Chemoradiotherapy for unresectable pancreatic cancer

ATG4B Inhibitor UAMC-2526 Potentiates the Chemotherapeutic Effect of Gemcitabine in a Panc02 Mouse Model of Pancreatic Ductal Adenocarcinoma

Resistance against anti-cancer therapy is one of the major challenges during treatment of multiple cancers. Gemcitabine is a standard first-line chemotherapeutic drug, yet autophagy is highly activated in the hypoxic microenvironment of solid tumors and enhances the survival of tumor cells against gemcitabine chemotherapy. Recently, we showed the add-on effect of autophagy inhibitor UAMC-2526 to prevent HT-29 colorectal tumor growth in CD1^-/- Foxn1nu mice treated with oxaliplatin. In this study, we aimed to investigate the potential beneficial effects of UAMC-2526 in a syngeneic Panc02 mouse model of pancreatic ductal adenocarcinoma (PDAC). Our data showed that UAMC-2526 combined with gemcitabine significantly reduced tumor growth as compared to the individual treatments. However, in contrast to in vitro experiments with Panc02 cells in culture, we were unable to detect autophagy inhibition by UAMC-2526 in Panc02 tumor tissue, neither via western blot analysis of autophagy markers LC3 and p62, nor by transmission electron microscopy. In vitro experiments revealed that UAMC-2526 enhances the potential of gemcitabine to inhibit Panc02 cell proliferation without obvious induction of cell death. Altogether, we conclude that although the combination treatment of UAMC-2526 with gemcitabine did not inhibit autophagy in the Panc02 mouse model, it has a beneficial effect on tumor growth inhibition.

Effectiveness and feasibility of concurrent chemoradiotherapy using simultaneous integrated boost-intensity modulated radiotherapy with and without induction chemotherapy for locally advanced pancreatic cancer

Purpose

To evaluate the effectiveness and feasibility of chemoradiotherapy (CRT) using simultaneous integrated boost-intensity modulated radiotherapy (SIB-IMRT) in locally advanced pancreatic cancer (LAPC) patients.

Materials and Methods

Between January 2011 and May 2015, 47 LAPC patients received CRT using SIB-IMRT. Prior to SIB-IMRT, 37 patients (78.7%) received induction chemotherapy (IC-CRT group) and remaining 10 patients (21.3%) did not received induction chemotherapy (CRT group). During SIB-IMRT, all patients received concomitant chemotherapy, with gemcitabine (n = 37) and capecitabine (n = 10).

Results

At the time of analysis, 45 patients had died and 2 patients remained alive and the median follow-up time was 14.2 months (range, 3.3 to 51.4 months). For all patients, the median times of local progression-free survival (LPFS), progression-free survival (PFS), and overall survival (OS) were 18.1, 10.3, and 14.2 months, respectively. The median time of LPFS between IC-CRT and CRT groups was similar (18.1 months vs. 18.3 months, p = 0.711). IC-CRT group had a higher trend in PFS (10.9 months vs. 4.1 months, p = 0.054) and had significantly higher OS (15.4 months vs. 9.5 months, p = 0.007) than CRT group. In multivariate analysis, the use of induction chemotherapy and tumor response were significant factors associated with OS (p < 0.05, each). During SIBIMRT, toxicity of grade ≥3 was observed in 7 patients (14.9%) in all patients.

Conclusions

CRT using SIB-IMRT is feasible and promising in LAPC patients.

Matrine suppresses KRAS-driven pancreatic cancer growth by inhibiting autophagy-mediated energy metabolism

Matrine is a natural compound extracted from the herb Sophora flavescens Ait which is widely used in traditional Chinese medicine for treating various diseases. Recently, matrine was reported to have antitumor effects against a variety of cancers without any obvious side effects; however, the molecular mechanisms of its antiproliferative effects on cancer are unclear. Here, we report that matrine inhibits autophagy-mediated energy metabolism, which is necessary for pancreatic cancer growth. We found that matrine significantly reduces pancreatic cancer growth in vitro and in vivo by insufficiently maintaining mitochondrial metabolic function and energy level. We also found that either pyruvate or α-ketoglutarate supplementation markedly rescues pancreatic cancer cell growth following matrine treatment. Inhibition of mitochondrial energy production results from matrine-mediated autophagy inhibition by impairing the function of lysosomal protease. Matrine-mediated autophagy inhibition requires stat3 downregulation. Furthermore, we found that the antitumor effect of matrine on pancreatic cancer growth depends on the mutation of the KRAS oncogene. Together, our data suggest that matrine can suppress the growth of KRAS-mutant pancreatic cancer by inhibiting autophagy-mediated energy metabolism.

