% received adjuvant chemotherapy. Overall, recurrence rate was 40.2%, while 5-year overall survival and disease specific survival (DSS) were 65.3% and 69.4%, respectively. N1 disease (HR5.58, CI95% 2.49-12.51, p < 0.01), tubular type (HR2.35, CI95% 1.71-4.82, p = 0.05) and G3 tumors (HR4.54, CI95% 2.12-15.49, <0.01) were predictors of reduced DSS. Overall, there was no difference in the 5-year DSS comparing patients treated with adjuvant chemotherapy to surgery alone (61.8 vs. 69.4%, p = 0.8). Adjuvant chemotherapy significantly improved DSS only in N1 (5-years-DSS 76 vs. 35.8%, p = 0.01) and tubular carcinomas (5-years-DSS 88.9 vs. 53%, p = 0.03).

CONCLUSIONS

Adjuvant therapy improves survival only in invasive IPMNs with nodal disease or tubular differentiation. Future trials are needed to improve the level of evidence about adjuvant chemotherapy.

TGFβ receptor inhibitor galunisertib is linked to inflammation- and remodeling-related proteins in patients with pancreatic cancer

PURPOSE

Galunisertib, the first small molecule transforming growth factor beta (TGFβ) receptor inhibitor, plus gemcitabine resulted in the improvement of survival in patients with unresectable pancreatic cancer, but markers to identify patients likely to respond are lacking.

METHODS

In the Phase 1b/2 JBAJ study, 156 patients were randomized 2:1 to galunisertib + gemcitabine (N = 104) or placebo + gemcitabine (N = 52). Clinical outcome data were integrated with baseline markers and pharmacodynamic markers while patients were on treatment, including circulating proteins using a multi-analyte panel, T cell subset evaluation, and miRNA profiling.

RESULTS

Baseline biomarkers associated with overall prognosis regardless of treatment included CA19-9 and TGF-β1. In addition, IP-10, FSH, MIP-1α, and PAI-1 were potential predictive proteins. Baseline proteins that were changed during treatment included amphiregulin, CA15-3, cathepsin D, P-selectin, RAGE, sortilin, COMP, eotaxin-2, N-BNP, osteopontin, and thrombospondin-4. Plasma miRNA with potential prognostic value included miR-21-5p, miR-301a-3p, miR-210-3p, and miR-141-3p, while those with potential predictive value included miR-424-5p, miR-483-3p, and miR-10b-5p.

CONCLUSIONS

Galunisertib + gemcitabine resulted in improvement of overall survival, and 4 proteins (IP-10, FSH, MIP-1α, PAI-1) were potentially predictive for this combination treatment. Future studies should also include baseline evaluation of miR-424-5p, miR-483-3p, and miR-10b-5p.

TRIAL REGISTRATION

Clinicaltrials.gov NCT01373164.

Trial design for a phase 3 study evaluating pemigatinib (INCB054828) versus gemcitabine plus cisplatin chemotherapy in first-line treatment of patients with cholangiocarcinoma with FGFR2 rearrangement

