Gemcitabine (G) is standard therapy for pancreatic cancer. Enzastaurin (E) inhibits PKCβ and PI3K/AKT signaling pathways with a dose-dependent effect on growth of pancreatic carcinoma xenografts. Data suggest that the GE combination may improve clinical outcomes.
Primary objective was overall survival (OS); secondary objectives assessed progression-free survival (PFS), response rate (RR), quality of life (QOL), toxicity, and relationships between biomarker expression and clinical outcomes. Patients were randomly assigned (2:1) to GE or G treatment; GE arm: E 500 mg p.o. daily; loading-dose (1200 mg; Day 1 Cycle 1 only) and G 1000 mg/m(2) i.v. Days 1, 8, and 15 in 28-day cycles; G arm: G as in GE. Biomarker expression was assessed by immunohistochemistry.
Randomization totaled 130 patients (GE = 86, G = 44); 121 patients were treated (GE = 82, G = 39). GE/G median OS was 5.6/5.1 months; median PFS was 3.4/3.0 months. GE responses: 1 complete response (CR, 1.2%), 6 partial response (PR, 7.4%), and 33 stable disease (SD, 40.7%); disease control rate (DCR=CR+PR+SD, 49.4%). G responses: 2 PR (5.3%) and 16 SD (42.1%); DCR (47.4%). No QOL differences were noted between arms. GE/G Grade 3-4 toxicities included: neutropenia (18.3%/28.2%); thrombocytopenia (14.6%/25.6%); and fatigue (11.0%/7.7%). No statistically significant relationships between biomarker expression and outcomes were observed. However, patients with low expression of cytoplasmic pGSK-3β trended toward greater OS with GE treatment.
OS, PFS, QOL, and RR were comparable between arms. Adding E to G did not increase hematologic toxicities. GE does not warrant further investigation in unselected pancreatic cancer patients.
"Clinical experience with inhibitors of the PI3K/Akt pathway in PDAC is mostly limited to mTOR or AKT inhibitors. Everolimus and enzastaurin failed to demonstrate significant clinical activity when tested in gemcitabine-refractory (Wolpin et al., 2009) or advanced PDAC (Richards et al., 2011), respectively. "
"This finding emphasises the general importance of defining critical molecular markers that are associated with a potential resistance towards novel targeted therapy compounds, because otherwise it might lead to the treatment of patients that, by their molecular condition, are unable to respond to the novel drug. In fact, this might be one of the explanations as to why initial clinical trials with Enz that were not associated with parallel translational molecular studies at the resected tumour tissue of treated patients, led to initial contradictory results (Casey et al, 2009; Richards et al, 2009; Kreisl et al, 2010; Wick et al, 2010). However, with our results we might give an additional encouragement for the initiation of more tailored-therapy clinical studies, in which putatively essential molecular markers associated with response or resistance are being measured before the decision for a certain combination of therapies in the individual patient. "
[Show abstract][Hide abstract] ABSTRACT: Enzastaurin (Enz) is a serine/threonine kinase inhibitor blocking protein kinase C (PKC)beta/AKT pathway. However, an ability of this compound to inhibit cancer invasion and metastasis is not yet clearly elucidated.
The ability of Enz to inhibit invasion and metastasis, and to target molecules was investigated in non-small cell lung cancer (NSCLC) by RT-PCR validated microarray, Matrigel, and in vivo chorionallantoic membrane (CAM) assays.
Enzastaurin significantly reduced migration, invasion, and in vivo metastasis to lungs and liver (CAM assay) of diverse NSCLC cell lines. Genes promoting cancer progression (u-PAR, VEGFC, and HIF1alpha) and tumour suppression (VHL, RASSF1, and FHIT) of NSCLC were significantly (P<0.05) down- or upregulated after Enz treatment in H460, A549, and H1299 cells, respectively. Luciferase/chromatin immunoprecipitation analysis showed that Enz transcriptionally controls urokinase-type plasminogen activator receptor (u-PAR) expression by promoter inhibition through Sp1, Sp3, and c-Jun(AP-1). Moreover, siRNA knockdown of u-PAR re-sensitised Enz-resistant cells and induced apoptosis, suggesting u-PAR as a marker of Enz resistance.
This study shows that Enz inhibits migration, invasion, and in vivo metastasis by targeting u-PAR, besides further targeting progression-related and tumour-suppressor genes in NSCLC. Together with u-PAR being a novel putative marker of Enz response, these data encourage molecularly tailored clinical studies on Enz in NSCLC therapy.
British Journal of Cancer 09/2010; 103(6):802-11. DOI:10.1038/sj.bjc.6605818 · 4.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer related mortality in the United States. The prognosis of patients with PDAC is extremely poor with a median survival of 6 months, in part due to the advanced stage at the time of diagnosis and early metastatic spread. A considerable body of evidence points to the involvement of the tyrosine kinase and serine/threonine kinase pathways as major effectors in pancreatic cancer development and as potential targets for intervention. These pathways regulate multiple cellular processes including cell growth, proliferation, migration, invasion and resistance to apoptosis. The relatively recent introduction of novel therapies targeting tyrosine kinase and serine/threonine kinase pathways have yielded dramatic results in certain hematological malignancies, and have resulted in significant advances in our ability to treat patients with melanoma, breast, lung and colon cancer, thereby leading to improved survival and quality of life. Unfortunately, similar therapeutic improvements have not occurred in PDAC. Thus, despite encouraging phase I/II studies, the vast majority of phase-III studies have failed to demonstrate improved efficacy in PDAC. This review will provide an overview on the different kinase signaling pathways in PDAC and the supporting data on targeted therapies available from pre-clinical and clinical studies.
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