Autophagy is required for PDAC glutamine metabolism

Macroautophagy (autophagy) is believed to maintain energy homeostasis by degrading unnecessary cellular components and molecules. Its implication in regulating cancer metabolism recently started to be uncovered. However, the precise roles of autophagy in cancer metabolism are still unclear. Here, we show that autophagy plays a critical role in glutamine metabolism, which is required for tumor survival. Pancreatic ductal adenocarcinoma (PDAC) cells require both autophagy and typical glutamine transporters to maintain intracellular glutamine levels. Glutamine deprivation, but not that of glucose, led to the activation of macropinocytosis-associated autophagy through TFEB induction and translocation into the nucleus. In contrast, glutamine uptake increased as a compensatory response to decreased intracellular glutamine levels upon autophagy inhibition. Moreover, autophagy inhibition and glutamine deprivation did not induce cell death, while glutamine deprivation dramatically activated apoptotic cell death upon autophagy inhibition. Interestingly, the addition of α-ketoglutarate significantly rescued the apoptotic cell death caused by the combination of the inhibition of autophagy with glutamine deprivation. Our data suggest that macropinocytosis-associated autophagy is a critical process providing glutamine for anaplerosis of the TCA cycle in PDAC. Thus, targeting both autophagy and glutamine metabolism to completely block glutamine supply may provide new therapeutic approaches to treat refractory tumors.

Gene expression disorders of innate antibacterial signaling pathway in pancreatic cancer patients: implications for leukocyte dysfunction and tumor progression

The study was carried out to investigate changes in gene expression of innate antibacterial signaling pathways in patients with pancreatic cancer. Expression of the following genes was measured in peripheral blood leukocytes of 55 patients with pancreatic adenocarcinoma using real-time polymerase chain reaction (RT-PCR): TLR4, NOD1, MyD88, TRAF6 and HMGB1. The levels of expression of TLR4, NOD1 and TRAF6 genes were significantly elevated (p = 0.007; p = 0.001 and p = 0.01, respectively), while MyD88 expression was markedly reduced (p = 0.0002), as compared to controls. Expression of TLR4 and NOD1 exceeded the normal level more than 3.5-fold and there was a significant correlation found between the expression of these genes (r = 0.558, p < 0.001). TLR4, NOD1 and MyD88 genes were expressed at a similar level both before and after surgery. No significant changes in the expression of HMGB1 gene were observed. The results of the study clearly indicate abnormal expression of genes belonging to innate antibacterial signaling pathways in peripheral blood leukocytes of patients with pancreatic cancer, which may lead to leukocyte dysfunction. Overexpression of TLR4, NOD1 and TRAF6 genes, and decreased MyD88 gene expression may contribute to chronic inflammation and tumor progression by up-regulation of the innate antibacterial response. The parameters tested are useful for monitoring innate immunity gene disorders and pancreatic cancer progression.

Radiosensitization of Pancreatic Cancer Cells In Vitro and In Vivo through Poly (ADP-ribose) Polymerase Inhibition with ABT-888

OBJECTIVES

To determine whether poly (ADP-ribose) polymerase-1/2 (PARP-1/2) inhibition enhances radiation-induced cytotoxicity of pancreatic adenocarcinoma in vitro and in vivo, and the mechanism by which this occurs.

METHODS

Pancreatic carcinoma cells were treated with ABT-888, radiation, or both. In vitro cell viability, apoptosis, and PARP activity were measured. Orthotopic xenografts were generated in athymic mice and treated with ABT-888 (25mg/kg), radiation (5Gy), both, or no treatment. Mice were monitored with bioluminescence imaging.

RESULTS

In vitro, treatment with ABT-888 and radiation led to higher rates of cell death after 8days (P < .01). Co-treatment with 5Gy and 1, 10 or 100μmol/l of ABT-888 led to dose enhancement factors of 1.29, 1.41 and 2.36, respectively. Caspase activity was not significantly increased when treated with ABT-888 (10 μmol/l) alone (1.28-fold, P = .08), but became significant when radiation was added (2.03-fold, P < .01). PARP activity increased post-radiation and was abrogated following co-treatment with ABT-888. In vivo, treatment with ABT-888, radiation or both led to tumor growth inhibition (TGI) of 8, 30 and 39days, and survival at 60days of 0%, 0% and 40%, respectively.