TPS462

Background: Dysregulation of fibroblast growth factor receptor (FGFR) signaling by FGFR genetic alterations is implicated in many cancers, including cholangiocarcinoma (CCA). FGFR2 translocations with fusion partners occur in ≈10% to 20% of intrahepatic CCA tumors. Pemigatinib is a selective oral inhibitor of FGFR-1, 2, 3. Preliminary data from the ongoing phase 2 study show efficacy and tolerable safety in patients (pts) with CCA with FGFR2 translocations. We present the design for a phase 3, open-label, randomized trial investigating pemigatinib monotherapy versus gemcitabine plus cisplatin chemotherapy in the first-line treatment of pts with advanced/metastatic or unresectable CCA with FGFR2 rearrangement. Methods: Eligible pts (target, N = 432) are ≥ 18 years (≥ 20 years for Japanese pts) and have ECOG performance status ≤ 1 and histologically confirmed advanced (locally advanced, metastatic, or recurrent) CCA with a documented FGFR2 rearrangement. Key exclusion criteria include prior systemic therapy, excluding adjuvant/neoadjuvant treatment completed ≥ 6 months before enrollment; current evidence of clinically significant corneal or retinal disorder; history of calcium and phosphate homeostasis disorder or systemic mineral imbalance with ectopic calcification of soft tissues; and known, untreated CNS metastases or history of uncontrolled seizures. Pts are randomized 1:1 and stratified by geographic region and tumor burden into 2 treatment groups: pemigatinib starting dose 13.5 mg once daily continuously on a 3-week cycle; or gemcitabine (1000 mg/m2) and cisplatin (25 mg/m2) administered intravenously on days 1 and 8 of every 3-week cycle for up to 8 cycles until disease progression or unacceptable toxicity. Crossover to pemigatinib may be allowed once progressive disease is confirmed. The primary endpoint is progression-free survival (based on independent central review using RECIST v1.1). Secondary endpoints include overall response rate, overall survival, duration of response, disease control rate, safety and tolerability, and impact on quality of life. Clinical trial information: NCT03656536.

Second-line treatment efficacy and toxicity in older vs. non-older patients with advanced gastric cancer: A multicentre real-world study

OBJECTIVES

Although gastric cancer (GC) incidence rises with age, older patients are poorly represented in clinical trials, whose results are therefore difficult to translate into standard management of older patients. Purpose of this study was to compare clinico-pathological features and survival outcomes between older and non-older patients with advanced GC treated with at least two chemotherapy lines.

MATERIALS AND METHODS

Clinico-pathological characteristics, basal values, and treatment data of older (≥70 years at second-line start) and non-older patients were compared using chi-square test or 2-tailed Fisher exact test. The Kaplan-Meier estimation was used to calculate progression-free survival (PFS) and overall survival (OS), which were examined by log-rank test.

RESULTS

Older patients represented 31.8% of the population (N = 868). Intestinal type was more frequent in older patients (P = .02). Poorly differentiated tumours were more often observed in non-older patients (P = .009). At stage IV diagnosis, the rate of liver metastases was higher in older patients (P = .02), while peritoneal spread was more represented in non-older patients (P = .002). Although older patients were more often treated with monotherapy (P = .001), they had similar PFS (HR 0.86, 95%CI 0.71-1.03, P = .102) and OS (HR 0.82, 95%CI 0.65-1.02, P = .08) compared to the non-older counterpart. No statistical differences were observed in treatment-related adverse events, hospital admissions, or further treatment lines between age groups.

CONCLUSION

In our large cohort study, despite some differences in tumour characteristics and treatment intensity, no survival difference was found between older and non-older patients with advanced GC treated with at least two chemotherapy lines. Incidence of adverse events was similar between age groups.

Induction of immunosuppressive functions and NF-κB by FLIP in monocytes

Immunosuppression is a hallmark of tumor progression, and treatments that inhibit or deplete monocytic myeloid-derived suppressive cells could promote anti-tumor immunity. c-FLIP is a central regulator of caspase-8-mediated apoptosis and necroptosis. Here we show that low-dose cytotoxic chemotherapy agents cause apoptosis linked to c-FLIP down-regulation selectively in monocytes. Enforced expression of c-FLIP or viral FLIP rescues monocytes from cytotoxicity and concurrently induces potent immunosuppressive activity, in T cell cultures and in vivo models of tumor progression and immunotherapy. FLIP-transduced human blood monocytes can suppress graft versus host disease. Neither expression of FLIP in granulocytes nor expression of other anti-apoptotic genes in monocytes conferred immunosuppression, suggesting that FLIP effects on immunosuppression are specific to monocytic lineage and distinct from death inhibition. Mechanistically, FLIP controls a broad transcriptional program, partially by NF-κB activation. Therefore, modulation of FLIP in monocytes offers a means to elicit or block immunosuppressive myeloid cells.