CONCLUSIONS

ABT-888 with radiation significantly enhanced tumor response in vitro and in vivo. ABT-888 inhibited PAR protein polymerization resulting in dose-dependent feedback up-regulation of PARP and p-ATM suggesting increased DNA damage. This translated into enhancement in TGI and survival with radiation in vivo. In vitro PAR levels correlated with levels of tumor apoptosis suggesting potential as a predictive biomarker. These data are being used to support a Phase I study in locally advanced pancreatic cancer.

Autophagy is needed for the growth of pancreatic adenocarcinoma and has a cytoprotective effect against anticancer drugs

BACKGROUND AND AIM

Autophagy is a regulated process of degradation and recycling of cellular constituents. The role of autophagy in pancreatic cancer is still not clear. Some studies indicate that in pancreatic cancer autophagy exerts cytoprotective effects, whereas others suggest that autophagy positively contributes to cell death by enhancing cytotoxicity of anticancer drugs. The aim of this study was to investigate the role of autophagy in pancreatic cancer, and to provide insights into new strategies for treatment.

MATERIALS AND METHODS

Pancreatic cancer cell lines PANC-1 and BxPC-3 were treated with anticancer drugs (5-fluorouracil or gemcitabine) alone and in combination with autophagy inhibitors (chloroquine or wortmannin). Biopsy samples were retrieved from patients from pancreatic normal tissue and adenocarcinoma. Western blot of microtubule-associated protein 1 light chain 3 (LC3)-II was performed to investigate the degree of autophagy and cell proliferation was assessed by a crystal violet assay.

RESULTS

Autophagy was active in PANC-1 cells under basal conditions. Autophagy was significantly induced in pancreatic ductal adenocarcinoma compared to healthy pancreatic tissue in patients. Inhibition of autophagy by chloroquine suppressed the growth of PANC-1 and BxPC-3. Autophagy was markedly increased after treatment with 5-fluorouracil or gemcitabine. Inhibition of autophagy by chloroquine potentiated the inhibition of cell proliferation of PANC-1 and BxPC-3 by 5-fluorouracil and gemcitabine.

CONCLUSIONS

Our results with pancreatic cancer cell lines and human pancreatic adenocarcinoma suggest that autophagy contributes to pancreatic cancer cell growth. Autophagy has a cytoprotective effect against 5-fluorouracil and gemcitabine in pancreatic cancer cells. Combination therapy of these anticancer drugs and chloroquine should be investigated.

Aberrant glycogen synthase kinase 3β in the development of pancreatic cancer

Development and progression of pancreatic cancer involves general metabolic disorder, local chronic inflammation, and multistep activation of distinct oncogenic molecular pathways. These pathologic processes result in a highly invasive and metastatic tumor phenotype that is a major obstacle to curative surgical intervention, infusional gemcitabine-based chemotherapy, and radiation therapy. Many clinical trials with chemical compounds and therapeutic antibodies targeting growth factors, angiogenic factors, and matrix metalloproteinases have failed to demonstrate definitive therapeutic benefits to refractory pancreatic cancer patients. Glycogen synthase kinase 3β (GSK3β), a serine/threonine protein kinase, has emerged as a therapeutic target in common chronic and progressive diseases, including cancer. Here we review accumulating evidence for a pathologic role of GSK3β in promoting tumor cell survival, proliferation, invasion, and resistance to chemotherapy and radiation in pancreatic cancer. We also discuss the putative involvement of GSK3β in mediating metabolic disorder, local inflammation, and molecular alteration leading to pancreatic cancer development. Taken together, we highlight potential therapeutic as well as preventive effects of GSK3β inhibition in pancreatic cancer.

Radiation dose ≥54 Gy and CA 19-9 response are associated with improved survival for unresectable, non-metastatic pancreatic cancer treated with chemoradiation

BACKGROUND

Unresectable pancreatic cancer (UPC) has low survival. With improving staging techniques and systemic therapy, local control in patients without metastatic disease may have increasing importance. We investigated whether the radiation dose used in chemoradiation (CRT) as definitive treatment for UPC and the CA 19-9 response to therapy have an impact on overall survival (OS).

METHODS

From 1997-2009 46 patients were treated with CRT for non-metastatic UPC. Median prescribed RT dose was 54 Gy (range 50.4-59.4 Gy). All patients received concurrent chemotherapy (41: 5-fluorouracil, 5: other) and 24 received adjuvant chemotherapy.