Signaling and transcriptional regulation of MDSC activity remains largely undefined. Here the authors show that monocytic MDSC immunosuppression is triggered by c-FLIP and requires NFκB, implicate this axis in cancer prognosis and response to therapy, and employ ectopic FLIP to treat immunopathology.

Quality of life in metastatic pancreatic cancer patients receiving liposomal irinotecan plus 5-fluorouracil and leucovorin

BACKGROUND

The NAPOLI-1 study (NCT01494506) reported that liposomal irinotecan plus 5-fluorouracil and leucovorin (nal-IRI+5-FU/LV) improved overall survival vs 5-FU/LV with manageable toxicity in patients with metastatic pancreatic adenocarcinoma previously treated with gemcitabine-based therapy. Yet, clinicians need treatment strategies that also maintain the patient's health-related quality of life (HRQOL). Here, we report the HRQOL data.

METHODS

Patients completed the European Organisation for Research and Treatment of Cancer QOL core questionnaire C30 (EORTC QLQ-C30) at baseline, every 6 weeks, and at 30 days after discontinuation of study treatment. Patient-reported outcomes (PROs) were scored according to EORTC guidelines. nal-IRI+5-FU/LV HRQOL was compared with 5-FU/LV. The PRO population comprised intent-to-treat patients who completed baseline and at least one subsequent assessment on the EORTC QLQ-C30. Data were also analysed for missingness.

RESULTS

Of 236 patients in the intent-to-treat population, 128 (54.2%) comprised the PRO population (71 in the nal-IRI+5-FU/LV arm; 57 the in 5-FU/LV arm). Of the remaining 108 patients (45.8%) not included in the PRO population, most progressed rapidly, making participation difficult. Median change from baseline was ≤10 points at weeks 6 and 12 in global health status or functional and symptom scale scores, except for fatigue, which deteriorated by 11.1 points with nal-IRI+5-FU/LV but did not change vs 5-FU/LV. The proportion of patients whose HRQOL improved or deteriorated was not significantly different between the arms.

CONCLUSION

In the NAPOLI-1 study, HRQOL was maintained with nal-IRI+5-FU/LV in patients with metastatic pancreatic adenocarcinoma previously treated with a gemcitabine-based regimen, while survival was significantly extended.

Galunisertib plus gemcitabine vs. gemcitabine for first-line treatment of patients with unresectable pancreatic cancer

Background

Galunisertib is the first-in-class, first-in-human, oral small-molecule type I transforming growth factor-beta receptor (ALK5) serine/threonine kinase inhibitor to enter clinical development. The effect of galunisertib vs. placebo in patients with unresectable pancreatic cancer was determined.

Methods

This was a two-part, multinational study: phase 1b was a non-randomised, open-label, multicentre, and dose-escalation study; phase 2 was a randomised, placebo- and Bayesian-augmented controlled, double-blind study in patients with locally advanced or metastatic pancreatic adenocarcinoma considered candidates for first-line chemotherapy with gemcitabine. Patients were randomised 2:1 to galunisertib–gemcitabine (N = 104) or placebo-gemcitabine (N = 52). Gemcitabine dose was 1000 mg/m² QW. Primary endpoints for phases 1b and 2, respectively, were phase 2 dose and overall survival. Secondary objectives included tolerability and biomarkers.

Results

Dose-escalation suggested a 300-mg/day dose. Primary objective was met: median survival times were 8.9 and 7.1 months for galunisertib and placebo, respectively (hazard ratio [HR] = 0.79 [95% credible interval: 0.59–1.09] and posterior probability HR < 1 = 0.93). Lower baseline biomarkers macrophage inflammatory protein-1-alpha and interferon-gamma-induced protein 10 were associated with galunisertib benefit.

Conclusions

Galunisertib–gemcitabine combination improved overall survival vs. gemcitabine in patients with unresectable pancreatic cancer, with minimal added toxicity. Future exploration of galunisertib in pancreatic cancer is ongoing in combination with durvalumab.