RESULTS

41 patients were inoperable due to T4 disease and 5 patients with T3 disease were medically inoperable. Five patients did not complete CRT due to progressive disease or treatment-related toxicity (median RT dose 43.2 Gy). Overall, 42 patients were dead of disease at the time of last follow-up. The median and 12 month OS were 8.8 months and 35%, respectively. By univariate analysis, minimum CA 19-9 post-CRT <90 U/mL was favorably associated with OS (12.3 versus 8.8 months, p = 0.012). Radiotherapy dose ≥54 Gy trended towards improved OS (11.3 versus 6.8 months, p = 0.089). By multivariable analysis, a delivered RT dose of ≥54 Gy (HR 0.47, p = 0.028) and minimum CA 19-9 post-CRT of <90 U/mL (HR 0.35, p = 0.008) were associated with OS.

CONCLUSIONS

CRT as definitive treatment for UPC had low survival. However, our retrospective data suggest that patients treated to ≥54 Gy or observed to have a minimum post-CRT CA 19-9 <90 U/mL had improved likelihood of long-term survival.

Inhibition of non-homologous end joining repair impairs pancreatic cancer growth and enhances radiation response

Pancreatic ductal adenocarcinoma (PDAC) is amongst the deadliest of human cancers, due to its late diagnosis as well as its intense resistance to currently available therapeutics. To identify mechanisms as to why PDAC are refractory to DNA damaging cytoxic chemotherapy and radiation, we performed a global interrogation of the DNA damage response of PDAC. We find that PDAC cells generally harbor high levels of spontaneous DNA damage. Inhibition of Non-Homologous End Joining (NHEJ) repair either pharmacologically or by RNAi resulted in a further accumulation of DNA damage, inhibition of growth, and ultimately apoptosis even in the absence of exogenous DNA damaging agents. In response to radiation, PDAC cells rely on the NHEJ pathway to rapidly repair DNA double strand breaks. Mechanistically, when NHEJ is inhibited there is a compensatory increase in Homologous Recombination (HR). Despite this upregulation of HR, DNA damage persists and cells are significantly more sensitive to radiation. Together, these findings support the incorporation of NHEJ inhibition into PDAC therapeutic approaches, either alone, or in combination with DNA damaging therapies such as radiation.

Is celiac axis resection justified for T4 pancreatic body cancer?

BACKGROUND

The clinical impact of the distal pancreatectomy with en-bloc celiac axis resection for locally advanced pancreatic body cancer remains unclear.

METHODS

We reviewed the records of 13 patients who underwent distal pancreatectomy-celiac axis resection between 1991 and 2009, 58 patients who underwent distal pancreatectomy for pancreatic body cancer involving major vessels, the extrapancreatic neural plexus or other organs (T4 according to the Japanese stage classification) between 1991 and 2009, and 24 patients with unresectable locally advanced pancreatic cancer without distant metastases (unresectable group) between 2001 and 2009. The clinicopathologic factors and overall survival among the 3 groups were compared.

RESULTS

The distal pancreatectomy-celiac axis resection group was associated with a significantly higher incidence of morbidity (92% vs 60%, P = .03) and positive surgical margins (69% vs 26%, P = .003) than the distal pancreatectomy group; however, no survival difference was found between the 2 groups. No survivor has lived more than 3 years after operation in the distal pancreatectomy-celiac axis resection group. The distal pancreatectomy-celiac axis resection group had a significantly better prognosis than the unresectable group (median survival time, 20.8 vs 9.8 months; P = .01).

CONCLUSION

Aggressive resection for T4 pancreatic body cancer by distal pancreatectomy-celiac axis resection can be justified for otherwise unresectable tumors. The surgical indication should be evaluated carefully because of the higher incidence of morbidity and lower incidence of curability compared with distal pancreatectomy, as well as because there have been no long-term survivors so far.

Increased organ sparing using shape-based treatment plan optimization for intensity modulated radiation therapy of pancreatic adenocarcinoma

PURPOSE

To develop a model to assess the quality of an IMRT treatment plan using data of prior patients with pancreatic adenocarcinoma.

METHODS

The dose to an organ at risk (OAR) depends in large part on its orientation and distance to the planning target volume (PTV). A database of 33 previously treated patients with pancreatic cancer was queried to find patients with less favorable PTV-OAR configuration than a new case. The minimal achieved dose among the selected patients should also be achievable for the OAR of the new case. This way the achievable doses to the OARs of 25 randomly selected pancreas cancer patients were predicted. The patients were replanned to verify if the predicted dose could be achieved. The new plans were compared to their original clinical plans.

RESULTS

The predicted doses were achieved within 1 and 2 Gy for more than 82% and 94% of the patients, respectively, and were a good approximation of the minimal achievable doses. The improvement after replanning was 1.4 Gy (range 0-4.6 Gy) and 1.7 Gy (range 0-6.3 Gy) for the mean dose to the liver and the kidneys, respectively, without compromising target coverage or increasing radiation dose to the bowel, cord or stomach.

CONCLUSIONS

The model could accurately predict the achievable doses, leading to a considerable decrease in dose to the OARs and an increase in treatment planning efficiency.

Pancreatic cancers require autophagy for tumor growth

Macroautophagy (autophagy) is a regulated catabolic pathway to degrade cellular organelles and macromolecules. The role of autophagy in cancer is complex and may differ depending on tumor type or context. Here we show that pancreatic cancers have a distinct dependence on autophagy. Pancreatic cancer primary tumors and cell lines show elevated autophagy under basal conditions. Genetic or pharmacologic inhibition of autophagy leads to increased reactive oxygen species, elevated DNA damage, and a metabolic defect leading to decreased mitochondrial oxidative phosphorylation. Together, these ultimately result in significant growth suppression of pancreatic cancer cells in vitro. Most importantly, inhibition of autophagy by genetic means or chloroquine treatment leads to robust tumor regression and prolonged survival in pancreatic cancer xenografts and genetic mouse models. These results suggest that, unlike in other cancers where autophagy inhibition may synergize with chemotherapy or targeted agents by preventing the up-regulation of autophagy as a reactive survival mechanism, autophagy is actually required for tumorigenic growth of pancreatic cancers de novo, and drugs that inactivate this process may have a unique clinical utility in treating pancreatic cancers and other malignancies with a similar dependence on autophagy. As chloroquine and its derivatives are potent inhibitors of autophagy and have been used safely in human patients for decades for a variety of purposes, these results are immediately translatable to the treatment of pancreatic cancer patients, and provide a much needed, novel vantage point of attack.

Metabolic disorder, inflammation, and deregulated molecular pathways converging in pancreatic cancer development: implications for new therapeutic strategies

Pancreatic cancer develops and progresses through complex, cumulative biological processes involving metabolic disorder, local inflammation, and deregulated molecular pathways. The resulting tumor aggressiveness hampers surgical intervention and renders pancreatic cancer resistant to standard chemotherapy and radiation therapy. Based on these pathologic properties, several therapeutic strategies are being developed to reverse refractory pancreatic cancer. Here, we outline molecular targeting therapies, which are primarily directed against growth factor receptor-type tyrosine kinases deregulated in tumors, but have failed to improve the survival of pancreatic cancer patients. Glycogen synthase kinase-3β (GSK3β) is a member of a serine/threonine protein kinase family that plays a critical role in various cellular pathways. GSK3β has also emerged as a mediator of pathological states, including glucose intolerance, inflammation, and various cancers (e.g., pancreatic cancer). We review recent studies that demonstrate the anti-tumor effects of GSK3β inhibition alone or in combination with chemotherapy and radiation. GSK3β inhibition may exert indirect anti-tumor actions in pancreatic cancer by modulating metabolic disorder and inflammation.

Clinical impact of radiotherapy for locally advanced pancreatic cancer

BACKGROUND

Although a randomized controlled trial for locally advanced pancreatic cancer (PC) has demonstrated a survival advantage for treatment with gemcitabine alone, chemoradiotherapy remains the treatment of choice for locally advanced disease in Japan. The aim of this study was to compare the survival benefits associated with gemcitabine and concurrent chemoradiotherapy in locally advanced unresectable PC.

PATIENTS

Seventy-seven patients with locally advanced unresectable PC were retrospectively enrolled from April 2001 to December 2006. All cases were histologically proven, and patients received gemcitabine chemotherapy (n = 30) or concurrent chemoradiotherapy (based on 5-fluorouracil, n = 28, or gemcitabine, n = 19, as a radiosensitizer) at Aichi Cancer Center Hospital.

RESULTS

Patients who received chemoradiotherapy had significantly better performance status than those who had chemotherapy. Tumor response was 0% for chemotherapy and 13% chemoradiotherapy, but survival benefit was similar among patients in the chemotherapy group (overall response (OS) 12 months; progression-free survival (PFS), 3 months) and those in the chemoradiotherapy group (OS, 13 months; PFS, 5 months). Two-year survival was 21% for chemotherapy patients and 19% for chemoradiotherapy patients. Severe toxicities (Grade 3-4 National Cancer Institute-Common Toxicity Criteria, version 3.0) were significantly more frequent for chemoradiotherapy than for chemotherapy.

CONCLUSIONS

Gemcitabine chemotherapy showed similar survival benefit compared to 5-fluorouracil- and gemcitabine-based chemoradiotherapy.