CT Texture Analysis of Ductal Adenocarcinoma Downstaged After Chemotherapy

BACKGROUND/AIM

Re-staging of ductal adenocarcinoma using computed tomography (CT) scan can be problematic so new imaging techniques and evaluation parameters are required. The aim of the study was to evaluate the added value of CT texture analysis in estimation of tissue changes in ductal adenocarcinoma downsized and resected after chemotherapy.

MATERIALS AND METHODS

Patients with ductal adenocarcinoma downstaged after neoadjuvant treatment, and resected, were included. A pre- and post-treatment CT was obtained. In comparison, patients with disease progression were included for texture analysis evaluation at CT pre- and post-treatment. CT texture analysis results were compared.

RESULTS

A total of 17 patients affected by un-resectable or borderline ductal adenocarcinoma reached the resectable stage after treatment. The comparison between Kurtosis pre- and Kurtosis post-treatment showed a statistically significant difference. On the contrary, in the comparison group composed of 14 patients with disease progression there was no statistical difference regarding this parameter.

CONCLUSION

This evaluation may represent an added value in tumor tissue changes judgment and can be extremely useful to diagnose downstaging in those cases with no evident downsizing after chemotherapy.

Abstract 3339: Modulating TAK1 expression through the inhibition of GSK3 impairs YAP/TAZ oncogenic functions in pancreatic cancer

Background: Resistance to chemotherapeutic drugs poses one of the greatest challenges in pancreatic cancer (PC) treatment. TGFβ-activated kinase 1 (TAK1) has been demonstrated to drive chemoresistance in PC through the phosphorylation-dependent activation of the NF-κB transcription factor. The transcriptional regulators Yes Associated Protein (YAP) and transcriptional coactivator with a PDZ binding domain (TAZ) are central determinants of malignancy and have been identified as a critical oncogenic effectors of KRAS in PC. We hypothesized that TAK1 could drive PC aggressiveness by sustaining YAP and TAZ oncogenic activities.

Methods: TAK1 expression was silenced by shRNA in AsPC1, Panc1, and MDA-Panc28 cell lines. GSK3 was targeted by using the small molecule inhibitor LY2090314. The expression of TAK1, YAP/TAZ and their target genes in PC cell lines was studied by both Western blot and qPCR. Cell migration was assessed by transwell assays, and stemness by both spheroid formation and percentage of cancer stem cells (CSC). SRB assays were used to assess the in vitro chemopotentiation of nab-paclitaxel, gemcitabine, oxaliplatin, and SN-38. In vivo activity of LY2090314 alone or in combination with nab-paclitaxel was evaluated in an orthotopic nude mouse model with luciferase-expressing AsPC1 tumors. Expression of YAP/TAZ target genes in tumor samples was measured by both qPCR and IHC.

Results: knockdown of TAK1 resulted in inhibition of K48-linked ubiquitination and proteasomal degradation of YAP and TAZ, which was independent on TAK1 kinase activity. Significant reduction of proliferation, migration and chemoresistance of shTAK1 PC cell lines was also observed. Treatment with LY2090314 induced silencing of TAK1, as well as a remarkable reduction of the expression of both YAP and TAZ and their targets. In combination, the GSK3 inhibitor strongly potentiated the cytotoxic activities of chemotherapeutic agents in all three PC cell lines. In nude mice, i.p. admnistration of LY2090314 plus nab-paclitaxel significantly reduced tumor burden.

Conclusions: Our study identified GSK3 and TAK1 as major modulators of YAP and TAZ stability and oncogenic activities, thus indicating that inhibition of TAK1 expression by modulating GSK3 activity could represent a valid approach to revert in vivo the intrinsic chemoresistance of PC.

Citation Format: Raffaela Santoro, Marco Zanotto, Geny Piro, Carmine Carbone, Giampaolo Tortora, Davide Melisi. Modulating TAK1 expression through the inhibition of GSK3 impairs YAP/TAZ oncogenic functions in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3339.

Abstract 3501: Adipocytes sustain pancreatic cancer progression through a non-canonical WNT paracrine network inducing ROR2 nuclear shuttling

Background: Solid epidemiological evidences connect obesity with incidence, stage, and survival in pancreatic cancer. However, the underlying mechanistic basis linking adipocytes to pancreatic cancer progression remain largely elusive. We hypothesized that factors secreted by adipocytes could be responsible for epithelial-to-mesenchymal transition (EMT) induction and, in turn, a more aggressive phenotype in models of pancreatic preneoplastic lesions.

Methods: We studied the role of factors secreted by two adipogenic model systems from primary human Bone Marrow Stromal Cells (hBMSC) in an in vitro experimental cell transformation model system of human pancreatic ductal epithelial (HPDE) cell stably expressing activated KRAS (HPDE/KRAS).

Results: We measured a significant induction of EMT and aggressiveness in HPDE and HPDE/KRAS cell lines when cultured with medium conditioned by fully differentiated adipocytes (ADIPOCM) if compared with the same cells cultured with medium conditioned by hBMSC (hBMSCCM) from two different healthy donors. Several genes coding for soluble modulators of the non-canonical WNT signaling pathway, including FRZB, SFRP2, RSPO1, WNT5A and 5B were significantly overexpressed in fully differentiated adipocytes than in their respective in hBMSC. ADIPOCM induced the overexpression and the nuclear translocation of the Frizzled family member Receptor tyrosine kinase-like orphan receptor (Ror) 2 in HPDE and HPDE/KRAS cells. Vantictumab, an anti-Frizzled monoclonal antibody, reduced ROR2 nuclear translocation and in turn the EMT and aggressiveness in HPDE and HPDE/KRAS cells.

Conclusions: We demonstrated that adipocytes could induce EMT and aggressiveness in models of pancreatic preneoplastic lesions by orchestrating a complex paracrine signaling of soluble modulators of the non-canonical WNT signaling pathway that determine, in turn, the activation and nuclear translocation of ROR2. This signaling pathway could represent a novel target for pancreatic cancer chemoprevention. Most importantly, these factors could serve as novel biomarkers to

select a risk population among obese subjects for screening and, thus, early diagnosis of pancreatic cancer.

Citation Format: Carmine Carbone, Geny Piro, Raffaela Santoro, Francesca Simionato, Valeria Merz, Camilla Zecchetto, Aldo Scarpa, Giampaolo Tortora, Davide Melisi. Adipocytes sustain pancreatic cancer progression through a non-canonical WNT paracrine network inducing ROR2 nuclear shuttling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3501.

MEKK3 Sustains EMT and Stemness in Pancreatic Cancer by Regulating YAP and TAZ Transcriptional Activity

BACKGROUND/AIM

Pancreatic cancer is one of the most threatening and poorly understood human malignancies. MEKK3 (MAP3K3) is a serine/threonine kinase activated by different signaling pathways. YAP and TAZ are critical oncogenic effectors in pancreatic cancer. We hypothesized that MEKK3 could sustain pancreatic cancer by inducing YAP/TAZ oncogenic activities.

MATERIALS AND METHODS

In Panc1 and AsPC1 pancreatic cancer cell lines MEKK3 was knocked-out (KO) by the CRISPR/Cas9 method. These cells were used to evaluate MEKK3 contribution to the expression of YAP/TAZ and their target genes, cell migration, stemness, and in vivo tumor growth.

RESULTS

MEKK3 KO reduced both EMT and cell migration, the size of 3D colonies and the percentage of CD44⁺/CD24⁺/EpCAM⁺ CSC, promoter recruitment of YAP/TAZ and the expression of their target genes. It reduced tumor growth and prolonged mice overall survival.

CONCLUSION

Silencing of MEKK3 represents a valid approach to revert in vivo the aggressiveness of pancreatic cancer by modulating YAP/TAZ transcriptional activities.

Predictive biomarkers for the treatment of resectable esophageal and esophago-gastric junction adenocarcinoma: from hypothesis generation to clinical validation

INTRODUCTION

Esophageal and esophago-gastric junction (EGJ) adenocarcinomas remain a major health problem worldwide with a worryingly increasing incidence. Recent trials indicate survivals benefit for preoperative or perioperative chemoradiotherapy compared to surgery alone. Beside standard chemoradiotherapy regimens, new therapeutic approaches with targeted therapies have been proposed for the treatment of resectable disease. However, clinical outcomes remain extremely poor due to drug resistance phenomena. The failure of these approaches could be partially ascribed to their incorrect application in patients. Therefore, the identification of strong biomarkers for optimal patient management is urgently needed. Areas covered: This review aims to summarize and critically discuss the most relevant findings regarding predictive biomarker development for neoadjuvant treatment of resectable esophageal and esophago-gastric junction adenocarcinoma patients. Expert commentary: Optimizing the currently available therapeutic modalities through a more accurate selection of patients may avoid the use of ineffective and potentially toxic treatments. During the last decade, the advent of high-throughput '-omics' technologies has set the basis for a new biomarker discovery approach from 'molecule by molecule' screening towards a large-scale systematic screening process with exponential increases in putative biomarkers, which often failed to provide adequate clinical validation.

The curious case of Gαs gain-of-function in neoplasia

BACKGROUND

Mutations activating the α subunit of heterotrimeric Gs protein are associated with a number of highly specific pathological molecular phenotypes. One of the best characterized is the McCune Albright syndrome. The disease presents with an increased incidence of neoplasias in specific tissues.

MAIN BODY

A similar repertoire of neoplasms can develop whether mutations occur spontaneously in somatic tissues during fetal development or after birth. Glands are the most "permissive" tissues, recently found to include the entire gastrointestinal tract. High frequency of activating Gαs mutations is associated with precise diagnoses (e.g., IPMN, Pyloric gland adenoma, pituitary toxic adenoma). Typically, most neoplastic lesions, from thyroid to pancreas, remain well differentiated but may be a precursor to aggressive cancer.

CONCLUSIONS

Here we propose the possibility that gain-of-function mutations of Gαs interfere with signals in the microenvironment of permissive tissues and lead to a transversal neoplastic phenotype.

Peroxiredoxin-2: A Novel Regulator of Iron Homeostasis in Ineffective Erythropoiesis

AIMS

Iron overload (IO) is a life-threatening complication of chronic hemolytic disorders such as β-thalassemia. IO results in severe cellular oxidative damage, leading to organ failure. Peroxiredoxin-2 (Prx2), a typical 2-cysteine-(Cys)-peroxiredoxin, is an important component of the cytoprotective system, but its response to IO is still to be fully defined.

RESULTS

We studied the effects of IO on Prx2-knockout mice (Prx2^-/-). The absence of Prx2 enhanced toxicity due to IO on erythropoiesis. We found that IO failed to induce the typical hepcidin (Hamp) upregulation in Prx2^-/- mice due to its failure to activate the signal transducer and activator of transcription-3 (STAT3) with intact Jak2 signaling. In Prx2^-/- mice, the loss of Hamp response was also observed after administration of a single dose of oral iron. When lipopolysaccharide (LPS) was used to explore IL6-STAT3 activation in Prx2^-/- mice, STAT3 activation and Hamp upregulation were once again defective. Treatment with PEP-fusion-recombinant-Prx2 (PEP Prx2) significantly increased STAT3 activation with upregulation of Hamp expression in both IO- and LPS-exposed Prx2^-/- mice. We also confirmed the beneficial effects of PEP Prx2 on Hamp expression through STAT3 activation in β-thalassemic mice.

INNOVATION

We propose that Prx2 plays a key role in responding to cytotoxicity of IO, directly targeting STAT3-transcriptional factor in a Jak2-independent fashion and regulating Hamp in response to canonical stimuli.

CONCLUSION

Collectively, our data highlight a novel role of Prx2 in iron homeostasis. Prx2 is a key cytoprotector against IO that is induced either by iron supplementation or due to chronic hemolysis as in β-thalassemia. Prx2 is required to support STAT3 transcriptional activity and regulation of Hamp expression. Antioxid. Redox Signal. 28, 1-14.